JPH1174774A - Detector for touchless switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detector for touchless switch capable of limiting detecting position within a narrow range. SOLUTION: This detector is provided with a light emitting element at the position where an actual image 8a to be formed in the air can be projected, a half mirror 10 between an image forming means 9 and an original picture 8, and a light receiving element 5 at the position where the light emitted from the light emitting element is reflected on an object to be detected and is reached through the image forming means 9 and the half mirror 10. In this case, the detector is provided with a light emitting element driving circuit 3 to output a pulse modulation signal, a frequency divider circuit 4 to divide the pulse modulation signal to be outputted by the light emitting element driving circuit 3 into two pulse signals, two light emitting elements 1, 2 at a specified position so that light axes are crossed and a synchronization detection circuit 6 at a post stage of the light receiving element 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to Japanese Patent Application No. 7-313.
More particularly, the present invention relates to a touchless switch detection device having a configuration in which a half mirror is provided between a plate on which a character or a picture is drawn and an imaging unit.

[0002]

2. Description of the Related Art The present applicant filed an application for a touchless panel switch on December 5, 1994 as a completely new type of non-contact switch (Japanese Patent Application No. Hei 6-333727).
On October 24, 1995, a similar non-contact switch, a touchless switch, was filed (Japanese Patent Application No. Hei 7-313440). In the touchless switch, there has been proposed an idea of a touchless switch having a configuration in which a half mirror is provided between a plate on which a character or a picture is drawn and a gradient index lens element serving as an imaging unit.

A detection device according to the present invention detects a touchless switch having a configuration in which a half mirror is provided between a plate on which a character or a picture is drawn and an imaging means (for example, a gradient index lens element). Related to the device,
The term touchless switch particularly means only this type of touchless switch.

A touchless switch will be described with reference to FIG. The touchless switch projects (maps) an object that is a transmission source (hereinafter also referred to as an original picture 8) into the air by an imaging unit 9 (for example, a gradient index lens element), and outputs a real image 8a of the object to the switch. It is intended to be displayed in the air as a key and to be used as a target for a switch operation. In this touchless switch, an object to be detected (not shown, such as an operator's finger) approaching a key displayed in the air has been detected as follows.

The key in the air, that is, the real image 8a of the original picture
The light emitting element 1 is provided at a predetermined position where light can be irradiated (one or a plurality of light emitting elements may be provided). The light (including infrared rays) emitted from the light emitting element 1 is reflected by the finger approaching the key and transmitted to the original picture 8 via the image forming means 9. Since a half mirror 10 is provided between the original picture 8 and the image forming means 9, light emitted from the light emitting element 1 and reflected by a finger and passed through the image forming means 9 is partially reflected by the half mirror. Reflect at 10. Since the light receiving element 5 is provided at a position where the light from the light emitting element 1 reflected by the half mirror 10 can be received, an object (finger) coming into contact with a key in the air can be detected.

The position where the light receiving element 5 is provided depends on the distance of the trajectory of the light beam from the time when the light emitted from the light emitting element 1 is reflected by the finger to the time when the light enters the image forming means 9, and after the light is emitted from the image forming means 9. The position where the distance of the trajectory of the light beam reflected by the half mirror 10 and incident on the light receiving element 5 is almost equal is most desirable.

In such a conventional touchless switch, a modulation signal is input to the light emitting element 1, the modulated light is emitted, the modulated light is received by the light receiving element 5, and synchronous detection / demodulation is performed. It is conceivable to detect an object. That is, a so-called modulation type photoelectric switch is used. Rather, a touchless switch that is resistant to noise can be configured.

FIG. 2 is a block diagram when a modulation type photoelectric switch is used in a conventional touchless switch detection device. If it is assumed that an object is present at point A, point B, point C, point D, or point E, the object may be detected at each of those points. The point at which the object can be detected and the point at which the object cannot be detected are determined by the light emitting element 1.
, The directivity, the light emission intensity, the optical axis, directivity, light receiving sensitivity of the light receiving element 5 and the optical characteristics of the imaging means 9.

In any case, the range in which the object can be detected is considerably wide, and the photoelectric switch (light emitting element and light receiving element) is set so that the object can be detected only at a predetermined location.
Coordinating was difficult.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the drawbacks of the conventional touchless switch detection device (modulation type photoelectric switch), and its object is to narrow the detection location to a narrow range. It is an object of the present invention to provide a touchless switch detection device that can be limited.

[0011]

A light emitting element is provided at a position where a real image formed in the air can be irradiated, and a half mirror is provided between the image forming means and the original picture. A touchless switch detection device in which a light receiving element is provided at a position where the reflected light can be reflected by an object to be detected and reach via the image forming means and the half mirror, including a light emitting element driving circuit for outputting a pulse modulation signal. A frequency dividing circuit that divides a pulse modulation signal output by the light emitting element driving circuit into two pulse signals; two light emitting elements are provided at predetermined positions such that optical axes intersect; A synchronization detection circuit is provided at a subsequent stage. Note that the synchronization detection circuit in this specification means a circuit including a circuit for demodulating a pulse modulation signal.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Among the members constituting the present invention, a light emitting element driving circuit, a synchronization detecting circuit, a light emitting element and a light receiving element are the same as those used in a modulation type photoelectric switch and its driving and detecting circuit. It is sufficient to use similar configurations or components.

The two light emitting elements are set at predetermined positions so that their optical axes intersect. The intersection of the two optical axes and the space around it are the detectable range of the object.

FIG. 3 is a schematic diagram showing a pulse modulation signal and its divided pulse waveform (output signal of a frequency dividing circuit).
The frequency dividing circuit divides the pulse modulation signal into two pulses and divides the frequency as shown in FIG. One of the divided pulse signals is a signal for driving the first light-emitting element, and the other is a pulse signal for driving the second light-emitting element.

If the object exists in the detectable range of the object, that is, at the intersection of the optical axes of the two light emitting elements and in the vicinity thereof, the light receiving element can receive the modulated light from the two light emitting elements. it can. The synchronization detection circuit performs synchronization detection and demodulation based on the output of the light receiving element, and outputs a detection signal.

[0016]

FIG. 1 is a schematic view showing an embodiment of the present invention. The first and second two light emitting elements (1, 2) are installed so that their optical axes intersect, and the installation position and the optical axis are set such that the intersection of the optical axes becomes a target to be detected. Has been adjusted.

The light emitting element driving circuit 3 includes an oscillation circuit (not shown) and outputs a pulse modulation signal. The frequency dividing circuit 4 divides the pulse modulated signal into two such that the peaks of the pulse signal of the frequency-divided pulse signal are alternately present as shown in FIG.

As the light emitting elements (1 and 2), an infrared light emitting diode or a light emitting diode is used. One divided pulse signal causes the first light emitting element 1 to emit light, and the other divided pulse signal causes the second light emitting element 2 to emit light. That is, the light emitting elements (1, 2) emit light alternately.

The light receiving element 5 outputs a signal corresponding to the incident light to the synchronization detecting circuit 6. Therefore, the modulated light from the two light emitting elements (1, 2) reflected by the object at and around the point where the optical axis of the first light emitting element 1 and the optical axis of the second light emitting element 2 intersect. Enters the light receiving element 5 via the imaging means 9 and the half mirror 10. In FIG. 1, the detected object is probably detected only at the point c and its vicinity.

The light receiving element 5 outputs a signal equivalent to the case where modulated light of the original pulse modulated signal before frequency division is received. Therefore, the synchronization detecting circuit 6 can synchronously detect the modulation signals from the two light emitting elements (1, 2). The synchronization detection circuit 6 includes a demodulation circuit 7,
The demodulation circuit includes, for example, an integration circuit, a comparison circuit, an output circuit, and the like (not shown).

[0021]

Since the present invention is configured as described above, the following effects can be obtained. With one light emitting element driving circuit 3, one light receiving element 5, and one synchronization detecting circuit 6, modulated light from two light emitting elements (1, 2) can be received, demodulated and detected. Only when there is an object to be detected at the intersection of the optical axes of the two light emitting elements (1, 2) and around it, the synchronous detection can be performed with respect to the original pulse modulation signal. Therefore, it is possible to provide a touchless switch detection device capable of improving detection stability.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one embodiment of the present invention.

FIG. 2 is a block diagram when a modulation type photoelectric switch is used in a conventional touchless switch detection device.

FIG. 3 is a schematic diagram showing a pulse modulation signal and its divided pulse waveforms.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 First light emitting element 2 Second light emitting element 3 Light emitting element driving circuit 4 Divider circuit 5 Light receiving element 6 Synchronous detection circuit 7 Demodulation circuit 8 Original picture 9 Image forming means 10 Half mirror i, b, c, d, e Point indicating a predetermined position on the optical axis of the light emitting element

Claims (1)

[Claims] A light emitting element is provided at a position capable of irradiating a real image formed in the air, a half mirror is provided between an image forming means and an original picture, and light emitted from the light emitting element is covered by the light emitting element. In a touchless switch in which a light receiving element is provided at a position where the light is reflected by a detection object and can be reached via the imaging means and the half mirror, two light emitting elements are provided at predetermined positions so that optical axes intersect, A light emitting element driving circuit that outputs a pulse modulation signal; a frequency dividing circuit that divides the pulse modulation signal into two pulse signals and outputs the pulse modulation signal to the light emitting element; A touchless switch detection device provided with the touchless switch.