JPH0687004B2 - How to read the received light output signal of the optical touch panel - Google Patents

Description

The present invention relates to a method for reading a light reception output signal of an optical touch panel into a storage device.

(Prior Art) FIG. 2A is an explanatory diagram of an optical touch panel. In FIG. 2a, 11 is a light emitting element array, 11a is a light emitting element, 12 is a light receiving element array, 12a is a light receiving element, 13 is a display, and 14 is a light-shielding object.

As shown in FIG. 2a, the optical touch panel has a light emitting element array 11 in which a large number of infrared light emitting elements 11a are arranged and a large number of infrared light receiving elements 12a arranged around a display surface of a display 13. The light receiving element rows 12 are arranged to face each other horizontally and vertically, and the unit optical system formed so that the light emitting elements 11a and the light receiving elements 12a, which face each other, operate in cooperation, are sequentially swept in the horizontal and vertical directions. , An infrared ray matrix formed on the display surface of the display 13 by reading the light receiving output signal levels of the light emitting element for each unit optical system when the light emitting element does not emit light and when emitting light, and comparing the levels. The orthogonal coordinates of the position of the light-shielding object 14 touching the intersection of are detected and the position information is output.

FIG. 2b is a diagram for explaining the configuration of the unit optical system. 11a is a light emitting element, 12a is a light receiving element, 15a and 15b are analog switches, 16
Is an amplifier, 17 is a load resistance, and 18 is a received light output signal. When this unit optical system receives the sweep signal, the analog switch 15a first comes into contact with the light receiving element 12a to be in the operating state.
Subsequently, the analog switch 15b is kept in contact for a certain period of time, the light emitting element 11a emits light, and when the light receiving element 12a receives the light, a current flows through the load resistor 17 and the generated voltage is amplified by the amplifier 16 and output as the light receiving output signal 18. To do.

The received light output signal 18 is pulse noise generated by a transient current when the analog switch 15a is in contact with the light receiving element.
When the light emitting element 11a does not emit light, the dark current of the light receiving element 12 and the current due to the ambient light cause the load resistor 17a to operate when the light emitting element 11a is activated.
And a high level signal when the light emitting element 11a emits light. Of these signals, a low level signal and a high level signal are read into a storage device (not shown) at a fixed timing. Conventionally, the low level signal is waited until the pulse noise is attenuated, and then the low level signal is first read. I was reading a signal and then a high level signal.

FIG. 3 is a conventional reading time chart of the received light output signal 18 of FIG. 2b. In FIG. 3, (a) is a pulse for driving the analog switch 15a. (B) is a pulse that drives the analog switch 15b. (C) is the received light output signal 18
Waveform (tw is the read waiting time in the figure). (D)
Is a low level signal reading pulse. (E) is a high level signal reading pulse.

A large number of unit optical systems arranged horizontally and vertically around the display surface of the display device sequentially activate the light receiving element by the pulse (a) and sequentially cause the light emitting element to emit light by the pulse (b) by sweeping. However, the low level signal is stored by the pulse of (d) after the waiting time tw until the pulse noise generated when the analog switch 15a comes into contact with the pulse of (b) is attenuated and becomes a steady state. After reading into the device, the device emits light, and the pulse of (e) reads the high level signal into the storage device.

As described above, in the conventional method of reading the received light output signal of the optical touch panel into the storage device, the low level signal is read before the reading of the high level signal.

(Problems to be Solved by the Invention) As described above, the optical touch panel has a large number of unit optical systems arranged around the display surface of the display unit and sweeps them to form an infrared ray matrix. Touch the to detect the Cartesian coordinates of the position of the object that blocks the infrared rays, output the position information, and receive the information from the computer. Therefore, a device with a high detection speed is required. However, conventionally, as described above, the pulse noise generated when the light receiving element of the unit optical system is driven is attenuated, wait until the steady state is reached, and then read the low level signal of the light reception output signal and then emit light. The device was driven and the high level signal was read. Since this waiting time occupies a considerable time in the time required to read the light reception output signal of the unit optical system, it is said that the sweep speed cannot be increased and the detection speed of the position of the touched object cannot be increased. There was a flaw.

The present invention is not affected by the pulse noise described above,
It is an object of the present invention to provide a method for reading a received light output signal that can increase a sweep speed and a detection speed by reading a low level signal.

(Means for Solving the Problems) According to the present invention, when the unit optical system is swept and the light receiving element is swept, the timing of reading the received light output signal of the light receiving element of the unit optical system into the storage device at high level and low level Without waiting for the pulse noise generated when driven to be sufficiently attenuated, the light emitting element is driven to read the high level signal of the light reception output signal and read the low level signal after the light emission is stopped. The waiting time is greatly reduced, the sweep speed is increased, and the detection speed is increased.

(Operation) As described above, the light emitting element is caused to emit light before the pulse noise generated when the light receiving element of the unit optical system is driven is sufficiently attenuated, and the high level signal of the light reception output signal is read to emit light. Since the low level signal is read after the stop, the waiting time can be greatly shortened, and the sweep speed can be increased and the detection speed can be increased.

Example An example of the present invention will be described with reference to FIG. 1 and FIG. 2b.

FIG. 1 is a time chart of the embodiment of the present invention. First
In the figure, (a) is the analog switch 15a drive pulse of FIG. 2b, (b) is the analog switch 15b drive pulse of FIG. 2b, (c) is the waveform of the received light output signal 18 of FIG. 2b,
(D) is a high-level signal reading pulse, and (e) is a low-level signal reading pulse.

In the unit optical system shown in FIG. 2b, the conventional method of reading the received light output signal 18 into the storage device is that the unit optical system is swept and the analog switch 15a comes into contact when the operation is started,
At the same time when the power supply is connected to the light receiving element 12a, a transient current flows and pulse noise is generated, so that this noise is sufficiently attenuated and becomes a steady state, that is, a voltage due to the dark current of the light receiving element and the disturbance light receiving current. Wait for a while, read the low-level signal of the received light output signal 18, and then read the analog switch.
15b is in contact, the light emitting element 11a emits light, and the received light output signal
It was the timing to read the high level signal of.

According to the present invention, as shown in the time chart of FIG. 1, when the analog switch 15a is brought into contact with the driving pulse of the analog switch 15a in (a) and the power source is connected to the light receiving element 12a, a pulse due to a transient current is generated as shown in (c). Noise is generated, but without waiting for this noise to be attenuated sufficiently,
(B) The analog switch 15b drive pulse causes the analog switch 15b to be in contact and the light emitting element 11a to be in contact for a predetermined time to emit light. As a result, the received light output signal 18 is superposed on the noise as shown in (c) to generate a high level received light output, and during this time, the high level signal is read into the storage device by the high level signal read pulse in (d). (B)
When the pulse of is cut off and the light emission is stopped, the light receiving element 12a returns to the steady state, and the steady state continues until the pulse of (a) is cut off. Read the signal into storage.

By sweeping at the timings described above, the time during which the analog switch 15a for each unit optical system is in contact is greatly shortened, so the sweep speed can be increased.

(Effects of the Invention) As described in detail above, according to the present invention, a high-level signal is first output from the light-receiving output signals that are made to emit light immediately after the unit optical system is swept and driven in the optical touch panel and read into the storage device. Since the reading and the low-level signal are read later, there is almost no need to wait for the attenuation of pulse noise due to the transient current generated when the unit optical system is driven, and the sweep speed is greatly increased. Since it can be increased, the detection speed can be increased, and the effect that the response speed of the system incorporating the touch panel can be significantly increased can be expected.

[Brief description of drawings]

FIG. 1 is a time chart of an embodiment of the present invention, FIG. 2a is an explanatory view of an optical touch panel, FIG. 2b is an explanatory view of the unit optical system of FIG. 2a, and FIG. 3 is FIG. 9 is a conventional reading time chart of the light reception output signal 18 of FIG. 11 ... Light receiving element array, 11a ... Light emitting element, 12 ... Light receiving element array, 12a ... Light receiving element, 13 ... Display, 14 ... Shading object, 15a, 15b ... Analog switch, 16 ... Amplifier , 17
...... Load resistance, 18 …… Received light output signal.

Claims (1)

[Claims] 1. A light emitting element row and a light receiving element row are arranged horizontally and vertically opposite to each other around a display surface of a display to form both element rows, and a single light emission facing each other. A unit optical system in which the element and the light receiving element are linked to each other is swept and driven to form an optical matrix, and the respective levels of the light receiving output signal at the time of light emission and at the time of no light emission are read into the storage device, and both levels are read. In the method of reading the received light output signal of the optical touch panel that detects the orthogonal coordinates of the position of the object to be shielded by touching on the display surface and outputs the position information, a low light emission output signal A method for reading a light reception output signal of an optical touch panel, wherein the reading of the level signal into the storage device is performed after the reading of the high level signal during light emission into the storage device.