JPS62106536A - Liquid crystal input and output device - Google Patents

Abstract

PURPOSE:To obtain a liquid crystal input/output device containing both functions for input and display of coordinates by using the gate part of the switch elements constituting each display cell as a light receiving element. CONSTITUTION:The gate electrode of switch element 3 is connected electrically to an address bus electrodes 1 and the light can be irradiated to the gate electrode part from outside. Thus a switching action is possible even with the light given from outside. The element 3 is actuated by the light 10 irradiate from a light emitting element 8. The element 3 is also actuated when the light is irradiated to its gate electrode 20. A filter 21 set over the electrode 20 transmits only the light having the wavelength of the light 10. This prevents such a case where a liquid crystal input/output device has a malfunction owing to the ambient illumination light or natural light reached the electrode 20.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a liquid crystal input/output device having an image display function and a coordinate input function.

[Background of the invention]

Handwritten input type WordFlosser, Telewriter, etc.
An image display device equipped with a coordinate input function has been proposed. Conventionally, this scale device has a transparent coordinate input function (transparent electrode panel) overlaid on the image display section, but there are problems such as the coordinates of the image display section and handwritten input coordinates not matching accurately. There was a problem that it was difficult to make it thinner.

As a means to solve this problem, there is a method of optically inputting information by incorporating a light receiving element inside the display cell, as described in Japanese Patent Application Laid-Open No. 57-52089.

However, the method described in this publication requires two path lines: a drive circuit for display and a light reception detection circuit for input, so that it can be used commonly as a display element and a light reception element (imaging element). However, it has the disadvantage that the number of wires increases due to the two path lines, the disadvantage that the circuit scale increases due to the two bus line drive circuits, and the conventional method does not require input. When used as a liquid crystal display element, there is a drawback that one system of the pass line and its driving circuit is wasted. Further, the method described in the above-mentioned publication does not take into consideration the point of performing highly accurate position input by optical writing using a light emitting element or the like.

[Purpose of the invention]

It is an object of the present invention to provide a liquid crystal input/output device which eliminates the drawbacks of the above-mentioned prior art, eliminates waste in construction even when used simply as a display device, and has both functions of input and display. be.

[Summary of the invention]

In order to achieve this purpose, the present invention uses a display path line also as an input detection line, selects a display cell by a display drive circuit, and determines whether or not there is input data in this display cell. By irradiating the input light to increase or decrease the electric charge stored in the liquid crystal display cell used for display, it detects the increase or decrease in the amount of lightning or load on a specific display cell and calculates the coordinates. The feature is that K is made to know the input information.

[Embodiments of the invention]

Hereinafter, the implementation of the present invention will be explained using the drawings.

FIG. 1 is a partial diagram showing an embodiment of a liquid crystal input/output device according to the present invention, in which 1 is an electrode for an address bus, 2 is an electrode for a delta path, 3 is a switch element composed of an MO5 type FET, 4 is a charge storage capacitor, 5 is a liquid crystal display section, 6 is a transparent common electrode of the display panel, 7 is a pulse generator, 8 is a light emitting element, 9 is a microswitch provided on the light emitting element, 10 is a light emitting element from the light emitting element 8. Reflective light, 11 is a switch,
12 is a charge charging circuit, 13 is a charge amount measuring circuit, 14 is a charge amount discharging circuit, and 17 is a charge accumulation amount reading circuit.

In the figure, 1 to 6 indicate equivalent circuits of display cells corresponding to one pixel, 7 to 10 equivalent circuits corresponding to movable light emitting elements, and 11 to 14 circuit means for reading out the amount of accumulated charge. (load accumulation! readout circuit 17).

The gate voltage vpL of the switch element 3 is the address bus tt.
. This switch element 3 receives irradiated light 10 from the light emitting element 8.
Operated by.

In the liquid crystal input/output device ff/ according to the present invention, one pixel is
There is one set of movable light emitting elements (light pens) per display panel, and one set of charge storage amount readout circuit 17 per display panel or one set for each data bus.
A pair is fine.

Next, Toge will explain the input detection operation.

FIG. 2 is a timing chart illustrating the detection order of wandering input in the configuration of FIG.
When the microswitch 9 is brought into contact with the display panel, the microswitch 9 is operated and detection of the input seat is started. Light emitting element 8
With zero emission stopped, a conduction pulse is applied to electrode 1 for the address bus and [412] for the data bus so as to select a specific display cell. In the v1 diagram, a specific display cell is assumed to correspond to the illustrated display cell and is displayed between stations.

At this time, in FIG. 2, it corresponds to the shape PA, and the charge charging circuit 1
2 is charged with electric charge via the switch 11. next,
Electrode 1. As the pole 2 becomes non-selected, the charge remains accumulated in the capacitor 4 in the display cell.

In state B, the electrode 2 is connected to the charge discharge circuit 14 by the switch 11, and the pulse generator 7 applies four driving pulses to the light emitting element 8, so that the irradiation light 10 from the light emitting element 8 is transmitted to the switch element 3. enters the light receiving section. As a result, the switch element 3 becomes conductive, and the charge stored in the capacitor 4 is discharged. Of course, if the light emitting element 8 is directed to another display cell at this time, the content 4 will not be discharged.

Next, in state C, the light emitting element 8 has stopped emitting light,
A conduction pulse is again applied to electrodes 1 and 2 to select this display cell, and the amount of charge on capacitor 4 is supplied to charge amount measuring circuit 13 via switch 11. The charge amount measuring circuit 13 determines whether or not the capacitor 4 is discharged, and if there is discharge, it is detected that this display cell has been selected as a seat input.

In state gD, a conduction pulse is applied to electrodes 1 and 2 to select this display cell again, and the same data as the original pixel is written to the display cell in the charge charging cycle P12, thereby displaying a normal image. Return to state.

The operating characteristics of liquid crystals are generally such that there is a delay time between the application of a display drive signal and the display state, and this time is used to detect the presence or absence of an input.

That is, when the device according to the present invention operates as an input/output device, it transitions between states A and D in FIG. 2, and when it operates only as a display device, it takes state DcI:).

Note that the timing shown in FIG. 2 is controlled by the timing pulse generation circuit 18 shown in FIG.

FIG. 3 is an overall configuration diagram showing an embodiment of a liquid crystal input/output device according to the present invention, in which each display cell displays an image as a liquid crystal display device by time sharing as shown in the timing chart of FIG. 2. It has a function to detect input from the armpit.

In the figure, the same symbols as in figure P1 indicate the same parts, and 1
5 is a drive circuit connected to the address bus electrode 1, 16 is a drive circuit connected to the data bus lightning pole 2, 18 is a timing pulse generation circuit, and 19 is an image memory. The drive circuits 15, 16 apply conduction pulses to the electrodes 1.2, and the phase of this conduction pulse determines which of the display cells arranged in a matrix is selected.

The drive circuit v-16 includes the charge storage amount reading circuit 17 described in FIG. The timing pulse generation circuit 18 is connected to each display cell 3, 3 . . . . are selected in order to check whether there is a coordinate input instruction.

Image memo+719 supplies image data for display to each display cell.

In the configuration shown in FIG. 3, it can be easily inferred that the presence or absence of coordinate input can be determined by sequentially measuring the increase or decrease in the amount of charge for each display cell, as explained in FIG. 1. As the number of display cells increases, the coordinate input is determined for each display cell according to the timing chart shown in FIG. 2, and the time increases by 5 hours. To deal with this,
Use the following method.

That is, in state A shown in FIG. 2, electrode 1;
(On the other hand, all electrodes 2 are selected, voltage is applied to all data buses, charges are simultaneously accumulated in all capacitors 4 of display cells arranged in the row direction, and then in state B, all data buses are The potential is set to 0■ to cause the light emitting element 8 to emit light.At this time, only the display cells that receive half the irradiation light 10 have their capacitors discharged.Next, for each display cell, the j■th order, IC and D (repeatedly perform rg scale input detection and data transfer from the original image memory for all display cells in the row direction.

By sequentially performing the above operations for each row, it is possible to display data in the image memory and detect coordinate input for all display cells.

Note that a light emitting diode or the like may be used as the above-mentioned light emitting element 8, but since it is a liquid crystal display and normal illumination light and natural light also enter the display panel, it is necessary to prevent these from entering the display cell. It is necessary to devise ways to

FIG. 4 is a cross-sectional view for explaining the light receiving section of the liquid crystal input/output device according to the present invention, in which the same reference numerals as in FIG. (light receiving part), 21 is a filter, 22 is a display electrode, 23
24 is a transparent p-edge plate, 24 is a liquid crystal layer, 25 is an interlayer insulating film, 26
27 is a circuit board on which an MO8 type FET (switch element) and a charge storage capacitor are mounted, and 27 is a reinforcing board.

In the figure, the switch element 3 is also operated by irradiating the pole 20 with light.

The filter 21 provided on the soil part of the gate electrode 20 has a characteristic of passing only light having the wavelength of the irradiation light 10 emitted by the light emitting element 80, and the device may malfunction if ambient lighting or natural light reaches the gate electrode 20. It prevents you from doing so.

〔Effect of the invention〕

As explained above, according to the present invention, by using the gate portion of the switch element constituting each display cell as a light receiving element, the appearance of the display panel becomes similar to a display-only liquid crystal panel, and handwritten input is possible. In addition to being used as a coordinate input and output device, the present invention can also be used as a display-only device, and can provide a liquid crystal input/output device with excellent functions, except for the drawbacks of the prior art.

[Brief explanation of drawings]

11 is a configuration diagram showing an embodiment of the liquid crystal input/output device according to the present invention, FIG. 2 is a timing chart showing the detection order of coordinate input in the configuration of FIG. 1, and FIG. 3 is an embodiment of the liquid crystal input/output device of the present invention. FIG. 4 is a sectional view for explaining the light receiving section of the liquid crystal input/output device according to the present invention. 1 electrode for near address bus, 2: t pole for data bus,
3: Switch element, 4: Capacitor, 5: Liquid crystal display section,
6: Transparent electrode, 7: Pulse generator, 8: Light emitting element, 9:
Micro switch, 10: Irradiation light, 11: Switch, 1
2: Load charging circuit, 13: Charge measuring circuit, 14: Charge amount discharging circuit, 15゜16: Drive circuit, 17: Load amount reading circuit, 18: Timing pulse generation circuit, ]9
: Image memory, 20: Light receiving part of gate TfL pole, 21:
Filter, 22: Display electrode, 23: Transparent insulating plate, 24
: Liquid crystal layer, 25: Interlayer insulating film, 26: Circuit board, 27:
Reinforcement board. Agent: Patent Attorney Kenji Takeshi (1 other person)j
"Figure 1 Figure 2 Figure 4

Claims (1)

[Claims] A display panel consisting of a plurality of display cells arranged in a matrix, a display drive circuit, a light emitting element movable with respect to the display panel, a timing pulse generation circuit for controlling the light emission timing of the light emitting element, In a liquid crystal input/output device comprising a charge storage amount readout circuit for reading the charge storage amount of an arbitrary display cell of a display panel, the display cell has a liquid crystal display section, a charge storage capacitor, and a switch element for charging and discharging the charge. The switch element has a light receiving part that operates even when irradiated with light, and the input coordinates are determined based on the light emission timing of the light emitting element and the change in the charge accumulation amount of the display cell at the position of the light emitting element read by the charge accumulation amount reading circuit. A liquid crystal input/output device characterized in that it is configured to enable coordinate input by detecting.