CN219016582U - distance sensing device - Google Patents

Abstract

The utility model provides a distance sensing device. Provide ranging light to the ranging target to generate reflected light. During the photo-sensing period, according to the photo-sensing signal generated by the photo-sensing diode sensing the reflected light during receiving the breakdown bias voltage, counting the breakdown times of the photo-sensing diode to generate a count value. The distance between the distance sensing device and the distance measuring target is judged according to the count value.

Description

distance sensing device

technical field

The utility model relates to a sensing device, in particular to a distance sensing device.

Background technique

Integrated chips (ICs) with photonic devices exist in many modern electronic devices. Generally speaking, light sensing chips usually convert the current into a voltage by means of photocurrent integration, and then use an analog-to-digital converter for decoding. Analog-to-digital converters have the disadvantages of complex design and power consumption, and in the case of low light sources, high-precision analog-to-digital conversion circuits are required for noise control or increasing the number of light-sensing diodes to improve sensing sensitivity. This increases the circuit area and increases the cost. In addition, signal processing by means of photocurrent integration requires sufficient integration time to avoid low signal-to-noise ratio, but this will greatly limit the data report rate.

Utility model content

The utility model provides a distance sensing device, which can provide good sensing quality and data return rate without increasing the circuit area, cost and power consumption. Compared with the traditional light sensing diode, it can be more Small circuit area achieves the same sensing sensitivity. In addition, in the case of low-intensity reflected light, the distance sensing device of the present invention can still provide good sensing quality.

The distance sensing device of the utility model comprises a light source, a bias voltage generating circuit, a light sensing diode, a quenching circuit, a counter circuit and a signal processing circuit. The light source provides ranging light to the ranging target to generate reflected light. The bias voltage generating circuit provides a breakdown bias voltage or a standard bias voltage. The cathode terminal of the photo-sensing diode is coupled to the bias voltage generating circuit, which senses the reflected light to generate a photo-sensing signal. The quenching circuit is coupled to the anode terminal of the photo-sensing diode to quench the photo-sensing diode. The counter circuit is coupled to the anode terminal of the photo-sensing diode, and counts the breakdown times of the photo-sensing diode according to the photo-sensing signal generated by the photo-sensing diode during receiving the breakdown bias voltage during the photo-sensing period to generate a count value. The signal processing circuit is coupled to the counter circuit, and judges the distance between the distance sensing device and the distance measuring target according to the count value.

Based on the above, the photo-sensing diode of the embodiment of the utility model can receive the collapse bias voltage and perform photo-sensing to generate a photo-sensing signal. The counter circuit can count the number of times the photo-sensing diode collapses according to the photo-sensing signal to generate count value, the signal processing circuit judges the distance between the distance sensing device and the distance measuring target according to the count value. In this way, using the photo-sensing diode in an extremely reverse-biased state to perform light sensing, and using the count value of the counter circuit to calculate the light intensity sensed by the photo-sensing diode can avoid the use of an integrator circuit, and can be used without In the case of increasing circuit area, cost, and power consumption, it provides good sensing quality and data return rate, and compared with traditional photo-sensing diodes, it can achieve the same sensing sensitivity with a smaller circuit area. In addition, in the case of low-intensity reflected light, the distance sensing device of the present invention can still provide good sensing quality.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific embodiments are described in detail with accompanying drawings.

Description of drawings

FIG. 1 is a schematic diagram of a distance sensing device according to an embodiment of the present invention.

FIG. 2 is a waveform diagram of a light sensing signal according to an embodiment of the present invention.

FIG. 3 is a schematic diagram of a distance sensing device according to another embodiment of the present invention.

Fig. 4 is a schematic diagram of the relationship between the count value and the distance according to the embodiment of the present invention.

FIG. 5 is a schematic diagram of a distance sensing device according to another embodiment of the present invention.

FIG. 6 is a flowchart of a sensing method of a distance sensing device according to an embodiment of the present invention.

Detailed ways

In order to make the content of the utility model more understandable, the following specific embodiments are taken as examples in which the utility model can indeed be implemented. In addition, wherever possible, components/members with the same reference numerals are used in the drawings and embodiments to represent the same or similar parts.

Please refer to FIG. 1 below. FIG. 1 is a schematic diagram of a distance sensing device according to an embodiment of the present invention. The distance sensing device may include a bias voltage generating circuit 102, a light sensing diode PD1 (for example, a Single Photon Avalanche Diode, SPAD), a quenching circuit 104, a counter circuit 106, a signal processing circuit 108, and The light source 110, the bias voltage generating circuit 102 are coupled to the cathode terminal of the photo-sensing diode PD1, and the quenching circuit 104 is coupled to the anode terminal of the photo-sensing diode PD1. The bias voltage generating circuit 102 can be used to provide a breakdown bias voltage to the photo-sensing diode PD1, so that the photo-sensing diode PD1 enters an extremely reverse-biased state, so that when a photon is injected into the depletion layer of the photo-sensing diode PD1, it can The photo-sensing diode PD1 is triggered to generate an avalanche current to provide a photo-sensing signal S1. In addition, the quenching circuit 104 can quench the photo-sensing diode PD1 after the photo-sensing diode PD1 provides the photo-sensing signal S1, so as to return the anode terminal voltage of the photo-sensing diode PD1 to the voltage before providing the photo-sensing signal S1 , The quenching circuit 104 is active or passive, which is not limited in the present invention. It should be noted that in the embodiment of FIG. 1, although only one light sensing unit formed by the light sensing diode PD1 and the quenching circuit 104 is shown, it is not limited thereto. In other embodiments, the distance sensing The device may include more photo-sensing units, such as an array of photo-sensing units formed of a plurality of photo-sensing units.

The counter circuit 106 can count the number of collapses of the light sensing diode PD1 according to the light sensing signal S1 to generate a count value C1 to the signal processing circuit 108, and the signal processing circuit 108 can judge the light sensed by the light sensing diode PD1 according to the count value C1 strength. For example, as shown in FIG. 2 , the signal processing circuit 108 can count the number of pulses of the photo-sensing signal S1 during the photo-sensing period T1 according to the counter circuit 106 (that is, the number of collapses of the photo-sensing diode PD1 during the photo-sensing period T1 ) to determine the light intensity sensed by the light sensing diode PD1 during the light sensing period T1, where the larger the count value C1 represents the light intensity sensed by the light sensing diode PD1 during the light sensing period T1 The stronger the light intensity. The photo-sensing period T1 can be, for example, the period during which the photo-sensing diode PD1 receives the breakdown bias voltage, but it is not limited thereto, and can also be set to other periods according to user needs, for example, the light source 110 provides the distance-measuring light L1 period, the period when the photo-sensing diode PD1 is in the reverse bias state, or the period when the counter circuit 106 performs counting.

As shown in Figure 3, when the distance sensing device performs distance sensing, the light source 110 can provide distance measuring light L1, and the distance measuring light L1 generates reflected light L2 after being reflected by the distance measuring target OB1, and the light source 110 can be, for example, a laser Light source, but not limited to this. The photo-sensing diode PD1 can sense the reflected light L2 to generate a photo-sensing signal S1. The counter circuit 106 counts the breakdown times of the photo-sensing diode PD1 according to the photo-sensing signal S1 to generate a count value C1 to the signal processing circuit 108 . The signal processing circuit 108 can determine the distance between the distance sensing device and the ranging object OB1 according to the count value C1, wherein a larger count value C1 means a shorter distance between the distance sensing device and the ranging object OB1.

In this way, by biasing the photo-sensing diode PD1 to an extremely reverse-biased state, the resistance of the distance sensing device to noise can be improved, even when the reflected light L2 received by the photo-sensing diode PD1 has a low intensity. The distance between the distance sensing device and the ranging object OB1 can be accurately judged, and the sensing quality is good. For example, when the photo-sensing diode PD1 is applied to a proximity sensor, the intensity of the reflected light L2 received by the photo-sensing diode PD1 decreases significantly due to the relatively long distance between the proximity sensor and the ranging target. Under such circumstances, the sensing diode PD1 can still provide a light sensing signal S1 with a high signal-to-noise ratio, so as to accurately determine the distance between the adjacent sensor and the ranging target. In addition, the counter circuit 106 is used to count the number of breakdowns of the photo-sensing diode PD1 to generate the count value C1 to determine the distance between the distance sensing device and the distance-measuring target OB1, which eliminates the need for an integrator and an analog-to-digital converter, and further reduces the circuit size. area, lower power consumption, and lower production costs. Compared with conventional light-sensing diodes, the same sensing sensitivity can be achieved with a smaller circuit area.

In addition, the signal processing circuit 108 can also determine whether to execute a preset operation according to the distance between the distance sensing device and the ranging object OB1. Wherein the default operation can vary with the application of the distance sensing device. For example, if the distance sensing device is applied to a mobile phone, the default operation can be, for example, turning on or off the screen display of the mobile phone. When the distance between the device and the ranging object OB1 changes from greater than the distance threshold value to less than the distance threshold value, the signal processing circuit 108 can turn off the screen function of the mobile phone, and when the distance between the distance sensing device and the ranging object OB1 changes from less than the distance threshold value When the threshold value changes to be greater than the distance threshold value, the signal processing circuit 108 can turn on the screen function of the mobile phone, so that the screen function of the mobile phone can be turned off when the user answers the call, and the screen function of the mobile phone can be restored when the user ends the call and moves the mobile phone away from the face.

The distance threshold value can be achieved as shown in Figure 4 by setting the count threshold value TH1 corresponding to the distance threshold value. When the count value C1 is greater than the count threshold value TH1, it means that the distance between the distance sensing device and the ranging target OB1 is less than The distance threshold value, and when the count value C1 is less than the count threshold value TH1, it means that the distance between the distance sensing device and the ranging object OB1 is greater than the distance threshold value. It is worth noting that the preset operation is not limited to turning on the screen function of the mobile phone. In other embodiments, the preset operation can also be the activation and deactivation of the connection function of the Bluetooth headset, for example, when the distance sensing device and the distance measuring device When the distance between the objects OB1 changes from greater than the distance threshold value to less than the distance threshold value, the signal processing circuit 108 can enable the connection function of the Bluetooth headset to connect with the playback device, and when the distance between the distance sensing device and the ranging object OB1 When the distance changes from less than the distance threshold to greater than the distance threshold, the signal processing circuit 108 can disable the connection function of the Bluetooth headset to disconnect the playback device. It should be noted that the number of distance thresholds is not limited to the embodiment shown in Figure 4. In other embodiments, a plurality of different distance thresholds can also be set, and according to the distance between the count value C1 and the plurality of distance thresholds Changes in the size relationship of , set different preset operations, and are not limited to the embodiment in FIG. 4 .

In addition, in some embodiments, the signal processing circuit 108 can also correct the distance between the distance sensing device and the ranging target according to the error compensation count value, wherein the error compensation count value can include, for example, when the light source 110 does not provide the distance measuring light L1 The counter circuit 106 counts according to the photo-sensing signal S1 provided by the photo-sensing diode PD1, and the count value obtained by the counter circuit 106 according to the photo-sensing diode PD1 sensing objects other than the distance-measuring target OB1 to reflect the distance-measuring light L1 The count obtained by counting the light sensing signal generated by counting the reflected light (for example, the reflected light generated by the distance measuring light L1 being reflected by other components in the distance sensing device due to the diffusion effect, but not limited thereto) value of at least one of them. The signal processing circuit 108 may, for example, subtract the error compensation count value from the count value C1 to more accurately obtain the count value corresponding to the reflected light L2 generated after being reflected by the ranging object OB1 , thereby improving the sensing quality of the distance sensing device.

FIG. 5 is a schematic diagram of a distance sensing device according to another embodiment of the present invention. In this embodiment, the distance sensing device may further include a switch SW1, a switching circuit 502, and a readout circuit 504, wherein the switch SW1 is coupled between the anode terminal of the photo-sensing diode PD1 and the quenching circuit 104, and the switching circuit 502 It is coupled between the anode terminal of the photo-sensing diode PD1 , the counter circuit 106 and the readout circuit 504 , and the readout circuit 504 is also coupled to the signal processing circuit 108 . The readout circuit 504 can be implemented by, for example, switches SW2 and SW3, the switch SW2 is coupled between the anode terminal of the photo-sensing diode PD1 and the counter circuit 106, and the switch SW3 is coupled between the anode terminal of the photo-sensing diode PD1 and the readout circuit 106. out of circuit 504.

The signal processing circuit 108 can control the conduction states of the switches SW1 - SW3 according to the sensing mode of the distance sensing device. For example, when the distance sensing device is in the high-sensitivity sensing mode, the control bias voltage generation circuit 102 provides a collapse bias voltage to the cathode end of the photo-sensing diode PD1, the control switch SW1 is turned on and the switching circuit 502 is controlled to switch the photo-sensing The anode of the detection diode PD is switchably connected to the counter circuit 106 (that is, the control switch SW2 is turned on and the switch SW3 is turned off), so that the distance sensing device can maintain good sensing quality even in low light environments. When the distance sensing device is in the normal sensing mode, the signal processing circuit 108 can control the bias voltage generating circuit 102 to provide a standard bias voltage to the cathode end of the photo-sensing diode PD1, control the switch SW1 to turn off and control the switching circuit 502 Switch the anode end of the photo-sensing diode PD1 to the readout circuit 504 (that is, the control switch SW2 is turned off, and the control switch SW3 is turned on), so that the distance sensing device is suitable for light detection in a relatively high-light environment. Sensing.

Wherein the standard bias voltage is less than the collapse bias voltage, the standard bias voltage can make the light-sensing diode PD1 enter a forward-biased but non-conducting state or a reverse-biased state but not enter an extremely reverse-biased state, that is to say, the photosensitive diode PD1 The detection diode PD1 does not have the characteristics of a single photon avalanche diode at this time. The readout circuit 504 may, for example, include an integrator and an analog-to-digital converter. The integrator may perform an integral operation on the light-sensing signal provided by the photo-sensing diode PD1 to generate an integrated signal, and the analog-to-digital converter may convert the integrated signal into a digital signal. And generate the sensing value SD1 to the signal processing circuit 108 . In this way, switching the photo-sensing diode PD1 to the counter circuit 106 or the readout circuit 504 under different lighting environments can expand the applicable range of light intensity of the distance sensing device for light sensing, and improve the convenience of use of the distance sensing device. sex.

FIG. 6 is a flowchart of a sensing method of a distance sensing device according to an embodiment of the present invention. It can be known from the above embodiments that the sensing method of the distance sensing device may at least include the following steps. Firstly, a ranging light is provided to a ranging target to generate reflected light (step S602 ). Then, provide a breakdown bias voltage to the photo-sensing diode (step S604). Next, during the photo-sensing period, according to the photo-sensing signal generated by the photo-sensing diode sensing the reflected light during receiving the breakdown bias voltage, counting the breakdown times of the photo-sensing diode to generate a count value (step S606 ). Afterwards, the distance between the distance sensing device and the distance measuring target is determined according to the count value (step S608 ). In some embodiments, the distance between the distance sensing device and the distance measurement target can be determined according to the error compensation count value and the count value, for example, the count value is subtracted from the error compensation count value to correct the sensing result of the distance sensing device . The error compensation count value may, for example, include the count value obtained by counting according to the light sensing signal provided by the light sensing diode when the light source does not provide the distance measuring light, and the count value obtained by sensing the reflection of objects other than the distance measuring target by the light sensing diode. At least one of the count values obtained by counting the light sensing signal generated by the reflected light generated by the distance light. Then, determine whether to execute the preset operation according to the distance between the distance sensing device and the ranging target (step S610 ), for example, determine whether to perform the preset operation according to the distance between the distance sensing device and the ranging target and a distance threshold.

In summary, the photo-sensing diode of the embodiment of the present invention can receive the breakdown bias voltage and perform photo-sensing to generate a photo-sensing signal. A count value is generated, and the signal processing circuit judges the distance between the distance sensing device and the distance measuring target according to the count value. In this way, using the photo-sensing diode in an extremely reverse-biased state to perform light sensing, and using the count value of the counter circuit to calculate the light intensity sensed by the photo-sensing diode can avoid the use of an integrator circuit, and can be used without increasing In terms of circuit area, cost, and power consumption, it provides good sensing quality and data return rate, and compared with traditional light sensing diodes, it can achieve the same sensing sensitivity with a smaller circuit area. In addition, in the case of low-intensity reflected light, the distance sensing device of the present invention can still provide good sensing quality.

Although the present utility model has been disclosed above with the embodiments, it is not intended to limit the present utility model. Any person skilled in the art may make some changes and modifications without departing from the spirit and scope of the present utility model. Therefore, the protection scope of the present utility model should be as defined by the claims.

Claims (9)

1. A distance sensing device, comprising:

a light source for providing ranging light to the ranging target to generate reflected light;

a bias voltage generating circuit for providing a breakdown bias voltage or a standard bias voltage;

a photo-sensing diode, the cathode terminal of which is coupled to the bias voltage generating circuit, for sensing the reflected light to generate a photo-sensing signal;

the quenching circuit is coupled with the anode end of the light sensing diode and used for quenching the light sensing diode;

the counter circuit is coupled with the anode end of the light sensing diode and used for counting the breakdown times of the light sensing diode according to the light sensing signal generated by the light sensing diode in the period of receiving the breakdown bias voltage in the light sensing period to generate a count value; and

and the signal processing circuit is coupled with the counter circuit and used for judging the distance between the distance sensing device and the distance measuring target according to the count value.

2. The distance sensing device of claim 1, wherein the signal processing circuit further determines a distance between the distance sensing device and the ranging target based on an error compensation count value and the count value.

3. The distance sensing apparatus according to claim 2, wherein the error compensation count value includes a count value counted by the counter circuit according to the light sensing signal provided by the light sensing diode when the light source does not provide the distance measuring light.

4. The distance sensing apparatus according to claim 2, wherein the error compensation count value includes a count value obtained by counting by the counter circuit in accordance with a light sensing signal generated by the light sensing diode sensing reflected light generated by reflecting the distance measuring light by an object other than the distance measuring target.

5. The distance sensing apparatus according to claim 2, wherein the signal processing circuit subtracts the error compensation count value from the count value to compensate the count value, and determines a distance between the distance sensing apparatus and the ranging target based on the compensated count value.

6. The distance sensing device according to claim 1, wherein the signal processing circuit further determines whether to perform a predetermined operation according to a distance between the distance sensing device and the ranging target and a distance threshold value.

7. The distance sensing device of claim 1, further comprising:

a first switch coupled between the anode terminal of the photo-sensing diode and the quenching circuit;

the switching circuit is coupled between the anode end of the light sensing diode and the counter circuit; and

the sensing circuit is coupled between the switching circuit and the signal processing circuit, and is used for performing an integration operation on the photo-sensing signal to generate a sensing value for the signal processing circuit, and when the distance sensing device is in a high-sensitivity sensing mode, the signal processing circuit controls the bias voltage generating circuit to provide the breakdown bias voltage to the cathode end of the photo-sensing diode, controls the first switch to be conducted and controls the switching circuit to switch and connect the anode end of the photo-sensing diode to the counter circuit, and when the distance sensing device is in a normal sensing mode, controls the bias voltage generating circuit to provide the standard bias voltage to the cathode end of the photo-sensing diode, and controls the first switch to be disconnected and controls the switching circuit to switch and connect the anode end of the photo-sensing diode to the sensing circuit, wherein the standard bias voltage is smaller than the breakdown bias voltage.

8. The distance sensing device of claim 7, wherein the switching circuit comprises:

the second switch is coupled between the anode end of the light sensing diode and the counter circuit, is controlled by the signal processing circuit to be conducted in the high-sensitivity sensing mode and is disconnected in the general sensing mode; and

and the third switch is coupled between the anode end of the light sensing diode and the readout circuit, is controlled by the signal processing circuit to be turned on in the general sensing mode and turned off in the high-sensitivity sensing mode.

9. The distance sensing device of claim 1, wherein the light source comprises a laser light source.

Images