JPH0973040A - Scan driving method of infrared device and scan driving device - Google Patents

Abstract

The present invention relates to a scan driving method and a scan driving apparatus for an infrared device, and economically and highly accurately drives a scanning mirror. SOLUTION: A scanning mirror 2 for scanning and inputting infrared rays to an infrared detector 8, and a drive motor 3 for scanning and driving the scanning mirror 2.
And a position sensor 4 for detecting the scanning position of the scanning mirror 2 and a servo circuit for driving the drive motor 3,
In an infrared device that scans and drives the scanning mirror 2 by a servo system, an angle sensor 5 that detects a predetermined scanning angle of the scanning mirror 2 and a scanning angular velocity of the scanning mirror 2 are obtained from a detection signal of the angle sensor 5, An angular velocity determination circuit 7 that applies a correction signal to the servo circuit 6 is provided so that the error with respect to the scanning angular velocity becomes zero.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scan driving method and a scan driving apparatus for an infrared device having a scanning mirror for scanning and inputting infrared rays to an infrared detector. The infrared detector is also known to have a two-dimensional array of sensing elements, but a single element or a one-dimensional array element is relatively popular. When an infrared detector composed of such a single or one-dimensional array of detection elements is used, infrared rays are scanned and input by a scanning mirror. When the scanning angle or the scanning angular velocity of the scanning mirror in this case changes, the displayed image is distorted.
Therefore, it is necessary to drive the scanning mirror with high stability.

[0002]

2. Description of the Related Art FIG. 4 is an explanatory view of a conventional example, showing a case of an analog servo system, 31 is a display device, and 32 is a display device.
Is a scanning mirror, 33 is a drive motor, 34 is an analog position sensor, 36 is a servo circuit, 38 is an infrared detector, 39 is an amplifier, 40 is a scan conversion circuit, and 41 is a TDI (Time D).
The main part of the elay and integration system is shown, where 42 is a multi-element infrared detector, PA is a preamplifier, and DL is a delay circuit.

A scanning mirror 32 for scanning and inputting infrared rays to an infrared detector 38 is directly connected to a rotation shaft of a drive motor 33, and a position sensor 34 for detecting the rotation position thereof is provided to servo an analog detection signal indicating the rotation position. Add to circuit 36. Since the scanning position of the scanning mirror 32 according to the passage of time is set in advance, an error amount from the position detected by the position sensor 34 is obtained and the drive signal applied to the drive motor 33 is corrected. That is, the scanning mirror 32 is scan-driven by the servo loop including the drive motor 33, the position sensor 34, and the servo circuit 36.

The drive motor 33 has a structure similar to that of a galvanometer, for example, and is rotated by a servo circuit 36, for example, in one direction at a constant scanning angular velocity, and the scanning mirror 32 in this period causes an infrared detector. The infrared light scanned and input to 38 is converted into an electric signal, amplified by the amplifier 39, scan-converted by the scan conversion circuit 40, and displayed on the display device 31. In the other direction, it returns to the original position at a high speed, and this return period becomes the blanking period of the display on the display device 31. Therefore, the scanning mirror 32 is driven according to the sawtooth waveform. The scanning angle range of the scanning mirror 32 is usually about several degrees.

The infrared detector 38 is composed of a single element or a one-dimensional array element, and in the case of a single element, a scanning mirror in the scanning direction orthogonal to the scanning direction of the scanning mirror 32 is provided. A dimensional scan is performed. In the case of a one-dimensional array element, scanning by the scanning mirror 32 is performed as shown in the figure. The detection signal from the infrared detector 38 is supplied to the amplifier 3
It is amplified by 9 and input to the scan conversion circuit 40, and is converted into a scanning system according to the display scan of the display device 31. Thereby, the captured infrared image by the scanning mirror 32 and the infrared detector 38 is displayed on the display device 31.

Further, the TDI system is a multi-element infrared detector 4
The preamplifier PA and the delay circuit DL are connected to correspond to each element of 2, and the delay circuit DL is connected in the order according to the scanning direction,
The output signal of the final stage is applied to the scan conversion circuit 40. This T
In the DI method, about the point of a certain subject,
Since the same detection signal is sequentially output from each element of the infrared detector 42 according to the scanning speed, a delay time according to the scanning speed is given to the detection signal of each element by the delay circuit DL and combined. Therefore, the S / N can be significantly improved without lowering the resolution.

The position sensor 34 described above outputs an analog detection signal corresponding to the rotational position, and various configurations are known. There is also known a digital servo system in which a position sensor such as a rotary encoder that outputs a digital signal is used and the drive motor 33 is controlled by digital processing.

[0008]

As described above, the scanning angle of the scanning mirror 32 driven by the drive motor 33 is a minute angle of about several degrees due to the limitation of the optical lens system. In addition, the imaging frame rate is the display device 3
Since the display frame rate of 1 is normally matched, when a television monitor is used as the display device 31,
The frame rate is about 60 Hz. Therefore, the scanning mirror 3
No. 2 requires high-speed scanning in a minute angle range. For that purpose, it is necessary to detect the position of the scanning mirror 32 at a high speed by the position sensor 34 and control the drive motor 33 by the servo circuit 36.

As the servo system, there are the digital servo system and the analog servo system as described above, and either one of them will be adopted, but the digital servo system has various advantages. However, a position sensor such as a rotary encoder having high resolution and high speed operation is required, and such a position sensor has a drawback that it is large and expensive.

On the other hand, the analog servo system is
The position sensor that outputs an analog detection signal has the advantages of being relatively small and inexpensive. However, the position sensor that outputs this analog detection signal has a problem that the detection sensitivity changes due to changes in the environment such as temperature and humidity and changes over time. Therefore, it is conceivable to readjust the servo circuit 16 according to the change in the detection sensitivity of the position sensor, but there is a problem that the maintenance work as the infrared device becomes complicated. Further, it is conceivable to provide a sensitivity compensating circuit for compensating for the change in the detection sensitivity, but there is a problem that the cost increases due to that.

When the scanning angle or the scanning angular velocity of the scanning mirror 32 changes, the infrared image displayed on the display device 31 is distorted in the scanning direction. For example, when the scanning angle becomes smaller than the reference value or when the scanning angular velocity becomes larger than the reference value, the display device 31 displays the image enlarged in the scanning direction. On the contrary, when the scanning angle becomes larger than the reference value or when the scanning angular velocity becomes smaller than the reference value, the image is reduced and displayed in the scanning direction. Therefore, when the scanning drive is not stable, the scanning angle or the scanning angular velocity of the scanning mirror 32 changes, which causes a problem of distortion of the displayed image.

When the TDI method is applied, the scanning mirror 32
When the scanning angular velocity changes, the detection signals of the respective elements of the infrared detector 42 are not combined for the same point of the subject due to an error with respect to the delay time of the delay circuit DL, and the detection signals of the adjacent elements are included. In some cases, there is a problem that the resolution deteriorates along with the S / N deterioration. An object of the present invention is to drive a scanning mirror economically and with high accuracy.

[0013]

A method for driving and scanning an infrared device according to the present invention will be described with reference to FIG. 1. (1) The scanning position of a scanning mirror 2 for scanning and inputting infrared rays to an infrared detector 8 In the scan driving method of the infrared device, which detects the analog position sensor 4 and drives and controls the scanning mirror 2 by the analog servo system, a predetermined scanning angle of the scanning mirror 2 is detected, and a detection signal of this scanning angle is detected. The angular velocity determination circuit 7 or the like determines the scanning angular velocity of the scanning mirror 2, and the scanning mirror 2 is drive-controlled so that the scanning angular velocity becomes the reference scanning angular velocity.

(2) Further, the scanning angle at two predetermined positions of the scanning mirror 2 is detected, the scanning angular velocity is obtained based on the time interval of the detection signal of the scanning angle at these two positions, and this scanning angular velocity is the reference scanning angular velocity. The scanning mirror 2 can be driven and controlled so that

(3) Further, a scanning mirror 2 for scanning and inputting infrared rays to the infrared detector 8, a drive motor 3 for driving the scanning mirror 2, and an analog position sensor 4 for detecting a scanning position of the scanning mirror 2. In the infrared device including the servo circuit 6 that controls the drive motor 3 based on the detection signal of the analog position sensor 4, the angle sensor 5 that detects the scanning angle of at least two positions of the scanning mirror 2 and the infrared sensor 5. An angular velocity determination circuit 7 is provided which determines the scanning angular velocity of the scanning mirror based on the time interval of the detection signal of the angle sensor 5 and applies a correction signal to the servo circuit 6 so that this scanning angular velocity becomes the reference scanning angular velocity. Reference numeral 1 is an optical system lens, 9 is an amplifier, and 10 is a scan conversion circuit.

The angle sensor 5 includes, for example, a light emitting element having a wavelength different from the infrared wavelength and a light receiving element. For example, when the scanning mirror 2 has a predetermined scanning angle, the light from the light emitting element is reflected and input to the light receiving element. As a configuration, the predetermined scanning angle can be detected. The detection signal is applied to the angular velocity determination circuit 7, the scanning angular velocity of the scanning mirror 2 is obtained from the time interval of the detection signal, this scanning angular velocity is compared with the reference scanning angular velocity, and the correction signal that makes the error zero is servo-controlled. Add to circuit 6. Thereby, the drive signal applied from the servo circuit 6 to the drive motor 3 is corrected, and the scanning angular velocity is controlled to be the reference scanning angular velocity. Therefore, analog
The sensitivity change of the position sensor 4 in the servo system can be corrected, and the scanning mirror 2 can be scanned and driven with high accuracy.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is an explanatory view of an embodiment of the present invention.
11 is a lens, 12 is a scanning mirror, 13 is a drive motor, 14 is an analog position sensor, 15A and 15B are angle sensors,
Reference numeral 16 is a servo circuit, 17 is an angular velocity determination circuit, 18 is an infrared detector, 19 is an amplifier, 20 is a scan conversion circuit, and 21 is a display device.

The scanning mirror 12, the drive motor 13, and the position sensor 14 are mechanically connected as in the conventional example. Further, the detection signal of the position sensor 14 that detects the rotational position of the scanning mirror 12 is applied to the servo circuit 16, and the drive signal of the drive motor 13 is controlled so that the error with respect to the reference scanning position of the scanning mirror 12 becomes zero. , Scan mirror 1 by drive motor 13
2 is driven like rotational vibration as shown by the solid and dotted lines.

The detection signal from the infrared detector 18 is amplified by the amplifier 19 and input to the scan conversion circuit 20. The scan conversion circuit 20, for example, samples the amplified output signal of the amplifier 19 by a predetermined sampling clock, converts it into a digital signal, temporarily stores it in a memory, and reads it from the memory according to the display scan of the display device 21. It can be scan converted. An infrared image is displayed by applying the scan-converted signal to the display device 21.

Angle sensors 15A and 15B are provided so that the scanning angles of at least two positions of the scanning mirror 12 can be detected. These angle sensors 15A and 15B are, for example,
A light emitting element that emits light of a wavelength different from infrared light and a light receiving element that detects the light are combined, light from the light emitting element is incident on the scanning mirror 12, and the scanning mirror 1 at a predetermined scanning angle.
A predetermined scanning angle can be detected as a configuration in which the light is reflected from 2 and enters the light receiving element.

Further, in this embodiment, the same reflecting surface as the infrared reflecting surface of the scanning mirror 12 is used to detect a predetermined scanning angle, but the rear surface of the scanning mirror 12 is used. It is also possible to arrange the angle sensors 15A and 15B so as to detect the scanning angle. Further, the scanning angular velocity of the scanning mirror 12 can be detected by one angle sensor, but the scanning angular velocity can be accurately and easily obtained by using at least two angle sensors 15A and 15B as in the embodiment. .

FIG. 3 is a diagram for explaining the operation of the embodiment of the present invention. The upper side shows the horizontal axis as time and the vertical axis as angle, and the scanning mirror 12 is based on the case of being driven by scanning with the characteristic of solid line S1. Then, when the sensitivity of the position sensor 14 becomes high, the analog detection signal level of the position sensor 14 becomes the same level as when the position sensor 14 reaches the predetermined angular position before the predetermined angular position. Is the dashed-dotted line S2
The scanning drive is performed with the characteristic of. On the contrary, when the sensitivity of the position sensor 14 becomes low, the analog detection signal level of the position sensor 14 becomes the same level as when the position sensor 14 reaches the predetermined angular position when it exceeds the predetermined angular position. Will be scan driven with the characteristics of the dotted line S3.

Therefore, the angle position of −θ from the center is set as the predetermined scanning angle and detected by the angle sensor 15A, and the angle position of + θ from the center is also set as the predetermined scanning angle and detected by the angle sensor 15B. To configure. That is, the scanning angles at two predetermined positions are detected.

When the scanning mirror 12 is driven to scan with the reference characteristic of the solid line S1, the angle sensor 15A obtains a detection signal as indicated by A1 and the angle sensor 15B obtains a detection signal as indicated by B1. In that case, the time interval of the detection signal of the predetermined scanning angle is T1. Further, the scanning angle at this time is set as a reference scanning angle.

When the sensitivity of the position sensor 14 is increased and the scanning mirror 12 is driven to scan with the characteristic of the alternate long and short dash line S2, the angle sensor 15A obtains a detection signal as indicated by A2, and the angle sensor 15B outputs B2. A detection signal is obtained as shown by, and the time interval between the detection signals of A2 and B2 is T
2 (> T1). In this case, since the detection signal level tends to increase, the scanning angle becomes small.

On the contrary, when the sensitivity of the position sensor 14 becomes low and the scanning mirror 12 is driven to scan with the characteristic of the dotted line S3, the angle sensor 15A obtains a detection signal as indicated by A3, and the angle sensor 15B gives a detection signal. A detection signal is obtained as indicated by B3. The time interval of the detection signals of A3 and B3 is T3 (<T1). In this case, since the detection signal level tends to be low, the scanning angle becomes large.

The angular velocity determination circuit 17 includes an angle sensor 15
The scanning angular velocity of the scanning mirror 12 can be obtained based on the time intervals T1, T2, T3 of the detection signals of A and 15B. When T1 is the reference scanning angular velocity, an error of ΔT = T2−T1> 0 occurs when the sensitivity of the position sensor 14 becomes high. Therefore, a correction signal such that ΔT → 0 is formed and added to the servo circuit 16. As a result, even if the sensitivity of the position sensor 14 is increased, the servo circuit 16 causes the scanning mirror 1 to have the same scanning angle and scanning angular velocity in the case of the reference value.
2 can be scan driven.

When the sensitivity of the position sensor 14 becomes low, an error of ΔT = T3−T1 <0 occurs. Then, Δ
The servo circuit 16 is formed by forming a correction signal such that T → 0.
Add to Therefore, the servo circuit 16 uses the position sensor 14
Even if the sensitivity becomes low, the scanning mirror 12 can be driven to scan at the same scanning angle and scanning angular velocity as in the case of the reference value.

The above-described angular velocity determination circuit 17 is provided with, for example, a timer activated by a detection signal of the angle sensor 15A or a counter for starting the counting of a clock, and the time measurement by the timer is performed by the detection signal of the angle sensor 15B or the counter is started. A time interval T1, T2, T3 is obtained by time measurement based on the count content, a reference value T is set in advance, a comparison circuit for obtaining a difference from the reference value is provided, and a correction signal corresponding to the difference is provided to the servo circuit 16 It can be configured by a relatively simple logic circuit added to. Alternatively, it can be realized by the arithmetic function of the processor.

In the above embodiment, two angle sensors 15 are used.
The case where A and 15B are provided is shown, but it is also possible to provide three or more angle sensors to more finely determine the scanning angular velocity of the scanning mirror 12. In addition, a case where a predetermined scanning angle of the scanning mirror 12 is detected by using a light having a wavelength different from the infrared wavelength of the detection sensitivity of the infrared detector 18 by using the infrared reflecting surface will be described. When the opposite side is used, light of any wavelength including infrared can be used. Further, although the angle sensors 15A and 15B show the case where the light emitting element and the light receiving element are matched with each other, it is of course possible to use the angle sensor having this structure.

[0031]

As described above, according to the present invention, it is possible to use the small and inexpensive position sensor 4 by performing the scanning drive of the scanning mirror 2 by the analog servo system, and the scanning of the scanning mirror 2 can be performed. There is an advantage that the drive device can be downsized and economical. Further, by detecting a predetermined angular position of the scanning mirror 2 by the angle sensor 5, the angular velocity determination circuit 7 obtains the angular velocity of the scanning mirror 2, and a correction signal corresponding to an error from the reference scanning angular velocity is added to the servo circuit 6, Since the sensitivity change of the position sensor 4 can be compensated and the scanning mirror 2 can always be driven accurately and stably, there is an advantage that distortion of the displayed infrared image can be suppressed. Even when the TDI method is applied, S due to the sensitivity change of the position sensor 4
It is possible to avoid deterioration of / N and resolution. Therefore, there is an advantage that a high quality infrared image can be stably displayed.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is an explanatory diagram of an example of the present invention.

FIG. 3 is an operation explanatory diagram of the embodiment of the present invention.

FIG. 4 is an explanatory diagram of a conventional example.

[Explanation of symbols]

 1 Lens 2 Scanning Mirror 3 Drive Motor 4 Position Sensor 5 Angle Sensor 6 Servo Circuit 7 Angular Velocity Judgment Circuit 8 Infrared Detector 9 Amplifier 10 Scan Conversion Circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mikiyasu Okamoto 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Kiyo Takenoi, 1015, Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited

Claims (3)

[Claims] 1. A scan driving method of an infrared device for detecting a scanning position of a scanning mirror for scanning and inputting infrared rays to an infrared detector, and drivingly controlling the scanning mirror by an analog servo system. An infrared device characterized in that a predetermined scanning angle is detected, a scanning angular velocity of the scanning mirror is obtained from a detection signal of the scanning angle, and the scanning mirror is drive-controlled so that the scanning angular velocity becomes a reference scanning angular velocity. Scan driving method. 2. A scanning angle at two predetermined positions of the scanning mirror is detected, a scanning angular velocity is obtained based on a time interval of a detection signal of the scanning angle, and the scanning angular velocity becomes a reference scanning angular velocity. The method of driving a scan of an infrared device according to claim 1, wherein the scan mirror is driven and controlled. 3. A scanning mirror for scanning and inputting infrared rays to an infrared detector, a drive motor for driving the scanning mirror, an analog position sensor for detecting a scanning position of the scanning mirror, and a detection signal of the analog position sensor. In an infrared device including a servo circuit for controlling the drive motor based on the above, an angle sensor for detecting a scanning angle of at least two positions of the scanning mirror, and the scanning mirror according to a time interval of a detection signal of the angle sensor. And an angular velocity determination circuit that applies a correction signal to the servo circuit so that the scanning angular velocity becomes the reference scanning angular velocity.