JPH0454622A - Pen type coordinate input device - Google Patents

Abstract

PURPOSE:To know the input coordinate position by detecting a dark level signal by a pen type photodetector by writing the dark level signal for an arbitrary prescribed time in accordance with a timing at the time of rewriting of a static operation, and thereafter, writing original pixel information. CONSTITUTION:A liquid crystal cell 63 is driven by an accumulated voltage of a capacitor 62 in the case of a regular state (non-selection state). In the case of a selection state, a voltage on an (x) line is applied to the capacitor 62 and information is rewritten. That is, cells selected by (x) and (y) are rewritten successively, and except the time of rewriting, the state is not varied. In a driving state of a liquid crystal panel at the time of reading a position of the liquid crystal panel, a part or the whole is bright. In such a state, a dark level signal becomes a dark level in point sequence by length of one horizontal scanning period. When a delay time of elements (liquid crystal, photodetector) is corrected from a point for going down to the dark level (point for going up to the dark level), a coordinate of a position which a pen type coordinate input device comes into contact with (detects) is derived.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a light pen type coordinate input device suitable for a static type display device such as an active matrix type liquid crystal.

[Conventional technology]

There is a strong demand for office computers and personal computers to be thin and lightweight, and display devices using liquid crystals, plasma, etc. are increasingly being used instead of CRTs. liquid crystal.

A display such as a plasma display is not a dot sequential scanning type like a CRT, but a line sequential (including multiple lines simultaneously) scanning type. Furthermore, active matrix type liquid crystals, memory type plasmas, etc. operate statically. Therefore, a light pen type coordinate input device such as a CRT display cannot be applied to the coordinate input of the above-mentioned thin display such as liquid crystal or plasma.
There is 921. Since there is a 1:1 code for address number 2 and the plasma shines, the detection time is constant regardless of the light pen position, but the number of addresses is limited.

There are problems such as an increase in the flicker cycle speed, so it is not suitable for static operation liquid crystal and plasma displays. Also,
The coordinate input device installed in front of the display element can be applied to point-sequential, line-sequential, or static types; however,
Since the coordinate input device is incorporated on the display surface, the display becomes difficult to see. Particularly in active matrix type liquid crystals, the display quality is significantly degraded. Furthermore, the coordinate input device is thick and causes a step difference in coordinate input due to parallax.

[Problem to be solved by the invention]

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to input data using a simple light pen in a static drive type display without combining a transparent member for a coordinate input device on the viewing surface of the display device. The purpose of this invention is to provide a coordinate input device that can perform the following tasks.

[Means to solve the problem]

A dark level signal is written for an arbitrary certain period of time in accordance with the rewriting timing of the static operation, and then the original pixel information is written. Note that the insertion period of the dark level signal is determined based on the coordinate input speed and visual characteristics (period at which flicker is not noticeable). The dark level signal is detected by a pen-shaped light receiving element and the input coordinate position is determined.

[Effect]

The dark level signal becomes clear level point by point with the length of the -horizontal scanning period. By correcting the delay time of the elements (liquid crystal, light-receiving element) from the point where the light level drops to the clear level (the point where it rises from the dark level), the coordinates of the position touched (detected) by the pen-type coordinate input device can be determined.

〔Example〕

The present invention will be explained in detail using FIGS. 1 to 5. FIG. 1 is a diagram showing the configuration of a pen-type coordinate position input device of the present invention. Reference numeral 6 indicates a liquid crystal panel (active matrix type, eg TPT, MIM, etc.), and 5 and 4 indicate a signal driver and a row driver of the liquid crystal panel 6, respectively. The normal driving of the liquid crystal panel 6 will be explained with reference to FIGS. 1 and 2.

Here, FIG. 2 shows an equivalent circuit for one cell of the liquid crystal panel 6, in which 61 is a switch element, 62 is a capacitor, and 63 is a liquid crystal cell. The liquid crystal cell 63 is driven by the voltage stored in the capacitor 62 in the normal state (non-selected state II). This operation is a static operation.0
In the selected state, the voltage on the X line is applied to 62 and the information is rewritten. That is, the cells selected by x and y are sequentially rewritten, and there is no change in state except during rewriting.

The driving state of the liquid crystal panel 6 when reading the position on the liquid crystal panel 6 is that part or all of the liquid crystal panel 6 is lit.

(In the case of color, it is sufficient that any color bit is lit for 1 pixel) To input the position, read the coordinates where the light receiving part of the pen-shaped light receiver 7 touches the liquid crystal panel 6 from among the above shining places. Spread.

Here, as shown above, row driver 4. The operation of the signal driver 5 will be explained. Note that the video signal is scanned and rewritten one frame at a time point-by-point.

(Non-interlane) First, the row driver 4 will be explained. The liquid crystal panel 6 is the fifth
As shown in the figure, the odd numbered row (solid line; example V m-Re
ye V 1141 line) and even numbered line (dashed line; example)
'a-1y! Divide into m + □ rows). Consider the period f of any one frame. During the odd-numbered scanning period in FIG. 5, for example, at the timing of scanning the y line (1, period), y, +□ is scanned, and t.

During the scanning period, the level of the video signal for each pixel is set to a dark level. That is, in the period t, the pixels above ye+ sequentially become dark level according to the horizontal scan s y*+1
At the timing of scanning the line (tm+□ period), y
The direction is y, the +1 line is selected again, and the original video signal is supplied from the X line in accordance with the horizontal scanning. As a result, the y, (odd number) line is not selected and maintains the state of the previous frame, and the ya+z (even number) line is selected at t2.
Period, t. Both periods are selected, and the period t is a dark level, and the period t, . . .+1 is a period in which video information for pixels is written. This frame f1 is assumed to be an even line selection frame. Next, consider the odd line selection frame fJ. In the fJ line, 1, for example, je-
Line y is selected for both period 1 and period t, and y, -
, the line maintains the state of the previous frame.

That is, odd lines are selected and even lines are not selected. The f frame is also the same as the f1 frame except for the selected and non-selected lines.

In addition to ft=fp, a frame in which video information for pixels is sequentially written for all lines is f.

Frame.

The combination of f,,f,,f,frames is determined by the response speed of the pen-type position input device and the degree of screen flickering caused by inserting a dark level signal.For example, the frame period is 1/30. If the position input speed is 5 seats 1/sec or more, fl: f, : f
, it is preferable to choose a ratio of 1:l:4. From the above, f and frames may be omitted in some cases.

Next, the signal driver 5 supplies a video signal or a dark level signal to the X signal line for each cell of the liquid crystal panel 6 for each pixel in accordance with horizontal scanning.

The timing gate controls the combination of f1:f,:f, and the control signal generator 3 controls the timing gate 2.
1 line driver 4. Generates a control clock for the signal driver 5.

FIG. 4 shows the output at the dark level timing when the pen-shaped light receiver 7 is placed in contact with x, y in FIG. 3. The signal names correspond to A, B, and C in FIG.

The output B of the pen-shaped light receiver 7 is converted into a waveform C by waveform shaping 8. The delay time of the liquid crystal panel 6 and the pen-shaped receiver 7 is TΩ.
shall be. The position determination circuit 9 determines the coordinate position 1j y based on the time T from the frame starting point signal (vertical synchronization signal).
By measuring T from the output C of the waveform shaper, T can be calculated by subtracting the above delay time, and from T8, the coordinate position X can be calculated.

I understand. In the above explanation, the input coordinates were found at the falling edge of the C waveform, but the same effect can be obtained even if the input coordinates are found at the rising edge.

In the above explanation, the dark level signal is inserted sequentially from top to bottom on odd-numbered lines and even-numbered lines at any frame time, but the insertion position and time are as follows:
The number of frames per second can be selected arbitrarily depending on the visual characteristics. Control signal generator 32-row driver 4. Timing gate 2. The relationship between the signal driver 5 and the position determination circuit 9 may be matched.

Further, although the above explanation uses an active matrix liquid crystal, it can be similarly applied to a static operation display panel.

Although the timing for inputting coordinates by touching the pen-shaped receiver 7 to the display surface is not specifically explained above, it can be done using a commonly used switch installed on the pen-shaped receiver 7. good.

〔Effect of the invention〕

By using the present invention, it becomes possible to input coordinates in a static drive type display as if using a light pen, without providing a member for a coordinate input device on the surface of the display, which would impair display quality.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the pen-shaped coordinate positioning device of the present invention, Fig. 2 is an equivalent circuit diagram of an active matrix type liquid crystal panel, Fig. 3 is a diagram showing the coordinate position of the panel, and Fig. 4 is the operation. The time chart in FIG. 5 is an explanatory diagram of fL, f, and frames. 1... Video signal amplifier, 2... Timing gate. 3... Control signal generator, 4... Row driver, 5...
- Signal driver, 6... Liquid crystal panel, 7... Pen type receiver. 8... Waveform shaper, 9... Position determination circuit, 61.
...Switch element, 62...Capacitor, 63...
liquid crystal cell. island! Illustrated calculation + Illustrated diagram

Claims (1)

[Claims] 1. In a static operation display such as an active matrix type liquid crystal display, there is a means for displaying a dark level dot-sequentially for each pixel at an arbitrary timing, and the dark level signal is sent to the display surface side of the display. 1. A pen-type coordinate input device, characterized in that it has means for detecting with a light receiver. 2. In claim 1, the timing of inserting the dark level signal includes means for inserting the dark level signal in an even scanning period and means for inserting the dark level signal in an odd scanning period with respect to an arbitrary scanning frame,
A pen-type coordinate input device characterized by combining two periods for inserting the dark level and a frame for inserting the end of the dark level. 3. The pen-type coordinate input device according to claim 1 or 2, wherein the period of the dark level is one horizontal period.