JPH06187087A - Positional coordinate detector - Google Patents

Abstract

PURPOSE:To detect the position coordinates on the screen of a display device for which display data are line sequentially written and driven without using a touch panel concerning a positional coordinate detector for detecting the positional coordinates on the screen of the display device by using a write pen. CONSTITUTION:A display data switching circuit 22 displays a black belt-like picture part provided with a longitudinal direction in the vertical direction of the screen and the width of one picture element on a liquid crystal panel 20 so as to move from the left end of the screen to right end for respective frames. A data scanning monitoring circuit 23 detects coordinates in the horizontal direction of the screen by detecting the black belt-like picture part by the light pen 11. A gate scanning monitoring circuit 24 detects the coordinates in the vertical direction of the screen by detecting spike-like optical pulses generated for the respective frames.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position coordinate detecting device, and more particularly to a position coordinate detecting device for detecting a position coordinate on a screen of a display device using a light pen.

With the rapid progress and development of large-scale semiconductor integrated circuit (LSI) technology in recent years, a liquid crystal display device which can be driven at a low voltage by an ordinary LSI, consumes less power, is small and lightweight, and is inexpensive is increasingly available. It has become widely used. Along with this trend, liquid crystal display devices are required to have a large screen, and even if the screen is enlarged, a light pen that is easy to operate can easily detect the coordinates of any position on the screen. You need to be able to.

[0003]

2. Description of the Related Art FIG. 15 is a block diagram showing an example of a conventional position coordinate detecting device. The position coordinate detecting device comprises a position coordinate detecting circuit 1 and a light pen 2. The light pen 2 has a built-in light receiving element such as a photodiode, and its light receiving surface is located at a position intended by the user in the screen 3a of the cathode ray tube (CRT) 3 and detects light emission of that portion.

In the position coordinate detection circuit 1, a control signal input to the CRT 3 together with a video signal is branched and input, while an output signal of the light pen 2 is supplied. The control signals are the frame signal shown in FIG. 16A, the line signal shown in FIGS. 16B and 16E, and the dot signal shown in FIGS.

The light detection signal from the light pen 2 is shown in FIG.
As shown in (D), it is once in one frame. For example, as shown in the enlarged view of (G) in the figure, the dot signal after inputting the line signal ((E) in the figure) immediately after the frame signal ((F) in the figure) ), The position coordinate detection circuit 1 detects that the line pen 2 is at the position coordinates of the fourth horizontal dot and the first vertical line.

FIG. 17 is a block diagram of another example of a conventional position coordinate detecting device. The position coordinate detecting device comprises a touch panel 5 and open / short inspection drivers 6 and 7.

The touch panel 5 has a structure in which a large number of transparent switches 5a are formed in a matrix on a transparent flexible substrate, and is arranged at a position facing the screen 8a of the CRT 8. The open / short inspection driver 6 inspects whether each transparent switch 5a aligned in the column direction is open or short. The open / short inspection driver 7 inspects whether each transparent switch 5a arranged in the row direction is open or short.

A screen 8 displayed through the touch panel 5
When the user presses the desired position on the touch panel 5 with a finger or a pen while looking at the image of a, only the pressed transparent switch 5a is short-circuited. As a result, the coordinates detected by the open / short inspection driver 6 as a short state are output as the ordinate, and the coordinates detected by the open / short inspection driver 7 as the abscissa are output.

The above is an example of the CRT 2 or 8 as the display device. In recent years, however, the light pen 2 or the touch panel 5 is used to detect the position coordinates even for a liquid crystal display device which is in the limelight. Can be considered. A liquid crystal panel forming the screen of this liquid crystal display device is generally represented by an equivalent circuit shown in FIG. One pixel is a pixel electrode LC
D, capacitor CA, thin film transistor (TFT) TR
And each end of the pixel electrode LCD and the capacitor CA is commonly connected to the source of the thin film transistor TR. Liquid crystal is sandwiched between the pixel electrode LCD and the common electrode on the counter substrate.

A large number of pixels are arranged in a matrix, and the gates of the thin film transistors TR of a plurality of pixels arranged in the row direction (line direction) are commonly connected by a gate bus GB and arranged in a column direction. The drains of the thin film transistors TR of the pixels are commonly connected by the drain bus DB.

When a selection signal is input to one gate bus, a plurality of thin film transistors commonly connected to the gate bus are turned on, and the drain bus voltage is supplied via the drain and the source of each turned on transistor. Are simultaneously written in each pixel electrode, that is, each liquid crystal (so-called line sequential writing). The liquid crystal changes its transmittance according to this writing voltage. Gate bus to GB _n , G
One frame is completed by sequentially selecting B _{n + 1} , GB _{n + 2} , ... And writing data in all pixels.

When the position coordinates are detected on the liquid crystal panel by using the light pen 2 described above, the CRT 3 performs the dot sequential writing, while the liquid crystal panel performs the line sequential writing as described above. Therefore, the light pen cannot be used because the coordinates in the line direction cannot be specified.

That is, the position of the light pen is specified only by specifying the gate bus. If the gate buses are arranged in the vertical direction and are scanned sequentially in the vertical direction, only the position of the vertical direction, that is, the line is specified. No (1 to n lines can be detected, but the drain bus line, that is, the column direction cannot be specified).

On the other hand, when a liquid crystal panel is used instead of the CRT 8 of the conventional apparatus shown in FIG. 17 and the position coordinates are detected by the touch panel 5, the touch panel 5 is independent of the liquid crystal panel, and therefore the position coordinates can be detected. Is. However, since the device scale is large and it is difficult to provide a large number of fine transparent switches 5a in manufacturing, it is difficult to specify the location corresponding to the pixel. Also, with the increase in screen size,
Although it is necessary to increase the size of the touch panel, this increase is also difficult in manufacturing.

Therefore, the present applicant has previously filed Japanese Patent Application No. 4-145.
No. 986, in a projection type liquid crystal display device for enlarging and projecting a plurality of liquid crystal panels and synthesizing them on a screen, by making the scanning direction of at least one liquid crystal panel orthogonal to the scanning directions of other liquid crystal panels, We proposed a position coordinate detection device that can detect position coordinates in the line direction.

Here, the liquid crystal panel is the liquid shown in FIG.
Crystal panel gate bus GB_n, GB _{n + 1}, GB_{n + 2}To
The frame signal shown in FIG. 19A and the frame signal shown in FIG.
19 (C), (D) and (E) in synchronization with the line signal.
The gate signals shown in are sequentially input to other gate buses.
Input the gate signal in sequence and the drain bus voltage (write
Data to be embedded) is written in all pixels. At this time, the liquid crystal is reliable
To improve writing performance, it is necessary to drive symmetrically
Data needs to be inverted every frame.

Therefore, the liquid crystal applied voltage of each pixel on the n line, for example, applied through the drain bus is shown in FIG.
As shown in (1), it is inverted every frame in synchronization with the n-line gate signal. When the data is “1”, the voltage value | V _P | in FIG. 19F is larger than that when the data is “0”.

Thus, the gate bus GB_nAnd drain
Bus DB_mLarge value V in the A pixel at the intersection with_D(Day
Of the A pixel when the drain voltage of "1") is applied.
The optical response is as shown in Fig. 19 (G).
GB_nAnd drain bus DB _{m + 1}B pixel at the intersection with
Less than V_D(Data “0”) drain voltage is applied
The optical response of the B pixel at the time of irradiation is as shown in FIG.
, And the gate bus GB regardless of the data value_nAt the gate
Spike-shaped at each frame timing when the signal is applied
A light pulse is generated. And this spike-shaped optical pulse
Occur on the same line and move sequentially with each horizontal scanning cycle.
To go.

Therefore, the position coordinate detection device proposed by the applicant of the present invention monitors the position coordinates by monitoring the above-mentioned spike-shaped light pulse generated in each of the liquid crystal panels whose scanning directions are orthogonal to each other with a light pen. To identify.

[0020]

However, in the position coordinate detecting device proposed by the present applicant, it is necessary to use a plurality of liquid crystal panels and make the scanning directions orthogonal to each other, so that only the projection type liquid crystal display device is applied. Cannot be applied to a direct-viewing type liquid crystal display device having a single scanning direction. Therefore, it is difficult to increase the size of the touch panel for detecting the coordinates of the direct-viewing type liquid crystal display device, and the touch panel becomes large in size. There is no choice but to increase the size.

The present invention has been made in view of the above points, and a period for displaying an image in which the brightness in the horizontal direction of the screen is periodically different is provided, and the above change in brightness is detected based on a detection signal from the light pen. By doing so, it is an object of the present invention to provide a position coordinate detection device that solves the above problems.

[0022]

In order to achieve the above object, the present invention has a matrix of n pixels in the vertical direction and m pixels in the horizontal direction, as shown in the principle diagram of FIG. It has a light pen 11 for indicating an arbitrary position on a display screen 10 of a display device in which display data is line-sequentially written and driven to obtain a light detection signal, a display data generating means 12 and a position coordinate detection circuit 13. .

Here, the pixel data generating means 12 displays on the display screen 10 of the display device a coordinate detection image in which the brightness of each of a plurality of band-shaped image portions dividing the screen in the horizontal direction changes periodically. Generate display data Further, the position coordinate detection circuit 13 receives the light detection signal from the light pen 11 as an input signal, detects the coordinate in the vertical direction of the screen based on the detection signal of the spike-like light pulse, and uses it as the brightness detection signal of the coordinate detection image. Based on this, the coordinates in the horizontal direction of the screen are detected.

[0024]

In the present invention, the horizontal direction of the display screen 10 is divided into a plurality of areas, and the coordinate detection image composed of a plurality of band-shaped image portions whose brightness changes periodically is displayed for a predetermined period. Since the output light detection signal level of 1 indicates the brightness of the plurality of band-shaped image portions, the position coordinate detection circuit 13 can detect the horizontal coordinate of the screen from the change of the light detection signal level.

Further, since the spike-shaped light pulse generated on the same line by line-sequential writing moves from the top to the bottom of the screen every horizontal scanning cycle, the position coordinate detection circuit 13 detects this spike from the light detection signal of the light pen 11. By detecting the light pulse having a circular shape, the coordinates in the vertical direction of the screen can be detected in the same manner as the previously proposed device of the present applicant.
Therefore, in the present invention, the coordinates of an arbitrary position on the display screen of the display device in which the display data is written and driven line-sequentially can be detected using the light pen 11.

[0026]

FIG. 2 is a block diagram of an embodiment of the position coordinate detecting device according to the present invention. In the figure, the same components as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. In FIG.
Reference numeral 20 denotes a liquid crystal panel which is a display screen of the liquid crystal display device and corresponds to the display screen 10 and is represented by the equivalent circuit shown in FIG. 18 and has m pixels in the horizontal direction of the screen and n pixels in the vertical direction of the screen. They are arranged in a matrix.

The light pen 11 has a photodiode 11a inside and a switch 11b outside. The switch 11b is operated by the user, at the time of ON and applies the display data switching circuit 22 to supply voltage V _X as a coordinate detection start signal.

The display signal generator 21 and the display data switching circuit 22 constitute the display data generating means 12. The display signal generator 21 is a known circuit including a computer and the like, and generates a frame signal, a horizontal synchronizing signal (line signal) and a dot clock together with the display data to be displayed and supplies them to the display data switching circuit 22.

The display data switching circuit 22 will be described later.
During the period from the input of the coordinate detection start signal from the switch 11b of the light pen 11 to the input of the detection completion signal from the data scan monitor circuit 23, the display data for coordinate detection described later is generated, and the other period The display data from the display signal generator 21 is passed as it is, supplied to the liquid crystal panel 20 and the gate scan monitor circuit 24, respectively, and output address signals to the data scan monitor circuit 23 and the gate scan monitor circuit 24, respectively.

The data scan monitor circuit 23 and the gate scan monitor circuit 24 respectively constitute the position coordinate detection circuit 13 described above. As will be described later, the data scan monitor circuit 23 displays the coordinates in the horizontal direction of the screen (hereinafter, “column coordinates”).
(Also referred to as), and the detected column coordinates are displayed on the display signal generator 2
Supply to 1. The gate scan monitor circuit 24 detects coordinates in the vertical direction of the screen (hereinafter, also referred to as “row coordinates”),
The detection row coordinates are supplied to the display signal generator 21.

Next, the configuration of each part of this embodiment will be described in more detail. FIG. 3 shows a circuit diagram of an embodiment of the display data switching circuit 22. In the figure, the OR circuit 31 obtains a signal obtained by logically adding the coordinate detection start signal from the switch 11b of the light pen 11 and the detection completion signal from the data scan monitor circuit 23 to the clock of the D-type flip-flop 32. Apply to the terminal. The D-type flip-flop 32 has its inverting output terminal connected to the data input terminal, and its non-inverting output terminal generates and outputs a signal that is inverted every time a high-level signal is applied to the clock terminal, and a switch circuit. It is applied to 33 as a switching signal.

The switch circuit 33 is connected to the terminal 33a after the initial state and after the detection completion signal is input, and the display signal generator 2 is connected.
The display data from No. 1 is output to the terminal 37 as it is through the common terminal 33c, and when the coordinate detection start signal is input, the data is switched from the terminal 33b to the data from the ROM (read only memory) 36. Is output to the terminal 37 via the common terminal 33c.

On the other hand, the frame signal, the line signal and the dot clock generated by the display signal generator 21 are directly output to the liquid crystal panel (see 20 in FIG. 2), while the frame signal is output to the counters 34 ₁ and 34 ₂ . The line signals are respectively applied as clocks and counted, and the line signals are respectively applied as clocks to the counters 35 ₁ and 35 ₂ and counted.

The counters 34 ₁ and 34 ₂ are "1" corresponding to the number of pixels m in the horizontal direction of the screen of the liquid crystal panel 20.
Addresses from "m" to "m" are sequentially generated in a frame cycle, and the addresses are supplied to the data scan monitor circuit 23 via the terminal 38 and to the address terminals of the ROM 36. The ROM 36 generates display data for coordinate detection, which will be described later, whose luminance changes in a frame cycle by the input of this address signal, and outputs it to the terminal 33b of the switch circuit 33.
To enter.

The counters 35 ₁ and 35 ₂ correspond to the pixel number n in the vertical direction of the screen of the liquid crystal panel 20 and are "1".
To "n" are sequentially generated in one horizontal scanning cycle, and the addresses are supplied to the gate scan monitor circuit 24 through the terminal 39.

FIG. 4 shows a first embodiment of the coordinate detection image displayed on the liquid crystal panel by the coordinate detection display data generated by the ROM 36. As shown in the figure, in the coordinate detection image, the longitudinal direction is the screen vertical direction, and the band-shaped image portion having a width obtained by dividing the horizontal direction of the screen by m is shown in FIG.
The images are moving rightward on the screen as indicated by 41 ₁ , 41 ₂ , ... 41 _m in (B) and (C). Here, the brightness of the band-shaped image portions 41 _{1 to} 41 _m is sufficiently lower than the brightness of other image portions, for example, black, and the other image portions are white. In the figure, reference numeral 45 indicates the position of the light pen 11.

When the coordinate detection image of this embodiment is used,
When the coordinate detection start signal is input as shown in FIG. 5B, the display data is synchronized with the frame signal shown in FIG. The detection time is generated and output. Here, if the light pen is 4 from the left side of the screen as shown by 45 in FIGS. 4 (A) to 4 (C).
Assuming that the light detection signal of the light pen is located on the th pixel position, the light detection signal of the light pen shows a black band image portion after the fourth frame signal input from immediately after the coordinate detection start signal is input, as schematically shown in FIG. The level drops significantly because it is detected. Therefore, the data scan monitor circuit 23 can know from this that the position coordinate of the light pen in the horizontal direction of the screen is the fourth position from the left of the screen.

FIG. 6 shows a circuit diagram of an embodiment of the data scan monitor circuit 23. Data scan monitor circuit 23
Is the logical product of the inspection signal generating circuit 51 to which the frame signal and the line signal are input, the comparator 52 for discriminating the output light detection signal level of the light pen, and the output signals of both the inspection signal generating circuit 51 and the comparator 52. AND circuit 53 and "1" in which the value changes by "1" for each frame
Is composed of a latch circuit 54 which latches a coordinate address having a value of "m" with an output signal of the AND circuit 53.

Data scan monitor circuit 2 having such a configuration
3, the inspection signal having the frame period shown in FIG. 7C is output from the inspection signal generating circuit 51 to which the frame signal shown in FIG. 7A and the line signal shown in FIG. 7B are input. Generated and output. On the other hand, as shown in FIG. 7 (D), the light pen (refer to 11 in FIG. 2) emits a high level light when any of the black band-shaped image portions (vertical lines) 41 _{1 to} 41 _m is detected. The detection signal is extracted (for convenience of illustration, the polarity of FIG. 7D is inverted from that of FIG. 5D).

As a result, the AND circuit 53 outputs the data shown in FIG.
As shown in (E), when a black vertical line is detected, an inspection signal is output and applied to the latch circuit 54 to latch the coordinate address. Therefore, the value "1" to
Among the coordinate addresses of "m", the coordinate address of the value when the output signal of the AND circuit 53 falls, for example, is shown in FIG.
It is held in (F) as indicated by 58, and this held coordinate address is output as the column coordinate address.

FIG. 8 is a block diagram of an embodiment of the gate scan monitor circuit 24. As shown in FIG. 8A, the gate scan monitor circuit 24 includes a light output correction comparison circuit 61 and a latch circuit 62. The light output correction comparison circuit 61, as shown in FIG. 8B, has a switch circuit 65 whose switching is controlled by display data, and a comparator 66 which compares the output voltage of the switch circuit 65 with the output light detection signal of the light pen 11. And consists of.

Gate scan monitor circuit 2 having such a configuration
4 will be described. As described above, in the liquid crystal, as described above, the write data is inverted every frame to improve reliability, and the gate bus line is synchronized with the line signal shown in FIG. Is selected line by line from top to bottom. Therefore, the light detection signal extracted from the photodiode 11a of the light pen 11 has a detection portion of a spike-shaped light pulse generated in each frame period in which the horizontal scanning line on which the light pen 11 is positioned is driven. Become.

FIG. 9C shows the above photodetection signal, where c ₁₁ and c ₁₂ are the above-mentioned spike-like optical pulse detection portions when the write data is "1", and c ₂₁ and c ₂₂ are the write data "0". The above-mentioned spike-shaped optical pulse detection portion at the time of "is shown. In this way, the write data (display data) is "0"
In both cases of "1" and "1", the photodetection signal shown in FIG.
Although it has a spike-shaped optical pulse detection portion having a frame period in synchronization with the frame signal shown in FIG. 9A, the level is different when the display data is "0" and "1".

Therefore, in the light output correction / comparison circuit 61, the switch circuit 65 shown in FIG. 8 (B) is switched according to the value of the display data, and the threshold value applied to the comparator 66 is the display data "1". If, V ₁ , "0"
In case of, switch to V ₂ (however, V ₂ <V ₁ ). As a result, the spike-shaped light pulse detection portion is accurately detected by the comparator 66 of the light output correction comparison circuit 61 regardless of whether the display data is "0" or "1".
A detection signal as shown in (D) is taken out.

The latch circuit 62 of FIG. 8A latches the coordinate address whose value sequentially changes from "1" to "n" in the horizontal scanning period at the falling edge of this detection signal, for example, and also the frame signal. Is reset by. As a result, the latch circuit 62 holds the coordinate address at which the light pen 11 is located, as indicated by 68 and 69 in FIG. 9E, and this coordinate address is output as the row coordinate address.

Next, the operation of the apparatus of this embodiment shown in FIG. 2 will be described with reference to the flowchart of FIG. The user fixes the light pen at an arbitrary position on the liquid crystal panel 20.
At this time, a normal image based on the display data from the display signal generator 21 is displayed on the liquid crystal panel 20 (step 71). In this state, when the user turns on the switch 11b of the light pen 11 (step 72), the coordinate detection start signal is supplied to the display data switching circuit 22 at that moment, and the position coordinate detection period starts, and the display data switching circuit 22 is started.
Displays the entire screen of the liquid crystal panel 20 in white (step 7).
3).

Next, the display data switching circuit 22 is shown in FIG.
As shown in, the strip-shaped image portion 41 _{1 in} which each pixel at the leftmost end of the screen is displayed in black is displayed on the liquid crystal panel 20 (step 74). At this time, the data scan monitor circuit 23 receives the coordinate address “1” (= m) currently displayed in black from the display data switching circuit 22 and the light pen 11
It is checked whether the image is black or white based on the light detection signal level from (step 75). Further, at this time, the gate scan monitor circuit 24 checks whether or not the spike-like light pulse is detected based on the light detection signal level from the light pen 11 (step 75), and when the spike-like light pulse is detected. Holds row coordinates.

Subsequently, the data scan monitor circuit 23 determines whether or not the light detection signal from the light pen 11 indicates the black level (step 76), and when it does not indicate the black level, the value of the coordinate address m. Is added by "1" (step 77), and in the next frame, the display data switching circuit 22 causes the second pixel from the left end of the screen to be black as shown in FIG. ₂ for LCD panel 2
It is displayed at 0 (step 74).

Based on the light detection signal level, the gate scan monitor circuit 24 again checks the row coordinates by checking the spike-like light pulse and the data scan monitor circuit 23 checks the level (step 75). It is determined whether or not (step 7)
6). Then, when it is not the black level, the coordinate address m is again incremented by "1" (step 77).

Thereafter, steps 74 to 7 are carried out in the same manner as above.
The operation of 7 is repeated until the black level is determined in step 76. When the data scan monitor circuit 23 determines that the light detection signal from the light pen 11 indicates the black level, the column coordinates based on the value of the coordinate address m at that time and the row coordinates detected in step 75 are detected. Is output to the display signal generator 21 (step 7
8) The detection end signal is output from the data scan monitor circuit 23 to the display data switching circuit 22 to end the coordinate position detection operation, and the normal display of step 71 is resumed.

In this embodiment, during the position coordinate detection period,
The line coordinates are detected every time the image is judged to be black or white,
The row coordinates are also output when the detection of the column coordinates is confirmed, but the detection of the row coordinates is performed in the strip-shaped image portions 41 _{1 to} 41 _m.
May be performed at any time regardless of detection of.

Next, another embodiment of the present invention will be described. FIG. 11 shows a second embodiment of the coordinate detection image in the present invention. In the present embodiment, the display data read from the ROM 36 in the display data switching circuit 22 shown in FIG. 3 is, for example, eight strip-shaped image portions (e.g., eight strip-shaped image portions having a longitudinal direction in the vertical direction) in the liquid crystal panel 20 as shown in FIG. Vertical line) 8
Of 1 _{1-81 8,} together with the interleaved between white and black for each x present, to display an image so as to vary the x book by a power of two for each frame.

That is, in the first frame, as shown in FIG.
As shown in FIG. ₁~ 81₈Strange
The numbered strip image area is black and the even numbered strip image area is white.
1 as displayed (= 2⁰) Alternate black and white display for each book
It In the second frame, 8 lines as shown in FIG.
Band image part 81₁~ 81₈2 (= 2¹) Black and white for each book
Alternate display. Then, in the third frame, as shown in FIG.
As shown in (C), eight strip-shaped image portions 81₁~ 81₈
4 (= 2²) Alternate black and white display for each book.

According to the present embodiment, when the light pen is at the position indicated by 45 in FIG. 11, the data scan monitor circuit 23 outputs, for example, "0" when the light detection signal level from the light pen 11 indicates black. , White is stored as “1” and a detection result of “001” is obtained in three frames.
This detection result is expressed as a 3-bit binary number in which the value of the first frame is LSB and the value of the third frame is MSB, and therefore the data scan monitor circuit 23 detects that the column coordinate is "4".

When the coordinate detection image of the first embodiment shown in FIG. 4 is displayed, a maximum of 8 frames is required to detect the column coordinates of the light pen 11 in the above example, whereas in the present embodiment, it is necessary. 3 (≧ log ₂ 8) since it is detected in the column coordinate frame can be shortened as compared with the coordinate detection period to the first embodiment. This is particularly effective as the number of pixels m in the horizontal direction of the screen increases.

FIG. 12 shows an image for coordinate detection in the present invention.
A third embodiment will be described. Display data switching circuit of FIG. 3 described above
The display data read from the ROM 36 in the 22 is the book
In the embodiment, as shown in FIG. 12 in the liquid crystal panel 20.
, For example, eight strip-shaped image portions having a longitudinal direction in the vertical direction
91₁~ 91₈The brightness (gradation) of each from left to right
Images that become larger one after another are displayed. Here, the strip image part
91₁The brightness of 1/8, and the band-shaped image portion 91₈Brightness of 8 /
8 (that is, white), and the band-shaped image portion 91₂~ 91 ₇Is left
From the right to the right, the image is such that the brightness is increased by 1/8.
It

The data scan monitor circuit 23 in the case of detecting coordinates with a light pen using such a coordinate detection image has a configuration as shown in FIG. In the figure, the circuit switching circuit 95 is switched, for example, by a line signal, when each received by the light pen 11 to each luminance of the strip image portion 91 _{1-91 8} described above, light pen 1
Eight kinds of reference voltages corresponding to the photodetection signal levels obtained from No. ₁ are sequentially selected and output in an order corresponding to the arrangement order of the strip image portions 91 _{1 to} 91 ₈ .

The comparison circuit 96 compares the levels of the eight types of reference voltages selected and output by the switch circuit 95 in a predetermined order in the horizontal scanning cycle with the light detection signals from the light pen 11, and the two match. When it does, a coincidence signal of a predetermined level is output. The counter 97 counts the line signal and supplies the count output to the latch circuit 98.

The latch circuit 98 latches the count output of the counter 97 when the coincidence signal is input from the comparison circuit 96. Here, since the count output of the counter 97 is synchronized with the switching of the switch circuit 95 and indicates which number of reference voltage is output, the latch circuit 98 is indicated by the output light detection signal of the light pen 11. The order of the reference voltage indicating the luminance, that is, the value indicating the order of the strip-shaped image portion from the left side of the screen in FIG. 12 is latched. Therefore, the column coordinate address is fetched from the latch circuit 98.

According to the present embodiment, in principle, the position coordinate detection period may be one frame, and it is effective to shorten the detection period. However, since the liquid crystal may have one frame, that is, the writing speed may not reach the written gray level due to the slow response speed of the liquid crystal, the position coordinate detection period may be set to several frames (other The same applies to the examples).

FIG. 14 is a block diagram of another embodiment of the main part of the display data switching circuit 22. In this embodiment, the display data generation unit of the display data switching circuit 22 is the same as that shown in FIG. 3, but is characterized in that the frequency of the control signal output to the liquid crystal panel 20 or the internal address counter is set higher than the normal frequency. .

In FIG. 14, the oscillation signal of a predetermined frequency output from the oscillator 101 is sequentially divided by the dot clock counter 102, the line signal counter 103, and the frame signal counter 104, for example, 100 Hz.
After that, it is input to the terminal b of the switch 107. The output signals of the dot clock counter 102 and the line signal counter 103 are also input to the terminals b of the switches 105 and 106, respectively.

Here, the switches 105, 106 and 10
A dot clock, a line signal, and a frame signal are input to the respective terminals a of 7 from the signal generator 21 shown in FIG. On the other hand, the signal input to the terminal b of the switch 105 has a frequency higher than the dot clock frequency, the signal input to the terminal b of the switch 106 is higher than the regular line signal frequency, and the terminal of the switch 107 further. The signal input to b is set to a frequency of 100 Hz, which is higher than the regular frame signal frequency of 60 Hz.

The switches 105, 106 and 107 are respectively connected to the terminal b side by a coordinate detection start signal, and are switched and connected to the terminal a side by a detection completion signal. As a result, during the coordinate detection period, the signals extracted from the switches 105, 106 and 107 connected to the terminal b side are used as the dot clock, the line signal and the frame signal, respectively, so that the conventional 10 frames, that is, 167 ms.
(= 16.7ms × 10) Required coordinate detection time is 100
This is possible in ms (= 10 ms × 10), which is effective in shortening the coordinate detection time.

By the way, in the first embodiment, the number of frames corresponding to the number of pixels m in the horizontal direction of the screen is required to detect the column coordinates.
In the second embodiment, a memory having a log ₂ m bit number is required for coordinate calculation. Furthermore, in the third embodiment, it is premised that the liquid crystal panel 20 can perform gradation display with the number of pixels m in the horizontal direction of the screen. From the above, it is possible to alleviate the above problems by using each of the embodiments together.

For example, when the screen is divided into a plurality of parts in the horizontal direction, the second embodiment is applied to one divided screen, and the divided screens to which the second embodiment is applied are assigned in the first embodiment, The memory capacity can be reduced as compared with the case where the second embodiment is applied to all screens.

The present invention is not limited to a liquid crystal display device, but can be applied to any display device such as electroluminescence which drives line-sequentially to write and drive display data.

[0068]

As described above, according to the present invention, the coordinates of an arbitrary position on the display screen of a display device in which display data is written and driven line-sequentially can be detected by using a light pen. Not only LCD type liquid crystal display device but also direct view type liquid crystal display device can be applied, the device scale can be downsized compared to touch panel, and since touch panel is not used, it is easy to enlarge the display screen. It has features such as being able to deal with.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is a block diagram of an embodiment of the device of the present invention.

FIG. 3 is a circuit diagram of an embodiment of a display data switching circuit.

FIG. 4 is an explanatory diagram of a first embodiment of a coordinate detection image.

5 is a time chart for explaining coordinate detection using the image of FIG.

FIG. 6 is a circuit diagram of an embodiment of a data scan monitor circuit.

7 is a time chart for explaining the operation of FIG.

FIG. 8 is a configuration diagram of an embodiment of a gate scan monitor circuit.

9 is a time chart for explaining the operation of FIG.

FIG. 10 is a flowchart for explaining the operation of the embodiment of the present invention.

FIG. 11 is an explanatory diagram of a second embodiment of the coordinate detection image.

FIG. 12 is an explanatory diagram of a third embodiment of the coordinate detection image.

FIG. 13 is a configuration diagram of another embodiment of the main part of the device of the present invention.

FIG. 14 is a configuration diagram of another embodiment of the main part of the display data switching circuit.

FIG. 15 is a configuration diagram of an example of a conventional device.

16 is a time chart for explaining the operation of FIG.

FIG. 17 is a configuration diagram of another example of a conventional device.

FIG. 18 is an equivalent circuit diagram of an example of a liquid crystal panel.

FIG. 19 is a time chart for explaining the operation of the applicant's previous proposed device.

[Explanation of reference numerals] 10 display screen 11 light pen 12 display data generating means 13 position coordinate detecting means 20 liquid crystal panel 21 display signal generator 22 display data switching circuit 23 data scan monitor circuit 24 gate scan monitor circuit 36 read only memory _{(ROM) 41 1 ~41 m,} 81 1 ~81 7, 91 1 ~91 7 band image 51 test-signal generating circuit 52, 66 a comparator 54,62,98 latch circuit 61 the light output correction comparator circuit 96 comparison circuit 101 oscillator 102 dot clock counter 103 line signal counter 104 frame signal counter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hisashi Yamaguchi 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited

Claims (5)

[Claims] 1. A display screen (10) of a display device in which n pixels in the vertical direction and m pixels in the horizontal direction are arranged in a matrix and display data is written and driven line-sequentially by designating an arbitrary position. A light pen (11) that obtains a light detection signal and a coordinate detection image in which the brightness of each of a plurality of band-shaped image portions that divide the screen lateral direction periodically change are displayed on the display screen (10) of the display device for a predetermined period. Display data generating means (12) for generating display data to be displayed and a light detection signal from the light pen (11) are received as input signals, and the vertical coordinate of the screen is detected based on the detection signal of the spike-like light pulse. A position coordinate detection circuit (13) for detecting coordinates in the horizontal direction of the screen based on a brightness detection signal of the coordinate detection image. 2. The display data generating means (12) sets only one band-shaped image part of the plurality of band-shaped image parts to a predetermined brightness different from each brightness of the other band-shaped image parts, and the predetermined brightness. Display data such that one strip-shaped image portion of the light pen (1) is sequentially shifted for each frame, and the position coordinate detection circuit (13) causes the light pen (1
2. The position coordinate detecting device according to claim 1, wherein the coordinates in the horizontal direction of the screen are detected by detecting the predetermined brightness from the output light detection signal of 1). 3. The display data generating means (12) alternately arranges a first brightness and a second brightness for every x lines of the plurality of strip-shaped image portions, and the x lines for each frame. Generate display data in which the power of 2 changes, and the position coordinate detection circuit (13) causes the light pen (1
2. The position coordinate according to claim 1, wherein the coordinate in the horizontal direction of the screen is detected based on the detection pattern of the first brightness and the second brightness in a predetermined frame period from the output light detection signal of 1). Detection device. 4. The display data generation means (12) generates display data in which the plurality of band-shaped image portions are displayed with different luminances, and the position coordinate detection circuit (13) includes the light pen ( 1
The coordinate in the horizontal direction of the screen is detected from the brightness identified based on the output light detection signal level of 1).
The position coordinate detection device described. 5. The display data generating means (12) sets and displays a frame signal frequency, a horizontal scanning frequency and a dot clock frequency higher than the normal frequency during the predetermined period for displaying the image for coordinate detection. The position coordinate detecting device according to claim 1, wherein the position coordinate detecting device generates data.