Display unit having a coordinate input mechanism

• US 5,633,659 A
• Filed: 09/19/1994
• Issued: 05/27/1997
• Est. Priority Date: 09/17/1993
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Tsunekawa, Satoru, Suzuki, Tetsuya, Furuhashi, Tsutomu, Takita, Isao, Mano, Hiroyuki, Nishitani, Shigeyuki, Ikeda, Makiko, Kitajima, Masaaki, Hamada, Tatsuzo
• Primary Examiner(s): Powell, Mark R.
• Assistant Examiner(s): Luu, Matthew
• Application Number:
  US08/308,297
• Time in Patent Office: 981 Days
• Field of Search: 345/173, 345/179, 345/87, 345/103, 345/104, 178/18, 178/19
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0441 using active external devices, e.g. active pens, for receiving changes in electrical potential transmitted by the digitiser, e.g. tablet driving signals
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

A display unit which can detect the X coordinate of a position with which a pen is in contact more efficiently. In a non-display period, X-electrodes are grouped into N regions according to the X-electrode arrangement, each region is divided into two parts according to the X-electrode arrangement, and selection voltage is applied to the X-electrodes belonging to each part having larger X coordinates. The process is repeated in order while N is doubled from one to the half value of the number of the X-electrodes of a liquid crystal panel. If a pen coming in contact with the liquid crystal panel and detecting X-electrode selection voltage detects selection voltage with respect to each N value, the Nth most significant bit of the X coordinate of the position with which the pen is in contact is set to `1.` If the pen does not detect selection voltage, the bit is set to `0.` Thus, the X-electrode of the position with which the pen is in contact can be detected at the number of selection voltage application times equal to the minimum number of bits that can represent each of the X-electrodes.

Claims

1. A display unit comprising:

a flat display comprising M×

N display elements in a matrix consisting of M rows and N columns, M pieces of Y-electrodes each connected to each of the rows of the display elements, respectively, and N pieces of X-electrodes each connected to each of the columns of the display elements, respectively;

a detector for detecting, through an electrostatic capacity coupling, a voltage pulse applied to the column and row corresponding to a position on a display surface of said flat display with which said detector is in contact;

each of said display elements of said flat display being adopted to enter a display state when predetermined voltages are applied to both the Y- and X-electrodes connected to the display element;

a Y-electrode driver for applying a voltage pulse to the Y-electrodes in a row arrangement order in a display period;

an X-electrode driver for applying voltage pulses to the N pieces of X-electrodes with a voltage pulse application pattern specified in a given data string;

means for supplying to said X-electrode driver a data string for specifying a voltage pulse application pattern corresponding to a display pattern to be displayed on the N display elements on a row to which a voltage pulse is applied in a display period;

means for supplying L data strings for specifying L different voltage pulse application patterns to said X-electrode driver in order in a non-display period;

Y coordinate detection means for determining a Y coordinate of a position with which said detector is in contact in response to a Y-electrode to which a voltage pulse is applied at a point in time said detector detects the voltage pulse in a display period;

X coordinate detection means for determining an X coordinate of a position with which said detector is in contact in response to L detection values each indicating whether or not said detector detects a voltage pulse for each of the L voltage pulse application patterns applied to the N pieces of X-electrodes in response to L data strings in a non-display period; and

said L voltage pulse application patterns containing H voltage application patterns each for applying a voltage pulse to X-electrodes belonging to every other region in an X-electrode arrangement direction in 2×

k equal regions into which the N pieces of X-electrodes are grouped according to the X-electrode arrangement with respect to H different arbitrary values k in the range of 1 to H (where H≦

L).

2. The display unit as claimed in claim 1 wherein

H=L=log₂ N, and wherein

said L voltage pulse application patterns contain log₂ N voltage application patterns each for applying a voltage pulse to X-electrodes belonging to every other region in an X-electrode arrangement direction in 2×

k equal regions into which the N pieces of X-electrodes are grouped according to the X-electrode arrangement with respect to log₂ N different arbitrary values k in the range of 1 to log₂ N.

10. The display unit as claimed in claim 1 wherein

H<

L, and wherein

said L voltage pulse application patterns contain;

said H voltage pulse application patterns; and

P voltage application patterns each provided by shifting the voltage application pattern when k=H in the display element row direction by a mutually different shift amount S with respect to X-electrodes.

16. The display unit as claimed in claim 10 wherein ##EQU2## and said shift amount S is ≦

S≦

P or -P≦

S≦

-1, and wherein

said X coordinate detection means determines the X coordinate represented by log₂ N bits, of the position with which said detector is in contact in response to the L detection values.

18. The display unit as claimed in claim 1 wherein

said L voltage pulse application patterns contain:

said H voltage pulse application patterns; and

voltage pulse application patterns for applying no voltage pulses to the N pieces of X-electrodes, and wherein

the data strings for specifying Q voltage application patterns of said H voltage pulse application patterns with respect to k corresponding to values of 1 to Q (where Q<

H) are supplied to said X-electrode driver in the ascending order of the k values, and

one of the data strings for specifying H-Q voltage application patterns of said H voltage pulse application patterns with respect to k corresponding to values of Q+1 to H and one of the voltage pulse application patterns for applying no voltage pulses are alternately supplied to said X-electrode driver in the ascending order of the k values.

24. The display unit as claimed in claim 18 wherein

said X coordinate detection means determines the X coordinate represented by log₂ N bits, of the position with which said detector is in contact in response to only the detection values corresponding to the H voltage pulse application patterns, of the L detection values.

26. The display unit as claimed in claim 1 wherein

said Y coordinate detection means has means for correcting the determined Y coordinate by adding a predetermined value thereto.

28. The display unit as claimed in claim 1 further including means for correcting each of the data strings to a data string for specifying a voltage pulse application pattern provided by changing the voltage pulse application pattern specified in the data string so as not to apply a voltage pulse to a predetermined number of X-electrodes from both ends of each X-electrode region to which a voltage pulse is applied, and supplying it to said X-electrode driver.

30. The display unit as claimed in claim 1 further including means for canceling the detection result of said detector if the voltage level of the voltage pulse detected by said detector does not satisfy a predetermined voltage level condition.

32. The display unit as claimed in claim 1 further including means for detecting said detector being in or out of contact with the display surface of said flat display and supplying the detection result.

34. An information processing system comprising:

the display unit as claimed in claim 1; and

a processor which supplies data for specifying contents displayed on said flat display to said display unit, reads X and Y coordinates determined by said X and Y coordinate detection means of said display unit, and performs processing in response to the read X and Y coordinates.

3. A display unit comprising:

a flat display comprising M×

N display elements in a matrix consisting of M rows and N columns, M pieces of Y-electrodes each connected to each of the rows of the display elements, respectively, and N pieces of X-electrodes each connected to each of the columns of the display elements, respectively;

a detector, through an electrostatic capacity coupling, for detecting a voltage pulse applied to the column and row corresponding to a position on a display surface of said flat display with which said detector is in contact;

each of said display elements of said flat display being adopted to enter a display state when predetermined voltages are applied to both the Y- and X-electrodes connected to the display element;

a Y-electrode driver for applying a voltage pulse to the Y-electrodes in a row arrangement order in a display period;

an X-electrode driver for applying voltage pulses to the N pieces of X-electrodes with a voltage pulse application pattern specified in a given data string;

means for supplying to said X-electrode driver a data string for specifying a voltage pulse application pattern corresponding to a display pattern to be displayed on the N display elements on a row to which a voltage pulse is applied in a display period;

means for supplying L data strings for specifying L different voltage pulse application patterns to said X-electrode driver in order in a non-display period;

Y coordinate detection means for determining a Y coordinate of a position with which said detector is in contact in response to a Y-electrode to which a voltage pulse is applied at a point in time said detector detects the voltage pulse in a display period;

X coordinate detection means for determining an X coordinate of a position with which said detector is in contact by judging an X-electrode range with which said detector is in contact in order in response to whether or not said detector detects a voltage pulse for each of the L voltage pulse application patterns applied to the N pieces of X-electrodes in response to L data strings in a non-display period; and

said L voltage pulse application patterns containing H voltage application patterns consisting of;

one voltage application pattern for applying a voltage pulse to X-electrodes belonging to one of two equal regions into which the N pieces of X-electrodes are grouped according to X-electrode arrangement; and

H-1 voltage application patterns each for applying a voltage pulse to X-electrodes belonging to one of two equal regions into which the range judged to be in contact with said detector in detection for the preceding voltage application pattern is divided according to X-electrode arrangement while value k is incremented by one from 2 to H (where H≦

L) in order.

4. The display unit as claimed in claim 3 wherein

H=L=log₂ N, and wherein

said L voltage pulse application patterns contain H voltage application patterns consisting of:

one voltage application pattern for applying a voltage pulse to X-electrodes belonging to one of two equal regions into which the N pieces of X-electrodes are grouped according to X-electrode arrangement; and

said H-1 voltage pulse application patterns is log₂ N voltage application patterns consisting of one voltage application pattern for applying a voltage pulse to X-electrodes belonging to one of two equal regions into which the N pieces of X-electrodes are grouped according to X-electrode arrangement, and log₂ N-1 voltage application patterns each for applying a voltage pulse to X-electrodes belonging to one of two equal regions into which the range judged to be in contact with said detector in detection for the preceding voltage application pattern is divided according to X-electrode arrangement while value k is incremented by one from 2 to log₂ N in order.

11. The display unit as claimed in claim 3 wherein

H<

L, and wherein

said L voltage pulse application patterns contain;

said H voltage pulse application patterns; and

P voltage application patterns each provided by shifting the voltage application pattern when k=H in the display element row direction by a mutually different shift amount S with respect to X-electrodes.

17. The display unit as claimed in claim 11 wherein ##EQU3## and said shift amount S is ≦

S≦

P or -P≦

S≦

-1, and wherein

said X coordinate detection means determines the X coordinate represented by log₂ N bits, of the position with which said detector is in contact in response to the L detection values.

19. The display unit as claimed in claim 3 wherein

said L voltage pulse application patterns contain:

said H voltage pulse application patterns; and

voltage pulse application patterns for applying no voltage pulses to the N pieces of X-electrodes, and wherein

the data strings for specifying Q voltage application patterns of said H voltage pulse application patterns with respect to k corresponding to values of 1 to Q (where Q<

H) are supplied to said X-electrode driver in the ascending order of the k values, and

one of the data strings for specifying H-Q voltage application patterns of said H voltage pulse application patterns with respect to k corresponding to values of Q+1 to H and one of the voltage pulse application patterns for applying no voltage pulses are alternately supplied to said X-electrode driver in the ascending order of the k values.

25. The display unit as claimed in claim 19 wherein

said X coordinate detection means determines the X coordinate represented by log₂ N bits, of the position with which said detector is in contact in response to only the detection values corresponding to the H voltage pulse application patterns, of the L detection values.

27. The display unit as claimed in claim 3 wherein

said Y coordinate detection means has means for correcting the determined Y coordinate by adding a predetermined value thereto.

29. The display unit as claimed in claim 3 further including means for correcting each of the data strings to a data string for specifying a voltage pulse application pattern provided by changing the voltage pulse application pattern specified in the data string so as not to apply a voltage pulse to a predetermined number of X-electrodes from both ends of each X-electrode region to which a voltage pulse is applied, and supplying it to said X-electrode driver.

31. The display unit as claimed in claim 3 further including means for canceling the detection result of said detector if the voltage level of the voltage pulse detected by said detector does not satisfy a predetermined voltage level condition.

33. The display unit as claimed in claim 3 further including means for detecting said detector being in or out of contact with the display surface of said flat display and supplying the detection result.

35. An information processing system comprising:

the display unit as claimed in claim 3; and

a processor which supplies data for specifying contents displayed on said flat display to said display unit, reads X and Y coordinates determined by said X and Y coordinate detection means of said display unit, and performs processing in response to the read X and Y coordinates.

5. A display unit comprising:

a flat display comprising M×

N display elements in a matrix consisting of M rows and N columns, M pieces of Y-electrodes each connected to each of the rows of the display elements, respectively, and N pieces of X-electrodes each connected to each of the columns of the display elements, respectively;

a detector for detecting a voltage pulse applied to the column and row corresponding to a position on a display surface of said flat display with which said detector is in contact through an electrostatic capacity coupling;

each of said display elements of said flat display being adopted to enter a display state when predetermined voltages are applied to both the Y- and X-electrodes connected to the display element and an X coordinate represented by an A-bit value in binary notation is given to each of the columns;

a Y-electrode driver for applying a voltage pulse to the Y-electrodes in a row arrangement order in a display period;

an X-electrode driver for applying voltage pulses to the N pieces of X-electrodes with a voltage pulse application pattern specified in a given data string;

means for supplying to said X-electrode driver a data string for specifying a voltage pulse application pattern corresponding to a display pattern to be displayed on the N display elements on a row to which a voltage pulse is applied in a display period;

means for supplying to said X-electrode driver, data strings for specifying L voltage pulse application patterns containing H voltage pulse application patterns for applying a voltage pulse only to either of an X-electrode having a given X coordinate whose jth most significant bit has value `1` and an X-electrode having a given X coordinate whose jth most significant bit has value `0` in order with respect to H different arbitrary values j in the range of 1 to H (where H≦

A) in a non-display period;

Y coordinate detection means for determining a Y coordinate of a position with which said detector is in contact in response to a Y-electrode to which a voltage pulse is applied at a point in time said detector detects the voltage pulse in a display period; and

X coordinate detection means for determining the bit value of the jth most significant bit of the X coordinate of a position with which said detector is in contact in response to whether or not said detector detects a voltage pulse for the voltage pulse application pattern corresponding to the value of the j for each of the H values j in a non-display period.

12. The display unit as claimed in claim 5 wherein

H<

A, and wherein

said L voltage pulse application patterns contain;

said H voltage pulse application patterns; and

P voltage application patterns each provided by shifting the voltage application pattern when j=H in the display element row direction by a mutually different shift amount S with respect to X-electrodes.

20. The display unit as claimed in claim 5 wherein

said L voltage pulse application patterns contain:

said H voltage pulse application patterns; and

voltage pulse application patterns for applying no voltage pulses to the N pieces of X-electrodes, and wherein

the data strings for specifying Q voltage application patterns of said H voltage pulse application patterns with respect to j corresponding to values of 1 to Q (where Q<

H) are supplied to said X-electrode driver in the ascending order of the j values, and

one of the data strings for specifying H-Q voltage application patterns of said H voltage pulse application patterns with respect to j corresponding to values of Q+1 to H and one of the voltage pulse application patterns for applying no voltage pulses are alternately supplied to said X-electrode driver in the ascending order of the j values.

6. A display unit comprising:

a flat display comprising M×

N display elements in a matrix consisting of M rows and N columns, M pieces of Y-electrodes each connected to each of the rows of the display elements, respectively, and N pieces of X-electrodes each connected to each of the columns of the display elements, respectively;

a detector for detecting a voltage pulse applied to the column and row corresponding to a position on a display surface of said flat display with which said detector is in contact through an electrostatic capacity coupling;

each of said display elements of said flat display being adopted to enter a display state when predetermined voltages are applied to both the Y- and X-electrodes connected to the display element and an X coordinate represented by an A-bit value in binary notation is given to each of the columns;

a Y-electrode driver for applying a voltage pulse to the Y-electrodes in a row arrangement order in a display period;

an X-electrode driver for applying voltage pulses to the N pieces of X-electrodes with a voltage pulse application pattern specified in a given data string;

means for supplying to said X-electrode driver a data string for specifying a voltage pulse application pattern corresponding to a display pattern to be displayed on the N display elements on a row to which a voltage pulse is applied in a display period;

means for supplying to said X-electrode driver, data strings for specifying L voltage pulse application patterns containing H voltage pulse application patterns each corresponding to each of H values j incremented by one in the range of 1 to H (where H≦

A) in a non-display period;

Y coordinate detection means for determining a Y coordinate of a position with which said detector is in contact in response to a Y-electrode to which a voltage pulse is applied at a point in time said detector detects the voltage pulse in a display period;

X coordinate detection means for determining the bit value of the jth most significant bit of the X coordinate of a position with which said detector is in contact in response to whether or not said detector detects a voltage pulse for the voltage pulse application pattern corresponding to the value of the j for each of the H values j incremented by one in a non-display period;

the voltage pulse application pattern corresponding to j which is 1 is a pattern for applying a voltage pulse to either of an X-electrode having a given X coordinate whose most significant bit has value `1` and an X-electrode having a given X coordinate whose most significant bit has value `0`; and

said voltage pulse application patterns corresponding to j of 2 to H being each a pattern, with respect to the corresponding j, for applying a voltage pulse to an X-electrode which is either of an X-electrode having a given X coordinate whose jth most significant bit has value `1` and an X-electrode having a given X coordinate whose jth most significant bit has value `0`, with the value of the most significant bit to the (j-1)th most significant bit of the given X coordinate being equal to the value determined as the bit value of the most significant bit to the (j-1)th most significant bit of the X coordinate of the position with which the detector is in contact.

13. The display unit as claimed in claim 6 wherein

H<

A, and wherein

said L voltage pulse application patterns contain;

said H voltage pulse application patterns; and

P voltage application patterns each provided by shifting the voltage application pattern when j=H in the display element row direction by a mutually different shift amount S with respect to X-electrodes.

21. The display unit as claimed in claim 6 wherein

said L voltage pulse application patterns contain:

said H voltage pulse application patterns; and

voltage pulse application patterns for applying no voltage pulses to the N pieces of X-electrodes, and wherein

the data strings for specifying Q voltage application patterns of said H voltage pulse application patterns with respect to j corresponding to values of 1 to Q (where Q<

H) are supplied to said X-electrode driver in the ascending order of the j values, and

one of the data strings for specifying H-Q voltage application patterns of said H voltage pulse application patterns with respect to j corresponding to values of Q+1 to H and one of the voltage pulse application patterns for applying no voltage pulses are alternately supplied to said X-electrode driver in the ascending order of the j values.

7. A display unit comprising:

two flat displays each comprising M×

N display elements in a matrix consisting of M rows and N columns, M pieces of Y-electrodes each connected to each of the rows of the display elements, respectively, and N pieces of X-electrodes each connected to each of the columns of the display elements, respectively;

a detector for detecting a voltage pulse applied to the column and row corresponding to a position on a display surface of said flat display with which said detector is in contact through an electrostatic capacity coupling;

said two flat displays being placed so as to make up one screen;

each of said display elements of said flat display being adopted to enter a display state when predetermined voltages are applied to both the Y- and X-electrodes connected to the display element and an X coordinate represented by an A-bit value in binary notation is given to each of the columns;

a Y-electrode driver for applying a voltage pulse to the Y-electrodes for corresponding rows of said two flat displays in parallel in a row arrangement order in a display period;

two X-electrode drivers being disposed corresponding to said two flat displays, said two X-electrode drivers each for applying voltage pulses to the N pieces of X-electrodes of the corresponding flat display with a voltage pulse application pattern specified in a given data string;

means for supplying to each of said two X-electrode drivers a data string for specifying a voltage pulse application pattern corresponding to a display pattern to be displayed on the N display elements on a row of the corresponding flat display to which a voltage pulse is applied in a display period;

means for supplying to one of said two X-electrode drivers a data string for applying voltage pulses to all X-electrodes of the corresponding flat display, and supplying to the other X-electrode driver a data string for suppressing voltage pulse application to all X-electrodes of the corresponding flat display in a non-display period; and

Y coordinate detection means for determining a position in the flat display with which said detector is in contact in response to a Y-electrode to which a voltage pulse is applied at a point in time said detector detects the voltage pulse in a display period, and determining a Y coordinate on said screen with which said detector is in contact by judging that the flat display having all X-electrodes to which voltage pulses are applied, at a point in time said detector detects voltage pulse in a non-display period, is the flat display with which said detector is in contact.

8. The display unit as claimed in claim 7 further including:

means for supplying to said X-electrode driver corresponding to the flat display that said Y coordinate detection means judges said detector to be in contact with, data strings for specifying L voltage pulse application patterns containing H voltage pulse application patterns for applying a voltage pulse only to either of an X-electrode having a given X coordinate whose jth most significant bit has value `1` and an X-electrode having a given X coordinate whose jth most significant bit has value `0` in order with respect to H different arbitrary values j in the range of 1 to H (where H≦

A) in a non-display period; and

X coordinate detection means for determining the bit value of the jth most significant bit of the X coordinate of a position with which said detector is in contact in response to whether or not said detector detects a voltage pulse for the voltage pulse application pattern corresponding to the value of the j for each of the H values j in a non-display period.

9. The display unit as claimed in claim 7 further including:

means for supplying to said X-electrode driver corresponding to the flat display that said Y coordinate detection means judges said detector to be in contact with, data strings for specifying L voltage pulse application patterns containing H voltage pulse application patterns each corresponding to each of H values j incremented by one in the range of 1 to H (where H≦

A) in a non-display period; and

X coordinate detection means for determining the bit value of the jth most significant bit of the X coordinate of a position with which said detector is in contact in response to whether or not said detector detects a voltage pulse for the voltage pulse application pattern corresponding to the value of the j for each of the H values j incremented by one in a non-display period, wherein

the voltage pulse application pattern corresponding to j which is 1 is a pattern for applying a voltage pulse to either of an X-electrode having a given X coordinate whose most significant bit has value `1` and an X-electrode having a given X coordinate whose most significant bit has value `0,` and

the voltage pulse application patterns corresponding to j of 2 to H are each a pattern, with respect to the corresponding j, for applying a voltage pulse to an X-electrode which is either of an X-electrode having a given X coordinate whose jth most significant bit has value `1` and an X-electrode having a given X coordinate whose jth most significant bit has value `0,` with the value of the most significant bit to the (j-1)th most significant bit of the given X coordinate being equal to the value determined as the bit value of the most significant bit to the (j-1)th most significant bit of the X coordinate of the position with which the detector is in contact.

14. The display unit as claimed in claim 8 wherein

H<

A, and wherein

said L voltage pulse application patterns contain;

said H voltage pulse application patterns; and

P voltage application patterns each provided by shifting the voltage application pattern when j=H in the display element row direction by a mutually different shift amount S with respect to X-electrodes.

15. The display unit as claimed in claim 7 further including:

means for supplying L data strings for specifying L different voltage pulse application patterns to said X-electrode driver in order in a non-display period;

X coordinate detection means for determining an X coordinate of a position with which said detector is in contact in response to L detection values each indicating whether or not said detector detects a voltage pulse for each of the L voltage pulse application patterns applied to the N pieces of X-electrodes in response to L data strings in a non-display period, wherein

said L voltage pulse application patterns contain;

H voltage application patterns each for applying a voltage pulse to X-electrodes belonging to every other region in an X-electrode arrangement direction in 2×

k equal regions into which the N pieces of X-electrodes are grouped according to the X-electrode arrangement with respect to H different arbitrary values k in the range of 1 to H (where H<

L); and

P voltage application patterns each provided by shifting the voltage application pattern when k=H in the display element row direction by a mutually different shift amount S with respect to X-electrodes.

22. The display unit as claimed in claim 8 wherein

said L voltage pulse application patterns contain:

said H voltage pulse application patterns; and

voltage pulse application patterns for applying no voltage pulses to the N pieces of X-electrodes, and wherein

the data strings for specifying Q voltage application patterns of said H voltage pulse application patterns with respect to j corresponding to values of 1 to Q (where Q<

H) are supplied to said X-electrode driver in the ascending order of the j values, and

one of the data strings for specifying H-Q voltage application patterns of said H voltage pulse application patterns with respect to j corresponding to values of Q+1 to H and one of the voltage pulse application patterns for applying no voltage pulses are alternately supplied to said X-electrode driver in the ascending order of the j values.

23. The display unit as claimed in claim 7 further including:

means for supplying L data strings for specifying L different voltage pulse application patterns to said X-electrode driver in order in a non-display period;

X coordinate detection means for determining an X coordinate of a position with which said detector is in contact in response to L detection values each indicating whether or not said detector detects a voltage pulse for each of the L voltage pulse application patterns applied to the N pieces of X-electrodes in response to L data strings in a non-display period, wherein

said L voltage pulse application patterns contain;

H voltage application patterns each for applying a voltage pulse to X-electrodes belonging to every other region in an X-electrode arrangement direction in 2×

k equal regions into which the N pieces of X-electrodes are grouped according to the X-electrode arrangement with respect to H different arbitrary values k in the range of 1 to H (where H<

L); and

voltage pulse application patterns for applying no voltage pulses to the N pieces of X-electrodes, and wherein

the data strings for specifying Q voltage application patterns of said H voltage pulse application patterns with respect to k corresponding to values of 1 to Q (where Q<

H) are supplied to said X-electrode driver in the ascending order of the k values, and

one of the data strings for specifying H-Q voltage application patterns of said H voltage pulse application patterns with respect to k corresponding to values of Q+1 to H and one of the voltage pulse application patterns for applying no voltage pulses are alternately supplied to said X-electrode driver in the ascending order of the k values.