irradiance meter

Abstract

The object of the present invention is to provide an irradiance meter having an electronic circuit whose response speed or resolution does not depend on an AD converter or a DA converter. [Solution] The above problem can be solved by an irradiance meter characterized by comprising: a light-receiving element (photodiode) into which the light to be measured is incident; a current-voltage conversion circuit that converts the output current of the light-receiving element into a voltage; a sensitivity adjustment circuit that adjusts the output of the current-voltage conversion circuit; an amplifier that amplifies the output of the sensitivity adjustment circuit; an AD conversion circuit that converts the output of the amplifier into a digital signal and inputs it to a first arithmetic processing unit (first microcontroller of the display unit); and an analog signal output unit that outputs the output of the amplifier to the outside.

Description

Technical Field

[0001] The present invention relates to an irradiance meter.

[0002] The electronic circuit of a conventional irradiance meter uses an AD converter, a microcomputer, and a DA converter to obtain an analog output corresponding to an irradiance value calculated using a sensitivity coefficient, and passes through a sampled discrete signal. (Patent Document 1)

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a conventional electronic circuit, the response speed or resolution depends on an AD converter, a microcomputer, a DA converter, or the sampling theorem. An object of the present invention is to provide an irradiance meter having an electronic circuit in which the response speed or resolution does not depend on an AD converter or a DA converter.

Means for Solving the Problems

[0005] As a result of intensive research on an irradiance meter having an electronic circuit that does not depend on an AD converter or a DA converter, the present inventor has surprisingly found that, with an electronic circuit having a specific configuration, the response speed or resolution does not depend on an AD converter or a DA converter. The present invention is based on such findings. Therefore, the present invention [1] A irradiance meter characterized by comprising: a photodetector (photodiode) into which the light to be measured is incident; a current-voltage conversion circuit that converts the output current of the photodetector into a voltage; a sensitivity adjustment circuit that adjusts the output of the current-voltage conversion circuit; an amplifier that amplifies the output of the sensitivity adjustment circuit; an AD conversion circuit that converts the output of the amplifier into a digital signal and inputs it to a first arithmetic processing unit (first microcontroller of the display unit); and an analog signal output unit that outputs the output of the amplifier to the outside. [2] The irradiance meter described in [1], wherein the sensitivity adjustment circuit is a variable resistor, [3] The irradiance meter described in [1], which includes a memory unit, wherein the sensitivity adjustment circuit consists of a digital potentiometer and a resistor, and the memory unit stores data that realizes the electrical resistance of the digital potentiometer corresponding to the measurement wavelength. [4] The first processing unit transmits data to the digital potentiometer that realizes a resistance value corresponding to the measurement wavelength stored in the memory unit, as described in [3]. [5] The irradiance meter described in [3], comprising a second arithmetic processing unit (second microcontroller of the photodetector) that controls the resistance value of the digital potentiometer, wherein the second arithmetic processing unit transmits data that realizes a resistance value corresponding to the measurement wavelength stored in the memory unit to the digital potentiometer, [6] A radiance meter as described in [5], comprising a light receiver housing the light receiving element, the digital potentiometer, and a second arithmetic processing unit, a current-voltage circuit, the resistor, the amplifier, the analog signal output unit, and a display unit housing the first arithmetic processing unit, wherein the light receiver and the display unit are connected by an electrical signal line, and [7] A irradiance meter according to any one of [4] to [6], comprising a dial unit capable of selecting a measurement wavelength corresponding to the wavelength of light to be measured incident on the light receiver, wherein the resistance value corresponding to the measurement wavelength stored in the memory unit is transmitted to the digital potentiometer by setting the dial unit, Regarding. [Effects of the Invention]

[0006] According to the irradiance meter of the present invention, the sensitivity to the signal voltage can be adjusted to an optimal level in analog terms. Therefore, it does not depend on the sampling frequency of the AD converter and DA converter, or the processing speed of the microcontroller. [Brief explanation of the drawing]

[0007] [Figure 1] These are photographs of the external appearance of a radiometer (A) equipped with a light receiver and display, and a radiometer (B) in which the light receiver and display are integrated. [Figure 2] This is a circuit diagram showing one example of the configuration of a separate-type irradiance meter. [Figure 3] This is a circuit diagram showing one example of the configuration of an integrated irradiance meter. [Modes for carrying out the invention]

[0008] The irradiance meter of the present invention comprises a photodetector (photodiode) into which the light to be measured is incident, a current-voltage conversion circuit that converts the output current of the photodetector into a voltage, a sensitivity adjustment circuit that adjusts the output of the current-voltage conversion circuit, an amplifier that amplifies the output of the sensitivity adjustment circuit, an AD conversion circuit that converts the output of the amplifier into a digital signal and inputs it to a first arithmetic processing unit (first microcontroller of the display), and an analog signal output unit that outputs the output of the amplifier to the outside. The irradiance meter of the present invention has a light-receiving element (photodiode), a current-voltage conversion circuit, a sensitivity adjustment circuit, an amplifier, and an analog signal output unit, thereby enabling it to have an analog voltage output function without performing digital conversion.

[0009] Photodiode (light-receiving element) The light-receiving element is a sensor that receives the light to be measured and converts the incident light into an electric current. While not limited to this, a GaP photodiode could be used, for example.

[0010] Current-voltage conversion circuit The current-voltage conversion circuit, also known as an IV amplifier, converts the current from the photodiode into a voltage. As shown in FIG. 2, for example, it can be configured to receive a range switching signal from the first microcontroller (CPU) of the display.

[0011] 《Sensitivity Adjustment Circuit》 The sensitivity adjustment circuit adjusts the output of the current-voltage conversion circuit.

[0012] (Variable Resistor) The sensitivity adjustment circuit is not limited, but for example, it may be a variable resistor. By adjusting the resistance value with a variable resistor, impedance adjustment can be performed.

[0013] (Analog Arithmetic Circuit) The sensitivity adjustment circuit is not limited, but it may also be an analog arithmetic circuit. The analog arithmetic circuit consists of, for example, a digital potentiometer and a resistor (FIG. 2 or FIG. 3), and multiplies the resistance value of the digital potentiometer by the voltage division ratio of, for example, the resistance value of the display = the reciprocal of the irradiance responsivity.

[0014] (Digital Potentiometer) Some digital potentiometers can set, for example, 10 kΩ in 1024 steps, and the adjustment of the resistance value does not depend on the skill of the adjuster. Also, automation of adjustment is possible, and high-precision adjustment can be performed at high speed. The digital potentiometer can be connected to the second microcontroller and also connected to the flash memory and the dial section from the second microcontroller.

[0015] (Resistor) The resistor can be used without limiting to the resistors commonly used in this field. For example, a semi-fixed resistor may be used.

[0016] 《Dial Section》 The dial part, for example, selects correction values for each wavelength. The irradiance meter of the present invention includes, although not limited thereto, a dial part capable of selecting a measurement wavelength corresponding to the wavelength of the light to be measured incident on the light receiver. By setting the dial part, the resistance value corresponding to the measurement wavelength stored in the storage part is transmitted to the digital potentiometer. The dial part may be connected to the second arithmetic processing part (the second microcomputer of the light receiver) as shown in FIG. 2, or may be connected to the first arithmetic processing part (the first microcomputer of the display) as shown in FIG. 3.

[0017] 《Storage part; Memory》 The irradiance meter of the present invention may include a storage part (memory), although not limited thereto. Specifically, the memory is preferably a flash memory. When including a storage part (memory), the sensitivity adjustment circuit preferably consists of a digital potentiometer and a resistor. The storage part (memory) stores data for realizing the electrical resistance of the digital potentiometer corresponding to the measurement wavelength. That is, the set value of the digital potentiometer is stored in the memory.

[0018] 《Second arithmetic processing part (the second microcomputer of the light receiver)》 The second microcomputer reads the dial part and controls the digital potentiometer. In the irradiance meter of the present invention, the second arithmetic processing part (the second microcomputer of the light receiver) is not an essential configuration. However, when the light receiver and the display are separated as described later, it is preferable to include a second arithmetic processing part (the second microcomputer of the light receiver) for controlling the resistance value of the digital potentiometer in the light receiver, and the second arithmetic processing part transmits data for realizing the resistance value corresponding to the measurement wavelength stored in the storage part to the digital potentiometer.

[0019] 《Amplifier》 The amplifier amplifies the output of the sensitivity adjustment circuit. It protects the ADC (analog-digital converter) so that current consumption does not affect voltage division, and is sometimes referred to as a buffer amplifier.

[0020] 《AD Conversion Circuit: Analog-to-Digital Converter (ADC)》 The AD conversion circuit converts the output of the amplifier into a digital signal and inputs it to the first arithmetic processing unit (the first microcontroller of the display). In other words, by performing analog-to-digital conversion, it enables the microcontroller (CPU) to handle the data.

[0021] Analog signal output section The analog signal output section is the part that outputs an analog signal from the amplifier.

[0022] 《First Processing Unit (First Microcontroller of the Display Unit)》 The first arithmetic processing unit (the first microcontroller of the display unit) is responsible for the overall control of the display unit. For example, as shown in Figure 2, it can control the display unit, memory, and / or the current-voltage conversion circuit. If the photodetector has a second microcontroller, it is not necessary to communicate with the second microcontroller of the photodetector. The first arithmetic processing unit may, but is not limited to, transmit data to the digital potentiometer that realizes a resistance value corresponding to the measurement wavelength stored in the memory. In this case, for example, as shown in Figure 3, the first arithmetic processing unit and the memory are connected, and the first arithmetic processing unit and the digital potentiometer are connected.

[0023] The irradiance meter of the present invention may be a separate type in which the light receiver and the display unit are separated, as shown in Figure 1(A). Alternatively, it may be an integrated type in which the light receiver and the display unit are combined, as shown in Figure 1(B).

[0024] Figure 2 shows an example of the configuration of a separate-type irradiometer. The light receiver may include, but is not limited to, a "sensor" which is a light-receiving element (photodiode), a "digital potentiometer" which is part of the sensitivity adjustment circuit, a "second microcontroller," "memory," and a "dial section." The display unit may, but is not limited to, include an "IV amplifier" which is a current-voltage conversion circuit, a "resistor" which is part of a sensitivity adjustment circuit, an "amplifier (buffer amplifier)", an "AD conversion circuit: analog-to-digital converter (ADC)" which converts analog signals to digital signals, a "first processing unit (first microcontroller; CPU)", a "display unit", "memory", and an "analog signal output unit". In other words, the irradiance meter of the present invention, although not limited thereto, may consist of a light receiver housing the light-receiving element, the digital potentiometer, and a second arithmetic processing unit, a current-voltage circuit, a resistor, an amplifier, an analog signal output unit, and a display unit housing the first arithmetic processing unit, wherein the light receiver and the display unit are connected by an electrical signal line. As shown in Figure 2, light incident on the sensor is converted into an electric current and sent to an IV amplifier (current-voltage converter), which is then converted back into a voltage. The voltage is adjusted by a sensitivity adjustment circuit to control the output of the current-voltage converter. Specifically, the output can be adjusted by the "digital potentiometer" of the light receiver and the "resistor" of the display unit. The output from the sensitivity adjustment circuit is amplified by the amplifier and output from the analog signal output unit. Furthermore, the digital potentiometer can be connected to a second microcontroller in the light receiver, and the second microcontroller may be connected to the flash memory and the dial unit. In addition, the amplifier (buffer amplifier) ​​of the display unit amplifies the output of the sensitivity adjustment circuit and sends it to the AD conversion circuit (ADC). The digitally converted signal is processed by the first arithmetic processing unit (the first microcontroller of the display unit) to control the display on the display unit, and the signal is stored in memory. The signal from the second microcontroller can also control the current-voltage conversion circuit of the display unit.

[0025] Figure 3 shows an example of the configuration of an integrated irradiance meter. An integrated irradiance meter with a photodetector and display may include, for example, a "sensor" which is a photodetector (photodiode), an "IV amplifier" which is a current-voltage conversion circuit, a "digital potentiometer" and "resistor" which are sensitivity adjustment circuits, an "amplifier (buffer amplifier)", an "AD conversion circuit: analog-to-digital converter (ADC)" which converts analog signals to digital signals, a "first arithmetic processing unit (first microcontroller; CPU)", a "dial unit", a "display unit", a "memory", and an "analog signal output unit". In this embodiment, there is no second microcontroller, and the IV amplifier and digital potentiometer can be controlled by a single first arithmetic processing unit (first microcontroller; CPU). As shown in Figure 3, light incident on the sensor is converted into an electric current and sent to an IV amplifier (current-voltage conversion circuit), which is then converted into a voltage. The voltage is adjusted by a sensitivity adjustment circuit to control the output of the current-voltage conversion circuit. Specifically, the output can be adjusted using a "digital potentiometer" and a "resistor". The output from the sensitivity adjustment circuit is amplified by an amplifier and output from the analog signal output section. Furthermore, the amplifier (buffer amplifier) ​​amplifies the output of the sensitivity adjustment circuit and sends it to the AD conversion circuit (ADC). The digitally converted signal is processed by the first arithmetic processing unit (first microcontroller) to control the display on the display unit, and the signal is stored in memory. In addition, the signal from the first microcontroller can control the current-voltage conversion circuit of the display unit. Furthermore, the first arithmetic processing unit (first microcontroller) can receive signals from the dial unit.

[0026] In the irradiance meter of the present invention, the resistance value can be set by storing multiple digital potentiometer setting values ​​in the flash memory of the microcontroller (first microcontroller or second microcontroller) and transmitting these values ​​to the digital potentiometer. This resistance value is derived from the optimal resistance value and the corresponding potentiometer setting value and stored in the microcontroller's flash memory. Furthermore, in order to support light sources of many wavelengths, for example, 10 resistance values ​​corresponding to each wavelength can be stored in the flash memory built into the photodetector's microcontroller. For example, by setting the wavelength of light emitted from a light source and selecting the measurement wavelength with the dial, a resistance value set for each wavelength is transmitted to a digital potentiometer (variable resistor). The voltage division of the analog signal voltage is then changed, altering the sensitivity to the signal voltage received by the microcontroller. This combination of digital potentiometer and resistor allows for analog-optimal sensitivity adjustment to the signal voltage. In other words, it does not depend on the sampling frequency of the AD converter and DA converter and / or the microcontroller processing speed, as in conventional systems. Therefore, it is possible to provide an analog output ultraviolet irradiometer with high response speed and no degradation of resolution. Specifically, high-speed pulsed light can be observed using an oscilloscope or similar device.

[0027] 《Action》 Conventional irradiometers use the mechanically held resistance value of a variable resistor, or store coefficients in the flash memory of a microcontroller and use them for calculations by the CPU. In the irradiometer of the present invention, for example, multiple setting values ​​for a digital potentiometer can be stored in flash memory and transmitted to the digital potentiometer to set the resistance value. Therefore, as described above, it is possible to provide an analog output ultraviolet irradiometer with a high response speed and no deterioration in resolution. [Industrial applicability]

[0028] Irradiometers can be used with a wide range of light sources of various wavelengths and can be equipped with an analog voltage output function.

Claims

1. A light-receiving element (photodiode) into which the light to be measured is incident, A current-voltage conversion circuit that converts the output current of the light-receiving element into a voltage, A sensitivity adjustment circuit that adjusts the output of the current-voltage conversion circuit, An amplifier that amplifies the output of the aforementioned sensitivity adjustment circuit, An A-D conversion circuit that converts the output of the amplifier into a digital signal and inputs it to the first arithmetic processing unit (the first microcontroller of the display unit), An analog signal output section that outputs the output of the aforementioned amplifier to the outside, A radiometer characterized by being equipped with the following features.

2. The irradiance meter according to claim 1, wherein the sensitivity adjustment circuit is a variable resistor.

3. Equipped with a memory unit, The aforementioned sensitivity adjustment circuit consists of a digital potentiometer and a resistor. The irradiance meter according to claim 1, wherein the memory unit stores data that realizes the electrical resistance of the digital potentiometer corresponding to the measurement wavelength.

4. The irradiance meter according to claim 3, wherein the first arithmetic processing unit transmits data that realizes a resistance value corresponding to the measurement wavelength stored in the memory unit to the digital potentiometer.

5. The digital potentiometer is equipped with a second processing unit (a second microcontroller for the photodetector) that controls the resistance value of the digital potentiometer. The irradiance meter according to claim 3, wherein the second processing unit transmits data that realizes a resistance value corresponding to the measurement wavelength stored in the memory unit to the digital potentiometer.

6. A light receiver housing the aforementioned light-receiving element, the aforementioned digital potentiometer, and a second processing unit, It consists of the current-voltage circuit, the resistor, the amplifier, the analog signal output unit, and a display unit that houses the first arithmetic processing unit, The irradiance meter according to claim 5, wherein the light receiver and the display are connected by an electrical signal line.

7. The light receiver is equipped with a dial that allows selection of the measurement wavelength corresponding to the wavelength of the light to be measured that is incident on it. The irradiance meter according to any one of claims 4 to 6, wherein, by setting the dial portion, a resistance value corresponding to the measurement wavelength stored in the memory portion is transmitted to the digital potentiometer.

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