Photoelectric signal conditioning and shaping circuit for eliminating interference of laser measuring instrument

Abstract

The utility model relates to the technical field of laser measurement, and discloses a photoelectric signal conditioning and shaping circuit for eliminating interference of a laser measuring instrument. The objective of the utility model is to solve the technical problem of inaccurate measurement results caused by interference of background light on measurement signals in a laser measurement process in the prior art. The device comprises a signal processing unit for subtraction, the input end of the signal processing unit is connected with a photoelectric conversion unit and a background light sampling and holding unit, and the output end forms a signal to be detected; the input end of the photoelectric conversion unit is connected with the photodiode so as to convert a current signal detected by the photodiode into a voltage signal, and the output end forms a measurement original signal; the to-be-detected signal is connected with the peak holding unit so as to capture and hold the peak voltage after subtraction processing; the peak voltage is connected with the level comparison unit to form a partial voltage comparison level. According to the utility model, signals generated by light emission of the steel can be effectively inhibited.

Description

Technical Field

[0001] This utility model relates to the field of laser measurement technology, and in particular to an optoelectronic signal conditioning and shaping circuit for eliminating interference in laser measuring instruments. Background Technology

[0002] With the rapid development of industrial automation and intelligent manufacturing, the demand for high-precision, fast, and non-contact measurement technologies is increasing in fields such as manufacturing, construction, and surveying. Traditional measuring tools, such as measuring tapes and theodolites, while still used in some scenarios, have many limitations, such as low measurement accuracy, cumbersome operation, and susceptibility to environmental influences. In recent years, laser measurement technology has gradually gained attention due to its advantages of high precision, non-contact measurement, and ease of operation. However, existing laser measurement equipment still has shortcomings in certain complex environments. The red light emitted by steel at high temperatures is thermal radiation with a wide wavelength range, which may overlap with the laser wavelength used by the measuring equipment. When this red light enters the optical sensor of the measuring equipment, it mixes with the laser signal used for measurement, causing the sensor to be unable to accurately distinguish between the measurement signal and the interference signal. The intensity of the red light may be high, especially when the surface temperature of the steel is high. This high-intensity red light may "overwhelm" the laser signal used for measurement, distorting the signal received by the sensor and thus affecting the measurement accuracy.

[0003] Chinese patent document 201710689239.8 discloses a portable laser measuring instrument for detecting the diameter of a circular hole. It consists of a handle, two laser rangefinders, and a data processing display mounted on a right-angled triangular base. During measurement, the right-angled edge of the triangular base is placed against any point on the circumference of the circular hole to be measured. The diameter of the circular hole is determined by the laser beams perpendicular to each other in the same plane, and then calculated using the Pythagorean theorem based on the mounting dimensions of the laser sensors and the rangefinder results.

[0004] However, the above-mentioned solution has at least the following technical problems during implementation: during laser measurement, background light interferes with the measurement signal, leading to inaccurate measurement results. Therefore, there is an urgent need to propose an optoelectronic signal conditioning and shaping circuit for eliminating interference in laser measuring instruments. Summary of the Invention

[0005] In view of the above technical problems, this disclosure provides an optoelectronic signal conditioning and shaping circuit for eliminating interference in laser measuring instruments, which solves the technical problem in the prior art that background light interferes with the measurement signal during laser measurement, resulting in inaccurate measurement results.

[0006] According to one aspect of this disclosure, a photoelectric signal conditioning and shaping circuit for eliminating interference in a laser measuring instrument is provided, comprising a signal processing unit capable of performing subtraction operations; the input terminal of the signal processing unit is connected to a photoelectric conversion unit and a background light sampling and holding unit, and the output terminal forms a signal to be measured; the input terminal of the photoelectric conversion unit is connected to a photodiode to convert the current signal detected by the photodiode into a voltage signal, and the output terminal forms a raw measurement signal; the signal to be measured is connected to a peak holding unit to capture and hold the peak voltage after subtraction processing; the peak voltage is connected to a level comparison unit to form a voltage divider comparison level; the output signal of the level comparison unit is connected to a NAND gate circuit to perform logical operations and output the signal.

[0007] In some embodiments of this disclosure, a virtual ground generation unit is also included for providing a virtual circuit potential; the virtual ground generation unit includes an operational amplifier U2.2, the voltage input terminal of which is connected to voltage divider resistors R4 and R5.

[0008] In some embodiments of this disclosure, the photoelectric conversion unit includes an operational transconductance amplifier U2.1, with its input terminal connected to a photodiode PD1 and its output terminal connected to a signal processing unit.

[0009] In some embodiments of this disclosure, the non-inverting input of the operational transconductance amplifier U2.1 is connected to an integrating circuit consisting of capacitor C3 and resistor R2 to filter out noise.

[0010] In some embodiments of this disclosure, the background light sampling and holding unit includes a sampling operational amplifier U3.1 and a holding operational amplifier U3.2, with U3.1 and U3.2 connected via a storage capacitor C8.

[0011] In some embodiments of this disclosure, the signal processing unit includes a differential amplifier U2.3 whose input is connected to the original measurement signal and the background light signal, and whose output forms the signal to be measured.

[0012] In some embodiments of this disclosure, the peak hold unit includes a sampling operational amplifier U3.3 and a hold operational amplifier U3.4 to output a peak voltage, with U3.3 and U3.4 connected via a storage capacitor C10.

[0013] In some embodiments of this disclosure, the level comparison unit includes voltage divider resistors R12, R13, and R14 connected to the peak voltage to form two comparison levels, which are respectively connected to the input terminals of comparators U5.1 and U5.2. The other input terminals of comparators U5.1 and U5.2 are both connected to the signal to be measured.

[0014] The beneficial effects of this utility model are as follows:

[0015] By eliminating background light interference through subtraction, the interference of background light on the measurement signal is effectively reduced, significantly improving measurement accuracy. The noise filtering function of the integrating circuit further improves signal purity and reduces measurement errors. The operational transconductance amplifier stably converts the current signal into a voltage signal, reducing signal distortion during the conversion process. The peak hold unit captures and holds the peak voltage, ensuring signal stability during subsequent processing and avoiding measurement errors caused by signal fluctuations. The virtual ground generation unit provides a stable reference potential for the circuit, ensuring stable operation of the entire circuit. This circuit design effectively addresses measurement needs in complex environments, accurately measuring target signals even in scenarios with strong background light interference. The integrated circuit design reduces the complexity and cost of the measuring equipment, improving its reliability and maintainability. The optimized signal processing flow reduces signal processing time and improves measurement efficiency. It is suitable for high-precision, high-speed measurement needs and meets the real-time monitoring and quality control requirements of modern industrial production. Attached Figure Description

[0016] Figure 1 Schematic diagram of an optoelectronic signal conditioning and shaping circuit for eliminating interference in a laser measuring instrument;

[0017] Figure 2 This is a waveform diagram of the photoelectric signal from the laser measuring instrument. Detailed Implementation

[0018] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention. Example 1

[0019] This example discloses an optoelectronic signal conditioning and shaping circuit for eliminating interference in laser measuring instruments. See [link to relevant documentation]. Figures 1 to 2 ;

[0020] The system includes a signal processing unit capable of performing subtraction operations. The input of the signal processing unit is connected to a photoelectric conversion unit and a background light sampling and holding unit, and the output of the signal to be measured is formed. The input of the photoelectric conversion unit is connected to a photodiode to convert the current signal detected by the photodiode into a voltage signal, and the output of the photodiode forms the original measurement signal. The signal to be measured is connected to a peak holding unit to capture and hold the peak voltage after subtraction. The peak voltage is connected to a level comparison unit to form a voltage divider comparison level. The output signal of the level comparison unit is connected to a NAND gate circuit to perform logical operations and output the signal.

[0021] It also includes a virtual ground generation unit for providing virtual circuit potential; the virtual ground generation unit includes an operational amplifier U2.2, the voltage input terminal of which is connected to voltage divider resistors R4 and R5.

[0022] The photoelectric conversion unit includes an operational transconductance amplifier U2.1, whose input terminal is connected to a photodiode PD1 and whose output terminal is connected to a signal processing unit.

[0023] The non-inverting input of the operational transconductance amplifier U2.1 is connected to an integrating circuit consisting of capacitor C3 and resistor R2 to filter out noise.

[0024] The background light sampling and holding unit includes a sampling operational amplifier U3.1 and a holding operational amplifier U3.2, which are connected by a storage capacitor C8.

[0025] The signal processing unit includes a differential amplifier U2.3 whose input is connected to the original measurement signal and the background light signal, and whose output forms the signal to be measured.

[0026] The peak hold unit includes a sampling operational amplifier U3.3 and a holding operational amplifier U3.4 to output the peak voltage. U3.3 and U3.4 are connected via a storage capacitor C10.

[0027] The level comparison unit includes voltage divider resistors R12, R13, and R14 connected to the peak voltage to form two comparison levels, which are respectively connected to the input terminals of comparators U5.1 and U5.2. The other input terminal of comparators U5.1 and U5.2 is connected to the signal to be measured.

[0028] During operation, photodiode PD1 detects the laser signal or background light signal and converts it into a current signal. This current signal is then converted into a voltage signal by operational transconductance amplifier U2.1, forming the original measurement signal. The non-inverting input of the operational transconductance amplifier is connected to an integrating circuit consisting of capacitor C3 and resistor R2 to filter out noise and ensure the purity of the original measurement signal. Sampling operational amplifier U3.1 acquires the background light signal and stores it on storage capacitor C8. Holding operational amplifier U3.2 maintains the background light signal on storage capacitor C8 at a stable level, providing a reference signal for subsequent subtraction operations. The input of differential amplifier U2.3 is connected to both the original measurement signal and the background light signal. Through subtraction, it eliminates the interference of background light on the measurement signal and outputs the signal under test. The signal under test is the pure measurement signal after background light interference elimination. Sampling operational amplifier U3.3 captures the peak voltage in the signal under test and stores it on storage capacitor C10. Holding operational amplifier U3.4 maintains the peak voltage on storage capacitor C10 at a stable level, ensuring signal stability during subsequent processing. The peak voltage is divided into two comparison levels by voltage divider resistors R12, R13, and R14, which are connected to the inputs of comparators U5.1 and U5.2, respectively. The other input of comparators U5.1 and U5.2 is connected to the signal under test. By comparing the signal under test with the two comparison levels, a logic signal is output. This logic signal reflects the high and low level states of the signal under test. The logic signal output from the level comparison unit is connected to a NAND gate circuit. Through logical operations, a stable measurement result is finally output. The NAND gate circuit ensures the accuracy of the logic state of the output signal, meeting the requirements of the measurement equipment. The virtual ground generation unit provides a stable virtual potential for the entire circuit through operational amplifier U2.2 and voltage divider resistors R4 and R5. The stability and accuracy of the virtual ground are crucial for the normal operation of the circuit, ensuring that each unit operates under a stable reference potential.

[0029] Although some preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0030] Obviously, those skilled in the art can make various modifications and variations to this utility model without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this application and their equivalents, this utility model also intends to include these modifications and variations.

Claims

1. An optoelectronic signal conditioning circuit for interference cancellation in a laser measuring instrument, characterized by: The signal processing unit which can be used for subtraction operation is connected with the photoelectric conversion unit and the background light sampling holding unit at the input end and forms the signal to be measured at the output end; the input end of the photoelectric conversion unit is connected with the photodiode to convert the current signal detected by the photodiode into a voltage signal, and the output end forms the measurement original signal; the signal to be measured is connected with the peak holding unit to capture and hold the peak voltage after subtraction processing; the peak voltage is connected with the level comparison unit to form the divided voltage comparison level; The output signal of the level comparison unit is connected with the NAND gate circuit to realize the logic operation and then output.

2. The photoelectric signal conditioning shaping circuit for eliminating interference of a laser measuring instrument according to claim 1, characterized in that: The virtual ground generating unit is further included to provide the circuit virtual potential; the virtual ground generating unit includes the operational amplifier U2.2, and the voltage input end of U2.2 is connected with the divided resistors R4 and R5.

3. The photoelectric signal conditioning and shaping circuit for eliminating interference of laser measuring instrument according to claim 1, characterized in that: The photoelectric conversion unit includes the operational transconductance amplifier U2.1, and the input end of U2.1 is connected with the photodiode PD1, and the output end is connected with the signal processing unit.

4. The photoelectric signal conditioning and shaping circuit for eliminating interference of laser measuring instrument according to claim 3, characterized in that: The in-phase input end of the operational transconductance amplifier U2.1 is connected with the integral circuit composed of the capacitor C3 and the resistor R2 to filter out the noise.

5. The photoelectric signal conditioning and shaping circuit for eliminating interference of laser measuring instrument according to claim 1, characterized in that: The background light sampling holding unit includes the sampling operational amplifier U3.1 and the holding operational amplifier U3.2, and U3.1 and U3.2 are connected through the storage capacitor C8.

6. The photoelectric signal conditioning and shaping circuit for eliminating interference of laser measuring instrument according to claim 1, characterized in that: The input end of the signal processing unit includes the differential amplifier U2.3, and the measurement original signal and the background light signal are connected at the output end to form the signal to be measured.

7. The photoelectric signal conditioning and shaping circuit for eliminating interference of laser measuring instrument according to claim 1, characterized in that: The peak holding unit includes the sampling operational amplifier U3.3 and the holding operational amplifier U3.4 to output the peak voltage, and U3.3 and U3.4 are connected through the storage capacitor C10.

8. The photoelectric signal conditioning and shaping circuit for eliminating interference of laser measuring instrument according to claim 1, characterized in that: The level comparison unit includes the divided resistors R12, R13 and R14 connected with the peak voltage to form two comparison levels, and the two comparison levels are respectively connected with the input ends of the comparators U5.1 and U5.2, and the other input ends of U5.1 and U5.2 are both connected with the signal to be measured.

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