JPH1151765A - Photodetector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a photodetector which does not damage a photodiode even when light at a rated value or higher is input erroneously. SOLUTION: An optical shutter 1 which can shut off light to be input to a photodiode 2 is installed. When light at a rated value or higher is input to the photodiode 2, a computing device 6 turns off the optical shutter 1 by using an optical-shutter control signal 101, and light is not input to the photodiode 2. In addition, the optical shutter 1 forcibly shuts off light in a state that a power supply is turned off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photodetector for measuring the intensity of light received using a photodiode.

[0002]

2. Description of the Related Art FIG. 3 shows a block diagram of a conventional photodetector.

A conventional photodetector is a photodiode 2
, The photodetector circuit 3, the A / D converter 4, and the arithmetic unit 16
And a display unit 5.

[0004] The photodiode 2 converts the intensity of the received light into a signal and outputs the signal.

[0005] The photodetector circuit 3 amplifies the output signal of the photodiode 2 at a constant amplification factor and outputs it.

[0006] The A / D converter 4 A / D converts the output signal of the photodetector circuit 3 and outputs it as measurement data.

[0007] The arithmetic unit 16 causes the display unit 5 to display the measurement data from the A / D converter 4. The display unit 5 displays data measured according to an instruction from the arithmetic unit 16.

Next, the operation of the conventional photodetector will be described with reference to FIG.

The light received by the photodiode 2 is converted into a signal, amplified by a photodetector circuit 3, and then converted to a signal.
A / D conversion is performed by the D converter 4 and displayed on the display unit 5 by the arithmetic unit 16.

In this conventional photodetector, the photodiode 2 is damaged if light exceeding the rated value is erroneously input for a certain period of time.

[0011]

The above-mentioned conventional photodetector has a problem that the photodiode is damaged when light exceeding the rated value is inputted for a certain period of time.

An object of the present invention is to provide a photodetector in which a photodiode is not damaged even when light exceeding a rated value is erroneously input.

[0013]

To achieve the above object, a photodetector according to the present invention is a photodetector for measuring the intensity of light received by using a photodiode. And a light shutter for blocking light input to the photodiode in response to an instruction from the detecting means.

According to the present invention, an optical shutter capable of blocking light input to a photodiode is provided, and when light exceeding a rated value is input to the photodiode, the optical shutter is turned off by a detection means and the photodiode is turned off. Light is not input.

Therefore, the photodiode can be protected from damage even when light exceeding the rated value is input.

According to an embodiment of the present invention, the optical shutter shuts off light input to the photodiode when the power is off.

According to the present invention, even when the power is turned off,
The optical shutter forcibly blocks light input to the photodiode and prevents light having an intensity higher than a rated value from being input to the photodiode.

Therefore, the photodiode can be protected from damage even when the detecting means is not operating while the power is off.

[0019]

Next, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a photodetector according to one embodiment of the present invention, and FIG. 2 is an optical shutter 1 shown in FIG.
FIG. 3 is a diagram showing a specific structure of the embodiment. The same numbers as those in FIG. 3 indicate the same components.

The photodetector according to the present embodiment is different from the conventional photodetector shown in FIG. 3 in that an optical shutter 1 for interrupting light input to a photodiode 2 when an optical shutter control signal 101 is input is provided. The device 16 is replaced by the arithmetic device 6.

When the measurement signal output from the A / D converter 4 is equal to or larger than a predetermined value, in addition to the function of the arithmetic unit 16, the arithmetic unit 6 provides an optical shutter control signal 101
To turn off the optical shutter 1 to block light input to the photodiode 2.

Next, a specific structure of the optical shutter 1 will be described with reference to FIG.

The optical shutter 1 is supplied with power when the optical shutter control signal 101 is output, and applies a force in a direction in which the power is supplied to draw the iron core 13 and an end connected to the iron core 13 to pull out the iron core 13 from the solenoid 12. It comprises a spring 10, one end of which is connected to an iron core 13, a fulcrum 11 provided near the center, and a blocking member 14 for blocking the optical path of light input to the photodiode 2.

The optical shutter 1 has a solenoid 12
When power is not supplied to the solenoid, the iron core 13 is pulled out of the solenoid 12 by the force of the spring 10 as shown in FIG. 2A, and the blocking member 14 blocks the optical path.
Then, when power is supplied to the solenoid 12, the optical shutter 1 does not interrupt the optical path because the iron core 13 is drawn into the solenoid 12 and the blocking member 14 rotates about the fulcrum, as shown in FIG. 2B. State.

Next, the operation of this embodiment will be described with reference to FIGS.

When light of a rated value or more is input to the photodiode 2, the arithmetic unit 6 turns off the optical shutter 1 based on the measurement data input through the light detection circuit 3 and the A / D converter 4. The optical shutter control signal 101 is output. Therefore, the optical shutter 1 is turned off, and the light input to the photodiode 2 is cut off.

Then, the arithmetic unit 6 keeps this state until the measured data from the A / D converter 4 becomes equal to or less than a specified value, a certain time elapses, or is reset from the outside.

In this state, if the power of the photodetector is turned off, the optical shutter control signal 101 is not output, and the optical shutter 1 is automatically turned off as shown in FIG. The light input to the photodiode 2 is blocked. Thus, the photodiode 2 can be protected from damage even when the arithmetic unit 6 is not operating while the power is off.

Although the present embodiment has been described using an optical power meter that measures and displays the intensity of light, the present invention is not limited to this, and other photodetectors that detect or measure light include: For example, the present invention can be applied to an optical spectrum analyzer and the like.

[0031]

As described above, the present invention has an effect that the photodiode is not damaged even when light exceeding the rated value is input to the photodiode.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a photodetector according to an embodiment of the present invention.

FIG. 2 is a diagram showing a specific structure of the optical shutter 1 of FIG.

FIG. 3 is a block diagram showing a configuration of a conventional photodetector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical shutter 2 Photodiode 3 Photodetector circuit 4 A / D converter 5 Display unit 6 Computing device 10 Spring 11 Support 12 Solenoid 13 Iron core 14 Blocking member 16 Computing device 101 Optical shutter control signal

Claims (2)

[Claims] 1. A photodetector for measuring the intensity of light received by using a photodiode, wherein the detecting means detects that the intensity of light received by the photodiode is equal to or higher than the rated value of the photodiode. And a light shutter for blocking light input to the photodiode in accordance with an instruction of the detection means. 2. The photodetector according to claim 1, wherein said optical shutter blocks light input to said photodiode when power is turned off.