Method and apparatus for reading bar coded data wherein a light source is periodically energized

Claim 2

Apparatus for optically reading bar coded data wherein the binary bits are encoded in terms of bars of different widths of the same optical characteristic separated by areas of the opposite optical characteristic comprising optical sensing means for producing electrical signals representative of the optical characteristic of a surface presented thereto upon the production of relative movement between the surface and the senSing means, said sensing means having a normally de-energized light source and a light sensor for receiving the light rays from the light source reflected from the surface being sensed, and control circuit means including means for automatically and periodically energizing the light source coupled to be responsive to the sensor signals and maintaining the energization of the light source in response to a sensor signal of one kind and automatically de-energizing the light source in response to a sensor signal of the other kind.

Claim 3

Apparatus for optically reading bar coded data as defined in claim 1 wherein the light sensor and the control circuit means are differentially D.C. coupled thereby avoiding varying signal thresholds.

Claim 4

Apparatus for optically reading bar coded data wherein the binary bits are encoded in terms of bars of different widths of the same optical characteristic separated by areas of the opposite optical characteristic comprising optical sensing means for producing electrical signals representative of the optical characteristic of a surface presented thereto upon the production of relative movement between the surface and the sensing means, said sensing means having a normally de-energized light source and a light sensor for receiving the light rays from the light source reflected from the surface being sensed, the sensor electrical signals includes an unknown D.C. offset voltage, first amplifying circuit means coupled to be responsive to the signals from the light sensor including the offset voltages, second amplifying means normally coupled to receive the output signals from the first amplifying means and providing an output signal corresponding thereto for preselected periods, differential amplifying circuit means coupled to be responsive to the output signals from the first and second amplifying circuit means and providing output signals representative of the reflective characteristics of the sensed surface, and switching circuit means coupled to the light source for automatically and periodically energizing the light source for a preselected intervals and decoupling the first and second amplifying means during the intervals the light source is energized.

Claim 5

Apparatus for optically reading bar coded data wherein the binary bits are encoded in terms of bars of different widths of the same optical characteristic separated by areas of the opposite optical characteristic comprising optical sensing means for producing electrical signals representative of the optical characteristic of a surface presented thereto upon the production of relative movement between the surface and the sensing means, said sensing means having a normally de-energized light source and a light sensor for receiving the light rays from the light source reflected from the surface being sensed, the sensor electrical signals includes an unknown D.C. offset voltage, first amplifying circuit means coupled to be responsive to the signals from the light sensor including the offset voltages, second amplifying means normally coupled to receive the output signals from the first amplifying means and providing an output signal corresponding thereto for preselected periods, differential amplifying circuit means coupled to be responsive to the output signals from the first and second amplifying circuit means and providing output signals representative of the reflective characteristics of the sensed surface, and switching circuit means coupled to the light source for automatically and periodically energizing the light source for a preselected intervals and decoupling the first and second amplifying means during the intervals the light source is energized.

Claim 6

Apparatus for optically reading bar coded data as defined in claim 3 wherein said second amplifying means is a unity gain operational amplifier having signal storage means coupled in the circuit with the output signal from the first amplifying means at the input terminal of the second amplifying means.

Claim 7

Apparatus for optically reading bar coded data as defined in claim 3 wherein the signal storage means is a capacitor having one terminal connected in parallel circuit relationship to said input terminal and having its other terminal connected to a point of reference potential.

Claim 8

Apparatus for optically reading bar coded data as defined in claim 3 wherein the output signal from the second amplifying means is coupled in parallel circuit relationship with a current source to provide an input signal to the differential amplifying circuit of a preselected polarity when the light source is de-energized to thereby assure that the sensed surfaces of opposite optical characteristic provide output signals from the differential amplifier that are binary coded.

Claim 9

Apparatus for optically reading bar coded data as defined in claim 6 wherein the binary coded output signals are signals of opposite polarity.

Claim 10

Apparatus for optically reading bar coded data as defined in claim 3 wherein said first amplifying means is an operational amplifier having a high input impedance and is D.C. coupled to the light sensor.

Claim 11

Apparatus for optically reading bar coded data as defined in claim 3 including means for automatically and periodically energizing the light source and coupled to be responsive to the switching circuit means for energizing and de-energizing the light source in response thereto.

Claim 12

Apparatus for optically reading bar coded data as defiNed in claim 6 including means coupled to be responsive to said binary signals from the differential amplifier means for periodically energizing and de-energizing the light source in response to changes in the binary character of the signals.

Claim 13

Apparatus for optically reading bar coded data as defined in claim 3 wherein said light source is characterized as having a fast response time.

Claim 14

Apparatus for optically reading bar coded data as defined in claim 11 wherein said light source is a light emitting diode.

Claim 15

Apparatus for optically reading bar coded data as defined in claim 3 wherein said amplifying means are D.C. coupled throughout.

Claim 16

Apparatus for optically reading bar coded data wherein the binary bits are encoded in terms of bars of different widths of the same optical characteristic separated by areas of the opposite optical characteristics comprising optical sensing means for producing electrical signals representative of the reflective characteristic of a surface upon the production of relative movement between the two, said sensing means having a normally de-energized light source and a light sensor, the electrical signals produced including an unknown D.C. offset voltage, amplifying means coupled to be responsive to the signals from the sensing means including the offset voltages, differential amplifying means for receiving the signals from the amplifying means, sample and hold amplifying circuit means normally coupled to receive the output signals from said amplifying means and for coupling the output signals to said differential amplifying means, controller means coupled to be responsive to the output signals from said differential amplifying means for controlling the energization of the light source, said controller means providing a series of pulses adapted for automatically and periodically energizing the light source, and switching means coupled to be responsive to the series of pulses for switchably energizing the light source in response to the operation of the switching means and coupled between the output of said amplifying means and the input to said sample hold amplifying circuit to switchably de-couple said sample and hold circuit in response to the operation of the switching means, said controller means being effective for maintaining the switching means energized in response to a sensed reflective surface and for de-energizing the light source in response to a sensed absorptive surface.

Claim 17

Apparatus for optically reading bar coded data wherein the binary bits are encoded in terms of bars of different widths of the same optical characteristic separated by areas of the opposite optical characteristics comprising optical sensing means for producing electrical signals representative of the reflective characteristic of a surface upon the production of relative movement between the two, said sensing means having a normally de-energized light source and a light sensor, the electrical signals produced including an unknown D.C. offset voltage, amplifying means coupled to be responsive to the signals from the sensing means including the offset voltages, differential amplifying means for receiving the signals from the amplifying means, sample and hold amplifying circuit means normally coupled to receive the output signals from said amplifying means and for coupling the output signals to said differential amplifying means, controller means coupled to be responsive to the output signals from said differential amplifying means for controlling the energization of the light source, said controller means providing a series of pulses adapted for automatically and periodically energizing the light source, and switching means coupled to be responsive to the series of pulses for switchably energizing the light source in response to the operation of the switching means and coupled between the output of said amplifying means and the input to said sample hold amplifying circuit to switchably de-couple said sample and hold circuit in response to the operation of the switching means, said controller means being effective for maintaining the switching means energized in response to a sensed reflective surface and for de-energizing the light source in response to a sensed absorptive surface.

Claim 18

Apparatus for optically reading bar coded data wherein the binary bits are encoded in terms of bars of different widths of the same optical characteristic separated by areas of the opposite optical characteristic comprising optical sensing means for producing electrical signals representative of the optical characteristic of a surface presented thereto upon the production of relative movement between the surface and the sensing means, said sensing means having a normally de-energized light source and a light sensor for receiving the light rays from the light source reflected from the surface being sensed, differentially D.C. amplifying circuit means coupled to be responsive to the signals from the light sensor and providing binary coded signals representative of the optical characteristics of the sensed surface, and control circuit means including means for automatically and periodically energizing the light source coupled to be responsive to the binary coded signals and maintaining the energization of the light source in response to a binary signal of one kind and de-energizing the light source in response to a binary signal of the other kind.

Claim 19

Apparatus for optically reading bar coded data wherein the binary bits are encoded in terms of bars of different widths of the same optical characteristic separated by areas of the opposite optical characteristic comprising optical sensing means for producing electrical signals representative of the optical characteristic of a surface presented thereto upon the production of relative movement between the surface and the sensing means, said sensing means having a normally de-energized light source and a light sensor for receiving the light rays from the light source reflected from the surface being sensed, differentially D.C. amplifying circuit means coupled to be responsive to the signals from the light sensor and providing binary coded signals representative of the optical characteristics of the sensed surface, and control circuit means including means for automatically and periodically energizing the light source coupled to be responsive to the binary coded signals and maintaining the energization of the light source in response to a binary signal of one kind and de-energizing the light source in response to a binary signal of the other kind.

Claim 22

A method of optically reading bar coded data as defined in claim 16 including the steps of utilizing the electrical signals representative of a sensed reflective characteristic to maintain the light source energized to thereby permit reading of the bar coded data by the energized wand being moved over the bar coded data.

Claim 23

A method of optically reading bar coded data as defined in claim 17 including the step of utilizing the non-reflective elctrical signals for de-energizing the light source after the wand is moved past the bar coded data.

Claim 26

A method of optically reading bar coded data as defined in claim 19 including the steps of repeating the steps of determining the sensed reflective characteristic a preselected period after the light source is de-energized as a result of sensing a non-reflective surface.

Claim 29

A method of optically reading as defined in claim 21 including the steps of de-energizing the light source after the bar coded data is read in response to sensing a non-reflective surface, and repeating the step of energizing the light source a preselected time interval after the sensing of a non-reflectiVe surface to re-determine the light characteristic of the surface the wand is passed over.

Claim 32

A method of optically reading bar coded data as defined in claim 23 including the steps of determing the binary character of the binary signal and de-energizing the light source if a non-reflective surface has been sensed or maintaining the energization of the light source if a reflective surface has been sensed.