Display-integrated type tablet device

Claim 2

A display-integrated type tablet device as claimed in claim 1, wherein the shift data feed path switching circuit (13) is so arranged that it switches the shift data feed path to the parallel mode side for the display period while it switches the path to the serial mode side for the coordinate detection period, whereby the one side drive circuit (2U) and the other side drive circuit (2L) are driven in parallel during the display period to display an image simultaneously onto the one side half region and the other side half region of the display panel (1w) while the one side drive circuit (2U) and the other side drive circuit (2L) are driven in series during the coordinate detection period to scan the one side half region of the display panel (1w) and successively scan the other half region of the display panel (1w).

Claim 3

A display-integrated type tablet device as claimed in claim 1, wherein the one side drive circuit (2U) having a shift register is the one side common drive circuit (2U) while the other side drive circuit (2L) having a shift register is the other side common drive circuit (2L); the shift data feed path switching circuit (13) is a multiplexer (13); a shift data output terminal (DIO₂U) of the shift register of the one side common drive circuit (2U) is connected to one input terminal (A) of the multiplexer (13) and a shift data input terminal (DIO₁U) of the shift register of the one side common drive circuit (2U) is connected to the other input terminal (B) of the multiplexer (13) while a shift data input terminal (DIO₁L) of the shift register of the other side common drive circuit (2L) is connected to an output terminal (Y) of the multiplexer (13).

Claim 4

A display-integrated type tablet device as claimed in claim 1, wherein the drive circuit (2U, 2L) composed of the one side drive circuit (2U) and the other side drive circuit (2L) respectively having shift registers is the common drive circuit, the common drive circuit having an odd number of shift registers (LSI₁, LSI₂, LSI₃) connected in series; the shift data feed path switching circuit is a shift register (LSI₂) located at the center of the odd number of shift registers that the common drive circuit has; the shift register (LSI₂) located at the center having a first input terminal (DIO₁), through which shift data is inputted to the head of the shift register, and a second input terminal (DMIN), through which shift data is interruptively inputted to the center of the shift register, and so arranged as to control allowance or disallowance of interruptive input from the second input terminal (DMIN) depending on an external control signal, whereby during the parallel mode, interruptive input from the second input terminal (DMIN) of the shift register (LST₂) located at the center is allowed by the control signal to input shift data simultaneously into the head of the shift register at one end of the shift register row that the common drive circuit has and into the second input terminal (DMIN) of the shift register (LSI₂) located at the center, so that the one side common drive circuit having the one side half of the shift register row and the other side common drive circuit having the other side half of the shift register row are driven in parallel, while during the serial mode, interruptive input from the second input terminal (DMIN) of the shift register is inhibited by the control signal to input shift data only into the head of the shift register at the one end of the shift register row, so that the one side common drive circuit (2U) and the other side common drive circuit (2L) are driven in series.

Claim 5

A display-integrated type tablet device as claimed in claim 1, wherein the pulse width of the shift data in the coordinate detection period is made wider than the cycle of transfer clocks for the shift register.

Claim 6

A display-integrated type tablet device as claimed in claim 1, wherein at least one drive circuit of the segment drive circuit and the common drive circuit is arranged so as to effect electrode scanning a plurality of times during the one-time coordinate detection period.

Claim 7

A display-integrated type tablet device as claimed in claim 6, wherein either of the segment electrodes (XU, XL) or the common electrodes (Y), whichever farther from the detection pen (8), are scanned a plurality of times.

Claim 8

A display-integrated type tablet device having: a display panel (1w), in which display-use material is sandwiched between segment electrodes (XU, XL) and common electrodes (Y), orthogonally crossing each other, and which is driven by a duty-type drive method; a detection pen (8) having at its tip an electrode to be electrostatically coupled with the segment electrodes (XU, XL) and the common electrodes (Y) of the display panel (1w); a segment drive circuit (3U, 3L) for driving the segment electrodes (XU, XL); a common drive circuit (2U, 2L, 2D) for driving the common electrodes (Y); a display control circuit (6) for controlling the segment drive circuit (3U, 3L) and the common drive circuit (2U, 2L, 2D) during a display period to display an image onto the display panel (1w); a detection control circuit (6) for controlling the segment drive circuit (3U, 3L) during a coordinate detection period to successively scan the segment electrodes (3U, 3L) of the display panel (1w) while controlling the common drive circuit (2U, 2L, 2D) to successively scan the common electrodes (Y); an x-coordinate detection circuit (10) for detecting the x-coordinate on the display panel (1w) specified by the tip of the detection pen (8) from both the timing at which an output signal from the detection pen (8) is generated and the timing at which the segment electrodes (XU, XL) are scanned; and a y-coordinate detection circuit (11) for detecting the y-coordinate on the display panel (1w) specified by the tip of the detection pen (8) from both the timing at which an output signal from the detection pen (8) is generated and the timing at which the common electrodes (Y) are scanned, wherein the segment electrodes (XU, XL) are divided into two, one side segment electrodes (XU) belonging to one half region on one side of the display panel (1w) and the other side segment electrodes (XL) belonging to the other half region on the other side opposite to the aforementioned one side; the common electrodes (Y) are divided into two, one side common electrodes (Y₁, Y₂, Y₃, Y₄) belonging to one half region on one side of the display panel (1w) and the other side common electrodes (Y₅, Y₆, Y₇, Y₈) belonging to the other side half region opposite to the aforementioned one side; at least one of the segment drive circuit and the common drive circuit is composed of a one side drive circuit (3U) for driving the one side electrodes and the other side drive circuit (3L) for driving the other side electrodes; the drive circuit (2U, 2L, 2D) other than composed of a one side drive circuit (3L) and the other side drive circuit (3L) having the one side electrodes and the other side electrodes connected thereto in parallel and in conjunction with each other; the one side drive circuit (3U) and the other side drive circuit (3L) are so arranged that they generate a scan signal having a scan pulse of a voltage that does not contribute to display of the display panel depending on an external control signal during a coordinate detection period and they deliver the scan signal to all the electrodes (XU, XL) to be driven at the same timing; the x-coordinate detection circuit (10) is so arranged that it detects the region on the display panel in which the tip of the detection pen (8) exists, from both the timing at which a scan signal having a scan pulse of a voltage that does not contribute to the display from the one side segment drive circuit (3U) and the other side segment drive circuit (3L) is inputted and the timing at which an output signal from the detection pen (8) is generated and further from the peak value of the output signal while the y-coordinate detection circuit (11) is so arranged that it detects the region on the display panel in which the tip of the detection pen exists, from both the timing at which a scan signal having a scan pulse of a voltage that does not contribute to the display from the one side common drive circuit (2U) and the other side common drive circuit (2L) is inputted and the timing at which an output signal from the detection pen (8) is generated and further from the peak value of the output signal, whereby it is detected whether the tip of the detection pen exists in the one side half region of the display panel (1w) or in the other side half region thereof.

Claim 9

A display-integrated type tablet device as claimed in claim 8, wherein the coordinate detection period is divided into a region detection period for detecting a region on the display panel in which the tip of the detection pen exists, an x-coordinate detection period for detecting the x-coordinate on the display panel specified by the detection pen, and a y-coordinate detection period for detecting the y-coordinate specified by the detection pen (8), and wherein during the region detection period, from the one side drive circuit (3U) and the other side drive circuit (3L), scan signals having scan pulses of voltage which does not contribute to the display and which differ in phase between the drive circuits are outputted to scan the one side half region and the other side half region of the display panel (1w) at different timings in series, and during the x-coordinate detection period, the segment drive circuits (3U, 3L) are simultaneously controlled by the detection control circuit (6) to scan the one side half region and the other side half region of the display panel (1w) in parallel, while during the y-coordinate detection period, the common drive circuits are simultaneously controlled by the detection control circuit (6) to scan the one side half region and the other side half region of the display panel in parallel, the x-coordinate detection circuit (10) being arranged so that, during the region detection period, it detects the region on the display panel (1w) in which the tip of the detection pen (8) exits depending on an output signal from the detection pen (8) and, during the x-coordinate detection period, it determines the x-coordinate on the display panel (1w) specified by the tip of the detection pen (8) depending on detection result in the region detection period, the y-coordinate detection circuit (11) being arranged so that, during the region detection period, it detects the region on the display panel (1w) in which the tip of the detection pen (8) exists and, during the y-coordinate detection period, it determines the y-coordinate on the display panel (1w) specified by the tip of the detection pen (8) depending on detection result in the region detection period.

Claim 10

A display-integrated type tablet device as claimed in claim 8, wherein both of the segment drive circuit (3U, 3L) and the common drive circuit (2U, 2L) are composed of the one side drive circuit (3U, 2U) and the other side drive circuit (3L, 2L) and also the external control signal is inputted into all the drive circuits (3U, 2U, 3L, 2L), and during the coordinate detection period, for each of the drive circuits to generate a scan signal having a scan pulse of a voltage that does not contribute to the display and input it all the electrodes to be driven depending on an external control signal, the one side segment drive circuit (3U) and the one side common drive circuit (2U) generate scan signals having a scan pulse of the same voltage and input them at the same timing into the electrodes to be driven while the other side segment drive circuit (3L) and the other side common drive circuit (2L) generate scan signals differing in phase from the scan signals from the two one side drive circuits (3U, 2U) having the scan pulse of the same voltage to input them at the same timing into all the electrodes to be driven, and the x-coordinate detection circuit (10) or the y-coordinate detection circuit (11) detects the region on the display panel (1w) in which the tip of the detection pen (8) exists from both the timing at which the scan signal having the scan pulses of voltages that do not contribute to the display from the two one side drive circuits (3U, 2U) and the two other side drive circuits (3L, 2L) are inputted and the timing at which an output signal from the detection pen is generated and further from the peak value of the output signal.

Claim 11

A display-integrated type tablet, comprising: a duty-type display panel (1w), in which a display material is disposed between segment electrodes (XU, XL) and common electrodes (Y), the segment electrodes (XU, XL) being divided into upper segment electrodes (XU) and lower segment electrodes (XL) at approximately center of a display screen; an upper segment drive circuit (30) for driving the upper segment electrodes (XU); a lower segment drive circuit (3L) for driving the lower segment electrodes (XL); a common drive circuit (2U, 2L, 2D) for driving the common electrodes (Y); a display control circuit (5) for, during a display period, controlling the upper segment drive circuit (3U), the lower segment drive circuit (3L), and the common drive circuit (2U, 2L, 2D) to simultaneously effect the display of the upper half and the display of the lower half of the display panel (1w); a position detection control circuit (6) for, during a position detection period, controlling the upper segment drive circuit to successively scan the upper segment electrodes (3U) with an upper segment drive signal for x-coordinate detection, for controlling the lower segment drive circuit (3L) to successively scan the lower segment electrodes (XL) with a lower segment drive signal for x-coordinate detection, and for controlling the common drive circuit (2U, 2L, 2D) to successively scan the common electrodes (Y) with a common drive signal for y-coordinate detection; a position detection pen (8) to be coupled with the upper segment electrodes (XU), the lower segment electrodes (XY), and the common electrodes (Y); and a coordinate detection circuit (10, 11) for detecting coordinates of a position on the display panel specified by the position detection pen depending on an output signal of the position detection pen.

Claim 12

A display-integrated type tablet as claimed in claim 11, wherein the position detection control circuit (6) is so arranged as to scan the upper segment electrodes (XU) and the lower segment electrodes (XL) simultaneously in parallel and to scan the upper half of the display panel of the common electrodes (Y) during one period and scan the lower half of the display panel of the common electrodes (Y) during another period.

Claim 13

A display-integrated type tablet as claimed in claim 11, wherein the position detection control circuit (6) is so arranged as to scan the upper segment electrodes (XU) during one period and scan the lower segment electrodes (XL) during another period, and to scan the upper half of the common electrodes (Y) in the display panel and the lower half of the common electrodes (Y) of the display panel simultaneously in parallel, and the coordinate detection circuit (10, 11) is so arranged as to decide whether the position detection pen (8) exists in the upper half or in the lower half of the display panel, from both an output signal and scan timing of the position detection pen (8) in the scanning of the upper segment electrodes (XU) and both an output signal and scan timing of the position detection pen (8) in the scanning of the lower segment electrodes (XU, XL), and to detect the y-coordinate of the position of the position detection pen (8) from both the decision result and an output signal and scan timing of the position detection pen in the scanning of the common electrodes (Y).

Claim 14

A display-integrated type tablet as claimed in claim 11, wherein the position detection control circuit (6) is so arranged as to scan the upper segment electrodes (XU) and the lower segment electrodes (XL) simultaneously in parallel with an upper segment drive signal and a lower segment drive signal, which differ in phase from each other, respectively, and to scan the upper half of the common electrodes (Y) of the display panel (1w) and lower half of the common electrodes (Y) of the display panel (1w) simultaneously in parallel, and the coordinate detection circuit (10, 11) is so arranged as to decide whether the position detection pen (8) exists in the upper half or in the lower half of the display panel (1w) from phase difference between the output signal of the position detection pen (8) in the scanning of the upper segment electrodes (XU) and the lower segment electrodes (XL) and the upper segment drive signal or the lower segment drive signal and to detect the y-coordinate of the position of the position detection pen (8) from both the detection result and the output signal and scan timing of the position detection pen (8) in the scanning of the common electrodes (Y).

Claim 15

A display-integrated type tablet as claimed in claim 14, wherein the upper segment drive signal and the lower segment drive signal are high-frequency pulse signals of the same frequency which differ in phase from each other.

Claim 16

A display-integrated type tablet as claimed in claim 14, wherein the upper segment drive signal and the lower segment drive signal are high-frequency sine-wave signals of the same frequency which differ in phase from each other.

Claim 17

A display-integrated type tablet as claimed in claim 14, wherein the upper segment drive signal and the lower segment drive signal are single pulse signals which differ in phase from each other.

Claim 18

A display-integrated type tablet device provided with a liquid crystal display panel having segment electrodes (X) and common electrodes (Y) by which liquid crystals are sandwiched; a control drive circuit (2, 3, 4, 5, 6), which can set a display period and a coordinate detection period by time sharing, and which, during the display period, successively applies voltage for image display to both the segment and common electrodes (X, Y) and also periodically inverts the polarity of the voltage for image display at a timing at which the polarity of an a.c. conversion signal is inverted, and which, during the coordinate detection period, successively applies voltage for coordinate detection to both the segment and common electrodes (X, Y); a detection pen (8) which can be capacity-coupled with a specified electrode on the liquid crystal display panel out of both the segment and common electrodes (X, Y) to cause an electrostatically induced voltage to be developed; and a coordinate detection circuit (10, 11) for receiving the electrostatically induced voltage developed to the detection pen by the voltage for coordinate detection during the coordinate detection period and detecting and outputting the coordinate specified by the detection pen (8) based on the received electrostatically induced voltage, the display-integrated type tablet device further comprising: a mode detection circuit (23) for, during the display period, receiving the electrostatically induced voltage developed to the detection pen (8) depending on polarity inversion of the voltage for image display and comparing the received electrostatically induced voltage with a previously set reference voltage, whereby if the electrostatically induced voltage is greater than the reference voltage it decides as a detection mode in which coordinate detection is to be effected, while if the electrostatically induced voltage is smaller than the reference voltage it decides as a non-detection mode in which the coordinate detection is not to be effected, thus outputting a mode signal representing decision result; and a coordinate output selection circuit (28) for receiving a coordinate outputted by the coordinate detection circuit (10, 11) and a mode signal outputted by the mode detection circuit (23) and then outputting the coordinate as it is if the mode signal represents the detection mode while halting the output of the coordinate if the mode signal represents the non-detection mode.

Claim 19

A display-integrated type tablet device as claimed in claim 18, wherein the mode detection circuit (23) has a peak detector (24) which, receiving the electrostatically induced voltage, generates a d.c. voltage proportional to the peak value of the received electrostatically induced voltage.

Claim 20

A display-integrated type tablet device as claimed in claim 18, further comprising an amplification circuit (9) for amplifying the electrostatically induced voltage developed to the detection pen, wherein both the coordinate detection circuit (10, 11) and the mode detection circuit (23) receive the electrostatically induced voltage amplified by the amplification circuit.

Claim 21

A display-integrated type tablet device as claimed in claim 19, wherein the peak detector (24) has a filter circuit (C₁) for removing the d.c. component included in the received electrostatically induced voltage.

Claim 22

A display-integrated type tablet device as claimed in claim 21, wherein the filter circuit (C₁) is a band-pass filter whose pass band is basic frequencies of the a.c. conversion signal.

Claim 23

A display-integrated type tablet device as claimed in claim 21, wherein the filter circuit (C₁) includes a capacitor (C₁) formed by using a dielectric to cover the tip of the detection pen (8).

Claim 24

A display-integrated type tablet device as claimed in claim 19, wherein the peak detector (24) generates the d.c. voltage by integrating the electrostatically induced voltage within a period during which the electrostatically induced voltage is up, in synchronization with the timing at which the polarity of the a.c. conversion signal is inverted.

Claim 25

A display-integrated type tablet device as claimed in claim 19, wherein the mode detection circuit (23) outputs a mode signal representing a decision result accompanied by movement to the non-detection mode only when an output voltage of the peak detector (24) is once lower than the reference voltage and, after a specified time elapse, holds still lower.

Claim 26

A display-integrated type tablet device as claimed in claim 19, wherein the reference voltage is given in a plural number, and set so that one for moving from the detection mode to the non-detection mode is higher than another for moving from the non-detection mode to the detection mode.

Claim 27

A display-integrated type tablet device as claimed in claim 18, wherein the control drive circuit has a means (7') for receiving a mode signal outputted by the mode detection circuit (23) and setting both the display period and the coordinate detection period when the mode signal represents the detection mode by time sharing while setting only the display period when the mode signal represents the non-detection mode.

Claim 28

A display-integrated type tablet device as claimed in claim 27, wherein the control drive circuit has a means (5') for controlling image data transfer speed to an equal one between the display period set for the detection mode and the display period set for the non-detection mode.

Claim 29

A display-integrated type tablet device as claimed in claim 27, wherein the control drive circuit has a means (5') for transferring image data at a higher speed in the display period for the detection mode than in the display period for the non-detection mode, so that the number of frame frequency in the detection mode and that in the non-detection mode become the same one.

Claim 30

A display-integrated type tablet device having: a liquid crystal panel (1), in which liquid crystals are sandwiched between segment electrodes (X) and common electrodes (Y), orthogonally crossing each other, and which is driven by a duty-type drive method; a detection pen (8) having at its tip an electrode to be electrostatically coupled with the segment electrodes (X) and the common electrodes (Y) of the liquid crystal panel (1); a segment drive circuit (3) for driving the segment electrodes (X); a common drive circuit (2) for driving the common electrodes (Y); a display control circuit (5) for controlling the segment drive circuit (3) and the common drive circuit (2) during a display period to display an image onto the liquid crystal panel (1); a detection control circuit (6) for, during a coordinate detection period, controlling the segment drive circuit (3) to successively scan the segment electrodes (X) of the liquid crystal panel (1) while controlling the common drive circuit (2) to successively scan the common electrodes (Y); an x-coordinate detection circuit (10) for detecting the x-coordinate on the liquid crystal panel (1) specified by the tip of the detection pen (8) from both the timing at which an output signal from the detection pen (8) is generated and the timing at which the segment electrodes (X) are scanned; and a y-coordinate detection circuit (11) for detecting the y-coordinate on the liquid crystal panel (1) specified by the tip of the detection pen (8) from both the timing at which an output signal from the detection pen (8) is generated and the timing at which the common electrodes (Y) are scanned, the display-integrated type tablet device further comprising: inversion signal generation means (4, 5) for generating an inversion signal for setting in the display period a time point at which the direction of voltage applied to liquid crystals of the liquid crystal panel (1) is inverted; a first sampling means (AG₁) for selectively sampling an induced voltage developed to the electrode of the detection pen during a first specified interval in the display period including the time point at which the direction of voltage applied is inverted, the time point having been set depending on the inversion signal; a second sampling means (AG₂) for selectively sampling an induced voltage developed to the electrode of the detection pen during a second specified interval other than the first specified interval in the display period; a first processing means (123, 125) for converting the induced voltage sampled by the first sampling means (AG₁) into d.c. voltage and then comparing the value of the converted voltage with a reference voltage; a second processing means (124, 126) for converting the induced voltage sampled by the second sampling means (AG₂) into d.c. voltage and then comparing the value of the converted voltage with a reference voltage; and decision means (127) for deciding whether or not the tip of the detection pen (8) exists in proximity to the surface of the liquid crystal panel (1), depending on comparison result by the first processing means (123, 125) and comparison result by the second processing means (124, 126), and outputting a signal representing decision result.

Claim 31

A display-integrated type tablet device as claimed in claim 30, wherein the second processing means (124, 126) sample-holds the peak value resulting from converting the induced voltage sampled by the second sampling means (AG₂) into d.c. voltage and compares the sample-held peak value with a reference peak value.

Claim 32

A display-integrated type tablet device as claimed in claim 30, further comprising a third processing means (129, 130) for sample-holding the peak value resulting from converting the induced voltage sampled by the second sampling means (AG₂) into d.c. voltage and comparing the sample-held peak value with a reference peak value, wherein the second processing means (124, 126) converts the induced voltage sampled by the second sampling means (AG₂) into d.c. voltage and thereafter integrates the result, and further compares the resulting integrated voltage value with a reference voltage value; and the decision means (127) decides that the tip of the detection pen (8) does not exist in proximity to the surface of the liquid crystal panel (1), when comparison-objected value of at least one of the second processing means (124, 126) and the third processing means (129, 130) is greater than its reference value.

Claim 33

A display-integrated type tablet device as claimed in claim 30, wherein the first specified interval during which the first sampling means (AG₁) operates is an interval which includes a time point at which the level of the inversion signal generated by the inversion signal generation means (4, 5) is changed, and which is shorter than one half of the cycle of the inversion signal; and the second specified interval during which the second sampling means (AG₂) operates is an interval which starts after the first specified interval has been terminated and terminates before the next change in level of voltage of the inversion signal.

Claim 34

A display-integrated type tablet device as claimed in claim 33, wherein the inversion signal generation means (4, 5) generates the inversion signal whose half cycle is a plurality of times the cycle of the clock signal, depending on the clock signal for successively driving the common electrodes (Y) with the common drive circuit (2); the first specified interval during which the first sampling means (AG₁) operates is one cycle of the clock signal; and the second specified interval during which the second sampling means (AG₂) operates starts at a time point when it has elapsed a period which is at least three times time constant of an induced voltage to be sampled by the first sampling means and which is longer than the first specified interval, from a time point when the first specified interval has started.

Claim 35

A display-integrated type tablet device as claimed in claim 33, wherein the first sampling means (AG₁) and the second sampling means (AG₂) each operate a plurality of times during a one-frame period.

Claim 36

A display-integrated type tablet device as claimed in claim 35, wherein the first processing means (123, 125) and the second processing means (124, 126) convert the induced voltage sampled by the first sampling means (AG₁) or the second sampling means (AG₂) during a one-frame period into d.c. voltage and thereafter further integrate the result.

Claim 37

A display-integrated type tablet device having: a liquid crystal panel (1), in which liquid crystals are sandwiched between segment electrodes (X) and common electrodes (Y), orthogonally crossing each other, and which is driven by a duty-type drive method; a detection pen (8) having at its tip an electrode to be electrostatically coupled with the segment electrodes (X) and the common electrodes (Y) of the liquid crystal panel (1); a segment drive circuit (3) for driving the segment electrodes (X); a common drive circuit (2) for driving the common electrodes (Y); a display control circuit (5) for controlling the segment drive circuit (3) and the common drive circuit (2) during a display period to display an image onto the liquid crystal panel (1); a detection control circuit (6) for, during a coordinate detection period, controlling the segment drive circuit (3) to successively scan the segment electrodes (X) of the liquid crystal panel (1) while controlling the common drive circuit (2) to successively scan the common electrodes (2); an x-coordinate detection circuit (10) for detecting an x-coordinate on the liquid crystal panel (1) specified by the tip of the detection pen (8) from both the timing at which an output signal from the detection pen (8) is generated and the timing at which the segment electrodes (X) are scanned; and a y-coordinate detection circuit (11) for detecting a y-coordinate on the liquid crystal panel (1) specified by the tip of the detection pen (8) from both the timing at which an output signal from the detection pen is generated and the timing at which the common electrodes (Y) are scanned, the display-integrated type tablet device further comprising: inversion signal generation means (4, 5) for generating an inversion signal for setting in the display period a time point at which the direction of voltage applied to liquid crystals of the liquid crystal panel (1) is inverted; a first sampling means (AG₁) for selectively sampling an induced voltage developed to the electrode of the detection pen (8) during a first specified interval in the display period including the time point at which the direction of voltage applied is inverted, the time point having been set depending on the inversion signal; a second sampling means (AG₂) for selectively sampling an induced voltage developed to the electrode of the detection pen (8) during a second specified interval other than the first specified interval in the display period; a first processing means (123) for amplifying the induced voltage sampled at a first amplification factor and then converting the result into d.c. voltage; a second processing means (124) for amplifying the induced voltage sampled by the second sampling means (AG₂) at a second amplification factor greater than the first amplification factor and then converting the result into d.c. voltage; and decision means (131) for comparing an output voltage from the first processing means (123) and an output voltage from the second processing means (124) together, deciding whether or not the tip of the detection pen (8) exists in proximity to the surface of the liquid crystal panel (1), depending on the comparison result, and outputting a signal representing decision result.

Claim 38

A display-integrated type tablet device as claimed in claim 37, wherein the first specified interval during which the first sampling means (AG₁) operates is an interval which includes a time point at which the level of the inversion signal generated by the inversion signal generation means (4, 5) is changed and which is shorter than one half of the cycle of the inversion-signal; and the second specified interval during which the second sampling means (AG₂) operate is an interval which starts after the first specified interval has terminated and which terminates before the next change of the level of the inversion signal.

Claim 39

A display-integrated type tablet device as claimed in claim 38, wherein the inversion signal generation means (4, 5), depending on a clock signal for successively driving the common electrodes (Y) by the common drive circuit (2), generates the inversion signal whose half cycle is a plurality of times the cycle of the clock signal; the first specified interval during which the first sampling means (AG₁) operates is one cycle of the clock signal; and the second specified interval during which the second sampling means (AG₂) operates is an interval which starts at a time point when it has elapsed a period at least three times time constant of an induced voltage to be sampled by the first sampling means (AG₁) and also longer than the length of the first specified interval, from when the first specified interval starts.

Claim 40

A display-integrated type tablet device as claimed in claim 37, wherein the first sampling means (AG₁) and the second sampling means (AG₂) each operate a plurality of times during a one-frame period.

Claim 41

A display-integrated type tablet device as claimed in claim 40, wherein the first processing means (123) and the second processing means (124) convert the induced voltage sampled by the first sampling means (AG₁) or the second sampling means (AG₂) during a one-frame period into d.c. voltage and thereafter further integrate the conversion result.

Claim 42

A display-integrated type tablet having: a display panel having segment electrodes (X) and common electrodes (Y); a segment drive circuit (3) for applying voltage to the segment electrodes (X); a common drive circuit (2) for applying voltage to the common electrodes (Y); a detection pen (8) to be electrostatically coupled with the segment electrodes (X) and the common electrodes (Y); and means (9) for amplifying an electrostatically induced voltage of the detection pen, wherein carried out by time sharing are display of an image with the display panel and coordinate detection for determining the position of the detection pen (8) from a voltage induced to the detection pen put into contact with the surface of the display panel (1), characterized in that the segment drive circuit (3) is provided with a plurality of driving integrated circuits (3₁, 3₂, 3₃) connected in cascade by serial input/output terminals, the driving integrated circuits comprising: scan mode setting means (226) for setting scan mode of the driving integrated circuits to a first mode for a display period and to a second mode for a coordinate detection period; a data input terminal for receiving display data during the display period; a data latch (222) for latching the data inputted from the data input terminal; a line latch (223); a shift register (227); drive signal output means ; and control means (226), wherein the control means (226) serves, in the first mode, to make the serial input/output terminal (EIO1, EIO2) operate as a chip select terminal, to latch the display data inputted from the data input terminal (D₀-D₃) by the data latch (222), to move the one-line data latched by the data latch to the line latch (223), and to output drive signals based on the data moved to the line latch (223) simultaneously in parallel by the drive signal output means, while the control means (226) serves, in the second mode, to make the serial input/output terminal operate as a shift data input/output terminal, to serially output shift data inputted through a serial input/output terminal to another serial input/output terminal while shifting it by the shift register (227), and to successively serially output drive signals depending on the shift data shifted by the shift register (227) by the drive signal output means.

Claim 43

A display-integrated type tablet as claimed in claim 42, wherein the pulse width of the shift data is greater than the cycle of a clock signal which transfers the shift data.

Claim 44

A display-integrated type tablet as claimed in claim 42, further comprising shift data control means (100, 200) for, when carrying out the scanning of the segment drive circuit (3) and the scanning of the common drive circuit (2) by time sharing during the coordinate detection period, making shift data outputted from the final stage of a drive circuit to be scanned firstly and then inputted into the first stage of a drive circuit to be scanned secondly.

Claim 45

A display-integrated type tablet as claimed in claim 44, wherein the shift data control means (100, 200) serves to delay the shift data outputted from the final stage of the drive circuit to be scanned firstly and thereafter to input the same into the first stage of the drive circuit to be scanned secondly.

Claim 46

A display-integrated type tablet as claimed in claim 42, wherein the common drive circuit (2) is an integrated circuit having the same construction as that of the driving integrated circuit forming the segment drive circuit (3), and the scan mode setting means is provided by a plurality of integrated circuits, which are connected in cascade and which serve to set the scan mode normally to the second mode.

Claim 47

A coordinate input device including: a liquid crystal panel (1) in which a plurality of segment electrodes (X) and common electrodes (Y) in the form of strips are arranged so as to orthogonally cross each other; drive means (2, 3) for successively applying display voltage to the segment electrodes (X) and the common electrodes (Y) to drive the liquid crystal panel (1) for display and also effecting a.c. conversion driving so as to prevent electrolysis of liquid crystals; coordinate instruction means (8) provided with an electrode having a relatively high input impedance to be electrostatically coupled with the segment electrodes (X) and the common electrodes (Y); coordinate detection means (10, 11) for, during a coordinate detection period which is set so as to succeed a liquid crystal panel display period and which does not contribute to display, successively applying to the common electrodes (Y) and the segment electrodes (X) a coordinate detection voltage lower than a threshold voltage necessary for liquid crystal display, amplifying an voltage induced to the electrode of the coordinate instruction means (8), detecting both the timing at which the induced voltage is generated and its waveform, and calculating the input coordinate depending on both the timing at which the coordinate detection voltage is applied and the timing at which the induced voltage is generated, wherein the coordinate detection means (10, 11) comprises: d.c. voltage generation means (325) for detecting a voltage induced to the electrode of the coordinate instruction means during a period other than the coordinate detection period, generating a d.c. voltage proportional to the detection value, and holding the d.c. voltage until the coordinate detection period; and processing means (68) for performing normalization treatment of analog voltage induced to the electrode of the coordinate instruction means during the coordinate detection period, by using the d.c. voltage as an auxiliary voltage.

Claim 48

A coordinate input device as claimed in claim 47, wherein the d.c. voltage generation means (325) generates a d.c. voltage proportional to the peak value of a spike-shaped voltage induced to the electrode of the coordinate instruction means (8); and the processing means includes a comparator (323, 324) for digitizing the analog voltage into binary value and takes the d.c. voltage as a reference voltage for the comparator.

Claim 49

A coordinate input device as claimed in claim 47, wherein the d.c. voltage generation means (325) generates a d.c. voltage proportional to the peak value of a spike-shaped voltage induced to the electrode of the coordinate instruction means (8); and the processing means (68, 323, 324) digitizes the analog voltage into binary value with the peak value of the analog voltage held constant by feeding back the d.c. voltage to an amplifier (68) which amplifies the induced voltage.

Claim 50

A coordinate input device as claimed in claim 47, wherein the d.c. voltage generation means (325) generates a d.c. voltage proportional to the peak value of a spike-shaped voltage induced to the electrode of the coordinate instruction means; and the processing means feeds back the d.c. voltage to a power supply which feeds a bias voltage to the drive means during a position detection period to thereby control the bias voltage so as to become higher as the d.c. voltage lowers.

Claim 51

A coordinate input device having: a display panel (1) which has a plurality of segment electrodes (X) arranged in parallel and a plurality of common electrodes (Y) arranged in parallel and which is driven by a duty-type drive method; a detection pen (8) having at its tip an electrode to be coupled between the segment electrodes (X) and the common electrodes (Y) of the display panel with a floating capacity; a display control circuit (5) for outputting a display control signal for displaying an image onto a pixel matrix formed by regions at which the plurality of segment electrodes (X) and the plurality of common electrodes (Y) of the display panel (1) cross each other and also for outputting display data; a position detection control circuit (6) for outputting a scan control signal for scanning the segment electrodes (X) and the common electrodes (Y) of the display panel; a switching circuit (4) for, during a display period, outputting a display control signal and display data from the display control circuit (5) for the display panel (1) while, during a position detection period succeeding the display period, outputting a scan control signal from the position detection control circuit (6); a common drive circuit (2) for, during the display period, outputting a common electrode drive signal for successively selecting the common electrodes (Y) depending on a display control signal from the switching circuit (4) while, during the position detection period, outputting a common electrode scan signal for successively scanning the common electrodes (Y) without displaying an image onto the pixel matrix depending on the scan control signal from the switching circuit (4); a segment drive circuit (3) for, during the display period, outputting a segment electrode drive signal for displaying pixels pertaining to common electrodes (Y) selected by the common electrode drive signal depending on the display control signal and the display data from the switching circuit (4) while, during the position detection period, outputting a segment electrode scan signal for successively scanning the segment electrodes (X) without displaying an image onto the pixel matrix depending on the scan control signal from the switching circuit (4); and a coordinate detection circuit (101) for, during the position detection period, detecting a coordinate specified on the display panel (1) by the tip of the detection pen (8) depending on both the timing at which the common electrode scan signal and the segment electrode scan signal are applied to the common electrodes (Y) and the segment electrodes (X) and the induced voltage developed to the electrode of the detection pen (8), and outputting an x-coordinate signal and a y-coordinate signal, wherein a plurality of auxiliary electrodes (X₋₁, X₀, X m+1 , X m+2 , Y₋₁, Y₀, Y m+1 , Y m+2 ) parallel to the common electrodes (Y) and the segment electrodes (X) are provided outside the display region of the display panel (1), and wherein during the position detection period an electrode scan signal is successively applied to the auxiliary electrodes (X), the common electrodes, and segment electrodes (Y).

Claim 52

A coordinate input device as claimed in claim 51, wherein the potential of the scan signal for the auxiliary electrodes (X₋₁, X₀, X m+1 , X m+2 , Y₋₁, Y₀, Y m+1 , Y m+2 ) during the position detection period is the same as the potential of the scan signal applied to the common electrodes (Y) and the segment electrodes (X) within the display region.

Claim 53

A coordinate input device as claimed in claim 51, wherein the auxiliary electrodes (X₋₁, X₀, X m+1 , X m+2 , Y₋₁ Y₀, Y m+1 , Y m+2 ) are connected to the common drive circuit (2) and the segment drive circuit (3), and wherein, during the position detection period, the electrodes are scanned in the order of the auxiliary electrodes, the common electrodes (Y), and the auxiliary electrodes, and in the order of the auxiliary electrodes, the segment electrodes (X), and the auxiliary electrodes in a predetermined direction of arrangement.

Claim 54

A coordinate input device as claimed in claim 51, wherein electrode scan signals of the same potential are applied to the plurality of auxiliary electrodes arranged in parallel at the same timing with respect to a plurality of adjoining auxiliary electrodes.

Claim 55

A coordinate input device as claimed in claim 51, wherein the common drive circuit (2) and the segment drive circuit (3) each have a shift register (43, 44), clock and data of the shift register being equal between the scanning of the auxiliary electrodes and the scanning of the common electrodes or the segment electrodes during the position detection period.

Claim 56

A coordinate input device as claimed in claim 55, wherein the shift registers (43, 44) of the drive circuits (2, 3) have data interrupt function and operate during the display period for the display panel by interrupting data from a center portion of the shift register (43, 44) without scanning the auxiliary electrodes.

Claim 57

A coordinate input device as claimed in claim 51, wherein the coordinate detection circuit (101) converts a coordinate value calculated including the auxiliary electrodes (X₋₁, X₀, X m+1 , X m+2 , Y₋₁, Y₀, Y m+1 , Y m+2 ) into a coordinate value in the effective coordinate input region formed by crossing regions at which the common electrodes (Y) and the segment electrodes (X) cross each other.

Claim 58

A coordinate input device as claimed in claim 51, wherein the auxiliary electrodes (X₋₁, X₀, X m+1 , X m+2 , Y₋₁, Y₀, Y m+1 , Y m+2 ) are formed so as to be on the same plane as that of the common electrodes (Y) or the segment electrodes (X), and wherein width of the auxiliary electrodes and their spacing are selected to be the width of the common electrodes (Y) or the segment electrodes (X) and their spacing, respectively.

Claim 59

A coordinate input device as claimed in claim 51, wherein the widthwise length of the auxiliary electrodes in the region of arrangement of the auxiliary electrodes (X₋₁, X₀, X m+1 , X m+2 , Y₋₁, Y₀, Y m+1 , Y m+2 ) is selected to be longer than distance between the detection pen and common electrodes (Y) or the segment electrodes (X) when a coordinate input instruction is given for the display panel.

Claim 60

A coordinate input device as claimed in claim 51, wherein the auxiliary electrodes (X₋₁, X₀, X m+1 , X m+2 , Y₋₁, Y₀, Y m+1 , Y m+2 ) are formed on a plane other than that of the segment electrodes (X) or the common electrodes (Y).

Claim 61

A coordinate input device as claimed in claim 51, wherein the auxiliary electrodes (X₋₁, X₀, X m+1 , X m+2 , Y₋₁, Y₀, Y m+1 , Y m+2 ) are of the same material and formed by the same manufacturing processes as with the segment electrodes (X) and the common electrodes (Y).