WO2021152885A1

WO2021152885A1 - Sensor control circuit and device with built-in sensor

Info

Publication number: WO2021152885A1
Application number: PCT/JP2020/029930
Authority: WO
Inventors: 北野　幹夫
Original assignee: 北野　幹夫
Priority date: 2020-01-29
Filing date: 2020-08-05
Publication date: 2021-08-05
Also published as: JP2021117200A; JP6749717B1

Abstract

In a conventional sensor control circuit, there has been a problem that the transmission strength of a transmission element is fixed regardless of whether an object to be detected is present, and thus the power consumption of the transmission element used to detect the object to be detected is high. This sensor control circuit (10) comprises: an output terminal To that outputs, to a transmission element (21) which transmits a detection signal that is projected to an object (100) to be detected, a transmission element control signal Vout which controls the transmission strength of the detection signal; an input terminal Ti into which is input a monitor signal Vrec, a signal level of the monitor signal being varied by a reception element (22) that receives the detection signal according to the magnitude of the reception strength of the detection signal; and a transmission element control circuit (11) that generates the transmission element control signal Vout on the basis of the amount of change in a transmission rate βsen of the detection signal from the transmission element (21) to the reception element (22), the amount of change being obtained by the monitor signal Vrec. The transmission element control circuit (11) changes the transmission element control signal Vout in a direction to cancel out the change in the transmission rate βsen.

Description

Sensor control circuit and sensor embedded device

The present invention relates to a sensor control circuit and a sensor-embedded device, and relates to, for example, a sensor control circuit and a sensor-embedded device having a transmitting element for transmitting a detection signal and a receiving element for receiving the detection signal.

There is a sensor system that transmits and receives a detection signal between the transmitting element and the receiving element and detects that the object to be detected has entered the detection range set by the detection signal. In such a sensor system, the output intensity of the transmitting element may be controlled. Therefore, Patent Document 1 discloses an example of a method of controlling the output intensity of a transmitting element in a sensor system.

The semiconductor laser drive circuit described in Patent Document 1 is a semiconductor laser drive circuit for a semiconductor laser element including a semiconductor laser diode in which cathodes are commonly connected to each other and a photodiode for monitoring, and the semiconductor laser. The anode of the diode is connected to the power supply line side, and the anode of the monitoring photodiode is connected to the ground line side via a voltage generating means that generates a voltage corresponding to the amount of current flowing through the monitoring photodiode. Arranged between the power supply line and the anode of the semiconductor laser diode, or between the cathode of the semiconductor laser diode and the monitoring photodiode and the ground line, the amount of current supplied to the semiconductor laser diode is adjusted. In response to the voltage signal generated by the current control element and the voltage generating means, a control signal corresponding to the voltage signal level is given to the control terminal of the current control element, and the laser light output of the semiconductor laser diode is at a predetermined level. A feedback control means for feedback control so as to be, and a bias means for applying a reverse bias voltage to the monitor photodiode, which is arranged between the cathode of the semiconductor laser diode and the monitor photodiode and the ground line. Be equipped with.

Japanese Unexamined Patent Publication No. 2005-26371

However, the semiconductor laser drive circuit described in Patent Document 1 controls to keep the light emission output of the semiconductor laser diode serving as a light emitting element constant, and the amount of light emission output of the semiconductor laser diode regardless of the presence or absence of an object to be detected. Is constant, and there is a problem that the power consumption of the light emitting element used for detecting the object to be detected is high.

One aspect of the sensor control circuit according to the present invention is an output terminal that outputs a transmission element control signal that controls the transmission intensity of the detection signal to a transmission element that transmits a detection signal to irradiate the object to be detected, and the detection. The receiving element that receives the signal has an input terminal into which a monitor signal whose signal level fluctuates according to the magnitude of the receiving intensity of the detected signal is input, and the transmitting element acquired by the monitor signal to the receiving element. The transmission element control circuit includes a transmission element control circuit that generates the transmission element control signal based on the amount of change in the transmission rate of the detection signal, and the transmission element control circuit cancels the change in the transmission element control signal. To change.

One aspect of the sensor-embedded device according to the present invention includes the sensor control circuit, the transmitting element, and the receiving element.

According to the sensor control circuit and the sensor-embedded device according to the present invention, it is possible to suppress the transmission intensity of the transmitting element when the transmission rate of the detection signal is high and suppress the power consumption.

FIG. 5 is a block diagram of a sensor system to which the sensor control circuit according to the first embodiment is applied. It is a figure explaining the sensor detection type in a sensor system. It is a block diagram of the sensor system which applied the reflection type sensor circuit part in the sensor control circuit which concerns on Embodiment 1. FIG. It is a block diagram of the sensor system explaining the detailed structure of the sensor control circuit which concerns on Embodiment 1. FIG. It is a graph explaining the operation characteristic of the sensor control circuit which concerns on Embodiment 1. FIG. It is a block diagram of the sensor system which applied the reflection type sensor circuit part in the sensor control circuit which concerns on Embodiment 2, and is the output characteristic graph. It is a block diagram of the sensor system which applied the reflection type sensor circuit part in the sensor control circuit which concerns on Embodiment 3, and is the output characteristic graph. It is a block diagram of the sensor system which applied the reflection type sensor circuit part in the sensor control circuit which concerns on Embodiment 4. FIG. It is an output characteristic graph of the sensor control circuit which concerns on Embodiment 4. FIG. It is a block diagram of the sensor system which applied the reflection type sensor circuit part in the sensor control circuit which concerns on Embodiment 5. It is a block diagram of the sensor embedded device which concerns on Embodiment 6. It is a block diagram of the sensor embedded device which concerns on Embodiment 7.

Embodiment 1
In order to clarify the explanation, the following description and drawings have been omitted or simplified as appropriate. In addition, each element described in the drawing as a functional block that performs various processing can be composed of a CPU (Central Processing Unit), a memory, and other circuits in terms of hardware, and a memory in terms of software. It is realized by the program loaded in. Therefore, it is understood by those skilled in the art that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof, and is not limited to any of them. In each drawing, the same elements are designated by the same reference numerals, and duplicate explanations are omitted as necessary.

In addition, the above-mentioned program can be stored and supplied to a computer using various types of non-transitory computer readable medium. Non-temporary computer-readable media include various types of tangible storage media. Examples of non-temporary computer-readable media include magnetic recording media (eg, flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (eg, magneto-optical disks), CD-ROMs (Read Only Memory) CD-Rs, CDs. -R / W, including semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (Random Access Memory)). The program may also be supplied to the computer by various types of temporary computer readable medium. Examples of temporary computer-readable media include electrical, optical, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

In the following description, a sensor control circuit, a sensor system including a transmitting element and a receiving element which are sensor elements controlled by the sensor control circuit, and a sensor-embedded device that performs various controls using the output signal of the sensor system will be described. do.

Hereinafter, embodiments will be described. FIG. 1 shows a block diagram of a sensor system 1 to which the sensor control circuit 10 according to the first embodiment is applied. As shown in FIG. 1, the sensor system 1 according to the first embodiment includes a sensor control circuit 10 and a sensor circuit unit 20.

The sensor control circuit 10 has a transmission element control circuit 11, an input terminal Ti, and an output terminal To. The output terminal To outputs a transmission element control signal Vout that controls the transmission intensity of the detection signal to the transmission element 21 that transmits the detection signal to irradiate the object to be detected 100. The input terminal Ti is input with a monitor signal Vrec in which the receiving element 22 that receives the detection signal changes the signal level according to the magnitude of the reception intensity of the detection signal. The transmission element control circuit 11 generates a transmission element control signal Vout based on the amount of change in the transmission rate βsen of the detection signal from the transmission element 21 acquired by the monitor signal Vrec to the reception element 22. More specifically, the transmission element control circuit 11 changes the transmission element control signal Vout in a direction that cancels the change in the transmission rate βsen.

Here, the transmission rate βsen of the detection signal indicates the ratio of the detection signal output from the transmission element 21 and the reception signal received by the reception element 22. The transmission rate βsen is the distance between the transmitting element 21 and the receiving element 22, the ratio at which the detected signal is blocked by the detected object, the reflectance of the detected signal by the detected object, the distance between the transmitting element 21 or the receiving element 22 and the detected object, and the like. Varies depending on. One of the features of the sensor system 1 described below is that the signal level of the transmission element control signal Vout is controlled based on the amount of change in the transmission element βsen, not the absolute value of the transmission rate βsen.

Further, the sensor circuit unit 20 has a transmitting element 21 and a receiving element 22. The transmission element 21 outputs a detection signal whose output intensity increases or decreases according to the signal level of the transmission element control signal Vout generated in the sensor control circuit 10. The irradiation range of this detection signal is the detection range of the object to be detected 100 in the sensor system 1. The receiving element 22 receives the detection signal output by the transmitting element 21 and outputs a monitor signal Vrec whose signal level increases or decreases according to the received amount. The details of the transmission element control circuit 11 will be described later.

In the sensor system 1 according to the first embodiment, when the object to be detected 100 enters the detection range formed by the detection signal, the amount of the detection signal transmitted from the transmission element 21 to the reception element 22 decreases, so that the detection signal The transmission rate β-sen changes. Then, in the sensor system 1 according to the first embodiment, when the transmission rate βsen changes, the sensor control circuit 10 acquires the amount of change in the transmission rate βsen by the monitor signal Vrec and transmits the change in the transmission rate βsen in the direction of canceling the change. The element control signal Vout is changed. By performing such control, in the sensor system 1 according to the first embodiment, when the transmission rate βsen is lowered by the object to be detected, the output intensity of the detection signal is increased to the transmitting element 21 and the transmission rate βsen is increased. When the value rises, the transmission element 21 is controlled to weaken the output intensity of the detection signal.

Here, if the transmission element control signal Vout is changed in order to cancel the change in the transmission rate βsen, the change in the change rate βsen gradually disappears, that is, converges. The change in the transmission element control signal Vout stops according to the convergence of the change in the rate of change βsen. As a result, the transmission element control signal Vout changes according to the change in the rate of change βsen. That is, the change in the transmission element βsen is reflected in the change in the transmission element control signal Vout, and this transmission element control signal Vout corresponds to detecting the magnitude of the transmission element βsen.

Here, in the sensor circuit unit 20 shown in FIG. 1, there are a plurality of variations in the positional relationship between the method of arranging the transmitting element 21 and the receiving element 22 and the object to be detected 100. Therefore, FIG. 2 shows a diagram for explaining the sensor detection type in the sensor system. There are various types of sensors in which the transmitting element 21 and the receiving element 22 function as a pair with respect to the arrangement of the transmitting element and the receiving element. In FIG. 2, typical types are transmission type, reflection type, and regression type. Three reflective sensor detection types are shown.

In the transmission type, the transmitting element 21 and the receiving element 22 are arranged at positions facing each other, and the detection signal is transmitted from the transmitting element 21 toward the receiving element 22. Then, in the transmission type, the transmissibility βsen changes when the object to be detected 100 invades the detection range formed by the detection signal. Specifically, when the amount of the object to be detected 100 invading the detection range increases, the amount of the detection signal to be received by the receiving element 22 decreases, so that the transmission rate βsen decreases. That is, the amount of reception in the receiving element 22 is reduced. At this time, the sensor control circuit 10 changes the transmission element control signal Vout so as to increase the transmission amount of the transmission element 21. On the other hand, when the amount of the object to be detected 100 invading the detection range becomes small, the amount of the detection signal to be received by the receiving element 22 increases, so that the transmission rate βsen becomes large. That is, the reception amount in the receiving element 22 increases. At this time, the sensor control circuit 10 changes the transmission element control signal Vout so as to reduce the transmission amount of the transmission element 21.

In the transmission type, the receiving amount of the receiving element 22 changes not only by the amount of penetration of the object to be detected 100 into the detection range but also by the distance between the transmitting element 21 and the receiving element 22. At this time, the relationship between the change in the received amount and the change in the transmission element control signal Vout is the same as the above-mentioned change.

In the reflection type, the transmitting surface of the transmitting element 21 and the receiving surface of the receiving element 22 are arranged so as to face in the same direction. Then, in the reflection type, the detection signal output by the transmitting element 21 is reflected by the object to be detected 100, and the receiving element 22 receives the detection signal reflected by the object to be detected 100. Then, in the reflection type, the transmissibility βsen changes as the distance between the receiving element 22 (or the transmitting element 21) and the object to be detected 100 changes. Specifically, as the distance between the receiving element 22 and the object to be detected 100 increases, the amount of the detection signal reflected by the object to be detected 100 and reaches the receiving element 22 decreases, so that the transmission rate βsen becomes small. That is, the amount of reception in the receiving element 22 is reduced. At this time, the sensor control circuit 10 changes the transmission element control signal Vout so as to increase the transmission amount of the transmission element 21. On the other hand, when the distance between the receiving element 22 and the object to be detected 100 becomes small, the amount of the detection signal reflected by the object to be detected 100 and reaches the receiving element 22 increases, so that the transmission rate βsen increases. That is, the reception amount in the receiving element 22 increases. At this time, the sensor control circuit 10 changes the transmission element control signal Vout so as to reduce the transmission amount of the transmission element 21.

In the reflection type, the reception amount of the receiving element 22 changes even when the object to be detected 100 is moved in the vertical direction of the drawing with respect to the detection range. At this time, the relationship between the change in the received amount and the change in the transmission element control signal Vout is the same as the above-mentioned change.

In the regression reflection type, the receiving element 22 receives the detection signal by directing the transmitting surface of the transmitting element 21 and the receiving surface of the receiving element 22 in the same direction and reflecting the detection signal with the reflector. Then, in the regression type, the object 100 to be detected, which has a sufficiently lower reflectance than the reflector, blocks the detection signal reflected by the reflector (that is, the object 100 to be detected invades the detection range), so that the transmission rate βsen is increased. Change. Further, in the regression reflection type, the transmissibility βsen changes as the distance between the receiving element 22 (or the transmitting element 21) and the reflector changes. Specifically, when the amount of the object to be detected 100 invading the detection range increases, or when the distance between the receiving element 22 and the reflector increases, the amount of the detection signal reflected by the reflector and reaches the receiving element 22 decreases. The transmission rate βsen becomes smaller. That is, the amount of reception in the receiving element 22 is reduced. At this time, the sensor control circuit 10 changes the transmission element control signal Vout so as to increase the transmission amount of the transmission element 21. On the other hand, when the amount of the detected object 100 entering the detection range becomes small or the distance between the receiving element 22 and the reflector becomes small, the amount of the detection signal reflected by the reflector and reaching the receiving element 22 increases, so that the transmission rate βsen Becomes larger. That is, the reception amount in the receiving element 22 increases. At this time, the sensor control circuit 10 changes the transmission element control signal Vout so as to reduce the transmission amount of the transmission element 21.

In the regression reflection type, it is premised that there is no influence of reflection other than the reflector, and it is necessary to select the object to be detected 100 having a small degree of reflection.

Subsequently, the sensor control circuit 10 will be described in more detail. First, as the transmitting element 21 and the receiving element 22 used in the sensor control circuit 10, an element that transmits and receives a medium propagating in space as a detection signal is used. Visible light, invisible light, sound, ultrasonic waves, heat, water pressure, radio waves, and the like can be considered as the medium propagating in space. Therefore, in the following, an example of the sensor system 1 using the light emitting unit 23 and the light receiving unit 24 for transmitting and receiving visible light signals as the transmitting element 21 and the receiving element 22 will be described. Further, in the following description, a sensor system 1 that uses a sensor having a reflection type sensor detection type as the sensor circuit unit 20 will be described as an example.

Therefore, FIG. 3 shows a block diagram of the sensor system 1 to which the reflection type sensor circuit unit 20 is applied in the sensor control circuit 10 according to the first embodiment. In the example shown in FIG. 3, as the sensor circuit unit 20, the light emitting unit 23 and the light receiving unit 24 are provided with the above-mentioned reflection type configuration. Further, the sensor control circuit 10 gives a transmission element control signal Vout to the light emitting unit 23 and receives a monitor signal Vrec from the light receiving unit 24. Then, the sensor control circuit 10 outputs the transmission element control signal Vout based on the magnitude of the difference signal between the reference signal Vref and the monitor signal Vrec, which is the control reference, in the transmission element control circuit 11. Further, the transmission element control signal Vout is generated by the difference signal amplifier 12. Then, the sensor control circuit 10 controls that the light emitted by the light emitting unit 23 becomes weaker as the object to be detected 100 is closer to the sensor circuit unit 20. In other words, the sensor control circuit 10 according to the first embodiment determines the intensity of light emitted by the light emitting unit 23 so as to suppress fluctuations in the amount of light received by the light receiving unit 24 with respect to the distance between the object to be detected 100 and the sensor circuit unit 20. It can be said to control.

Subsequently, the detailed circuit configuration of the sensor system 1 according to the first embodiment shown in FIG. 3 will be described. Therefore, FIG. 4 shows a block diagram of the sensor system 1 for explaining the detailed configuration of the sensor control circuit 10 according to the first embodiment. Although the description regarding the object to be detected 100 shown in FIG. 3 is omitted in FIG. 4, the detection signal transmitted by the transmitting element 21 is reflected by the object to be detected 100 and received by the receiving element 22 in FIG. NS.

As shown in FIG. 4, the sensor control circuit 10 includes a transmission element control circuit 11. The transmission element control circuit 11 acquires the amount of change in the transmission rate βsen of the detection signal from the light emitting unit 23 to the light receiving unit 24 by the monitor signal Vrec, and uses the value of the reference signal Vref and the amount of change in the transmission rate βsen. , The transmission element control signal Vout is changed in the direction of canceling the change of the transmission rate βsen. In order to realize the operation of the transmission element control circuit 11, the difference signal amplifier 12 is used in the example shown in FIG. The configuration of the difference signal amplifier 12 described below is an example for realizing the difference signal amplifier 12, and other types or various amplifier circuits having a circuit configuration can be used.

The difference signal amplifier 12 has an amplifier OP, a first impedance element (for example, resistor R1), and a second impedance element (for example, resistor R2). The impedance element is not limited to a single resistor, but includes a capacitor, a circuit including a resistor and a capacitor, or other elements and circuits having various forms of impedance. The amplifier OP is an amplifier that amplifies and outputs the voltage difference between two input signals. The constant voltage source outputs the reference signal Vref. This reference signal Vref is given to the forward rotation input terminal of the amplifier OP. The resistor R2 is connected between the output terminal of the amplifier OP and the inverting input terminal. Further, a monitor signal Vrec is given to one end of the resistor R1, and the other end is connected to the inverting input terminal of the amplifier OP. The gain of the difference signal amplifier 12 using the amplifier OP in the sensor control circuit 10 can be changed by adjusting the resistance values of the resistors R1 and R2. Further, the output signal of the amplifier OP becomes the transmission element control signal Vout.

Here, a formula for determining the signal level of the transmission element control signal Vout in the difference signal amplifier 12 will be described. The transmission element control signal Vout is calculated by the equation (1).
Vout ≒ Vref × (R1 + R2) / R1-Vrec × (R2 / R1)
= Vref + (Vref-Vrec) × (R2 / R1) ・・・ (1)
That is, the difference signal amplifier 12 adds the value obtained by multiplying the difference between the value of the reference signal Vref and the value of the monitor signal Vrec by the ratio of the resistors R1 and R2 to the value of the reference signal Vref, and adds the value to the transmission element control signal. Let it be the signal level of Vout.

The light emitting unit 23 has a light emitting element Dtran and a resistor R4. In the light emitting element Dtran, a transmission element control signal Vout is given to the anode, and the cathode is connected to the ground node via the resistor R4. The amount of light emitted from the light emitting element Dtran changes depending on the flowing current. In the light emitting unit 23, the current flowing through the light emitting element Dtran is set by using the resistor R4. The circuit configuration of the light emitting unit 23 shown in FIG. 4 is an example, and other circuit configurations may be used.

The light receiving unit 24 has a light receiving element Trec and a resistor R5. In the light receiving element Trec, a power supply voltage VCS is applied to the collector, and the emitter is connected to the ground node via the resistor R5. The light receiving element Trec outputs a current having a magnitude corresponding to the magnitude of the light receiving amount from the emitter. The signal level of the monitor signal Vrec is determined by converting the current output from the emitter of the light receiving element Trec into a voltage using the resistor R5. That is, since the signal level of the monitor signal Vrec fluctuates according to the fluctuation of the transmission rate βsen of the detection signal and the fluctuation of the received light amount, the sensor control circuit 10 changes the transmission rate βsen by this monitor signal Vrec. Can be grasped. The circuit configuration of the light receiving unit 24 shown in FIG. 4 is an example using a phototransistor, and may be another circuit configuration (for example, a configuration using a photodiode).

In the difference signal amplifier 12 according to the first embodiment, the forward rotation input terminal and the inverting input terminal of the amplifier OP have the same potential due to a virtual short circuit. That is, the amplifier OP operates so that the inverting input voltage Vm of the inverting input terminal matches the value of the reference signal Vref given to the forward rotation input terminal regardless of the value of the monitor signal Vrec. More specifically, the difference signal amplifier 12 changes the transmission element control signal Vout so that the inverting input voltage Vm matches the value of the reference signal Vref when the monitor signal Vrec changes. By such an operation, the transmitting element control circuit 11 acquires the amount of change in the transmission rate βsen of the detection signal from the light emitting unit 23 to the receiving element 22 by the monitor signal Vrec, and changes the value of the reference signal Vref and the transmission rate βsen. The function of changing the transmission element control signal Vout in the direction of canceling the change of the transmission rate βsen is realized by using the amount.

Subsequently, the operating characteristics of the sensor system 1 according to the first embodiment will be described. Therefore, FIG. 5 shows a graph for explaining the operating characteristics of the sensor control circuit 10 according to the first embodiment. In the graph shown in FIG. 5, the horizontal axis shows the distance between the light receiving unit 24 and the light emitting unit 23 and the object to be detected 100, and the vertical axis shows the magnitude of the transmitting element control signal Vout. Further, in the graph shown in FIG. 5, a curve in which the value of the resistor R2 is changed in four ways while the resistor R1 is constant is shown.

As shown in FIG. 5, in the sensor system 1 according to the first embodiment, it can be seen that the transmission element control signal Vout increases as the distance between the light receiving unit 24 and the light emitting unit 23 and the object to be detected 100 increases. Further, the magnitude of the transmission element control signal Vout reaches an upper limit value (for example, power supply voltage) when the distance between the light receiving unit 24 and the light emitting unit 23 and the object to be detected 100 increases. Then, as shown in FIG. 5, it can be seen that by changing the resistor R2, the range in which the transmission element control signal Vout changes linearly and the slope of the change in the transmission element control signal Vout can be changed.

From the description with reference to FIGS. 1 to 5, in the sensor system 1 according to the first embodiment, the amount of the detected object 100 blocking the detection signal or the distance between the detected object 100 and the receiving element 22 or the transmitting element 21 changes. If so, the transmission rate β-sen of the detection signal changes. Then, the sensor control circuit 10 according to the first embodiment acquires the change amount of the transmission rate βsen of the detection signal by the monitor signal Vrec in the transmission element control circuit 11, and changes the value of the reference signal Vref and the transmission rate βsen. And, the transmission element control signal Vout is changed in the direction of canceling the change of the transmission rate βsen. As a result, in the sensor system 1 according to the first embodiment, for example, when the received amount in the receiving element 22 is reduced by the object to be detected 100, the transmission intensity of the transmitting element 21 is increased so as to compensate for the decrease in the received amount. Control to increase can be performed. That is, in the sensor system 1 according to the first embodiment, the detected object 100 can be detected while suppressing the power consumption of the transmitting element 21 in the standby state waiting for the detection of the detected object 100.

Further, in the sensor system 1 according to the first embodiment, for example, when a reflection type sensor is used as the sensor circuit unit 20, the transmission element control signal Vout depends on the distance between the sensor circuit unit 20 and the object to be detected 100. Can be changed. By utilizing this characteristic of the sensor system 1 according to the first embodiment, the power consumption of the distance sensor that detects a change in the object to be detected 100 such that the distance is short in the steady state and the distance is long at the timing to be detected. Can be reduced. Specifically, in the above-mentioned distance sensor using the sensor system 1 according to the first embodiment, when the distance between the object to be detected 100 and the sensor circuit unit 20 that are intermittently generated is long, the effect of reducing the power consumption is obtained. Although it is small, the power consumption is reduced when the distance between the object to be detected 100 and the sensor circuit unit 20, which are constantly generated for a long time, is short, so that the total usage time of the sensor system 1 is consumed. Power can be significantly reduced. Such a distance sensor can be used, for example, as a sensor for detecting the amount of pressing of a piano keyboard.

Further, in the sensor system 1 according to the first embodiment, when the reception amount in the reception element 22 decreases, the transmission intensity of the transmission element 21 is increased so as to compensate for the decrease. As a result, in the sensor system 1 according to the first embodiment, it is possible to prevent the received amount from being saturated even if the distance between the object to be detected 100 and the receiving element 22 becomes short. In addition, when the distance is long, the reception level can be maintained within a range in which the output on the transmitting side is not saturated, and it is possible to prevent the received signal from becoming too small to be detected. That is, in the sensor system 1 according to the first embodiment, the detection range can be made wider than that of the conventional sensor system.

Embodiment 2
In the second embodiment, the sensor control circuit 30 which is a modification of the sensor control circuit 10 according to the first embodiment will be described. Therefore, FIG. 6 shows a block diagram of the sensor system 2 to which the reflection type sensor circuit unit 20 is applied in the sensor control circuit 30 according to the second embodiment and an output characteristic graph thereof.

As shown in FIG. 6, the sensor control circuit 30 according to the second embodiment replaces the reference signal Vref in the sensor control circuit 10 according to the first embodiment with a reference signal Vref including a DC component and an AC component. be. By using the reference signal including the DC component and the AC signal as the reference signal in this way, the sensor system 2 according to the second embodiment becomes a system for feeding back the signal including the DC component and the AC component.

Further, as shown in the lower figure of FIG. 6, the output characteristics of the sensor control circuit 30 according to the second embodiment show that the DC component and the AC component become longer as the distance between the light emitting unit 23 and the light receiving unit 24 and the object to be detected 100 increases. Both get bigger.

In the example shown in FIG. 5, an example in which only the DC component is used as the detection signal of the visible light signal is shown as the sensor circuit unit 20, but the signal including the DC component and the AC component is used as the transmission element or the reception element of the sensor circuit unit 20. When an element that can be driven by the above is used, it is possible to use a signal that includes an AC component and a DC component in the reference signal as shown in FIG.

Although FIG. 6 uses a reference signal containing a direct current component and an AC component, it is also possible to use a reference signal containing only an AC component in the case of a medium that does not transmit direct current. That is, what kind of component is included as the reference signal can be determined by the characteristics of the medium for transmitting the detection signal and the sensor used as the sensor circuit unit 20.

In this way, by using the reference signal in which the AC component is superimposed on the DC component, the output by the DC component and the output by the AC component (amplitude of the AC signal, effective value, peak to peak value, etc.) are 2 You can get one. For example, as a crime prevention application, it is conceivable to apply it to an application such as a sensor light that discourages intrusion by turning on a light to notify an intruder that an intrusion has been detected. By using this proposal, to notify the intruder of the detection status that discourages intrusion, DC detection (notification to the intruder by the change in the brightness of the lighting) is applied to the security system where multiple lights are detected. An application that uses detection of AC components with different frequencies for notification is conceivable.

When using a plurality of "security lighting devices with sensors" that have both such lighting and sensor functions, the lighting that is the transmitter is driven by both AC and DC signals. At this time, by notifying the intrusion detection by the change in brightness due to the DC component, it is possible to be aware of the detection and to discourage the intrusion. On the other hand, in order to notify the host system of the presence or absence of an intruder using a lighting device for the purpose of intrusion prevention (security), the AC signal is set to a different frequency for each device in multiple "security lighting devices with sensors". It is conceivable that only the AC component of the output of the above is mixed, the AC component after mixing is multiplexed by FDM (Frequency Division Multiplexing), and the higher system such as the CPU is notified by one transmission line.

As the AC component included in the reference signal Vref, not only a signal having a constant amplitude and frequency but also a signal having a fluctuating amplitude and frequency such as a music signal can be used. Further, only one of the amplitude and frequency of this AC component may be constant.

Embodiment 3
In the third embodiment, the sensor control circuit 40 which is a modification of the sensor control circuit 10 according to the first embodiment will be described. Therefore, FIG. 7 shows a block diagram of the sensor system 3 to which the reflection type sensor circuit unit 20 is applied in the sensor control circuit 40 according to the third embodiment and an output characteristic graph thereof.

As shown in FIG. 7, the sensor control circuit 40 according to the third embodiment has a DC component (DC in the figure) and an AC component (AC in the figure) as a reference signal Vref in the sensor control circuit 10 according to the first embodiment. ) And a signal including. Further, the sensor control circuit 40 replaces the transmission element control circuit 11 with the transmission element control circuit 41. The transmission element control circuit 41 is the one in which the DC component removal circuit 42 is added in addition to the difference signal amplifier 12. The DC component removing circuit 42 removes the DC component of the signal obtained from the light receiving unit 24 to generate a monitor signal Vrec to be given to the difference signal amplifier 12.

By using a signal obtained by synthesizing a DC component and an AC component as a reference signal and returning only the AC component of the monitor signal Vrec, the sensor system 3 according to the third embodiment has a transmission element control signal. It is possible to construct a system in which only the AC component contained in Vout fluctuates. For example, even if it is not possible to transmit only the AC signal and the DC signal and the AC signal are transmitted, the effect is the same as if only the AC signal is transmitted, and in the third embodiment, the effect is the same. In comparison with the "security lighting with sensor" of the second embodiment, in order to detect the intrusion without notifying the intruder for the purpose of catching the intruder, sensing can be performed without changing the brightness of the lighting. The point is different.

With reference to the output characteristic graph shown in the lower figure of FIG. 7, the DC component of the transmission element control signal Vout of the sensor system 3 according to the third embodiment is the distance between the light emitting unit 23, the light receiving unit 24, and the object to be detected 100. It is constant regardless. On the other hand, the AC component of the transmission element control signal Vout of the sensor system 3 according to the third embodiment becomes larger as the distance between the light emitting unit 23 and the light receiving unit 24 and the object to be detected 100 increases. This is because only the AC component of the transmission element control signal Vout is fed back by the DC component removing circuit 42.

In the example shown in FIG. 7, an example in which a visible light signal is used as a detection signal is shown as the sensor circuit unit 20, but the sensor circuit unit 20 can be driven by a signal containing only an AC component as a transmission element or a reception element. When using an element (for example, a speaker and a microphone when sound is used as a detection signal), a signal containing only the AC component included in the reference signal without using the DC component removing circuit 42 as shown in FIG. The difference signal amplifier 12 is configured such that the output of the difference signal amplifier 12 changes in both directions ± with reference to the ground node with ± power supply. That is, as the reference signal, various signal sources can be used, such as a DC signal only, a signal obtained by combining a DC signal and an AC signal, and an AC signal only, depending on the application and specifications of the sensor system.

Embodiment 4
In the fourth embodiment, the sensor control circuit 50 which is a modification of the sensor control circuit 40 according to the third embodiment will be described. Therefore, FIG. 8 shows a block diagram of the sensor system 4 to which the reflection type sensor circuit unit 20 is applied in the sensor control circuit 50 according to the fourth embodiment.

As shown in FIG. 8, the sensor control circuit 50 according to the fourth embodiment has a transmission element control circuit 51 instead of the transmission element control circuit 11 according to the first embodiment. The transmission element control circuit 51 is a difference signal amplifier 12 plus a direct feedback circuit 52. Further, in the sensor control circuit 50 according to the fourth embodiment, the size of the transmission element control signal Vout1 corresponding to the transmission element control signal Vout of another embodiment and the magnitude of the AC component of the transmission element control signal Vout1 are used as output signals. The detection result signal Vout2 whose signal level changes proportionally is output. Further, the direct feedback circuit 52 according to the fourth embodiment generates a feedback signal whose signal level changes in proportion to the magnitude of the AC component of the transmission element control signal Vout1, and is on the inverting input terminal side of the difference signal amplifier 12. Give feedback to.

The direct feedback circuit 52 includes a filter circuit 53, an amplitude detection circuit 54, and an amplifier 55. The filter circuit 53 extracts the AC component of the transmission element control signal Vout1. The filter circuit 53 can use a high-pass filter, a band-pass filter, or the like when extracting the AC component of the transmission element control signal Vout1. On the other hand, when extracting the DC component of the transmission element control signal Vout1, a low-pass filter is used as the filter circuit 53. In the example shown in FIG. 8, a high-pass filter or a band-pass filter is used as the filter circuit 53 in order to extract the AC component.

The amplitude detection circuit 54 generates a detection result signal Vout2 having a DC component corresponding to the magnitude of the amplitude of the AC component extracted by the filter circuit 53. The amplifier 55 amplifies or attenuates the detection result signal Vout2 by a preset gain k to generate a feedback signal Vfb. This Vfb is combined with the monitor signal Vrec output by the DC component removing circuit 42, and is input to the inverting input terminal of the difference signal amplifier 12.

Here, the operation of the sensor control circuit 50 according to the fourth embodiment will be described. Therefore, FIG. 9 shows an output characteristic graph of the sensor control circuit 50 according to the fourth embodiment. In the graph shown in FIG. 9, the range of the fluctuation width of the signal of the AC component of the transmission element control signal Vout is shown by hatching with diagonal lines. As shown in FIG. 9, in the sensor control circuit 50 according to the fourth embodiment, the swing width of the AC component increases according to the distance between the light emitting unit 23 and the light receiving unit 24 and the object to be detected 100. This is because the sensor control circuit 50 has a signal path for feeding back the AC component of the reference signal via the light emitting unit 23 and the light receiving unit 24.

Then, in the sensor control circuit 50 according to the fourth embodiment, the detection result signal Vout2 is directly generated by the feedback circuit 52 according to the change in the magnitude of the AC component of the transmission element control signal Vout. That is, the signal level of the detection result signal Vout2 increases according to the distance between the light emitting unit 23 and the light receiving unit 24 and the object to be detected 100. Then, in the sensor control circuit 50, when the gain k of the amplifier 55 is set to 1, the DC component of the transmission element control signal Vout1 is generated by inverting and amplifying the difference value between the detection result signal Vout2 and the reference signal Vref. The gain k of the amplifier 55 can be selected as an appropriate value other than 1 in consideration of the feedback amount of the detection result signal Vout2 to be fed back and the gain of the entire direct feedback circuit 52.

By performing such control, in the sensor system 4 according to the fourth embodiment, even if the amplitude is increased according to the distance between the light emitting unit 23 and the light receiving unit 24 and the object to be detected 100, the alternating current of the light emitting unit 23 It is possible to prevent the emission intensity based on the signal from being saturated. On the other hand, in the sensor system 4 according to the fourth embodiment, the signal level of the DC component of the transmission element control signal Vout1 decreases according to the distance between the light emitting unit 23 and the light receiving unit 24 and the object to be detected, for example. When the light emitting unit 23 is used as the transmitting element 21, the amount of light emitted that can be visually observed increases as the distance between the object to be detected 100 and the sensor circuit unit 20 decreases.

Further, in the fourth embodiment, the feedback signal Vfb directly generated by the feedback circuit 52 is fed back to the inverting input terminal of the difference signal amplifier 12, but the destination to which the feedback signal Vfb is given is the forward rotation input terminal of the difference signal amplifier 12. It can also be used, or it can be a transmission element control signal Vout1. In this case, since the configuration for adjusting the polarity of the feedback signal Vfb according to the destination is an improvement within a range that can be easily conceived by those skilled in the art, description thereof will be omitted here. Further, in the direct feedback system configured by the direct feedback circuit 52 of the fourth embodiment, since the AC component is converted to DC and then negative feedback is provided, the change direction of the DC output is opposite to that of the AC output, but the positive feedback By returning with, the direction of change of direct current can be made the same as that of alternating current output.

Embodiment 5
In the fifth embodiment, the sensor control circuit 60 which is a modification of the sensor control circuit 10 according to the first embodiment will be described. Therefore, FIG. 10 shows a block diagram of the sensor system 5 to which the reflection type sensor circuit unit 20 is applied in the sensor control circuit 60 according to the fifth embodiment.

As shown in FIG. 10, in the sensor control circuit 60 according to the fifth embodiment, the digital arithmetic circuit 61 is used as the transmission element control circuit 11 according to the first embodiment. Further, the digital arithmetic circuit 61 includes an analog-to-digital conversion circuit 62, a register 63, a signal processing unit 64, and a digital-to-analog conversion circuit 65. In the example shown in FIG. 10, the digital arithmetic circuit 61 includes the analog-to-digital conversion circuit 62, the register 63, the signal processing unit 64, and the digital-to-analog conversion circuit 65 in the package. However, the analog-to-digital conversion circuit 62 and the register 63 are included in the package. , The signal processing unit 64 and the digital-to-analog conversion circuit 65 may be incorporated as separate parts, or a digital IO (for example, a speaker driven by a digital amplifier and a MEMS microphone) may be incorporated in the light emitting unit 23 and the light receiving unit 24. Can be directly connected to the signal processing unit 64 without including the analog-to-digital conversion circuit 62 and the digital-to-analog conversion circuit 65. Further, in the digital arithmetic circuit 61, it is assumed that the signal processing unit 64 executes a sensor control program that controls the sensor circuit unit 20. Further, the register 63 includes a reference value, and this reference value can be given from the outside without using the register 63. Further, the digital arithmetic circuit 61 having the same function as the transmission element control circuit 11 according to the first embodiment can be configured without using the reference value itself.

The analog-to-digital conversion circuit 62 converts the monitor signal Vrec having an analog value into a digital value. The register 63 holds a reference value that is a value of the reference signal Vref, which is the signal level of the reference signal. The signal processing unit 64 performs the control performed by the difference signal amplifier 12 composed of the amplifier OP, the resistor R1 and the resistor R2 according to the first embodiment. Specifically, the value obtained by amplifying the voltage difference between the reception level signal Vrec and the reference signal Vref with the gain A of the difference signal amplifier 12 according to the first embodiment is calculated as the value of the transmission element control signal Vout. The digital-to-analog conversion circuit 65 converts the digital value of the transmission element control signal Vout calculated by the signal processing unit 64 into an analog value, and outputs the transmission element control signal Vout having a voltage value corresponding to the analog value.

From the above description, it can be seen that in the sensor system 5 according to the fifth embodiment, a sensor control circuit 60 that performs the same function as the sensor control circuit 10 according to the first embodiment can be configured by a digital circuit. Further, by improving the processing in the signal processing unit 64, it is possible to realize the control described in the second to fourth embodiments.

Embodiment 6
In the sixth embodiment, a sensor-embedded device which is an application device using the sensor system 1 according to the first embodiment will be described. Therefore, FIG. 11 shows a block diagram of the sensor embedded device 6 according to the sixth embodiment. As shown in FIG. 11, in the sensor-embedded device 6 according to the sixth embodiment, the light emitting unit 23 includes an output element (for example, a light emitting element Dtran) that outputs a detection signal, and changes in the current flowing through the light emitting element Dtran. The sensor output signal that fluctuates according to the response is taken out, and the sensor output signal is used to control a device other than the transmitting element or another element.

More specifically, as shown in FIG. 11, the current flowing through the light emitting element Dtran is converted into a voltage value by the resistor R4 and becomes a sensor output signal. Then, in the example shown in FIG. 11, the sensor output signal is incorporated into a signal processing circuit 70 including an analog-to-digital conversion circuit that converts the sensor output signal into a digital value. Then, the signal processing circuit 70 uses the sensor output signal for various controls.

The sensor output signal converted into a voltage value by the resistor R4 has a dynamic range from 0 V to a voltage value close to the power supply voltage VCS (more specifically, a voltage obtained by subtracting the diode voltage of the light emitting element Dtran from the power supply voltage VCS). Since it has, it is suitable for conversion and use with an analog-digital conversion circuit.

Further, in the example shown in FIG. 11, the sensor-embedded device 6 according to the sixth embodiment controls a device other than the transmitting element or another element by using the transmitting element control signal Vout of the sensor control circuit 10.

More specifically, in the example shown in FIG. 11, the transmission element control signal Vout is given to the motor drive circuit 71 to drive the motor 72. As a result, the sensor-embedded device 6 can consider, for example, an application example in which the actuator is operated according to the detection result of the object to be detected 100.

Embodiment 7
In the seventh embodiment, another configuration for outputting a signal relating to the detection result to be output to the host system in the sensor system 2 according to the second embodiment will be described. Therefore, FIG. 12 shows a block diagram of the sensor embedded device 7 according to the seventh embodiment.

As shown in FIG. 12, the sensor embedded device 7 according to the seventh embodiment has a sensor circuit unit 80 instead of the sensor circuit unit 20 according to the second embodiment. Then, in the sensor circuit unit 80, a light receiving unit 81 is added to the light emitting unit 23 and the light receiving unit 24. The sensor circuit unit 80 detects the amount of light emitted from the light emitting unit 23 by the light receiving unit 81 regardless of the change in the position of the object to be detected 100, and outputs a transmission monitor signal whose signal level changes according to the detected amount of received light. do. Then, the transmission monitor signal output by the light receiving unit 81 is output via the high-pass filter 82 or the low-pass filter 84.

More specifically, in the sensor-embedded device 7 according to the seventh embodiment, the AC component of the transmission monitor signal is extracted by the high-pass filter 82, and the AC is a DC signal having a signal level corresponding to the amplitude of the extracted AC component. The component transmission monitor signal Vout_AC is output. Further, in the sensor-embedded device 7 according to the seventh embodiment, the DC component of the transmission monitor signal is extracted by the low-pass filter 84, and the DC component transmission monitor signal Vout_DC, which is a DC signal having the signal level of the extracted DC component, is output. ..

By obtaining the output result from the sensor system by the method shown in FIG. 12, the temperature characteristic of the light emitting unit 23 or the characteristic change due to the change with time (hereinafter, these characteristic change is simply referred to as the characteristic change). It is possible to obtain an output result that is not affected by. When the characteristic change occurs in the light emitting unit 23, in the system composed of the sensor control circuit 10, the light emitting unit 23, and the light receiving unit 24 constituting the sensor system, the transmission rate βsen is caused by the characteristic change of the light emitting unit 23. Since the change component is included, the output signal of the sensor control circuit 10 includes the change component due to the characteristic change of the light emitting unit 23. However, in the sensor-embedded device 7 according to the seventh embodiment, by providing the light receiving unit 81 that directly monitors the light emitting amount of the light emitting unit 23, it is possible to obtain an output result that is not affected by this characteristic change.

Further, by feeding back only the DC component of the transmission monitor signal output by the light receiving unit 81 to the transmission element control circuit 11, APC control for suppressing the change in the amount of light emitted by the light emitting unit 23 over time is performed, and the object to be detected is controlled by the AC component. Can also be detected.

The present invention is not limited to the above embodiment, and can be appropriately modified without departing from the spirit.

This application claims priority based on Japanese application Japanese Patent Application No. 2020-12792 filed on January 29, 2020, and incorporates all of its disclosures herein.

1 to 5 Sensor system 6, 7 Sensor built-in

device

10, 30, 40, 50, 60 Sensor control circuit 11 Transmission element control circuit 12 Difference signal amplifier 20 Sensor circuit unit 21 Transmission element 22 Reception element 23 Light emitting unit 24 Light receiving unit 41 Transmission Element control circuit 42 DC component removal circuit 51 Transmit element control circuit 52 Direct feedback circuit 53 Filter circuit 54 Oscillation detection circuit 55 Amplifier 61 Digital arithmetic circuit 62 Analog-to-digital conversion circuit 63 Register 64 Signal processing unit 65 Digital-to-analog conversion circuit 70 Signal processing circuit 71 Motor drive circuit 72 Motor 80 Sensor circuit part 81 Light receiving part 82 High-pass filter 83 Oscillation detection circuit 84 Low-pass filter 100 Detected object OP Amplifier Vref Reference signal Vrec Monitor signal Vm Inverted input voltage Vfb Feedback signal Vout Transmission element control signal R1, R2 , R4, R5 Resistance Dtran Light emitting element Trec Light receiving element Ti input terminal To output terminal

Claims

An output terminal that outputs a transmission element control signal that controls the transmission intensity of the detection signal to a transmission element that transmits a detection signal to irradiate the object to be detected.
An input terminal into which a receiving element that receives the detection signal inputs a monitor signal that fluctuates the signal level according to the magnitude of the reception intensity of the detection signal, and an input terminal.
The magnitude of the amount of change in the transmission rate of the detection signal from the transmission element to the reception element acquired by the monitor signal is detected by the difference between the reference signal whose signal level is predetermined and the monitor signal. It has a transmission element control circuit that generates the transmission element control signal whose magnitude changes according to the magnitude of the change amount.
The transmission element control circuit is a sensor control circuit that changes the transmission element control signal in a direction that cancels the change in the transmission rate.
The sensor control circuit according to claim 1, wherein the transmission element control circuit includes a difference signal amplifier that outputs the transmission element control signal.
The difference signal amplifier
A first impedance element to which the monitor signal is input to one end,
An amplifier in which the reference signal is input to the forward rotation input terminal, the other end of the first impedance element is connected to the inverting input terminal, and the transmission element control signal is output from the output terminal.
A second impedance element connected between the output terminal and the inverting input terminal of the amplifier,
The sensor control circuit according to claim 2.
The reference signal and the monitor signal contain at least an AC component and contain at least an AC component.
The difference signal amplifier changes the transmission element control signal of the AC component included in the transmission element control signal so that the magnitude of the difference component between the reference signal and the monitor signal becomes small. 3. The sensor control circuit according to 3.
The transmitting element control circuit is
The AC component of the transmission element control signal output by the difference signal amplifier is extracted to generate an amplitude level signal having a DC component corresponding to the magnitude of the extracted AC component, and the amplitude level signal is converted into the difference. The sensor control circuit according to claim 4, further comprising a direct feedback circuit that gives a signal amplifier as a feedback signal.
The transmission element control circuit is a signal processing unit that acquires a change in the transmission rate from the monitor signal by digital signal processing and changes the transmission element control signal in a direction that cancels the change in the transmission rate. 2. The sensor control circuit according to any one of 2, 4 or 5.
The sensor control circuit according to any one of claims 1 to 6, wherein the transmitting element and the receiving element transmit and receive a medium propagating in space as the detection signal.
A sensor-embedded device having the sensor control circuit, the transmitting element, and the receiving element according to any one of claims 1 to 7.
The influence of the transmission element control signal of the sensor control circuit, the sensor output signal that fluctuates according to the fluctuation of the current flowing through the output element that outputs the detection signal in the transmission element, or the influence of the object to be detected from the transmission element. At least one of the outputs of the monitor receiving element that monitors the detection signal output by the transmitting element without receiving the signal is used to the object to be detected with respect to a device other than the transmitting element or another element. The sensor-embedded device according to claim 8, wherein the control is performed according to the change in the transmission rate caused by the change.