JPH0241691Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention is a display device equipped with a quadrilateral display surface such as a CRT. This invention relates to an optical touch position detection device that selects and touches a desired item, detects the touched position, and advances the program to the next step.

[Technical background of the invention and its problems]

A conventional optical touch position detection device of this type is shown in FIG.

This will be explained below.

1 receives input from a computer, etc. from a CRT,
A display screen of a display device using a liquid crystal or the like, which displays images or images in response to input from a computer or the like.
It displays characters, etc.

A touch position detection device 2 that surrounds the display surface 1 is attached to this display device.

On two adjacent sides surrounding the display surface of this touch position detection device 2, transmitting LEDs 3 that emit light only toward the opposite side are installed at a certain interval, and on the remaining two sides, LEDs 3 and 3 are installed. At equal intervals,
A receiving photodiode 4 is installed to receive only the light beam from the LED 3 facing the LED 3.

Then, as shown in Figure 3, the
The LEDs 3 are turned on and off in sequence, and in synchronization with the lighting, it is detected whether or not a photodiode 4 installed at the bottom side is receiving light.

Through this detection, the touch position a in the X direction on the display surface 1 is determined, and in the same way, the left LED 3
The position a in the Y direction is determined by sequentially lighting and extinguishing the light, and in synchronization with the lighting, detecting whether or not the right photodiode 4 receives light, and the touch position a in both the X and Y directions is detected. It is something.

In this way, in the conventional optical touch position detection device, the LED 3 for transmitting and the photodiode 4 for receiving are connected with a small gap around the display surface 1.
It is necessary to arrange a large number of them.

For example, even if display surface 1 is 20 inches in size, LED
3 placed at 5mm intervals would require 130 LEDs.

In addition, detection by scanning a pair of LED 3 and photodiode 4 requires three steps: 1. Turning on the LED 2. Detecting the light from the opposing photodiode 3. Turning off the LED. A series of scans required a long time to transfer to the photodiode.

Furthermore, since a large number of transmitting LEDs 3 are provided, there is also a drawback that the amount of heat generated is large.

[Purpose of invention]

In order to eliminate the above-mentioned drawbacks of the conventional optical touch position detection device, the present invention reduces the LED width by using two transmitting LEDs.
The purpose of this is to reduce the amount of heat generated and shorten the time for position detection by a series of scans.

[Example of idea]

An embodiment of the present invention will be described below with reference to FIG.

Reference numeral 11 denotes a frame body formed to surround the display surface of a display that displays information using a CRT, liquid crystal, or the like.

At both left and right corners of the display surface surrounding side of the frame 11,
LEDs 12 are installed to illuminate the two sides surrounding the display surface facing each other at each corner.

Receiving photodiodes 13 are arranged at regular intervals on three sides of the display surface surrounding the LEDs 12 except for the upper side, that is, on both left and right sides, and on the lower side.

First, the upper left LED 12 is turned on, and this LED 12 illuminates the right side and the lower side opposite to it, and the photodiodes 13 arranged on both sides receive this light.

By scanning the presence or absence of this light reception, a line segment from the upper left LED 12 to the touch position a is set.

Next, turn off LED12 on the upper left, and LED1 on the upper right.
2 is turned on, the light received by the photodiodes 13 on the left side and lower side opposite to this is scanned, and a second line segment passing from the upper right LED 12 to the touch position a is determined.

By determining the above two line segments, the coordinates of the touch position a are determined.

[Effect of idea]

As described above, in the present invention, it is sufficient to place one light source such as an LED at two adjacent locations such as the two upper corners of the display surface on which characters, images, etc. are displayed.

The light-receiving elements such as photodiodes for light reception are placed on both the left and right sides and at the bottom, facing the light source installation corners.
Since the light source is installed on the side, neither the light source nor the light receiving element is placed on the upper side between the corners where the light source is installed.

Therefore, the total number of light sources and light receiving elements can be reduced because they are not placed on the sides between the corners where the light sources are installed, and if the cost of the light source and light receiving element is the same, the total cost will be approximately Can be reduced to 3/4.

Furthermore, since only two light sources are required, the amount of heat generated is also reduced.

Furthermore, since the light source is turned on while scanning a series of light-receiving elements, there is no need to turn off the light for each light-receiving element as in the conventional method. This has the effect of improving efficiency by reducing the length of time by two to three times.

[Brief explanation of the drawing]

FIG. 1 is a schematic front view showing an embodiment of the present invention, FIG. 2 is a schematic front view of a conventional optical touch position detection device, and FIG. 3 is a diagram of its principle. 11...Frame, 12...LED, 13...Photodiode, a...Touch position.

Claims (1)

[Scope of utility model registration request] A light source that emits light toward at least two sides of the display surface opposite to the corners is installed at two adjacent corners in front of the display surface of a display device having a quadrilateral display surface such as a CRT, and the light source An optical touch position detection device characterized in that a light-receiving element for receiving light from the light source is disposed on three sides other than one side where the light source is placed at both corners.