CN111025416A - Infrared sensing device - Google Patents
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- CN111025416A CN111025416A CN201811180808.7A CN201811180808A CN111025416A CN 111025416 A CN111025416 A CN 111025416A CN 201811180808 A CN201811180808 A CN 201811180808A CN 111025416 A CN111025416 A CN 111025416A
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- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
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Abstract
An infrared sensing device comprises an infrared emission module, a sensing unit, an ambient light compensation circuit and an output control circuit. The infrared emission module comprises a modulator and an infrared light source and provides modulated pulse infrared rays. The sensing unit comprises a light sensor and a photocurrent-to-voltage converter. The light sensor is used for sensing infrared signals and ambient light signals and converting and outputting photocurrent signals. The photocurrent-to-voltage converter receives the photocurrent signal and converts it into a pulse signal. The ambient light compensation circuit receives the pulse signal and outputs an ambient light compensation signal. The output control circuit receives the comparison voltage and the ambient light compensation signal respectively and then synchronously detects the comparison voltage and the ambient light compensation signal, and outputs a measured signal or a loss measurement signal of the object to be measured.
Description
[ technical field ] A method for producing a semiconductor device
The invention relates to an infrared sensing device with an ambient light automatic compensation circuit, in particular to a high-sensitivity infrared sensing device for intelligent household appliances.
[ background of the invention ]
Energy saving and carbon reduction are common problems faced by people in the 21 st century, and the popularization of household appliances with energy-saving marks is not easy. According to EIA statistics, the lighting of British and American families accounts for 15%, and the lighting of British and American families accounts for 19-22% in terms of cold and hot air. The human body position sensor can automatically enter an energy-saving mode when a person is absent, so that the energy-saving device is comfortable and energy-saving, has 20-28% of energy-saving effect when being applied to hotels or commercial places, and shows energy-saving benefit.
The traditional human body position sensor adopts a pyroelectric sensor (PIR), which can only perform dynamic sensing, when a human body is fixed or does not move for a long time, a signal disappears, and the pyroelectric sensor cannot distinguish whether a person is absent or not, so that troubles are often caused when the pyroelectric sensor is applied to reading lamps or toilet illumination and the like, and the energy-saving effect cannot be achieved due to the fact that cold air cannot be closed timely. In addition, it is more desirable to sense the presence of a person during the interaction between a machine and a person, such as an unmanned store or a vending machine, that automatically lights up when the person approaches. Due to the different residence time, a sensor for sensing the human body's presence (Occupancy) is required, which cannot be achieved by the conventional pyroelectric sensor.
Conventional toilet flushers can only sense the human body from a distance of about 0.3 m because the reflected signal is inversely proportional to the fourth power of the distance at a long distance (e.g., 1.5m), and the reflected signal is 0.16% of 0.3 m at a distance of 1.5m, requiring a more precise compensation circuit to more reliably detect the presence of the human body. In addition, the silicon light sensor, such as a photodiode or a phototransistor, has dark current output, and the dark current is multiplied every 10 ℃ increase of the ambient temperature.
On the other hand, the output of the light sensor is affected by the problems of the input offset voltage of the operational amplifier and the light change of the environment, which makes it impossible to calculate the level by a single comparator when sensing a long distance human body, otherwise, the sensed light change of the environment is much larger than the signal reflected by the human body, and the presence or absence of the human body cannot be reliably sensed.
Conventionally, a modulator is designed to modulate infrared light at a high frequency (e.g., 38kHz) to avoid noise signal interference, and a bandpass filter is used to filter the infrared light and amplify the filtered infrared light to distinguish between an optical signal reflected by an object to be measured (e.g., a human body) and ambient stray light and a dark current of a light sensor. However, in this method, the ambient stray light and the dark current of the photosensor are still modulated in the received light pulse during ac amplification, and cannot be effectively eliminated.
In view of the above, it is an object of the present invention to overcome the above-mentioned shortcomings of the conventional infrared sensor.
[ summary of the invention ]
The invention provides an infrared sensing device, which comprises an infrared emission module, a sensing unit, an ambient light compensation circuit and an output control circuit. The infrared emission module comprises a modulator and an infrared light source and provides modulated pulse infrared rays. The sensing unit comprises a light sensor and a photocurrent-to-voltage converter. The light sensor is used for sensing an infrared signal (the infrared signal is a reflection line of the modulated pulse infrared ray through the object to be measured) and an ambient light signal, and converting the infrared signal into an output photocurrent signal. The photocurrent-to-voltage converter receives the photocurrent signal and converts it into a pulse signal. The ambient light compensation circuit receives the pulse signal and outputs an ambient light compensation signal. The output control circuit receives and compares a comparison voltage and the ambient light compensation signal respectively, and then carries out synchronous detection after passing through the comparator, and outputs a measured signal or a loss detection signal.
The invention provides another infrared sensing device, which comprises an infrared emitting module, a sensing unit, an ambient light compensation circuit and an output control circuit. The ambient light compensation circuit receives the pulse signal, filters the pulse signal by the low-pass filter, and outputs a filtered ambient light compensation signal. The output control circuit receives and compares the pulse signal filtered by the low-pass filter and the ambient light compensation signal respectively and then synchronously detects the pulse signal and the ambient light compensation signal, so that the noise signal interference at the moment of switching on or switching off the photocurrent is reduced.
In another embodiment of the present invention, an infrared sensing apparatus includes an infrared emitting module, a sensing unit, an ambient light compensation circuit, and an output control circuit. The ambient light compensation circuit outputs an ambient light compensation signal after the resting time zone sampling signal received by the sampling circuit is processed by the inverter, the adder, the secondary amplifier and the low-pass filter. The infrared transmitting module is connected with the output control circuit through the detecting delay circuit, so that the delay influence caused by the low-pass filter is reduced.
The purpose, technical content, features and effects of the present invention will be more readily understood by the following detailed description of the embodiments taken in conjunction with the accompanying drawings.
[ description of the drawings ]
FIG. 1 is a schematic circuit diagram of an infrared human body sensing device according to an embodiment of the invention.
FIG. 2 is a timing diagram of the output of the modulator according to an embodiment of the invention.
FIG. 3 is a schematic diagram of an adder according to an embodiment of the invention.
FIG. 4 is a schematic circuit diagram of an infrared human body sensing device according to another embodiment of the invention.
FIG. 5 is a schematic circuit diagram of an infrared human body sensing device according to another embodiment of the invention.
[ notation ] to show
1. 2, 3: infrared sensing device
10: infrared emission module
20: sensing unit
30. 32, 34: ambient light compensation circuit
40: output control circuit
101: modulator
102: light emission driver
103: infrared light emitting source
104: light sensor
105: photocurrent to voltage converter
106: bias circuit
107: comparator with a comparator circuit
108: bias resistor
109: synchronization detection circuit
110: delay time adjuster
111: delay resistor
112: delay resistor
113: output push stage
114: open source output MOS transistor
121: sampling circuit
122: adder
123: inverter with a capacitor having a capacitor element
124: adder
125: two-stage amplifier
126. 131, 132: low-pass filter
133: detection delay circuit
[ detailed description ] embodiments
The following detailed description of the embodiments of the invention is provided in connection with the accompanying drawings. Aside from the specific details disclosed herein, this invention is capable of other embodiments and its several details are capable of modifications in various obvious respects, all without departing from the scope of the invention. In the description of the specification, numerous specific details are set forth in order to provide a more thorough understanding of the invention; however, the present invention may be practiced without some or all of these specific details. In other instances, well-known steps or elements have not been described in detail so as not to unnecessarily obscure the present invention. The same or similar components in the drawings will be denoted by the same or similar symbols. It is noted that the drawings are merely schematic and do not represent actual sizes or quantities of elements, and some details may not be fully drawn for brevity of the drawings.
Referring to fig. 1, a structure diagram of an infrared human body sensing device 1 according to an embodiment of the invention is shown. The infrared sensing device 1 includes an infrared emitting module 10, a sensing unit 20, an ambient light compensation circuit 30 and an output control circuit 40. The infrared emitting module 10 includes a modulator 101, an emitting driver 102 (e.g., an LED driver ic), and an infrared emitting source 103 (e.g., an infrared emitting diode) for providing a modulated pulsed infrared.
The sensing unit 20 receives the optical signal reflected by the infrared emitting module 10 through the object, and includes a light sensor 104, a photocurrent to voltage converter 105 and a bias circuit 106. The optical sensor 104 is used for sensing an infrared signal (including an infrared ray reflected by an object to be measured) and an ambient light signal, and converting and outputting a photocurrent signal. Since the photosensor 104 may have a dark current output, the dark current is a function of the ambient temperature. Therefore, the output photocurrent signal may include an infrared signal, an ambient light signal (ambient stray light), and a dark current.
The photocurrent-to-voltage converter 105 is, for example, a transimpedance amplifier, and an input terminal of the photocurrent-to-voltage converter 105 is electrically connected to the optical sensor 104, and receives the photocurrent signal and converts the photocurrent signal into a pulse signal. Another input terminal of the photocurrent to voltage converter 105 is electrically connected to the bias circuit 106, and provides a dc bias voltage through the bias circuit 106 and the bias resistor 108, wherein the dc bias voltage can be modulated by the bias resistor 108 to serve as a predetermined threshold voltage.
The ambient light compensation circuit 30 shown in fig. 1 includes a sampling circuit 121 and an adder 122, and the ambient light compensation circuit 30 is electrically connected to the output terminal of the photocurrent-to-voltage converter 105, receives the pulse signal and outputs an ambient light compensation signal. Sampling circuit 121 may include an analog switch and a sample storage capacitor (not shown). The sampling circuit 121 is electrically connected to the output terminal of the photocurrent-to-voltage converter 105, so as to sample the output of the photocurrent-to-voltage converter during the rest period (shown in fig. 2) of the modulated pulsed infrared ray. The sample storage capacitor can be used to store the dc voltage of the photocurrent to voltage converter 105 in the rest time zone Tb, and the dc voltage signal includes the bias voltage, the dark current of the photo sensor 104, the output offset voltage of the photocurrent to voltage converter 105, the ambient stray light sensed by the photo sensor 104, and the like. The adder 122 has an input electrically connected to the output of the sampling circuit 121, another input electrically connected to a fixed voltage (e.g., the bias voltage output by the bias circuit 106 and the bias resistor 108), and an output electrically connected to the output control circuit 40.
FIG. 2 is a timing diagram of the output of the modulator according to an embodiment of the invention. In one embodiment, the Duty ratio (Duty ratio) of the infrared light source can be modulated, that is, the infrared light source emits light in the emission time zone Ta and stops emitting light in the rest time zone Tb. Ta/Tb may be set to be less than 0.2, and the ratio of the transmission time zone Ta to the rest time zone Tb may be, for example, 1: 8 to 1: 1000, and preferably between 1: 8 to 1: 10, more preferably 1: 9. by making the rest time zone Tb much larger than the emission time zone Ta, a higher driving current (20mA) than normal, for example, 200mA driving current can be used to drive the infrared light emitting source, thereby increasing the optical power output (increasing the signal intensity of the photocurrent to the optical voltage). In addition, because the pause time zone Tb is longer, it can be used for sampling and detecting the ambient light and dark current for automatically adjusting the level of the comparator 107 (described in the next section).
The output control circuit 40 is electrically connected to the sensing unit 20 and the output end of the ambient light compensation circuit 30, and the output control circuit 40 includes a comparator 107, a synchronization detector 109, a delay time adjustment circuit 110, an output driving stage 113, and an open-source output MOS transistor 114. The comparator 107 includes two input terminals, respectively receiving and comparing a comparison voltage and the dc voltage after the ambient light compensation signal, providing the synchronization detector 109 for synchronization detection, and outputting a detected signal or a loss detection signal of the object to be detected by the synchronization detector 109. In this embodiment, the comparison voltage is, for example, a pulse voltage output by the photocurrent-to-voltage converter 105. The measured signal of the object to be measured is, for example, a signal that senses that a human body enters the sensing range, and the loss-detecting signal is, for example, a signal that senses that a human body leaves the sensing range.
FIG. 3 is a diagram of an adder according to an embodiment of the invention. The level difference of the comparator 107 represents the signal intensity actually reflected by the object to be measured (e.g. human body), so that the remote human body detection (e.g. 1.5m) can be performed. Specifically, the adder has a structure as shown in fig. 4. The two input voltages of the adder are Va and Vb respectively, the serially connected resistors are Ra and Rb respectively, and then the adder outputs
Vo is
Assuming that Va is the output sampled by the sampling circuit 121, Vb is the bias value, and Rb/(Ra + Rb) — 0.9, 90% of the ambient light variation effect can be reflected in the output of the adder 122, and can be used to fine-adjust the comparison level of the comparator 107 to overcome the ambient light variation effect. The influence of the ambient light variation described herein includes the dark current (influenced by the ambient temperature variation) of the photosensor 104.
The output of the comparator 107 is electrically connected to the synchronization detector 109, AND the synchronization detector 109 includes an AND circuit having two inputs, one of which is an output of the comparator, AND the other of which is a light-emitting time zone signal, so as to avoid the influence of ambient light, AND a synchronous sensing detection (Synchronized detection) principle is used to improve the reliability of the sensing output. The synchronization detector 109 samples the output of the comparator 107 only in the light emitting time zone (Ta, shown in fig. 2) to obtain the measured object (e.g. the measured signal for measuring the human body entering the sensing area), or the object disappears (e.g. the measured signal for measuring the human body leaving the sensing area). The output of the synchronization detector 109 is electrically connected to the delay time adjusting circuit 110, and the delay time of the detected Object (ON) and the detected Object (OFF) are respectively set by the delay resistor 111 and the delay resistor 112.
In the embodiment applied to the smart home appliance, the control signal is output after a delay of one second after the object to be measured (e.g., a human body) is detected, or the control signal is output after the object to be measured (e.g., a human body) is detected, for example, the output signal of the delay time adjusting circuit 110 is provided to the output driving stage 113 to adjust and control the state of the smart home appliance. The output driving stage 113 is, for example, a buffer amplifier, and is used to drive the open-source output MOS transistor 114 to provide an open-source output signal. The open-source output MOS transistor 114 has high breakdown voltage, and thus can be used for output control, such as driving a relay to perform high-current and high-voltage control.
Fig. 4 is a block diagram of an infrared human body sensing device 2 according to another embodiment of the invention. The infrared human body sensing device 2 is similar to the infrared human body sensing device 1 shown in fig. 1, and the description thereof is omitted. The infrared human body sensing device 2 includes an infrared emitting module 10, a sensing unit 20, an ambient light compensation circuit 32 and an output control circuit 40. The input terminal of the output control circuit 40 includes a first input terminal and a second input terminal, and the first input terminal is electrically connected to the ambient light compensation circuit 32 to receive a dc bias voltage compensated by ambient light as an ambient light compensation signal. The second input terminal is electrically connected to the photocurrent to the voltage converter 105 through the low pass filter 131 to receive the filtered pulse signal as the comparison voltage.
In this embodiment, the ambient light compensation circuit 32 further includes a low pass filter 132 electrically connected to the output end of the adder 122 for filtering the high frequency noise signal, and outputting the high frequency noise signal to the output control circuit 40. In addition, the low pass filter 131 is further electrically connected between the light sensing unit 20 and the output control circuit 40. After the photocurrent to voltage converter 105 outputs, the high frequency noise signal is filtered by the low pass filter 131 and then output to the output control circuit 40. The low pass filter 131 and the low pass filter 132 can filter the transient pulse signal generated at the transient of the photo current.
The output control circuit 40 is electrically connected to the output ends of the sensing unit 20 and the ambient light compensation circuit 30, receives and compares a comparison voltage and an ambient light compensation signal, and then synchronously detects the signals, and outputs a detected signal or a loss detection signal of the object to be detected. In this embodiment, the comparison voltage is, for example, a pulse voltage of the high frequency noise signal filtered by the low pass filter 131 after the output of the photocurrent-to-voltage converter 105. The ambient light compensation signal is outputted from the adder 122 shown in fig. 1, and then the low-pass filter 132 filters the high-frequency noise signal to fine-adjust the comparison level of the comparator 107, so as to reduce the influence of ambient light variation.
FIG. 5 is a block diagram of an infrared human body sensing device 3 according to another embodiment of the present invention, which can eliminate the influence of ambient light variation by 100%. The infrared human body sensing device 3 is similar to the infrared human body sensing device 1 shown in fig. 1, and the description thereof is omitted. The infrared human body sensing device 3 includes an infrared emitting module 10, a sensing unit 20, an ambient light compensation circuit 34 and an output control circuit 40.
In this embodiment, the ambient light compensation circuit 34 includes a sampling circuit 121, an inverter 123, an adder 124, a secondary amplifier 125, and a low pass filter 126. The sampling circuit 121 is electrically connected to and controlled by the modulator 101 to sample at the rest interval of the modulated pulsed infrared ray and output a sampling signal. The inverter 123 is electrically connected to the output terminal of the sampling circuit 121 to receive the sampling signal and output an inverted signal, which is a dc voltage noise signal sampled by the photocurrent-to-voltage converter 105 in the rest time zone Tb. The adder 124 is electrically connected to the inverter 123 and the photocurrent-to-voltage converter 105, respectively, for receiving the inverted signal and the modulated pulse signal of the pulsed infrared ray, and outputting a sum signal, which is used to eliminate the dc voltage noise signal. In other words, the output of the sampling circuit 121 passes through the inverter 123 and is added by the adder 124, and the dc output of the adder 124 can be returned to the bias value provided by the bias circuit 106 to the photocurrent to voltage converter 105. When the reflected light pulse comes, the direct current signal of the ambient light has been subtracted.
The second-stage amplifier 125 is electrically connected to the adder 124 for receiving the summed signal and outputting an amplified signal, and the second-stage amplifier 125 can reflect the actual signal of the object to be measured reflected by the infrared light. The output of the second-stage amplifier 125 is outputted through the low-pass filter 126 and then outputted to the comparator 107 of the output control circuit 40, so as to filter the transient pulse signal (high-frequency noise signal) at the moment of current conduction and disconnection.
The output control circuit 40 is electrically connected to the output ends of the sensing unit 20 and the ambient light compensation circuit 34, receives and compares a comparison voltage and an ambient light compensation signal, and then synchronously detects the signals, and outputs a detected signal or a loss detection signal of the object to be detected. In this embodiment, the output control circuit 40 includes a first input terminal electrically connected to the ambient light compensation circuit 34 for receiving the ambient light dc compensated second amplified pulse signal, and a second input terminal electrically connected to the bias circuit 106 for receiving the predetermined threshold voltage. The predetermined threshold voltage may be designed according to the parameters of the bias circuit 106, the bias resistor 108 and + V. The comparison voltage of this embodiment is, for example, a preset threshold voltage for fine-tuning the comparison level of the comparator 107 and for tuning the setting of the sensing distance (sensitivity setting).
The output control circuit 40 includes a comparator 107, a synchronization detector 109, a delay time adjusting circuit 110, an output driving circuit 113, and an open-source output MOS transistor 114. The comparator 107 is electrically connected to the preset threshold voltage and ambient light compensation circuit 34 formed by the bias resistor 108 of the bias circuit 106, and respectively receives the pulse signal and the dc bias voltage containing the reflected signal of the object to be measured. The synchronization detector 109 is electrically connected to the output terminal of the comparator 107 and the modulator 101 for sampling the light-emitting interval Ta of the infrared light source 103 and outputting a sampling signal. The delay time adjusting circuit 110 is electrically connected to the output end of the synchronous detector 109, and includes a first resistor 111 and a second resistor 112, and can adjust the delay time of the measured signal output after the object to be measured is measured and adjust the delay time of the loss signal output when the object to be measured disappears by designing the resistance value. The output driving circuit 113 is electrically connected to the output terminal of the delay time adjusting circuit 110, and provides an open source output signal according to the measured signal delay time and the loss signal delay time.
The infrared emission module of the present invention includes a modulator for distinguishing the emission and the rest of the light emitting diode. The light emitting diode is, for example, a high power infrared light emitting diode, and is driven by a large current to increase the output of light emission, and a smaller ratio (duty ratio) of emission (on) time to rest (off) time is modulated (modulated) so that the emission (on) time is shorter and the rest (off) time is longer, i.e., the light emitting diode can be driven by a higher driving current (e.g., 200mA) than a normal driving current (e.g., 20 mA). The ambient light and the dark current are detected during the off (rest) time, so as to automatically adjust the level of the comparator, reduce the interference of the ambient light and the dark current, and automatically adjust the level of the comparator, so that the level difference of the comparator is closer to the signal intensity reflected by the object to be detected (such as a human body), thereby achieving the effect of human body detection at a long distance (about 1.5 m). In addition, the influence of accidental ambient light is reduced through a synchronous sensing detection (Synchronized detection) principle, and the reliability of sensing output is improved.
The automatic ambient light compensation circuit of the invention detects ambient light by using the rest time of light emission, provides an output control circuit to adjust the comparison level, and amplifies the signal reflected by the object to be detected (human body) after automatically subtracting the direct current level, so that the long-distance human body reflection signal can be reliably detected, and the sensing target of sensing the object to be detected which is usually present can be achieved.
The above-described embodiments are merely illustrative of the technical spirit and features of the present invention, and the object of the present invention is to enable those skilled in the art to understand the content of the present invention and to implement the same, and the scope of the present invention should not be limited by the above-described embodiments, i.e., all equivalent changes and modifications made in the spirit of the present invention should be covered by the scope of the present invention.
Claims (10)
1. An infrared sensing device, comprising:
an infrared emission module, including a modulator and an infrared light source, for providing a modulated pulse infrared ray;
a sensing unit, receiving the pulse light signal that the pulse infrared after this modulation reflects back through an determinand, include:
a light sensor for sensing an infrared signal and an ambient light signal and converting them to output a photocurrent signal, wherein the infrared signal is the reflected light of the modulated pulsed infrared via the object to be measured;
a photocurrent-to-voltage converter electrically connected to the light sensor for receiving the photocurrent signal and converting the photocurrent signal into a pulse signal;
an ambient light compensation circuit, electrically connected to the output end of the photocurrent-to-voltage converter, for receiving the pulse signal and outputting an ambient light compensation signal;
and the output control circuit is electrically connected with the output ends of the sensing unit and the ambient light compensation circuit, receives and compares a comparison voltage and the ambient light compensation signal respectively, then synchronously detects the ambient light compensation signal, and outputs a measured signal or a loss measurement signal of the object to be detected, wherein the comparison voltage is related to the pulse signal or a preset critical value voltage.
2. The infrared sensing device as claimed in claim 1, wherein the infrared emission module further includes a light emission driver electrically connected to the modulator and the infrared light source, and the duty cycle and the output current of the light emission driver are adjusted by the modulator to drive the infrared light source, wherein the duty cycle is between 0.001 and 0.2.
3. The infrared sensing device as claimed in claim 1, wherein the ambient light compensation circuit includes a sampling circuit electrically connected to the output terminal of the photocurrent to voltage converter for sampling the output from the photocurrent to voltage converter during the rest period of the modulated pulsed infrared rays.
4. The infrared sensing device as set forth in claim 1, wherein the ambient light compensation circuit includes:
a sampling circuit connected to and controlled by the output terminal of the modulator; and
an adder having an input terminal electrically connected to the output terminal of the sampling circuit, another input terminal electrically connected to the predetermined threshold voltage, and an output terminal electrically connected to the output control circuit.
5. The infrared sensing device as set forth in claim 4, wherein the output of the adder is electrically connected to a first low pass filter, and is electrically connected to the output control circuit through the first low pass filter.
6. The infrared sensing device as claimed in claim 1, wherein the photocurrent to voltage converter is electrically connected to a second low pass filter and electrically connected to the output control circuit through the second low pass filter.
7. The infrared sensing device as set forth in claim 1, wherein the ambient light compensation circuit includes:
a sampling circuit, electrically connected to and controlled by the modulator, for sampling at the rest interval of the modulated pulse infrared ray and outputting a sampling signal;
an inverter electrically connected to the output terminal of the sampling circuit for receiving the sampling signal and outputting an inverted signal;
an adder electrically connected to the inverter and the photocurrent-to-voltage converter, respectively, for receiving the inverted signal and the pulse signal and outputting an added signal;
a second-stage amplifier electrically connected to the adder for receiving the summed signal and outputting an amplified signal; and
and the third low-pass filter is electrically connected with the secondary amplifier and the output control circuit to provide a filtering signal.
8. The infrared sensing device as claimed in claim 4, wherein the input terminals of the output control circuit include a first input terminal and a second input terminal, wherein:
the first input end is electrically connected with the ambient light compensation circuit to receive a DC bias voltage after ambient light compensation as the ambient light compensation signal; and
the second input end is electrically connected with the photocurrent-to-voltage converter through a second low-pass filter to receive a filtering pulse signal as the comparison voltage.
9. The infrared sensing device as claimed in claim 7, wherein the input terminals of the output control circuit include a first input terminal and a second input terminal, wherein:
the first input end is electrically connected with the ambient light compensation circuit to receive a secondary amplified pulse signal subjected to ambient light direct current compensation, and
the second input terminal is electrically connected to a bias circuit for receiving the predetermined threshold voltage.
10. The infrared human body sensing device of claim 1, wherein the output control circuit comprises:
a comparator having an input terminal receiving a DC bias voltage and another input terminal receiving the pulse signal;
a synchronous detector electrically connected to the output end of the comparator and the modulator for sampling in the light emitting interval of the infrared light source and outputting a sampling signal;
a delay time adjusting circuit, electrically connected to the output end of the synchronous detector, including a first resistor and a second resistor, for adjusting the delay time of the detected signal output after the object to be detected is detected and adjusting the delay time of the loss signal output when the object to be detected disappears; and
and the output pushing circuit is electrically connected to the output end of the delay time adjusting circuit and provides an open source output signal according to the measured signal delay time and the loss signal delay time.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113629997A (en) * | 2021-08-13 | 2021-11-09 | 无锡市晶源微电子有限公司 | Ambient light compensation circuit for infrared receiving device |
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| CN108169791A (en) * | 2018-03-23 | 2018-06-15 | 京东方科技集团股份有限公司 | For reading device and its method, the X-ray detector of X-ray detector |
| CN209148884U (en) * | 2018-10-09 | 2019-07-23 | 众智光电科技股份有限公司 | Infrared sensing device |
Cited By (1)
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| CN113629997A (en) * | 2021-08-13 | 2021-11-09 | 无锡市晶源微电子有限公司 | Ambient light compensation circuit for infrared receiving device |
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