JPH0548839A - Luminous intensity controller - Google Patents

Abstract

PURPOSE:To provide a luminous intensity controller capable of automatic fine adjustment of the luminous intensity without the change of the supply voltage to a light source. CONSTITUTION:This controller is provided with a pair of polarizing plates 14a, 14b which are arranged at about right angles to the incidence direction of light 16 and in parallel, a turning mechanism 24 which changes the relative angle of the pair of polarizing plates 14 and 14b, a motor 26 which drives the turning mechanism 24, a driver circuit 30 which controls the operation of the motor 26, sensor parts 32, 34 which output voltage corresponding to luminous intensities of light 22 passing the pair of polarizing plates 14a, 14b, and a comparing circuit 36 which compares the output voltages of sensor parts 32 and 34 with a preliminarily determined reference voltage and outputs the control signal of the driver circuit 30 in accordance with the difference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light intensity adjusting device, and more specifically, it provides a pair of polarizing plates and adjusts the light intensity of light passing through the polarizing plates by changing the relative angle between them. The present invention relates to a light adjusting device.

[0002]

2. Description of the Related Art For example, in an image processing apparatus, it is necessary to irradiate a specimen with light having a constant luminous intensity. When the light intensity changes, the output voltage of the CCD that outputs the image data of the sample changes, and stable data cannot be obtained. Therefore, there is a need for a device that maintains the light intensity of the irradiation light constant. Conventionally, in a light source such as a halogen lamp, a method has been generally used in which the light intensity of the irradiation light is detected by a sensor and the supply voltage to the light source is controlled to maintain the light intensity of the irradiation light constant.

[0003]

However, the conventional light intensity adjusting device has the following problems. The method of controlling the voltage supplied to the light source has a problem of shortening the life of the lamp in order to accelerate the deterioration of the lamp.
Particularly, since the halogen lamp has a relatively short life, there is a problem that the life is further shortened due to the fluctuation of the supply voltage. Recently, instead of halogen lamps, which have a relatively short lamp life, high-luminance, long-life xenon lamps have also been used, but since xenon lamps are discharge tubes, it is necessary to change the luminous intensity by controlling the supply voltage. Therefore, it is difficult to maintain a constant luminosity. Therefore, it has been proposed to provide a light amount absorption filter between the light source and the sample or to provide an automatic diaphragm device, but in the case of a filter, variable adjustment is impossible, and in the case of a diaphragm, the planar distribution of light is uneven. Is generated and is not practical. Therefore, it is an object of the present invention to provide a light intensity adjusting device capable of automatically variably adjusting the light intensity without changing the supply voltage to the light source.

[0004]

In order to solve the above problems, the present invention has the following constitution. That is, a pair of polarizing plates arranged substantially at right angles to the incident direction of light and parallel to each other, a rotation mechanism capable of changing the relative angle between the pair of polarizing plates, and the rotation mechanism. A motor for driving the mechanism, and a driver circuit for controlling the operation of the motor,
A sensor unit that outputs a voltage corresponding to the luminous intensity of the passing light that has passed through the pair of polarizing plates is compared with an output voltage of the sensor unit and a predetermined reference voltage. And a comparison circuit for outputting a control signal of the driver circuit. Further, in particular, a reference voltage adjusting circuit that can arbitrarily adjust the reference voltage may be provided.

[0005]

[Operation] The operation will be described. The sensor unit outputs a voltage corresponding to the luminous intensity of the passing light, and the comparison circuit compares the output voltage of the sensor unit with a predetermined reference voltage,
A control signal of a driver circuit for controlling the operation of the motor is output corresponding to the difference. With this control signal, the motor changes the relative angle of the polarizing plate through the rotation mechanism,
It is possible to automatically keep the intensity of the passing light constant.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings (FIG. 1). In this embodiment, a light intensity adjusting device used to adjust the light intensity of the light source of the image processing device will be described as an example. First, the configuration will be described. A light source 10 is, for example, a xenon lamp to which a constant power supply voltage is supplied. Reference numeral 12 is a cylinder, which is formed in a tubular shape with both ends open. The cylinder 12 is installed between the light source 10 and the sample (not shown). 14
Reference numerals a and 14b denote polarizing plates, which are arranged in the cylinder 12. The polarizing plates 14a and 14b are arranged parallel to each other in a direction substantially perpendicular to the incident light 16 from the light source 10. The polarizing plates 14a and 14b are formed in a disk shape having the same diameter. The polarizing plate 14a is non-rotatably fixed to the light source 10 side in the cylinder 12. On the other hand, the polarizing plate 14
In the large diameter portion 18 in the cylinder 12, b is rotatable about the axis of the cylinder 12. Polarizing plate 14
b is four support rollers 20 provided in the large diameter portion 18.
The rotation center is supported by (only two are shown) so as not to be biased. The support rollers 20 are arranged on the inner circumference of the large diameter portion 18 at equal intervals in the circumferential direction. When the polarizing plate 14b rotates, the relative angle between the polarizing plates 14a and 14b changes. Due to the change in the relative angle, the polarizing plates 14a, 1
The luminous intensity of the passing light 22 of 4b can be uniformly changed in a plane.

Reference numeral 24 denotes a rotating roller, which is an example of a rotating mechanism, and its outer peripheral surface is in contact with the outer peripheral surface of the polarizing plate 14b. When the rotating roller 24 rotates, the friction force between the outer peripheral surface of the rotating roller 24 and the outer peripheral surface of the polarizing plate 14b causes the polarizing plate 1 to rotate.
4b is adapted to rotate. A high friction material may be attached to the outer peripheral surface of the rotating roller 24 and / or the outer peripheral surface of the polarizing plate 14b. Reference numeral 26 is a DC servo motor which is an example of a motor. The motor 26 can rotate in the forward and reverse directions, and the rotation speed is reduced to a speed suitable for adjusting the light intensity. Motor 2
A drive roller 28 is fixed to the tip of the output shaft 6 and is rotatable together with the output shaft. The outer peripheral surface of the drive roller 28 is in contact with the outer peripheral surface of the rotating roller 24. When the driving roller 28 rotates, the rotating roller 24 and thus the polarizing plate 14b are rotated by the frictional force between the outer peripheral surface of the driving roller 28 and the outer peripheral surface of the rotating roller 24. A high friction material may be attached to the outer periphery of the drive roller 28. Thirty
Is a driver circuit that controls the operation of the motor. The voltage supplied from the driver circuit 30 determines the start, stop, rotation direction, etc. of the motor 26. An optical sensor 32 is provided on the sample side of the cylinder 12. When the light sensor 32 receives the passing light 22 that has passed through the cylinder 12, it outputs a voltage according to the luminous intensity of the passing light 22.

Reference numeral 34 is an amplifier circuit, which amplifies the output voltage of the optical sensor 32 by a predetermined multiplication factor so as to reach a level required for the subsequent processing. The amplifier circuit 34 and the optical sensor 32 form a sensor section. Reference numeral 36 is a differential amplifier circuit which is a comparison circuit, and compares the output voltage of the amplifier circuit 34 with a reference voltage which is a preset output voltage of the reference voltage generation circuit 38. The differential amplifier circuit 36 outputs a signal corresponding to the voltage difference, which is the result of the comparison, as a control signal for the driver circuit 30. That is, the optical sensor 32 to the differential amplifier circuit 36 constitute a feedback circuit for generating a control signal for controlling the rotation of the motor 26. The reference voltage generating circuit 38 is, for example, by a slidac method, and the operator arbitrarily and finely sets the reference voltage.
It is adjustable. Next, the operation of the above-described light intensity adjusting device will be described. First, the operator sets the output voltage of the reference voltage generation circuit 38 using a voltage equal to the output voltage of the amplifier circuit 34 corresponding to the ideal luminous intensity of the passing light 22 as a reference voltage. In this embodiment, the voltage supplied to the light source 10 is set to a voltage lower than the rated voltage. This is used at a voltage lower than the rated voltage in order to extend the life of the xenon lamp which is the light source 10.

When the light source 10 is turned on, the incident light 16 enters the cylinder 12, passes through the polarizing plates 14a and 14b, and is received by the optical sensor 32 as the passing light 22. The optical sensor 32 outputs an output voltage according to the luminous intensity of the received passing light 22,
The voltage is amplified by the amplifier circuit 34. Amplifier circuit 3
The output voltage of 4 is compared with the reference voltage in the differential amplifier circuit 36, and the differential amplifier circuit 36 outputs the control signal according to the voltage difference which is the comparison result. If the output voltage of the amplifier circuit 34 is lower than the reference voltage, it is determined that the luminous intensity is insufficient, and the motor 26 is rotated in a predetermined direction so as to change the relative angle between the polarizing plates 14a and 14b in the direction in which the luminous intensity of the passing light 22 increases. The signal is sent to the driver circuit 30. On the other hand, if the output voltage of the amplifier circuit 34 is higher than the reference voltage, it means that the luminous intensity is excessive, and the light passing through the relative angle of the polarizing plates 14a and 14b is 2.
The motor 26 is controlled so that the light intensity of 2 decreases.
Is sent to the driver circuit 30 for a control signal for rotating in a direction opposite to that in the previous case. If the output voltage of the amplifier circuit 34 is equal to the reference voltage, it is determined that the light intensity is appropriate and the polarization plates 14a, 14
Since it is not necessary to change the relative angle of b, the control signal is not sent to the driver circuit 30. By repeating the above operation, the luminous intensity of the passing light 22 can be adjusted without changing the voltage of the light source 10. Although various preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention. ..

[0010]

When the light intensity adjusting device according to the present invention is used,
The sensor unit outputs a voltage corresponding to the luminous intensity of the passing light, the comparison circuit compares the output voltage of the sensor unit with a predetermined reference voltage, and controls the operation of the motor according to the difference. The control signal of the driver circuit is output.
The control signal causes the motor to change the relative angle of the polarizing plate via the rotating mechanism, and the luminous intensity of the passing light can be automatically maintained constant, so that the voltage of the light source does not change. Therefore,
It is possible to suppress deterioration of the light source while maintaining the luminous intensity. Further, since the feedback type adjustment is performed, the luminous intensity of the passing light can be finely adjusted. Further, according to the configuration of claim 2, since the luminous intensity of the passing light can be set to an arbitrary luminous intensity, it is possible to provide a highly versatile luminous intensity adjusting device and the like.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a light intensity adjusting device according to the present invention.

[Explanation of symbols]

 14a, 14b Polarizing plate 16 Incident light 22 Passing light 24 Rotating roller 26 DC servo motor 30 Driver circuit 32 Optical sensor 34 Amplifying circuit 36 Differential amplifying circuit 38 Reference voltage generating circuit

Claims (2)

[Claims] 1. A pair of polarizing plates arranged substantially at right angles to the incident direction of light and parallel to each other, and a rotating mechanism capable of changing the relative angle between the pair of polarizing plates. A motor for driving the rotating mechanism, a driver circuit for controlling the operation of the motor, a sensor unit for outputting a voltage corresponding to the luminous intensity of the light passing through the pair of polarizing plates, A light intensity adjusting device comprising: a comparison circuit that compares an output voltage of the sensor unit with a predetermined reference voltage and outputs a control signal of the driver circuit according to the difference. 2. The light intensity adjusting device according to claim 1, further comprising a reference voltage adjusting circuit capable of adjusting the reference voltage arbitrarily.