Light intensity self-calibration circuit

Abstract

The utility model discloses a light intensity self-calibration circuit, which relates to the technical field of light detection and comprises a processor, an excitation light source constant-current control module, a light path module and a photoelectric conversion module. The DAC output end of the processor transmits an analog voltage signal serving as a reference to the excitation light source constant current control module, the excitation light source constant current control module outputs a light intensity signal to the photoelectric conversion module through the light path module, and the photoelectric conversion module transmits an output voltage signal to the processor through the emitter follower. The beneficial effects of the utility model are that the variable constant current technology is adopted, errors caused by circuit device differences and light path differences can be adaptively corrected, extremely high consistency of an output excitation light source and a light receiving circuit can be ensured, and the test result cannot be influenced by the circuit device differences and the light path differences.

Description

Technical Field

[0001] The utility model relates to the technical field of light detection, in particular to a light intensity self-calibration circuit. Background Art

[0002] In the existing common light detection circuit, the excitation light source is driven by a constant current source circuit, which can theoretically ensure the consistency of the excitation light output. However, in reality, due to the individual differences of the LED light source and the influence of environmental factors, the intensity of the output light will vary. In addition, the light receiving circuit will also have different circuit parameters and environmental conditions, as well as the differences in the optical transmission path and the optical path materials, and the measured light loss will be different, so the consistency of the receiving part cannot be guaranteed. Utility Model Content

[0003] Some simplifications or omissions may be made in this section and the abstract of the specification and the title of the utility model of this application to avoid blurring the purpose of this section, the abstract of the specification and the title of the utility model, and such simplifications or omissions shall not be used to limit the scope of the utility model.

[0004] In view of the above problems or problems existing in the prior art, the present utility model is proposed.

[0005] Therefore, the purpose of the present invention is to provide a light intensity self-calibration circuit, which is to solve the problem that the existing light intensity cannot be adjusted adaptively.

[0006] In order to solve the above technical problems, the utility model provides the following technical solutions: a light intensity self-calibration circuit, comprising a processor, an excitation light source constant current control module, an optical path module and a photoelectric conversion module; the DAC output end of the processor transmits a reference analog voltage signal for comparison to the excitation light source constant current control module, the excitation light source constant current control module outputs a light intensity signal to the photoelectric conversion module through the optical path module, and the photoelectric conversion module transmits an output voltage signal to the processor through an emitter follower.

[0007] As a preferred solution of the light intensity self-calibration circuit of the utility model, wherein: the excitation light source constant current control module includes a first operational amplifier and a transistor; the non-inverting input terminal of the first operational amplifier receives the analog voltage signal from the DAC output terminal of the processor as a reference for constant current comparison, and its inverting input terminal is connected to the emitter of the transistor, the output terminal of the first operational amplifier is connected to the base of the transistor after being connected in series with a second resistor, the positive power supply pin of the first operational amplifier is connected to a 5V voltage power supply, and the negative power supply pin of the first operational amplifier is grounded.

[0008] As a preferred solution of the light intensity self-calibration circuit of the utility model, the collector of the transistor is connected to a 5V voltage power supply, and the emitter of the transistor is connected in series with a third resistor and then grounded.

[0009] As a preferred solution of the light intensity self-calibration circuit of the utility model, wherein: an LED light emitting diode is connected in series in the circuit between the collector of the transistor and the 5V voltage power supply.

[0010] As a preferred solution of the light intensity self-calibration circuit described in the utility model, wherein: the optical path module includes an excitation light path and an excitation light path, one end of the excitation light path receives illumination from the LED light emitting diode of the excitation light source constant current control module, and the other end transmits a light intensity signal to the excitation light path through a photoexcitation material.

[0011] As a preferred solution of the light intensity self-calibration circuit of the utility model, wherein: the photoelectric conversion module includes a second operational amplifier and an emitter follower; the second operational amplifier constitutes an IV transimpedance amplifier circuit, the non-inverting input terminal is grounded, and its inverting input terminal is connected to the cathode of the photoelectric detection sensor, the first resistor is connected between the output terminal and the inverting terminal of the second operational amplifier, the positive power supply pin of the second operational amplifier is connected to a 3.3V voltage power supply, and the negative power supply pin of the second operational amplifier is grounded.

[0012] As a preferred solution of the light intensity self-calibration circuit of the utility model, the photoelectric detection sensor receives light from the excitation light path, the cathode of the photoelectric detection sensor is connected to the inverting end of the second operational amplifier, and the other end anode is grounded.

[0013] As a preferred solution of the light intensity self-calibration circuit of the utility model, the non-inverting input terminal of the emitter follower is connected to the output terminal of the second operational amplifier, the inverting input terminal of the emitter follower is connected to its own output terminal, the positive power supply pin of the emitter follower is connected to a 3.3V voltage power supply, the negative power supply pin of the emitter follower is grounded, and the output terminal of the emitter follower transmits a voltage signal to the analog-to-digital conversion port of the processor.

[0014] The beneficial effects of the utility model: the utility model adopts variable constant current technology, which can adaptively correct the errors caused by circuit component differences and optical path differences, and can ensure that the output excitation light source and the light receiving circuit are highly consistent. This design will not affect the test results due to circuit component differences and optical path differences. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0016] Figure 1 This is a circuit structure diagram of the light intensity self-calibration circuit of the utility model;

[0017] Figure 2 is a schematic diagram of an external DAC module in Example 2;

[0018] Figure 3 Schematic diagram of the light intensity self-calibration process of Example 3. DETAILED DESCRIPTION

[0019] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0020] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0021] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.

[0022] Example 1

[0023] Reference Figure 1 , which is the first embodiment of the utility model, and this embodiment provides a light intensity self-calibration circuit, which includes a processor 100, an excitation light source constant current control module 200, an optical path module 300 and a photoelectric conversion module 400; the DAC output end of the processor 100 transmits an analog voltage signal used as a reference to the excitation light source constant current control module 200, the excitation light source constant current control module 200 outputs a light intensity signal to the photoelectric conversion module 400 through the optical path module 300, and the photoelectric conversion module 400 transmits an output voltage signal to the processor 100 through the emitter follower U1.

[0024] The excitation light source constant current control module 200 includes a first operational amplifier U3 and a transistor Q1; the non-inverting input terminal of the first operational amplifier U3 receives an analog voltage signal from the DAC output terminal of the processor 100 as a reference for constant current comparison, and its inverting input terminal is connected to the emitter of the transistor Q1, the output terminal of the first operational amplifier U3 is connected in series with a second resistor R2 and then connected to the base of the transistor Q1, the positive power pin of the first operational amplifier U3 is connected to a 5V voltage power supply, and the negative power pin of the first operational amplifier U3 is grounded.

[0025] The collector of the transistor Q1 is connected to a 5V voltage power supply, and the emitter of the transistor Q1 is connected in series with a third resistor R3 and then grounded.

[0026] An LED light emitting diode is connected in series in the circuit between the collector of transistor Q1 and the 5V voltage power supply.

[0027] The optical path module 300 includes an excitation light path 301 and an excitation light path 302. One end of the excitation light path 301 receives light from the LED light emitting diode of the excitation light source constant current control module 200, and the other end transmits a light intensity signal to the excitation light path 302 through a photoexcitation substance.

[0028] The photoelectric conversion module 400 includes a second operational amplifier U2 and an emitter follower U1; the second operational amplifier U2 constitutes an IV transimpedance amplifier circuit, the non-inverting input terminal is grounded, and its inverting input terminal is connected to the cathode of the photoelectric detection sensor, the first resistor R1 is connected between the output terminal and the inverting terminal of the second operational amplifier U2, the positive power supply pin of the second operational amplifier U2 is connected to a 3.3V voltage power supply, and the negative power supply pin of the second operational amplifier U2 is grounded.

[0029] The photoelectric detection sensor D1 receives light from the excitation light path 302, the cathode of the photoelectric detection sensor D1 is connected to the inverting end of the second operational amplifier U2, and the other end of the anode is grounded.

[0030] The non-inverting input terminal of the emitter follower U1 is connected to the output terminal of the second operational amplifier U2, the inverting input terminal of the emitter follower U1 is connected to its own output terminal, the positive power supply pin of the emitter follower U1 is connected to the 3.3V voltage power supply, the negative power supply pin of the emitter follower U1 is grounded, and the output terminal of the emitter follower U1 transmits a voltage signal to the analog-to-digital conversion port of the processor 100.

[0031] Transistor Q1 is preferably MMBT3904, which is an NPN transistor commonly used in amplification, switching and other circuit applications. MMBT3904 is usually used in low-power and small-size circuit designs, with high frequency response and low noise. In addition, the transistor can also be replaced by a MOS tube to achieve full pin to pin.

[0032] The second operational amplifier U2 and the emitter follower U1 are preferably AD8605.

[0033] The resistance value of the first resistor R1 is preferably 12 megohms, and the resistance value of the second resistor R2 is preferably 1 kilohm.

[0034] The materials of the excitation light path 301 and the excitation light path 302 can be selected from light guide plates, optical fibers, etc., and the photoexcitation material can be selected from fluorescent materials, etc. In addition, the excitation light path 301 and the excitation light path 302 can also directly use the same optical fiber.

[0035] The emitter follower U1 plays two roles here: first, it acts as a circuit buffer to isolate the input signal resistance from the subsequent circuit, protecting the input signal source and the subsequent circuit from each other, which is very useful for applications that need to maintain high impedance isolation between the signal source and the subsequent circuit; second, it can provide impedance matching, so that the impedance matching between the input signal source and the subsequent circuit is better. This helps to maximize the transmission of signal energy and reduce signal loss and distortion.

[0036] Example 2

[0037] Reference Figure 2 , which is the second embodiment of the utility model, and which is different from the first embodiment in that: for a processor 100 without a built-in DAC function, an external DAC function can be selected, that is, an external DAC module can be selected to implement it, and the DAC voltage signal is transmitted to the processor 100 by using the subsequent excitation light source constant current control module 200, the optical path module 300 and the photoelectric conversion module 400, and the rest of the process is the same.

[0038] Example 3

[0039] Reference Figure 3 , which is the third embodiment of the utility model. What is different from the first two embodiments is that this embodiment provides a workflow for light intensity self-calibration.

[0040] The reference source of the excitation light source constant current control module 200 where the first operational amplifier U3 is located is connected to the DAC output port of the processor 100 circuit.

[0041] During the test, the circuit will first enter the calibration mode according to the set program, the DAC will send the typical value of the designed reference voltage value, the excitation light source constant current control module 200 will light up the LED within the set constant current value range, and after the set time (lighting time), the DAC output is 0V, the excitation light source constant current control module 200 stops working, and the LED light-emitting diode goes out. When the DAC outputs 0V, the photoelectric conversion circuit 400 synchronously detects the intensity of the light signal, converts the light intensity into a voltage signal output, and sends the voltage signal losslessly to the analog-to-digital conversion (ADC) port of the processor through the emitter follower U1. The processor 100 converts the port voltage value and compares the converted digital value with the value preset by the program.

[0042] If the measured value is lower than the preset value, the processor 100 will adjust the output voltage value of the DAC, so that the output voltage value is increased according to the set step length, thereby increasing the constant current value of the excitation light source constant current control module 200, so that the intensity of the excitation light source is enhanced. If the measured value is higher than the program preset value, the above process is reversed until the measured value is within the set allowable range. Subsequent constant current execution DAC will assign the modified value.

[0043] The above circuit design can ensure that the output excitation light source and the light receiving circuit are highly consistent, and the test results will not be affected by factors such as differences in circuit components and optical paths.

[0044] The core of this design is that the reference source of the constant current circuit is variable, so that the output constant current value can be changed and the intensity of the excitation light is adjusted to compensate for the correction influencing factor.

[0045] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and ratio of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), installation arrangements, use of materials, color, directional changes, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present utility model. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure described herein that performs the function, and is not only structurally equivalent but also an equivalent structure. Without departing from the scope of the present invention, other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the present invention is not limited to a specific embodiment, but extends to various modifications that still fall within the scope of the appended claims.

[0046] Additionally, in order to provide a concise description of example embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0047] It will be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will be a routine task of design, fabrication, and production for those of ordinary skill having the benefit of this disclosure without undue experimentation.

[0048] It should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.

Claims

1. A light intensity self-calibration circuit, characterized in that: include, A processor (100), an excitation light source constant current control module (200), an optical path module (300) and a photoelectric conversion module (400); The DAC output end of the processor (100) transmits an analog voltage signal used as a reference to the excitation light source constant current control module (200), the excitation light source constant current control module (200) outputs a light intensity signal to the photoelectric conversion module (400) through the optical path module (300), and the photoelectric conversion module (400) transmits an output voltage signal to the processor (100) through the emitter follower (U1).

2. The light intensity self-calibration circuit as claimed in claim 1, characterized in that: The excitation light source constant current control module (200) comprises a first operational amplifier (U3) and a transistor (Q1); The non-inverting input terminal of the first operational amplifier (U3) receives an analog voltage signal from a DAC output terminal of the processor (100), and the inverting input terminal thereof is connected to the emitter of the transistor (Q1). The output terminal of the first operational amplifier (U3) is connected in series with a second resistor (R2) and then connected to the base of the transistor (Q1). The positive power supply pin of the first operational amplifier (U3) is connected to a 5V voltage power supply, and the negative power supply pin of the first operational amplifier (U3) is grounded.

3. The light intensity self-calibration circuit as claimed in claim 2, characterized in that: The collector of the transistor (Q1) is connected to a 5V voltage power supply, and the emitter of the transistor (Q1) is connected in series with a third resistor (R3) and then grounded.

4. The light intensity self-calibration circuit as claimed in claim 3, characterized in that: An LED light emitting diode is connected in series between the collector of the transistor (Q1) and the 5V voltage power supply circuit.

5. The light intensity self-calibration circuit as claimed in claim 4, characterized in that: The optical path module (300) comprises an excitation light path (301) and an excitation light path (302); one end of the excitation light path (301) receives light from an LED light emitting diode of the excitation light source constant current control module (200), and the other end transmits a light intensity signal to the excitation light path (302) through a photoexcitation substance.

6. The light intensity self-calibration circuit according to any one of claims 1 to 5, characterized in that: The photoelectric conversion module (400) comprises a second operational amplifier (U2) and an emitter follower (U1); The second operational amplifier (U2) constitutes an IV transimpedance amplifier circuit, wherein the non-inverting input terminal is grounded, and the inverting input terminal is connected to the cathode of the photodetection sensor. The first resistor (R1) is connected between the output terminal and the inverting terminal of the second operational amplifier (U2). The positive power supply pin of the second operational amplifier (U2) is connected to a 3.3V voltage power supply, and the negative power supply pin of the second operational amplifier (U2) is grounded.

7. The light intensity self-calibration circuit as claimed in claim 6, characterized in that: The photoelectric detection sensor (D1) receives light from the excitation light path (302), the cathode of the photoelectric detection sensor (D1) is connected to the inverting end of the second operational amplifier (U2), and the other end of the anode is grounded.

8. The light intensity self-calibration circuit as claimed in claim 7, characterized in that: The non-inverting input end of the emitter follower (U1) is connected to the output end of the second operational amplifier (U2), the inverting input end of the emitter follower (U1) is connected to its own output end, the positive power supply pin of the emitter follower (U1) is connected to a 3.3V voltage power supply, the negative power supply pin of the emitter follower (U1) is grounded, and the output end of the emitter follower (U1) transmits a voltage signal to an analog-to-digital conversion port of a processor (100).

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