JP2006210974A - Reflecting photoelectric switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflecting photoelectric switch in which wrong operation due to disturbance light can be reduced sufficiently. <P>SOLUTION: If a light receiving means 31 detects light when a light emitting means 11 is in light projecting state, light projection from the light emitting means 11 is interrupted temporarily and when light is not detected by the light receiving means 31 due to temporary interruption of light projection, light projection from the light emitting means 11 is resumed while sustaining the intensity of light projection immediately before temporary interruption and current detection sensitivity of the light receiving means. When the light receiving means 31 detects light even after temporary interruption of light projection, detection sensitivity of the light receiving means 31 is lowered until light is not detected by the light receiving means 31 under temporary interruption state, and then light projection from the light emitting means 11 is resumed. On the other hand, intensity of projection light from the light emitting means 11 is increased until the light projected and reflected by an object can be detected by the light receiving means 31. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a reflective photoelectric switch that detects light by projecting light from a light emitting element and detecting light reflected from the object with a light receiving element.

  The reflection type photoelectric switch detects an object by projecting light from a light emitting element and detecting reflected light from the object by a light receiving element. In the reflection type photoelectric switch, the sensitivity of the light receiving element is set so that the light receiving element does not detect ambient external light when there is no reflected light from the object.

  However, the conventional reflective photoelectric switch often malfunctions due to disturbance light from an incandescent bulb or the like, even though there is no object that reflects the light projected from the light emitting element.

  In the prior art, an optical sensor that emits a modulated projection beam from a projector, receives a light beam from an object by a position detection element, and detects the distance from the object to the sensor by a triangulation method based on the signal. In order to reduce malfunction due to disturbance light, the pulse amplitude for modulating the projection beam emitted from the projector is automatically changed so as to keep the amount of reflected light from the object constant, and the difference in the object A feedback control system that corrects the difference in light intensity is provided, and the amplification level of the light receiving circuit is increased for low light reception and reduced for high light reception. When the amount of received light is extremely small as much as possible, it has been proposed to reduce the amplification level of the light receiving circuit to a predetermined reduction level.

However, even with the configuration of the prior art, it has been difficult to sufficiently reduce malfunction caused by ambient light such as an incandescent light bulb.
JP-A-5-3414

  The present invention has been made in view of the above points, and an object of the present invention is to provide a reflective photoelectric switch that can sufficiently reduce malfunction caused by ambient light.

  The present invention relates to a reflective photoelectric switch comprising a light emitting means for projecting light and a light receiving means capable of detecting light reflected by an object of light projected from the light emitting means, in the light projection state by the light emitting means. A light projection temporarily stopping means for temporarily stopping the light projection by the light emitting means when the light is detected by the means, and when the light receiving means stops detecting the light due to the light projection temporarily stopped, A light projection restarting means for restarting light projection by the light emitting means while maintaining the intensity of the projection light immediately before the light projection is temporarily stopped and the current detection sensitivity of the light receiving means; and the light receiving means even when the light projection is temporarily stopped. Detection sensitivity adjusting means for lowering the detection sensitivity of the light receiving means when the light projection is temporarily stopped, and the light receiving means by the detection sensitivity adjusting means when detecting light After reducing the detection sensitivity, the light projection by the light emitting means is resumed, and the light projection restarting and the projection light intensity adjusting means for increasing the intensity of the projection light by the light emitting means are provided. .

  According to the present invention, when light is detected by the light receiving means in the light projection state by the light emitting means, when the light projection by the light emitting means is temporarily stopped and the light receiving means stops detecting light, that is, the disturbance light If not affected, the light projection of the light emitting means is resumed while maintaining the projection light intensity immediately before the light projection is temporarily stopped and the current detection sensitivity of the light receiving means, and the light projection is resumed. When the light receiving means detects light even when stopped, the light receiving means is affected by disturbance light.Therefore, when light projection is temporarily stopped, the detection sensitivity of the light receiving means is lowered to reduce the influence of disturbance light. After the loss, the projection of the light by the light emitting means is resumed and the intensity of the projected light by the light emitting means is increased so that the reflected light from the object of the projected light is detected by the light receiving means without being affected by the disturbance light. It can be made possible.

  Embodiments of the present invention will be described below. FIG. 1 is a schematic block diagram showing the configuration of a reflective photoelectric switch according to an embodiment of the present invention.

  The reflective photoelectric switch 10 according to the embodiment shown in FIG. 1 includes a light emitting element 11, a light emitting element driving / projection light intensity adjusting circuit 21, a light receiving element 31, a light receiving element driving / detection sensitivity adjusting circuit 41, and a CPU 51. For example, ON / OFF of the operating device is controlled. Examples of the operating device include a faucet device in a bathroom, a screen device in an ATM such as a bank, and a driving device for a ventilation fan.

  The light emitting element 11 corresponds to a light emitting means capable of projecting light. The type of the light emitting element 11 is not particularly limited, but a light emitting diode is common.

  The light emitting element driving / projection light intensity adjustment circuit 21 drives the light emitting element 11 to project light from the light emitting element 11 and adjusts the projection light intensity of the light emitting element 11 with the CPU 51. This corresponds to the light projection temporarily stopping means and the projection light intensity adjusting means of the present invention.

  The light receiving element 31 corresponds to a light receiving means capable of detecting the light reflected by the object of the light projected from the light emitting element 11. The type of the light receiving element 31 is determined according to the light emitting element 11 and is not particularly limited. However, when the light emitting element 11 is a light emitting diode, the light receiving element 21 is generally a photodiode.

  The light receiving element drive / detection sensitivity adjustment circuit 41 corresponds to detection sensitivity adjusting means for driving the light receiving element 31 so as to be able to detect light and adjusting the detection sensitivity of the light receiving element 31 with the CPU 51 to decrease it.

  The CPU 51 controls the light emitting element drive / projection light intensity adjustment circuit 21 and the light receiving element drive / detection sensitivity adjustment circuit 41 and outputs a reflected light detection signal based on reflected light detection to the operating device 61. The reflected light detection signal is determined in accordance with the operating device 61, such as a signal received by the operating device 61 and used for control on the operating device 61 side, or an ON / OFF signal of the operating device 61.

  The light emitting element 11 and the light receiving element 31 are reflected light reflected by the object when the light projected forward from the light emitting element 11 is located at a predetermined distance in front of the reflective photoelectric switch 10. The direction and the like are set so that the light receiving element 31 can detect. The predetermined distance from the light emitting element 11 to the object is set according to the operating device 61.

  Next, the light emission / light reception processing by the CPU 51 in the reflective photoelectric switch 10 will be described. In the light emission / light reception process, as shown in the flow of FIG. 2, it is first determined whether the light receiving element 31 has detected light (S11). If no light is detected, the light emission / light reception process is started from the beginning. Repeated. On the other hand, when the light receiving element 31 detects light, the light projection by the light emitting element 11 is temporarily stopped (S12), and it is determined whether the light receiving element 31 stops detecting light due to the light projection temporarily stopped. (S13). When no light is detected, it is determined that the light detected by the light receiving element 31 before the light projection is temporarily stopped is reflected light by the object of the light projected from the emitting element 11, and the reflected light detection signal Is output to the operating device 61 (S14), and at the same time, the intensity of the projection light just before the light projection is temporarily stopped and the current detection sensitivity of the light receiving element 31 are maintained, and the light projection by the light emitting element 11 is resumed. (S15) Thereafter, the light emission / light reception process is repeated again from the beginning. The steps S11 and S12 correspond to the processing of the light projection temporarily stopping means, and the steps S13 and S15 correspond to the processing of the light projection restarting means.

  On the other hand, when the light receiving element 31 continues to detect light even after the light projection is temporarily stopped, disturbance light effect prevention control processing (S16) is performed. In the disturbance light effect prevention control process (S16), as shown in the flow of FIG. 3, first, the detection sensitivity of the light receiving element 31 is lowered until the light receiving element 31 stops detecting light (S16-1, S16-). 2). Next, the light projection of the light emitting element 11 is resumed (S16-3) and the intensity of the projection light is increased (S16-4), and then the light emission / light reception process is repeated again. Note that S16-1 and S16-2 correspond to processing of the detection sensitivity adjusting means.

  In the projection light intensity increasing process (S16-4), the light projected from the light emitting element 11 is reflected by an object located in front of the reflective photoelectric switch 10 by a predetermined distance, and the reflected light is in the detection sensitivity lowered state. The projected light intensity of the light emitting element 11 is increased so that the light receiving element 31 can detect the light. The method for increasing the intensity of the projected light at that time is appropriate. As an example, the intensity of the projected light by the light emitting element 11 when the object is positioned in front of the reflective photoelectric switch 10 by a predetermined distance, and the above-described case The relationship with the detection sensitivity of the light receiving element 31 capable of detecting the reflected light from the object is measured in advance, the projection light intensity-detection sensitivity data is stored in the CPU 51, and the projection light intensity increasing process (S16- 4), the light receiving element 31 determines the projection light intensity of the light emitting element 11 capable of detecting the reflected light of the object with the current detection sensitivity using the projection light intensity-detection sensitivity data, and the determined projection. An example in which the projection light intensity of the light emitting element 11 is increased to the light intensity will be described. Note that S16-3 and S16-4 correspond to the processing of the light projection resumption and the projection light intensity adjusting means.

  As described above, in the present invention, since the projection of light by the light emitting means is temporarily stopped to determine the influence of disturbance light, it is possible to correctly determine whether or not the influence of disturbance light is present, and furthermore, the influence of disturbance light. In the case of receiving light, the detection sensitivity of the light receiving element is lowered to a sensitivity that is not affected by disturbance light, and the light receiving element in a state where the detection sensitivity is lowered by increasing the projection light intensity of the light emitting element reflects the reflected light of the object. Since it can be detected, the influence of ambient light can be suppressed.

  In the embodiment, the influence of disturbance light is automatically determined to automatically reduce the detection sensitivity of the light receiving element and increase the projection light intensity of the light emitting element. Element / light reception processing may be performed. In that case, the reflection type photoelectric switch 10 is provided with a disturbance light judgment switch such as a push button for starting the light emission / light reception processing, and it is desired to investigate the influence of the disturbance light and adjust the detection sensitivity and the projection light intensity. Sometimes, the disturbance light determination switch may be turned on. In this case, the light emission / light reception process shown in FIG. 2 is not automatically repeated so as to end when it is performed to the end, and the reflected light detection signal output (S14) is omitted. Then, the light emission / light reception process may be dedicated to the disturbance light determination / adjustment process, and the process related to the output of the reflected light detection signal based on the detection of the reflected light may be performed separately.

  Furthermore, the detection sensitivity of the light receiving element 31 can be increased and the projection light intensity of the light emitting element 11 can be decreased, so that the detection sensitivity can be increased or the projection light intensity can be decreased when necessary. . For example, the light emitting element drive / projection light intensity adjustment circuit 21 can increase and decrease the projection light intensity, and the light receiving element drive / detection sensitivity adjustment circuit 41 can increase and decrease the detection sensitivity. Only when the reflective photoelectric switch 10 is turned on or when a reset button (not shown) is pressed, the projection light intensity of the light emitting element 11 is first reduced by a required amount and the detection sensitivity of the light receiving element 31 is required. An initial setting process for increasing the amount is performed, and thereafter, the processes after S11 in the light emission / light reception process are performed, and the initial setting process is omitted for the second and subsequent repetitions of the light emission / light reception process. You may make it perform the process after S11.

It is a schematic block diagram which shows the structure of the reflection type photoelectric switch which concerns on one Embodiment of this invention. It is a flowchart of the light emission and light reception processing in the same embodiment. It is a flowchart of disturbance light influence prevention control processing in the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Reflection type photoelectric switch 11 Light emitting element 21 Light emitting element drive / projection light intensity adjustment circuit 31 Light receiving element 41 Light receiving element drive / detection sensitivity adjustment circuit 51 CPU
61 Actuator

Claims (1)

In a reflective photoelectric switch comprising a light emitting means for projecting light, and a light receiving means capable of detecting reflected light from an object of light projected from the light emitting means,
A light projection temporarily stopping means for temporarily stopping light projection by the light emitting means when light is detected by the light receiving means in a light projection state by the light emitting means;
When the light receiving means stops detecting light due to the temporary stop of the light projection, the light emitting means maintains the intensity of the projection light immediately before the light projection is temporarily stopped and the current detection sensitivity of the light receiving means in the light emitting means. Light projection resumption means for resuming light projection by
When the light receiving means detects light even when the light projection is temporarily stopped, a detection sensitivity adjusting means for reducing the detection sensitivity of the light receiving means in the light projection temporarily stopped state;
After reducing the detection sensitivity of the light receiving means by the detection sensitivity adjusting means, the projection of light by the light emitting means is resumed, and the light projection restarting and projection light intensity adjusting means for increasing the intensity of the projected light by the light emitting means When,
A reflection type photoelectric switch comprising:

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