Improvements in or relating to a driving arrangement for a stepping motor

Claim 2

A driving device for a stepping motor comprises detecting means for detecting a voltage corresponding to an electric current flowing through field windings of individual phases of the stepping motor, storing means in which saturation curves of electric currents flowing through the 25 field windings of the phases are stored, analog to digital converter means for converting a voltage detected by the detecting means into a digital value, comparing means for comparing the voltage value thus converted by the analog to digital converter means with a value of the saturation cjjrves stored in the storing means, and driving signal developing means for develop- ing a driving signal for a subsequent next step when a difference between the voltage value and 30 the value of the saturation curves at the comparing means reaches a predetermined value.

Claim 3

A driving device according to claim 1, wherein said detecting means includes a resistor of a low resistance connected in series to each of the field windings of the motor.

Claim 4

A driving device according to claim 1 or 2, wherein said analog to digital converter means includes means for successively developing values in accordance with one of the saturation curves for a particular one of the field windings of the motor, a digital to analog converter for converting the successively developed values into a corresponding voltage, and comparator means for comparing the voltage detected by said detecting means for a particular field winding with the voltage from said digital to analog converter.

Claim 5

A driving device according to claim 3, wherein said detecting means includes a plurality of 40 resistors of a low resistance connected in series to the field windings of the motor, and said comparator means includes a plurality of comparators each connected to one of said resistors and to said digital to analog converter.

Claim 6

A. driving device according to claim 3, wherein said detecting means includes a plurality of resistors of a low resistance connected in series to the field windings of the motor, and said comparator means includes a data selector connected to said resistors for selectively developing a voltage detected by a particular one of said resistors, and a comparator connected to compare the voltage developed from said data selector with said detecting means with the voltage from said digital to analog converter.

Claim 7

A driving device according to any one of the preceding claims further comprising means 50 fthe device further comprises means for receiving a total step value indicative of a total number of steps for the motor to rotate, means containing a present step value indicative of a present number of steps the motor has rotated, and means responsive to the present number and/or the total number of steps for causing said driving signal developing means to produce a driving signal independent of the difference between the voltage value and the value of the saturated curves for a first and/or a last particular number of steps during rotation of the step motor for the total number of steps.

Claim 8

A driving device according to claim 6, wherein said particular number of steps is 3 or a value around 3.

Claim 9

A driving device according to any one of the preceding claims further comprises saturation 60 curve producing means for producing a saturation curve for one of the field windings of the motor and for storing several data of the saturation curve produced into said storing means.

Claim 10

A driving device according to any one of claims 1 to 7 further comprising saturation curve producing means for producing saturation curves for the field windings of the motor and for storing several data of the saturation curves produced into said storing means. 7 GB2181908A 7

Claim 11

A driving device according to claim 9, wherein said saturation curve producing means is operable each time the motor is to be rotated from one to another angular position.

Claim 12

A driving device according to claim 9 or 10, wherein said saturation curve producing means includes means for energizing one of the field windings of the motor with a predeter- mined voltage, means for measuring voltages at first, second and third points of time before and after starting energization of the field winding before and after saturation is reached, respectively, and means for calculating several data of a saturation curve from the voltages at the first, second and third points of time.

Claim 13

A simulating device for producing a simulated saturation curve for a field winding of a stepping motor, comprising means for detecting a current flow in the field winding as a voltage 10 signal, means for energizing the field winding with a first predetermined voltage insufficient for the motor to rotate, means for taking voltage signals from said means for detecting at different points of time befor and after starting energization of the field winding, means for calculating several data of a saturation curve from the voltage signals at the different points of time, means for storing the calculated data therein, means for successively recalling Ihe stored data when the 15 field winding is energized with a second predetermined voltage to rotate the motor, and means responsive to each of the recalled data for producing a voltage corresponding to the data.

Claim 14

A simulating device for producing a simulated saturation curve for a field winding of a stepping motor, comprising means for detecting a current flow in the field winding as a voltage 10 signal, means for energizing the field winding with a first predetermined voltage insufficient for the motor to rotate, means for taking voltage signals from said means for detecting at different points of time befor and after starting energization of the field winding, means for calculating several data of a saturation curve from the voltage signals at the different points of time, means for storing the calculated data therein, means for successively recalling Ihe stored data when the 15 field winding is energized with a second predetermined voltage to rotate the motor, and means responsive to each of the recalled data for producing a voltage corresponding to the data.

Claim 15

A simulating device according to claim 12, wherein said means for detecting is a resistor of a low resistance connected in series to the field winding.

Claim 16

A simulating device according to claim 12 or 12, wherein the different points of time 20 after energization of the field winding with the first predetermined voltage include first and second points of time before and after saturation is reached, respectively.

Claim 17

A driving device for a stepping motor substantially as herein described with reference to the accompanying drawings.

Claim 18

A driving device for a stepping motor substantially as herein described with reference to the accompanying drawings.

Claim 19

A simulating device for producing a simulated saturation curve substantially as herein 25 described with reference to the accompanying drawings.

Claim 20

A simulating device for producing a simulated saturation curve substantially as herein 25 described with reference to the accompanying drawings.

Claim 21

Any novel feature or combination of features disclosed herein. Printed for Her Majesty's Stationery Office by Burgess & Son (Abingdon) Ltd, Dd 8991685, 1987. Published at The Patent Office, 25 Southampton Buildings, London, WC2A 1 AY, from which copies may be obtained.

Claim 22

Any novel feature or combination of features disclosed herein. Printed for Her Majesty's Stationery Office by Burgess & Son (Abingdon) Ltd, Dd 8991685, 1987. Published at The Patent Office, 25 Southampton Buildings, London, WC2A 1 AY, from which copies may be obtained.