JPH0281222A - Touch panel input device - Google Patents

Abstract

PURPOSE:To prevent the title device from being influenced by a variance of characteristics of a photodetector and plural light source elements by detecting a light beam which intersects on a display by one photodetector through an optical fiber having plural optical input parts and one optical output part. CONSTITUTION:One end side of an optical fiber 5 becomes plural optical input parts 51-5n, the other end becomes an optical output part 50 from which a light beam which is made incident on plural optical input parts 51-5n is emitted, and a photodetector 6 for receiving the light beam emitted from said part is provided. From the element 6, plural light sources are driven successively by a light source driving circuit 4, and the light beam is emitted successively to the optical input parts 51-5n of the optical fiber 5. In such a case, when an obstacle exists in some position of a display 1, the light beam to a light incident part is obstructed, it is detected by a comparing means 8, and from its timing, position data is derived. In such a way, since one photodetector is used, an error caused by a variance of characteristics of detection sensitivity, etc. of the photodetector comes not to be generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical touch panel input device that uses a light beam such as an infrared beam.
A touch screen is installed around displays such as RTs, and allows users to input a specific position on a computer, such as a calculator, by specifying a specific position on the display with an obstacle such as a finger.
It relates to a panel input device.

<Prior art> An optical touch panel input device that uses a light beam works with various images and information displayed on the CR'r' to touch the screen at a specific position on the CRT with a finger. It is possible to easily input various data using methods such as
It is becoming widely used as an interface with computers.

Conventionally, as this type of touch panel input device, there is, for example, a device as disclosed in US Pat. No. 3,775,560.

5 and 6 are conceptual diagrams showing the configuration of the device disclosed herein.

In these figures, 1 is a display device, 2 is a display device, and 2 is a display device.
1 to 2n are a plurality of light sources arranged on two sides of the display device 1, and 31 to 3n are a plurality of light receiving elements arranged on the remaining two sides of the display device 1 so as to face the plurality of light sources 21 to 2n. It is. These plurality of light sources and light receiving elements are arranged in the mounting block 10 and are configured so that the light beams emitted from the light sources pass over the surface of the display device 1.

The output signals of the plurality of light receiving elements 31 to 3n are applied to the position detecting means 41.42 via the scanning means SWI, SW2, and the timing at which the amplitude of the signal from the light receiving elements changes is detected, and from this timing, The position specified by a finger or the like on the display device 1 is known.

<Problem to be solved by the invention> By the way, the touch panel input device having such a configuration has the following problems:
This method detects whether or not a light beam passing across a display device is blocked by determining whether the output signal level of multiple light receiving elements is higher or lower than a predetermined level setting, and the detection sensitivity of multiple light receiving elements varies. If it exists, there is a problem that it becomes impossible to accurately judge whether there is a touch or not.

The present invention has been made in view of these problems, and its purpose is to eliminate the need for multiple light receiving elements and eliminate errors caused by variations in characteristics such as detection sensitivity of the light receiving elements.
The object of the present invention is to realize a touch panel input device with a simple configuration.

Means for Solving the Problems> FIG. 1 is a block diagram showing the basic configuration of the present invention.

In the figure, 1 is a display, 21 to 2n are a plurality of light sources arranged on one side of the display 1, and 4 is a light source drive circuit that sequentially selects and drives the plurality of light sources 21 to 2n.

Reference numeral 5 denotes an optical fiber, one end of which is connected to a plurality of optical input sections 51 to 51.
5n, and a plurality of light sources 2 are connected to these optical input sections.
They are arranged on the side facing the light source so that the light beams from 1 to 2n are respectively incident thereon. The other end of this optical fiber 5 serves as a light output section 50 from which light that has entered the plurality of light input sections 51 to 5n is output.

Reference numeral 6 denotes a light-receiving element that receives the light emitted from the light output section 50 of the optical fiber 5; 7, a signal importing means that receives the signal from the light-receiving element 6 in synchronization with the timing of driving the plurality of light sources 21 to 2n; Comparison means 8 compares the level of the signal taken in through the signal import means 7 with a predetermined set level, and 9 calculates position data from the timing of the signal output from the comparison means 8 and outputs the position data. It is a position data output means.

Effect> The plurality of light sources are sequentially driven by a light source drive circuit and sequentially emit light beams toward the light input sections 51 to 5n of the optical fiber 5. If an obstacle exists at a certain position of the display 1 at this time, the light to the light incident part is blocked, this is detected by the comparison means, and position data is obtained from the timing.

<Example> Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a block diagram showing an embodiment of the present invention. Here, only the light beams that cross in the X-axis direction are shown, but there are also beams that cross in the Y-axis direction.
A plurality of light sources arranged on one side of the light source, such as LEDs, are used. Reference numeral 4 denotes a light source driving circuit that sequentially drives the plurality of light sources 21 to 2n starting from the light source 21.

5 is an optical fiber, and 6 is a light receiving element that receives an optical signal from the optical output section 50 of the optical fiber 5. For example, a phototransistor or the like is used.

70 is a gate, which receives the signal from the light receiving element 6 as one input. Reference numeral 91 denotes a sample/hold circuit that samples and holds the signal from the light receiving element 6 via the gate 70, and these constitute the signal acquisition means 7 in FIG.

92 is an A/D converter, and 90 is a microprocessor, which inputs the signal from the sample/hold circuit 91 via the A/I converter 92. 93 is a memory coupled to the microprocessor 90;

The microprocessor 90 controls the drive circuit 4 of the plurality of light sources, the gate 70, and the sample/hold circuit 91, and also controls the first
It functions as comparison means 8 and position data output means 9 in the figure. Although a circuit for receiving a light beam crossing in the Y-axis direction and processing a signal is omitted in this figure, it is similar to the signal processing circuit prepared for a light beam crossing in the X-axis direction.

The operation of the apparatus configured in this way will be explained next.

FIG. 3 is a flowchart showing an example of the operation performed by the microprocessor 90.

First, the microprocessor 90 sets an internal light source element number counter to "1" (step 1).
)0 Next, the drive circuit 4 drives the light source indicated by the light source element number counter (initially, the first light source 21), and a light beam is emitted from there so as to traverse the display 1. Then, at the timing when the light beam is emitted from the light source 21, the gate 70 is opened and the output signal Vx from the light receiving element 6 is output.
is read through the sample/hold circuit 91 and the A/I converter 92 (step 2).

Next, it is determined whether the magnitude of the read output signal Vx from the light receiving element 6 is larger than a predetermined level setting signal vth (step 3).

Here, the level of the setting signal vth is determined from the difference between the received output signal when there is no obstacle in the optical path of the light beam crossing the display 1 and when there is an obstacle, for example (1 ) is determined by the formula.

Vth=1/2・(Vno-Vc) (1) However, Vno is the light receiving element output signal level Vc when there is no obstacle in the optical path of the light beam. Light receiving element output signal level when present In step 3, if Vx≦vth, it is assumed that there is a touch and the process branches to step 6.

In addition, in step 3, if V31x>Vth, it is assumed that there is no touch, and the process moves to step 4, where +1 is added to the value of the light source element number counter, and the values of the light source element number counter are arranged in the X-axis direction. It is determined whether the number after fl (here, it is assumed that n numbers are arranged) has been reached, and if the last number has not been reached, the process returns to step 2 (step 5).

In the branched step 6, the value N of the light source element number counter is
is output as touch position data.

In the above explanation, a step is provided before step 2 to measure the output signal vb from the light receiving element in a state where the light source is not driven (a state in which no light beam is emitted), and from the output signal Vx read in step 2, The output signal vb is subtracted, and this subtraction result (Vx-Vb) and the setting signal vth
By providing such a step, even if there is external light other than the light beams from the light sources 21 to 2n, it is possible to accurately determine the presence or absence of a touch without being affected by this external light. It becomes possible to detect

FIG. 4 is an elliptical diagram of the main part showing another embodiment of the present invention. In this embodiment, an optical fiber 5a is provided on the side of the plurality of light sources 21 to 2n, into which part of the light beams emitted from these light sources enters, and a light receiving element is provided that receives light emitted from the other end of the optical fiber 5a. 6a is provided.

Then, the output signals of the light receiving elements 6 and 6a are transferred to a differential amplifier 60.
Differential amplification is performed by

By having such a configuration, each of the plurality of light sources 21 to
Changes in the magnitude of the signal from the light receiving element due to variations in the light intensity from the 2n light sources are canceled out by differential amplification, and errors caused by variations in each light source can also be eliminated.

<Effects of the Invention> As explained in detail above, the present invention transmits a light beam that has traversed a display to a single light receiving element via an optical fiber having a plurality of light input sections and a single light output section. It is designed to be detected by Therefore, according to the present invention, it is possible to provide a highly reliable touch panel input device that has a simple configuration and is not affected by variations in characteristics of a light receiving element or a plurality of light source elements.

[Brief Description of the Drawings] Figure 1 is a block diagram showing the basic configuration of the present invention, Figure 2 is a block diagram showing the basic configuration of the present invention;
The figure is a block diagram showing one embodiment of the present invention, FIG. 3 is a flowchart showing the operation, FIG. 4 is a block diagram of main parts showing another embodiment of the present invention, and FIGS. 5 and 6 are FIG. 2 is a conceptual diagram of the configuration of a conventional device. 1...Display, 21-2n...Light source element, 4...Drive circuit 5...
Optical fiber, 6... Light receiving element 7... Signal acquisition means 8... Comparison means, 9... Position data output means 90
...Microprocessor, 93...Memory Figure 1 Figure 2 Figure 4

Claims (2)

[Claims] (1) A plurality of light sources arranged on at least one side of the display, a drive circuit that sequentially selects and drives the plurality of light sources, and a plurality of light sources arranged so that the light beams from each of the plurality of light sources are respectively incident on the light sources. an optical fiber having a plurality of optical input sections arranged on opposite sides thereof and a light output section from which light incident on the optical input section is output; and a light receiving section for receiving light emitted from the optical output section of the optical fiber. an element, a signal capturing means for capturing signals from the light receiving element in synchronization with the driving timing of the plurality of light sources, and a comparing means for comparing the level of the signal captured through the signal capturing means with a predetermined set level. A touch panel input device comprising position data output means for determining position data from the timing of a signal output from the comparison means and outputting the position data. (2) It is provided on the side where each of the plurality of light sources is installed, and has a plurality of light input sections into which the light beams from each of the light sources enter, and a light output section from which the light incident on the light input section exits. It is characterized by providing another optical fiber and a light-receiving element that receives the light emitted from the optical output part of this optical fiber, and processing the signals by differentially amplifying each signal from the two light-receiving elements. A touch panel input device according to claim 1.