Photoelectric conversion circuit and photoelectric smoke detection circuit
By using capacitive components instead of signal amplification circuit in the photoinductor smoke detector, the problems of noise interference and cost increase are solved, and efficient signal gain and functional effects are achieved.
Patent Information
- Application Number
- CN202421478256.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-26
- Publication Date
- 2025-04-18
- Estimated Expiration
- 2034-06-26
AI Technical Summary
In existing photoinductor smoke detectors, signal amplification circuit and integral sampling circuit need to be added, resulting in noise interference and increased costs.
By using an additional capacitive element instead of the signal amplification circuit, the output signal of the photosensitive element is directly filtered through the capacitor and then input into the analog-to-digital converter to achieve signal gain and integration.
It effectively reduces noise interference, reduces production costs, while maintaining the same gain and functional effects as traditional photoinductor smoke detectors.
Smart Images
Figure CN222774108U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of fire protection, in particular to a photoelectric conversion circuit and a photoelectric smoke detection circuit. Background Art
[0002] Photoelectric smoke detectors use the scattering or absorption of light by smoke or pyrolytic ions generated during a fire. They periodically emit detection beams and receive light signals in a specific direction through photosensitive elements. The microcontroller samples the received light signals and processes the data to calculate the current smoke concentration value. Since the light signal is relatively weak, the photocurrent generated by the photosensitive element is also very small, usually in the nanoampere (nA) range. Generally, an amplifier circuit is required to amplify or integrate the photocurrent signal and convert it into a voltage signal that the microcontroller can directly sample through an analog-to-digital converter (ADC). The amplifier circuit is generally composed of discrete devices such as triodes and field-effect transistors or integrated operational amplifiers. Since the photocurrent signal is relatively weak, there are relatively high requirements for the temperature characteristics, input offset current, open-loop gain and other performance of the amplifier circuit, which will greatly increase the cost of the circuit.
[0003] On the other hand, the use of an amplifier circuit also requires power supply for the amplifier circuit, which increases the overall power consumption. The amplifier circuit will also amplify noise and interference signals, so it is usually necessary to add a metal shielding shell to shield the noise, thereby increasing additional costs. Utility Model Content
[0004] The purpose of the utility model is to provide a photoelectric conversion circuit and a photoelectric smoke detection circuit, which eliminates the noise interference problem caused by the amplifier circuit by using an external capacitive element to replace the signal amplification circuit, and reduces the cost of the photoelectric smoke detector and similar light intensity detection devices.
[0005] In order to solve the above technical problems, the utility model adopts the following technical solutions:
[0006] One aspect of an embodiment of the utility model provides a photoelectric conversion circuit, which is composed of a photosensitive element and an analog-to-digital converter; the first electrode of the photosensitive element is connected to a power supply, the photosensitive element is used to receive a light signal to output an electrical signal of a corresponding value according to the intensity of the light signal, and the second electrode of the photosensitive element is connected to the AD acquisition pin of the analog-to-digital converter.
[0007] In some embodiments, the power supply is a bias power supply, and the photosensitive element is a photodiode.
[0008] In some embodiments, the bias power supply includes a resistor and a capacitor, one end of the resistor is connected to the power supply, the other end of the resistor is connected to one end of the capacitor and the first electrode of the photosensitive element, and the other end of the capacitor is grounded.
[0009] One aspect of an embodiment of the utility model provides a photoelectric conversion circuit, which is composed of a photosensitive element, a capacitive element and an analog-to-digital converter; the first electrode of the photosensitive element is connected to a power supply, the photosensitive element is used to receive a light signal to output an electrical signal of a corresponding value according to the intensity of the light signal, the second electrode of the photosensitive element is connected to the AD acquisition pin of the analog-to-digital converter and one end of the capacitive element, the other end of the capacitive element is grounded, and the capacitive element is used for current integration.
[0010] In some embodiments, the power supply is a bias power supply, and the photosensitive element is a photodiode.
[0011] In some embodiments, the bias power supply includes a resistor and a capacitor, one end of the resistor is connected to the power supply, the other end of the resistor is connected to one end of the capacitor and the first electrode of the photosensitive element, and the other end of the capacitor is grounded.
[0012] One aspect of an embodiment of the utility model provides a photoelectric smoke detection circuit, which includes the photoelectric conversion circuit as described above, a light source emission circuit and a control module, wherein the control module is respectively connected to the light source emission circuit and the photoelectric conversion circuit.
[0013] In some embodiments, the photoelectric smoke detection circuit further includes a pull-up resistor, and two ends of the pull-up resistor are respectively connected to the control module and the first electrode of the photosensitive element.
[0014] According to the embodiment of the utility model, a photoelectric conversion circuit and a photoelectric smoke detection circuit have at least the following beneficial effects: some traditional photoelectric smoke detectors need to add a signal amplification circuit, and some need to add an integral sampling circuit, and then amplify the signal according to the needs. However, the present application only needs to collect the light signal through a photodiode, and then filter it through a capacitor and input it to the analog-to-digital converter. The gain obtained and the functional effect achieved are the same as those of the traditional photoelectric smoke detector. The reduction of the signal amplification circuit does not cause the analog-to-digital converter to fail to read the signal, nor does it cause the sensitivity of the photoelectric smoke detector to decrease. At the same time, the interference caused by the amplification circuit is reduced, which greatly saves the production cost of the photoelectric smoke detector.
[0015] It is to be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0017] Figure 1 This is a schematic diagram of a photoelectric conversion circuit of the first embodiment of the present application;
[0018] Figure 2 This is a schematic diagram of a photoelectric conversion circuit according to a second embodiment of the present application;
[0019] Figure 3 This is the schematic diagram of the photoelectric smoke detection circuit of this application. DETAILED DESCRIPTION
[0020] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the embodiments described without closed description are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.
[0021] The terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first", "second", and "third" may explicitly or implicitly include one or more of the features. In the description of the present utility model, unless otherwise specified, "plurality" means two or more.
[0022] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0023] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.
[0024] The first embodiment of the photoelectric conversion circuit of the embodiment of the present application is briefly described below:
[0025] According to some embodiments, Figure 1 As shown, the present application provides a photoelectric conversion circuit, which is composed of a photosensitive element D and an analog-to-digital converter;
[0026] The first electrode of the photosensitive element D is connected to a power supply. The photosensitive element D is used to receive a light signal to output an electrical signal of a corresponding value according to the intensity of the light signal. The second electrode of the photosensitive element D is connected to an AD acquisition pin of an analog-to-digital converter.
[0027] Based on the working principle of the above embodiment, in some specific embodiments, the photosensitive element D adopts a photodiode D. In other embodiments, the photosensitive element D may also adopt other photosensitive devices such as a photoresistor, which is not limited in this application. The cathode of the photodiode D is connected to the power supply, and the anode of the photodiode D is connected to the AD acquisition pin of the analog-to-digital converter. When the value of the electrical signal output by the photodiode D is large, the optical signal is determined to be strong; when the value of the electrical signal output by the photodiode D is small, the optical signal is determined to be weak. Among them, the electrical signal can be a voltage signal or a current signal. The analog-to-digital converter receives the electrical signal output by the anode of the photodiode D, and converts the analog signal into a digital signal output through analog-to-digital conversion.
[0028] Furthermore, in some embodiments, the power supply adopts a bias power supply, the bias power supply includes a resistor R1 and a capacitor C2, one end of the resistor R1 is connected to the power supply, the other end of the resistor R1 is connected to one end of the capacitor C2 and the cathode of the photodiode D, and the other end of the capacitor C2 is grounded.
[0029] The second embodiment of the photoelectric conversion circuit of the embodiment of the present application is briefly described below:
[0030] According to some embodiments, Figure 2 As shown, in addition to the first embodiment, in the second embodiment, the present application provides a photoelectric conversion circuit, which is composed of a photosensitive element D, a capacitive element C1 and an analog-to-digital converter;
[0031] The first electrode of the photosensitive element D is connected to a power supply. The photosensitive element D is used to receive a light signal to output an electrical signal of a corresponding value according to the intensity of the light signal. The second electrode of the photosensitive element D is connected to the AD acquisition pin of the analog-to-digital converter and one end of the capacitive element C1. The other end of the capacitive element C1 is grounded. The capacitive element C1 is used for current integration.
[0032] Based on the working principle of the above embodiment, in some specific embodiments, the photosensitive element D adopts a photodiode D, and in other embodiments, the photosensitive element D can also adopt other photosensitive devices such as a photoresistor, which is not limited in this application. The cathode of the photodiode D is connected to the power supply, and the anode of the photodiode D is connected to the AD acquisition pin of the analog-to-digital converter. When the value of the electrical signal output by the photodiode D is large, the light signal is determined to be strong; when the value of the electrical signal output by the photodiode D is small, the light signal is determined to be weak. Among them, the electrical signal can be a voltage signal or a current signal. The capacitive element C1 integrates the electrical signal output by the anode of the photodiode D and outputs it to the analog-to-digital converter. The analog-to-digital converter receives the integrated electrical signal output by the anode of the photodiode D, and converts the analog signal into a digital signal output through analog-to-digital conversion.
[0033] Among them, the capacitive element C1 uses capacitor C1, and there will also be a sampling capacitor in the analog-to-digital converter. Because the internal integral sampling of the analog-to-digital converter is easily affected by temperature, and the temperature stability of the external capacitor is relatively good, the capacitive element C1 can offset the change of the internal capacitance with temperature after being connected in parallel. Moreover, changing the capacitive element C1 can also adjust the integration time, which is equivalent to adjusting the gain of the circuit, which can increase the integration time and make the anti-interference performance better.
[0034] Furthermore, in some embodiments, the power supply adopts a bias power supply, the bias power supply includes a resistor R1 and a capacitor C2, one end of the resistor R1 is connected to the power supply, the other end of the resistor R1 is connected to one end of the capacitor C2 and the cathode of the photodiode D, and the other end of the capacitor C2 is grounded.
[0035] The following is a brief description of the photoelectric smoke detection circuit of the embodiment of the present application:
[0036] According to some embodiments, Figure 3 As shown, the present application provides a photoelectric smoke detection circuit, which includes the above-mentioned photoelectric conversion circuit, as well as a light source emission circuit and a control module, wherein the control module is respectively connected to the light source emission circuit and the photoelectric conversion circuit.
[0037] Further, such as Figure 3 As shown, the photoelectric smoke detection circuit further includes a pull-up resistor R2, and two ends of the pull-up resistor R2 are connected to the control module and the first electrode of the photosensitive element D respectively.
[0038] Based on the working principle of the above embodiment, there is an infrared transmitting tube in the light source transmitting circuit, and a photodiode D in the photoelectric conversion circuit. The photodiode D is used as an infrared receiving tube. The infrared transmitting tube and the infrared receiving tube (photodiode D) are at an angle to each other, and both are covered with filters to reduce the influence of other light signals. The control module controls the infrared transmitting tube to transmit infrared signals through the light source transmitting circuit. When there is no smoke, the infrared receiving tube (photodiode D) does not receive the infrared signal emitted by the infrared transmitting tube, and the infrared receiving tube (photodiode D) only receives the external light signal, and the opening degree of the infrared receiving tube (photodiode D) is small; when there is smoke, the infrared signal emitted by the infrared transmitting tube is reflected by the smoke to the infrared receiving tube (photodiode D), and the infrared receiving tube (photodiode D) increases the opening degree, that is, the photodiode D increases the opening degree, and the photoelectric conversion circuit outputs a larger electrical signal to the control module. After the control module detects the output electrical signal of the photoelectric conversion circuit, it determines whether the smoke concentration exceeds the alarm threshold according to the value of the electrical signal. Among them, the smoke concentration is proportional to the electrical signal output by the photoelectric conversion circuit.
[0039] The smoke detection method of the embodiment of the present application is briefly described below:
[0040] According to some embodiments, the present application provides a smoke detection method, which is applied to the above photoelectric smoke detection circuit, and the smoke detection method includes:
[0041] Step 101, controlling the pull-down switch inside the analog-to-digital converter to close, and when a capacitive element C1 is provided, the capacitive element C1 is discharged through the pull-down switch;
[0042] Step 102, controlling the sampling switch inside the analog-to-digital converter to close, and connecting the sampling capacitor inside the analog-to-digital converter to the pull-down switch to discharge the sampling capacitor;
[0043] Step 103, controlling the pull-down switch inside the analog-to-digital converter to be turned off, and the sampling capacitor and / or the capacitive element C1 integrates the current;
[0044] Step 104, turning on the light source emission circuit to control the light source emission circuit to work and emit light;
[0045] Step 105, completing analog-to-digital conversion, recording the analog-to-digital conversion result, and turning off the light source emission circuit;
[0046] Step 106, after a preset time interval, repeat steps 101 to 106.
[0047] Specifically, in step 101, the control module controls the pull-down switch inside the analog-to-digital converter to close. When a capacitive element C1 is provided externally, the capacitive element C1 discharges through the pull-down switch; when no capacitive element C1 is provided externally, the next step is entered.
[0048] In step 102, the sampling time of the analog-to-digital converter is set to the required first set time, wherein the first set time can be set according to actual needs. The control module controls the sampling switch inside the analog-to-digital converter to close, the sampling capacitor inside the analog-to-digital converter is connected to the sampling switch, the sampling switch is connected to the pull-down switch, and the sampling capacitor inside the analog-to-digital converter discharges current through the sampling switch and the pull-down switch in turn.
[0049] In step 103, the control module controls the pull-down switch inside the analog-to-digital converter to turn off. When a capacitive element C1 is provided externally, the sampling capacitor and the capacitive element C1 stop discharging current, and the sampling capacitor and the capacitive element C1 integrate the current; when the capacitive element C1 is not provided externally, the sampling capacitor stops discharging current, and the sampling capacitor integrates the current.
[0050] In step 104, the control module turns on the light source transmitting circuit and controls the light source transmitting circuit to work and emit light. When there is smoke outside, the photoelectric conversion circuit receives the external light signal and the light signal of the light source transmitting circuit reflected by the smoke; when there is no smoke outside, the photoelectric conversion circuit only receives the external light signal. The photoelectric conversion circuit performs photoelectric conversion and outputs the electrical signal to the analog-to-digital converter.
[0051] In step 105, the analog-to-digital converter performs analog-to-digital conversion, completes the analog-to-digital conversion after a second set time delay, records the analog-to-digital conversion result, controls the light source emission circuit to turn off, and controls the sampling switch inside the analog-to-digital converter to turn off, thereby completing a smoke detection. The second set time can be set according to actual needs.
[0052] In step 106, after a preset time interval, steps 101 to 106 are repeated again, so as to detect the smoke density outside in real time. The preset time interval can be set according to actual needs.
[0053] Furthermore, before step 101, the method further includes:
[0054] Step 91, the control module controls the pull-down switch inside the analog-to-digital converter to close. When a capacitive element C1 is provided externally, the capacitive element C1 discharges through the pull-down switch; when no capacitive element C1 is provided externally, the next step is entered.
[0055] Step 92, set the sampling time of the analog-to-digital converter to the required first set time, wherein the first set time can be set according to actual needs. The control module controls the sampling switch inside the analog-to-digital converter to close, the sampling capacitor inside the analog-to-digital converter is connected to the sampling switch, the sampling switch is connected to the pull-down switch, and the sampling capacitor inside the analog-to-digital converter is discharged through the sampling switch and the pull-down switch.
[0056] Step 93, the control module controls the pull-down switch inside the analog-to-digital converter to turn off. When a capacitive element C1 is provided externally, the sampling capacitor and the capacitive element C1 stop discharging current, and the sampling capacitor and the capacitive element C1 integrate the current; when the capacitive element C1 is not provided externally, the sampling capacitor stops discharging current, and the sampling capacitor integrates the current.
[0057] Step 94, pull up the sampling voltage through the pull-up resistor R2. When a capacitive element C1 is provided externally, the sampling capacitor inside the analog-to-digital converter and the capacitive element C1 receive the sampling current of the photosensitive element D in the photoelectric conversion circuit in response to the ambient light; when the capacitive element C1 is not provided externally, the sampling capacitor inside the analog-to-digital converter receives the sampling current of the photosensitive element D in response to the ambient light.
[0058] Step 95, the analog-to-digital converter performs analog-to-digital conversion, completes the analog-to-digital conversion after a second set delay, records the analog-to-digital conversion result, controls the light source emission circuit to turn off, controls the sampling switch inside the analog-to-digital converter to turn off, and enters step 101.
[0059] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.
[0060] Although the present disclosure has been described with reference to several typical embodiments, it should be understood that the terms used are illustrative and exemplary, rather than restrictive. Since the present disclosure can be implemented in a variety of forms without departing from the spirit or essence of the present application, it should be understood that the above-mentioned embodiments are not limited to any of the foregoing details, but should be widely interpreted within the spirit and scope defined by the appended claims, so all changes and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.
Claims
1. A photoelectric conversion circuit, characterized in that: The photoelectric conversion circuit is composed of a photosensitive element and an analog-to-digital converter; The first electrode of the photosensitive element is connected to a power supply. The photosensitive element is used to receive a light signal to output an electrical signal of a corresponding value according to the intensity of the light signal. The second electrode of the photosensitive element is connected to an AD acquisition pin of the analog-to-digital converter.
2. The photoelectric conversion circuit according to claim 1, characterized in that: The power supply is a bias power supply, and the photosensitive element is a photodiode.
3. The photoelectric conversion circuit according to claim 2, characterized in that: The bias power supply includes a resistor and a capacitor, one end of the resistor is connected to the power supply, the other end of the resistor is connected to one end of the capacitor and the first electrode of the photosensitive element, and the other end of the capacitor is grounded.
4. A photoelectric conversion circuit, characterized in that: The photoelectric conversion circuit is composed of a photosensitive element, a capacitive element and an analog-to-digital converter; The first electrode of the photosensitive element is connected to a power supply, and the photosensitive element is used to receive a light signal to output an electrical signal of a corresponding value according to the intensity of the light signal. The second electrode of the photosensitive element is connected to the AD acquisition pin of the analog-to-digital converter and one end of the capacitive element, and the other end of the capacitive element is grounded. The capacitive element is used for current integration.
5. The photoelectric conversion circuit according to claim 4, characterized in that: The power supply is a bias power supply, and the photosensitive element is a photodiode.
6. The photoelectric conversion circuit according to claim 5, characterized in that: The bias power supply includes a resistor and a capacitor, one end of the resistor is connected to the power supply, the other end of the resistor is connected to one end of the capacitor and the first electrode of the photosensitive element, and the other end of the capacitor is grounded.
7. A photoelectric smoke detection circuit, characterized in that: The photoelectric smoke detection circuit comprises the photoelectric conversion circuit according to any one of claims 1 to 6, a light source emission circuit and a control module, wherein the control module is connected to the light source emission circuit and the photoelectric conversion circuit respectively.
8. The photoelectric smoke detection circuit according to claim 7, characterized in that: The photoelectric smoke detection circuit further includes a pull-up resistor, and two ends of the pull-up resistor are respectively connected to the control module and the first electrode of the photosensitive element.