CN216904868U - Photosensitive device compensation circuit based on photosensitive current source - Google Patents
Photosensitive device compensation circuit based on photosensitive current source Download PDFInfo
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- CN216904868U CN216904868U CN202123338321.7U CN202123338321U CN216904868U CN 216904868 U CN216904868 U CN 216904868U CN 202123338321 U CN202123338321 U CN 202123338321U CN 216904868 U CN216904868 U CN 216904868U
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Abstract
The utility model discloses a photosensitive device compensating circuit based on a photosensitive current source, which comprises a +12V power supply circuit, a 10V voltage stabilizing circuit, a photosensitive element circuit, a filter circuit, a +5V reference voltage generating circuit, an integral operation circuit and a current source circuit, wherein the 10V voltage stabilizing circuit supplies power to an IC1, a T1 and a T2, the T1, r1 and R2 form a current source circuit, R5 and C3 form a filter circuit, IC1, R4 and C2 form an integral operation circuit, a 10V power supply is connected sequentially through R6 and R7 to generate +5V reference voltage, a collector of T1 is connected with a pin 3 of IC1 through R5, a pin 3 of IC1 is connected with the ground through C3, a connection point of R6 and R7 is connected with a pin 2 of IC1 through R4, a pin 2 of IC1 is connected with a pin 6 of IC1 through C2, a pin 6 of IC1 is connected with a base of T1 through R3, and A-B terminal voltage of a photosensitive device T2 is unsaturated Uterminal voltage o of the photosensitive device T2.
Description
Technical Field
The utility model relates to a photosensitive device compensation technology, in particular to a photosensitive device compensation circuit based on a photosensitive current source, wherein the photosensitive current source can change bias current according to the change of ambient light intensity, so that the bias voltage of a photosensitive device is kept constant.
Background
The photosensitive device is an element capable of converting an optical signal into an electrical signal, and can realize the interconversion of electricity → light and light → electricity by matching with a light emitting tube, and common photosensitive elements comprise a photoresistor, a photodiode and a phototriode.
The photodiode can realize photoelectric conversion, but has low sensitivity, and the photoelectric conversion sensitivity is greatly improved by using the phototriode.
The application of the photosensitive device is very wide, for example, a circuit which can sense the rapid change of the light intensity by using the photosensitive device, which is called an optical tachometer, the photosensitive device is influenced by the change of the light intensity of the environment, so as to change the bias voltage of the photosensitive device, if the bias current passing through the photosensitive device is fixed, the photosensitive device is saturated under the condition of high light intensity of the environment, and the situation is avoided in the actual working process.
The optical coupler is also one of applications of photosensitive devices, a phototriode in the optical coupler has three states of saturation, cut-off and amplification, and some phototriodes work in the cut-off state and the saturation state and are used as switches; some work is in the amplification state, for example the feedback opto-coupler of switching power supply, the linearity ratio of general opto-coupler is relatively poor, need use special linear opto-coupler or add special compensating circuit when making the signal amplification that requires higher, for example as the speech signal isolation of telephone circuit, require this kind of linear opto-coupler to can satisfy completely to general conversation.
When the phototriode is used as a receiving device in practice, in order to improve the receiving sensitivity or avoid entering a saturation state, an additional light can be applied to the phototriode by applying a proper bias current to enable the phototriode to enter a shallow amplification region.
Both applications emphasize that the photosensitive device is prevented from entering a saturation state as much as possible, the problem can be solved by using one photosensitive current source, and the photosensitive current source can change bias current according to the change of the light intensity of the environment, so that the bias voltage of the photosensitive device is kept constant.
Disclosure of Invention
The utility model aims to provide a compensation technology of a photosensitive device, which has the advantages of simple structure, low manufacturing cost and reliable use.
In order to achieve the above object, the present invention provides a photosensitive current source-based photosensitive device compensation circuit, which comprises a +12V power supply circuit, a 10V voltage regulator circuit, a photosensitive device circuit, a filter circuit, a +5V reference voltage generation circuit, an integration circuit, a current source circuit, a resistor R8, an electrolytic capacitor C1, and a zener diode D1, wherein the 10V voltage regulator circuit is formed by the +12V power supply circuit, the +12V power supply circuit is connected to operate sequentially through a resistor R8 and a reverse zener diode D1, the reverse zener diode D1 is connected in parallel with the forward electrolytic capacitor C1, the transistor T1, the resistor R1, and the resistor R2 form the current source circuit, the 10V stable power supply is connected to the base of the transistor T1 through the resistor R2, the 10V stable power supply is connected to the emitter of the transistor T1 through the resistor R1, the collector of the transistor T1 is connected to operate through the C-E pole of the photosensitive device circuit T2, the resistor R5 and the capacitor C3 form the filter circuit, the operational amplifier IC1, the resistor R4 and the capacitor C2 form the integral operation circuit, a 10V stable power supply is connected with the resistor R6 and the resistor R7 in sequence to work to form the +5V reference voltage generation circuit, a collector of the transistor T1 is connected with a pin 3 of a non-inverting input end of the operational amplifier IC1 through the resistor R5, a pin 3 of the operational amplifier IC1 is connected with a work ground through the capacitor C3, a connection point of the resistor R6 and the resistor R7 is connected with a pin 2 of an inverting input end of the operational amplifier IC1 through the resistor R4, a pin 2 of the inverting input end of the operational amplifier IC1 is connected with a pin 6 of an output end of the operational amplifier IC1 through the capacitor C2, a pin 6 of the output end of the operational amplifier IC1 is connected with a base of the transistor T1 through the resistor R3, and an A-B terminal voltage of the photosensitive device circuit T2 is an unsaturated Uterminal voltage o of the photosensitive device T2.
Drawings
Fig. 1 and 2 are included to provide a further understanding of the present invention and form a part of the present application, and fig. 1 is a schematic diagram of a photosensitive current source based photosensitive device compensation circuit; fig. 2 is a schematic diagram of an integral arithmetic circuit.
Detailed Description
The photosensitive current source-based photosensitive device compensation circuit is shown in fig. 1 and comprises a 10V voltage stabilizing circuit, a photosensitive device circuit, a filter circuit, a 5V reference voltage generating circuit, an integral operation circuit and a current source circuit.
The basic integration circuit formed by the basic operational amplifier and the feedback capacitor is shown in fig. 2.
The in-phase end of the operational amplifier passes through R’Grounded and over-operational amplifiers have the characteristic of "virtual ground", i.e. uP=uN=0, i.e. the voltage at the same phase equals the voltage at the opposite phase equals 0, and the current in the capacitor C in the circuit equals the current in the resistor R
The relationship between the output voltage and the voltage on the capacitor is
And the voltage on the capacitor is the integral of the current, therefore
At the solution of t1To t2Integral value of period
In the formulau O（t 1) For integrating the output voltage at the start of the integration, i.e. the start value of the integration operation, the end value of the integration being t2The output voltage at the moment. When u isIWhen constant, the output voltage
Photosensitive device compensation circuit introduces in detail: in the circuit shown in FIG. 1, the operational amplifier IC1And a capacitor C2Resistance R4Form an integral operation circuit, integrate with the circuit shown in FIG. 2In a circuit different from that of the IC1Is not a varying input signal, but is formed by a resistor R6、R7A voltage-dividing 10V stable power supply to obtain a stable reference voltage UREF=UIC1--=10*（R7/(R6+R7) ) =5V, i.e., the input signal is constant.
IC1And a capacitor C2Resistance R4The second difference between the integrated circuit of the configuration and the integrated circuit shown in fig. 2 is that IC is also used1Is not through a compensation resistor
Grounded, photosensitive device T2Bias voltage U ofABThrough a filter circuit (formed by a resistor R)5Capacitor C3Form) an input operational amplifier IC1Non-inverting input terminal of, bias voltage UABThe light intensity of the environment changes within a certain small range, so that the light intensity is not a constant in a strict sense, but can be obtained by a photosensitive current source T1Self-adjusting ofABEqual operational amplifier IC1The voltage at the inverting input (about 5V, i.e. the reference voltage U)REF）。
It will be appreciated that the light sensitive device compensation circuit is ultimately implemented as a self-adjusting light sensitive current source, transistor T1And base bias resistor R2Emitter bias resistor R1Forming a photosensitive current source, T1By an operational amplifier IC1Is passed through a current limiting resistor R3And (4) exciting.
Due to the current source T1Has extremely high output impedance, so that the output of the photosensitive device is not loaded.
The compensation circuit is actually a negative feedback circuit, the light intensity of the natural environment is increased, the photosensitive device tends to be saturated, and the voltage drop U on the photosensitive deviceABDecrease of UABThrough a filter circuit R5/C3Make IC1Integrated circuit IC for reducing voltage at inphase input terminal1The output voltage of (1) is reduced, the transistor T1Increase of emitter junction voltage, T1The conduction quantity is increased by the light sensitivityDevice T2So that the bias of the photosensitive device is kept constant.
To summarize, this feedback causes the IC1The output voltage is self-adjusting until T1The current is supplied such that the voltage drop across the photosensitive device is equal to the voltage at the inverting input of the operational amplifier (about 5V).
This ensures that if the ambient light intensity, and hence the resistance of the light sensitive device, changes, then T1The current source will regulate the current through the photosensitive device, thereby causing the output voltage U to beOAnd remain constant.
Resistance R8A voltage stabilizing diode D1Filter capacitor C1A simple voltage stabilizing circuit is formed, unstable 12V power supply is adopted to obtain stable 10V voltage output, and the stable voltage output is used as a transistor T1Operational amplifier IC1And the reference voltage generating circuit provides power feeding.
Error of the integrating circuit: in an actual integrating operation circuit, the following two factors mainly cause an integration error:
one is due to the non-ideal nature of the integrated op-amp. For example, when uI=0，uOShould also be zero, but since the input bias current of the op-amp flows through the integrating capacitor, u is caused to flowOThe longer the time is, the larger the error is. As another example, the passband of the integrated op-amp is not wide enough, which makes the integrator insensitive to rapidly changing input signals, causes output waveforms to lag, and so on.
Another cause of integration error is due to the integrating capacitance, e.g. when uIAfter returning to zero, uo should remain unchanged, but u is caused to leak due to the leakage resistance of the capacitorOGradually decreases, and for example, an integrating circuit is also subjected to an error due to the adsorption effect of the capacitor, and so on.
The above errors are somewhat unavoidable and some may minimize the effect of errors by optimizing the electronic component grade.
There is a situation where care should be taken if the incident light intensity is rapidFast change, too long response time of the current source due to error of the integrating circuit, etc., will not react to the fast change of the light intensity, but the fast change of the light intensity will still cause the output voltage uOCan cause the compensation circuit to be disabled.
Therefore, except for the operational amplifier IC1For its own reasons, in the compensation circuit of FIG. 1, due to the time constant R4/C2And R5/C3The compensation circuit being unable to respond to light intensity variations with a frequency greater than 2Hz, the current source T1These variations will be disregarded and a constant current will continue to be supplied.
Further, if the resistance of the photosensor changes due to a rapid change in light intensity, the output voltage U is outputOAnd changes correspondingly, which is a phenomenon that we are not willing to see and is a deficiency of the compensation circuit.
The circuit can be suitable for various photoresistors and phototransistors, and only one limiting condition is as follows: in the circuit of fig. 1, a phototransistor T2The type of the photosensitive element is selected according to the application environment, for example, 3DU2A, etc., and the resistance of the photosensitive element connected between the points a and B cannot be lower than 300 Ω, which is one of the considerations.
The total energy consumption of the designed circuit is between 20 and 35mA, and the specific value is determined by the current provided by the photosensitive device.
Claims (1)
1. A photosensitive device compensating circuit based on photosensitive current source is characterized in that: the compensation circuit comprises a +12V power supply circuit, a 10V voltage stabilizing circuit, a photosensitive device circuit, a filter circuit, a +5V reference voltage generating circuit, an integral operation circuit and a current source circuit, wherein the 10V voltage stabilizing circuit is formed by a resistor R8, an electrolytic capacitor C1 and a voltage stabilizing diode D1, the +12V power supply circuit is connected with a working place through a resistor R8 and a reverse voltage stabilizing diode D1 in sequence, the reverse voltage stabilizing diode D1 is connected with the forward electrolytic capacitor C1 in parallel, a transistor T1, a resistor R1 and a resistor R2 form the current source circuit, a 10V stable power supply is connected with a base electrode of a transistor T1 through a resistor R2, the 10V stable power supply is connected with an emitter electrode of a transistor T1 through a resistor R1, a collector electrode of the transistor T1 is connected with the working place through a C-E electrode of the photosensitive device circuit T2, the resistor R5 and a capacitor C3 form the filter circuit, an operational amplifier IC1, a resistor R4, a filter circuit, The capacitor C2 forms the integral operation circuit, the 10V stable power supply is connected with the non-saturation voltage generation circuit through the resistor R6 and the resistor R7 in sequence to form the +5V reference voltage generation circuit, the collector of the transistor T1 is connected with the 3 pin of the non-saturation input end of the operational amplifier IC1 through the resistor R5, the 3 pin of the operational amplifier IC1 is connected with the working ground through the capacitor C3, the connection point of the resistor R6 and the resistor R7 is connected with the 2 pin of the anti-phase input end of the operational amplifier IC1 through the resistor R4, the 2 pin of the anti-phase input end of the operational amplifier IC1 is connected with the 6 pin of the output end of the operational amplifier IC1 through the capacitor C2, the 6 pin of the output end of the operational amplifier IC1 is connected with the base of the transistor T1 through the resistor R3, and the A-B terminal voltage of the photosensitive device circuit T2 is the non-saturation voltage Uo of the photosensitive device T2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202123338321.7U CN216904868U (en) | 2021-12-28 | 2021-12-28 | Photosensitive device compensation circuit based on photosensitive current source |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202123338321.7U CN216904868U (en) | 2021-12-28 | 2021-12-28 | Photosensitive device compensation circuit based on photosensitive current source |
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| Publication Number | Publication Date |
|---|---|
| CN216904868U true CN216904868U (en) | 2022-07-05 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202123338321.7U Expired - Fee Related CN216904868U (en) | 2021-12-28 | 2021-12-28 | Photosensitive device compensation circuit based on photosensitive current source |
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2021
- 2021-12-28 CN CN202123338321.7U patent/CN216904868U/en not_active Expired - Fee Related
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Granted publication date: 20220705 |