JPH0459561B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] This invention forms an optical image of a target having a bright/dark boundary as an electronic image on the aperture surface of an image dissector tube by photoelectric conversion, and converts this electronic image into an aperture surface. This invention relates to a light test mechanism that sets the sensitivity of a non-contact photoelectric displacement meter that measures the displacement of an object to be measured based on a deflection coil current that is passed through a deflection coil that deflects an electron beam to form a fixed position on a surface.

[Conventional technology]

This type of photoelectric displacement meter is well known, which receives light emitted from a target having a bright and dark boundary and measures the displacement of an object to be measured.

In such a photoelectric displacement meter, before performing displacement measurement, it is necessary to aim the target object, set the magnification using the camera lens system, etc., and also initially set the light receiving sensitivity of the bright and dark parts of the target. This initial setting of brightness and darkness is called a light test, and conventionally it was performed using the following procedure.

That is, first, the camera lens of the photoelectric displacement meter is covered with a non-light-transmitting object to create a dark light-receiving state. In this state, the output signal level of the first-stage amplifier (current-voltage conversion amplifier that converts the output current from the electron multiplier tube of the image dissector tube into voltage) following the image dissector tube is adjusted to a predetermined value (lower limit value). .
Next, the camera of the displacement meter is moved or the dark part of the target is removed to bring it into a bright light-receiving state. In this state, the high voltage applied to the electron multiplier of the image dissector tube is adjusted so that the output signal of the first stage amplifier becomes a predetermined value (the upper limit value is larger than the lower limit value). Then, if necessary, repeat both of the above operations. Since such a light test operation also affects measurement accuracy, it is necessary to perform it before measurement.

In the actual light test mode, it is known that the level adjustment of the output signal in a dark light receiving state does not change much after the adjustment is made at the time of manufacturing or maintenance. Therefore, it is extremely important to adjust the bright light reception state.

In conventional light tests, a target with a bright and dark boundary is attached to the surface of the object to be measured, so the target cannot be moved arbitrarily, and the camera unit is usually moved. It was necessary to make initial settings in a bright light receiving state. However, the non-contact photoelectric displacement meter requires changing the adjustment of the camera lens system, and this change is not desirable for collecting data in terms of reliability and reproducibility. Furthermore, such manual light tests have to be performed frequently and are subject to individual differences, making quick and accurate measurements difficult.

[Problem of invention]

Therefore, an object of the present invention is to provide a light test mechanism for a light receiving system of a non-contact photoelectric displacement meter that can perform light tests automatically, quickly and accurately, and that eliminates the intervention of individual differences. Our goal is to provide the following.

[Means for Solving the Problem] The above problem is solved by the present invention, in which an optical image of a target having a bright-dark boundary is formed as an electronic image on the aperture surface of an image dissector tube by photoelectric conversion, and this electronic image is formed on the aperture surface of the image dissector tube. In the case of a light test mechanism that sets the sensitivity of a non-contact photoelectric displacement meter that measures the displacement of an object to be measured based on the deflection coil current that flows through the deflection coil that deflects the electron beam in order to form it at a fixed position, the deflection coil 4 a coil drive circuit 5 connected to the
A high-voltage circuit 10 that applies a high-voltage DC voltage to the electron multiplier section of the image dissector tube 2, and an aperture drive that connects to an aperture device 13 that can electrically control the aperture degree and is installed in front of the light receiving section of the image dissector tube 2. circuit 1
5 and the illumination power source 12 for the illumination lamp 16 illuminating the target 1, one digital-to-analog converter 6, 9, 11, 14 for converting the digital control signal from the computer into an analog control signal, respectively.
is connected, and the output end of the image dissector tube 2 is sequentially connected to the computer CPU via the first-stage amplifier 7 and the analog-to-digital converter 8, and in the write test mode, the target is A predetermined deflection current is applied to the deflection coil 4 so that the electron image corresponding to only the bright portion of the image 1 passes through the aperture of the aperture surface 2a, and under this light receiving condition, the electron image is transmitted from the image dissector tube 2 and the subsequent first stage amplifier 7. Based on the input value of the analog-digital converter 8, the computer CPU sets the output signal level of the light receiving detection system consisting of the digital-analog converter 9,
The solution is to send a control output signal to one or more of the transducers 11, 14.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings showing embodiments of the invention.

The accompanying drawings show the main parts of the non-contact photoelectric displacement meter and a block diagram of the light test mechanism according to the present invention. Light emitted from a target 1 having a bright-dark boundary enters an image dissector tube 2, is converted into photoelectrons by a photoelectric conversion surface, and is then multiplied by an electron multiplier section of the image dissector tube 2. As is well known, in this displacement meter, an optical image of the target is formed on a photoelectric conversion surface by a camera lens system (not shown), and photoelectrons generated from this photoelectric conversion surface are transferred to a cylindrical electrode section (also called a drift tube). ) to form an electron image on the aperture surface 2a. In that case, even if the target 1 is displaced as shown by the arrow 3, the required feedback current is passed through the deflection coil 4 disposed in the cylindrical electrode section between the photoelectric conversion surface and the aperture surface 2a, and the target 1 is The bright/dark boundary position of the electronic image is maintained constant at all times, and the displacement of the target 1 is read in accordance with the coil feedback current value.

The structure and operation of the write test mechanism according to the present invention are as follows.

In order to take in only the bright part of the target 1 onto the aperture surface 2a, it is necessary to apply a required coil current to the deflection coil 4. Therefore, a control signal corresponding to the required current value is introduced from the central processing unit CPU to the coil drive circuit 5 via the digital-to-analog converter 6. As this coil current gradually changes, the bright/dark boundary of the target gradually moves, eventually realizing a bright light receiving state. The output current of the electron multiplier of the image dissector tube 2 in this state is introduced to the central processing unit CPU as an output signal via the first stage amplifier 7 and the analog/digital converter 8.

The central processing unit CPU determines the maximum output current value in this case and holds the signal value corresponding to the maximum current. Furthermore, the central processing unit CPU converts the digital-to-analog converter 9 so that a predetermined output upper limit value of the first stage amplifier 7 corresponding to the reference light amount can be obtained.
The high voltage power supply 10 applied to the multi-stage electrodes of the electron multiplier is controlled via the high voltage power supply 10.

Simultaneously or independently, the illumination power supply 12 for the light source that illuminates the target 1 is controlled via another digital-to-analog converter 11, and a predetermined upper limit value of the output of the first stage amplifier 7 corresponding to the reference light amount is set. You can adjust as you like.

In addition, an aperture device 13 that can electrically control the aperture is arranged in front of the image desector 2, and the aperture is adjusted from the central processing unit CPU via the digital-to-analog converter 14 and the control circuit 15. By controlling the amount of light incident on 2, it is possible to obtain a predetermined upper limit value of the output of the first stage amplifier 7 corresponding to the reference amount of light.

When the central processing unit CPU is switched to the light test mode in such a configuration, the incident light is initially blocked to set a dark light reception state, and the output signal level of the first stage amplifier 7 is set. Next, the setting moves to a bright light reception state, and the central processing unit CPU sends the digital-to-analog converter so that all the light corresponding to electrons passing through the hole in the aperture surface 2a that moves the image of the target is in the bright part. A coil drive signal is output to the coil drive circuit 5 via 6. The maximum output current in the bright light reception state is held by the central processing unit CPU, and then
The applied voltage of the high voltage power supply 10, the illuminance of the illumination light source 16, and the The central processing unit adjusts the aperture of the aperture device 13.
This is done by the CPU. As a result, a predetermined output upper limit value of the first stage amplifier 7 corresponding to the reference light amount in a bright light receiving state is obtained, the light test of the light receiving system is completed, and it is possible to switch to the measurement mode.

In addition, the applied voltage of the high voltage power supply 10, the illumination light source 1
The illuminance of 6 and the aperture of the aperture device 13 are controlled by:
It is not necessarily necessary to carry out the entire operation at the same time; in particular, the illuminance of the illumination light source 16 and the aperture of the aperture device 13 can be controlled alternatively. Naturally, by combining all the components and controlling them comprehensively, it is possible to quickly and accurately set the bright light reception state.

Although the invention has been disclosed with reference to the accompanying drawings, which illustrate embodiments, it will be obvious that many modifications and improvements may be made within the scope of the invention. However, it goes without saying that any light test mechanism for a non-contact photoelectric displacement meter having the configuration described in the claims falls within the scope of the present invention.

〔Effect of the invention〕

The non-contact photoelectric displacement meter equipped with a light test mechanism according to the present invention makes it extremely easy to prepare for displacement measurements. High displacement measurement data can be obtained.

[Brief explanation of the drawing]

The accompanying drawing is a block diagram showing the main parts of a non-contact photoelectric displacement meter equipped with a light test mechanism according to the present invention. Reference numbers in the figure: 1...Target, 2...Electron multiplier, 4...Deflection coil, 10...High voltage circuit,
13...Aperture, 16...Light source, CPU...Central processing unit.

Claims (1)

[Claims] 1. An optical image of a target having a bright/dark boundary is formed as an electron image on the aperture surface of an image dissector tube by photoelectric conversion, and in order to form this electron image at a fixed position on the aperture surface, an electron beam is used. In a light test mechanism that sets the sensitivity of a non-contact photoelectric displacement meter that measures the displacement of an object to be measured based on a deflection coil current flowing through a deflection coil that deflects the object, the coil drive circuit 5 is connected to a deflection coil 4;
A high-voltage circuit 10 that applies a high-voltage DC voltage to the electron multiplier section of the image dissector tube 2, and an aperture drive that connects to an aperture device 13 that can electrically control the aperture degree and is installed in front of the light receiving section of the image dissector tube 2. circuit 1
5 and the illumination power source 12 for the illumination lamp 16 illuminating the target 1, one digital-to-analog converter 6, 9, 11, 14 for converting the digital control signal from the computer into an analog control signal, respectively.
is connected, and the output end of the image dissector tube 2 is sequentially connected to the computer CPU via the first-stage amplifier 7 and the analog-to-digital converter 8, and in the write test mode, the target is A predetermined deflection current is applied to the deflection coil 4 so that the electron image corresponding to only the bright portion of the image 1 passes through the aperture of the aperture surface 2a, and under this light receiving condition, the electron image is transmitted from the image dissector tube 2 and the subsequent first stage amplifier 7. Based on the input value of the analog/digital converter 8, the computer CPU selects one of the digital/analog converters 9, 11, and 14 so as to set the output signal level of the light receiving detection system to a predetermined value. A light test mechanism characterized by sending a control output signal to one or more transducers.