JPH06303499A - Image pickup device - Google Patents

Abstract

PURPOSE:To obtain an image pickup device which corrects electronically picture geometric distortion accompanying with rocking, and can obtain the picture of a high definition through simple gimbal structure. CONSTITUTION:A license output 6 is A/D-converted, and the output is stored in a first and a second line memories 25,26. The write-in and the read-out of the first and the second line memories 25,26 are switched alternately. The output of a first gyro 9 mounted on a gimbal 7 is integrated by an integration circuit 31, and is converted into a roll angle signal 32, and after being A/D-converted, it is inputted to a picture element address conversion ROM 34 to output address correction data corresponding to a roll angle. Since the address correction data 35 is outputted to the preset data input end of a second picture element counter 37, read-out address data 40 corrected by the portion of the deviation of the picture element corresponding to the roll angle is outputted from the second picture element counter 37, and is used for the read-out of license.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image sensor using a line sensor and an improvement for obtaining a high quality image by a simple space stabilizing means.

[0002]

2. Description of the Related Art FIG. 3 is a diagram showing an example of the configuration of a conventional image pickup apparatus, in which 1 is a mirror, 2 is an optical system, 3 is a detector,
4 is a preamplifier, 5 is a video processing circuit, 6 is a video signal,
7 is a gimbal, 8 is a gimbal drive mechanism, 9 is a first gyro, 10 is a first servo circuit, 11 is a motor, 12 is a speed reduction mechanism, 13 is a second gyro, and 14 is a second servo circuit. . In the figure, the mirror 1, the optical system 2, the detector 3, and the first gyro 9 are mounted on the gimbal 7,
The first gyro 9, the first servo circuit 10, and the gimbal drive mechanism 8 control the gimbal 7 so that it remains stationary in the inertial space. In the figure, the incident light from the target which is incident from above the mirror 1 is reflected by the mirror 1 and then is incident on the light receiving surface of the detector 3 which is a line sensor by the optical system 2 and is photoelectrically converted. The output of the detector 3 is subjected to necessary processing such as sensitivity correction in the preamplifier 4 and the image processing circuit 5 and output as a video signal 6.

FIG. 4 is a diagram for explaining coordinate axes and the like when this type of apparatus is mounted on an aircraft and a ground scene is imaged, 15 is a traveling direction, 16 is a pitch axis, 17 is a yaw axis,
18 is a roll direction, 19 is a pitch direction, 20 is a ground projection line sensor image, and 21 is an imaging area. Traveling direction 1
The roll No. 5 is usually called a roll axis, and a roll is generated around this axis during flight of the airframe. The ground projection line sensor image 20 which is a ground projection image of the detector 3 which is a line sensor is ground-scanned in the traveling direction 15 by the flight motion of the aircraft, and an image of the imaging area 21 is acquired.

FIG. 5 is a diagram for explaining the distortion situation of the image pickup area when the shake correction residuals in the roll direction 18 and the pitch direction 19 cannot be ignored during the above-mentioned image pickup. Is a pitch distortion line sensor image.
When there is substantially no shaking correction residual amount, the imaging area 21 is a rectangular shape without distortion as shown in FIG. When the fluctuation correction residual amount around the roll axis cannot be ignored, the Ero shown in the figure between adjacent lines as shown in FIG.
As a result, a roll distortion image pickup area 2 is formed as shown in FIG.
It becomes a distorted shape like 2. When the shake correction residual amount around the pitch axis cannot be ignored, the ground projection line sensor image temporally adjacent to the ground projection line sensor image 20 is pitched, that is, the traveling direction 15 as shown in FIG. Pitch distortion line sensor image 2 that jumps Epicth in the direction of
As a result, the amount of jumping occurs randomly for each line, and as a result, the captured image becomes difficult to discriminate because the ground projection line sensor images are replaced.

Therefore, in order to prevent the above-mentioned image distortion or line jump from occurring, the spatial stabilization accuracy must normally have the fluctuation correction residual amount within one pixel. By the way, generally, in the spatial stabilization by the gimbal structure as described above, the spatial stabilization accuracy is at most about 100 μ radians due to the restriction of the frequency response of the gimbal 7 and the like. In addition to the gimbal control loop, it is necessary to have a fast response visual axis precision stabilization loop. The mirror 1, the deceleration mechanism 12, the second gyro 13, and the second servo circuit 14 shown in FIG. 3 are a fast response visual axis control loop for this purpose. A second gyro 13 having a detection axis parallel to the rotation axis of the mirror 1 is provided, and disturbance about the rotation axis of the mirror 1 is reduced via a speed reduction mechanism 12 that reduces the rotation angular velocity of the mirror 1 to 1/2. By detecting and rotating the mirror 1 by the motor 11 in the opposite direction by 1/2 of the disturbance angle, the space of the visual axis is stabilized. Figure 3
In order to simplify the explanation, the visual axis control loop by the mirror is shown only about one axis, but in general, it is necessary to perform the visual axis control by the mirror as described above for each of three axes of pitch, roll and yaw.

[0006]

Since the conventional apparatus is configured as described above, in order to perform high-resolution imaging with an instantaneous viewing angle of several tens of radians or less, a mirror is used in addition to spatial stabilization by a gimbal. It is necessary to provide a plurality of high-speed visual axis control loops, which makes the device large and expensive.

According to the present invention, the exposure time of the line sensor is generally about 1 ms, and the gimbal space stabilization residual error within this minute time is several μ radians or less in angle, and an image blur due to blurring does not occur. It is intended to obtain a high-quality image with a simple gimbal structure by electronically correcting the geometric distortion of the image caused by the accumulation of gimbal space stabilization residual errors for a long time.

[0008]

An image pickup apparatus according to the present invention relates to a spatially stabilized residual error correction around a roll axis,
A roll rate sensor that detects a roll angular velocity, an A / D converter that performs A / D conversion after amplifying a line sensor output, first and second line memories that store the A / D converter output, and the first and second line memories. Means for alternately switching between writing and reading of the first and second line memories, an integrating circuit for integrating the roll rate sensor output to generate a roll angle signal, and an A / D conversion of the integrating circuit output for the roll Means for outputting address correction data according to a corner, a first pixel counter for inputting a pixel clock and counting the line sensor pixel address, and a line sensor pixel for inputting a pixel clock and setting the address correction data as preset data A second pixel counter for counting an address, and the first pixel counter output as write address data, It is provided with a means for switching the address data of the first and second line memory as a read address data to second pixel counter output.

Further, the image pickup apparatus according to the present invention relates to a spatial stabilization residual error correction around the pitch axis, a pitch rate sensor for detecting a pitch angular velocity, an A / D converter for A / D converting the line sensor output by an amplifier, An area memory for recording the output of the A / D converter; an integrating circuit for integrating the output of the pitch rate sensor to generate a pitch angle signal;
Means for A / D converting the output of the integrating circuit and outputting line address correction data according to the pitch angle; a line counter for inputting a line frame clock and counting the number of lines scanned by the line sensor; and the line counter output. An adder for adding the line address correction data and a unit for switching the line address data of the area memory using the line counter output as a read line address and the adder output as a write line address are provided.

[0010]

In the image pickup device according to the present invention, the roll direction image distortion caused by the spatial stabilization residual error around the roll axis caused by the gimbal is removed by the address control at the time of reading the line memory, so that the roll direction disturbance is large. Even in such a case, there is an effect of obtaining a high-quality image with a simple gimbal structure.

Further, in the image pickup apparatus according to the present invention, the pitch direction image distortion caused by the space stabilization residual error around the pitch axis caused by the gimbal is removed by the line address control at the time of writing in the area memory, so that the pitch direction disturbance is eliminated. Even when the size is large, a simple gimbal structure is effective in obtaining a high-quality image.

[0012]

EXAMPLES Example 1. FIG. 1 is a diagram showing a configuration of an apparatus according to the present invention, in which 24 is a first A / D converter, 25 is a first line memory, 26 is a second line memory, and 27.
Is address data, 28 is a first switch, 29 is roll correction video data, 30 is a roll rate signal, 31 is an integrating circuit, 32 is a roll angle signal, 33 is a second A / D converter, and 34 is a pixel. Address conversion ROM, 35 is address correction data, 36 is a first pixel counter, 37 is a second pixel counter, 38 is a pixel clock, 39 is write address data, and 40 is read address data. In the figure, the process in which the terrestrial scene is imaged on the image plane of the detector 3 by the optical system 2 and subjected to the amplification / image processing after photoelectric conversion and the video signal 6 is output is the same as that of the conventional device, so the explanation will be made. Is omitted. The video signal 6 is converted into a digital signal by the first A / D converter 24 and then passed through the first switch 28 to the first line memory 25 or the second line memory 26.
Entered in. The contacts of the first switch 28 are connected to the terminals by the odd search lines and the terminals of the even search lines. The figure illustrates an odd search line state, in which the image digital signal is written in the first line memory 25. At this time, the write address data 39 is used as the address data 27.
Is generated by counting the pixel clock 38 by the first pixel counter 36 from the start of pixel scanning of one line. On the other hand, the digital image of the previous scanning line is recorded in the second line memory 26, and the reading start address is corrected by the method described below to perform reading.

The space stabilizing roll residual angular velocity of the gimbal 7 is output from the first gyro 9 as a roll rate signal 30, which is integrated by the integrating circuit 31 and is shown in FIG.
The roll angle signal 32 corresponding to Eroll shown in (b) is converted, digitized by the second A / D converter 33, and then input to the address of the pixel address conversion ROM 34. Pixel number data corresponding to the Eroll is input to this address of the pixel address conversion ROM 34,
This pixel count data is used as the second address correction data 35
Is input to the preset data terminal of the pixel counter 37. The second pixel counter starts counting the pixel clock 38 using this address correction data 35 as a start address from the start of pixel scanning of one line, and is input to the second line memory 26 as read address data 40. Therefore, in the second line memory 26, the image data is read from the position where only the pixels corresponding to the deviation angle Eroll are corrected, and as a result, the roll correction in which the roll distortion shown in FIG. 5B is removed is performed. The video data 29 can be obtained.

Example 2. FIG. 2 is a diagram showing a part of the configuration according to the second embodiment of the present invention, in which 41 is an area memory,
42 is line address data, 43 is a second switch, 4
4 is a write line address, 45 is a read line address, 46 is a pitch rate signal, 47 is a pitch angle signal, 48 is a line address conversion ROM, 49 is line address correction data, 50 is an adder, 51 is a line counter, and 52 is a line counter. A line frame clock, 53 is pitch correction video data. In the figure, the process of obtaining the video signal 6 is the same as the conventional method, and therefore its explanation is omitted. After the video signal 6 is digitized by the first A / D converter 24,
It is recorded in the area memory 41 by the method described below.

The space-stabilized pitch residual angular velocity of the gimbal 7 is obtained as the pitch rate signal 46 from the first gyro 9, and the integrating circuit 31 makes the Epit of FIG. 5 (c).
It is converted into a pitch angle signal 47 corresponding to ch, and the second A
It is digitized by the / D converter 33 and input to the address of the line address conversion ROM 48. At this address of the line address conversion ROM 48,
The line width number corresponding to h is recorded, and is input to the adder 50 as the line address correction data 49. A line frame clock 52 is input to the line counter 51, the number of scanning lines associated with the flight motion is counted, and is output as a read line address 45 of the area memory 41 and also input to the adder 50. Adder 50
Outputs the write address 44 to which the line address correction data 49 is added. Therefore, the image data of the line jumped by Epit shown in FIG. 5C is corrected on the area memory 41 by the line address corresponding to the jump. Will be written to the address. By repeating this operation, even if a jump occurs in the pitch direction, the image is written in the correct line position in the area memory 41. Therefore, by reading this out using the read line address 45, the jump in the pitch direction is achieved. You can get images without. The operation of the second switch 43 is performed by selecting a contact and performing the above-described image writing while the image data is being acquired over a predetermined flight section, and then selecting the contact and reading the recorded image. Just dashi.

[0016]

As described above, according to the present invention, the image geometric distortion caused by the residual error in the space stabilization accompanying the roll motion of the airframe is added without adding the precise space stabilizing loop using the mirror as in the conventional art. Since the correction is performed electronically, it is possible to realize a high-quality image pickup device with a simple gimbal configuration even when the roll-direction spatial stabilization residual error cannot be ignored.

Further, according to the present invention, without adding a precise space stabilizing loop using a mirror as in the prior art,
Since the image geometric distortion associated with the spatial stabilization residual error due to the pitch motion of the airframe is electronically corrected, a high-quality imaging device with a simple gimbal configuration even when the spatial stabilization residual error in the pitch direction cannot be ignored. Can be realized.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an image pickup apparatus showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram of an image pickup apparatus showing Embodiment 2 of the present invention.

FIG. 3 is a diagram showing a conventional imaging device.

FIG. 4 is a diagram illustrating coordinate axes and an imaging situation.

FIG. 5 is a diagram illustrating an imaging situation when a spatial stabilization residual error cannot be ignored.

[Explanation of symbols]

 1 mirror 2 optical system 3 detector 4 preamplifier 5 image processing circuit 6 video signal 7 gimbal 8 gimbal drive mechanism 9 first gyro 10 first servo circuit 11 motor 12 speed reduction mechanism 13 second gyro 14 second servo circuit 15 traveling direction 16 pitch axis 17 yaw axis 18 roll direction 19 pitch direction 20 ground projection line sensor image 21 imaging area 22 roll distortion imaging area 23 pitch distortion line sensor image 24 first A / D converter 25 first line memory 26 Second line memory 27 Address data 28 First switch 29 Roll correction video data 30 Roll rate signal 31 Integrator circuit 32 Roll angle signal 33 Second A / D converter 34 Pixel address conversion ROM 35 Address correction data 36 First pixel counter 37 Second pixel counter Unter 38 pixel clock 39 write address data 40 read address data 41 area memory 42 line address data 43 second switch 44 write line address 45 read line address 46 pitch rate signal 47 pitch angle signal 48 line address conversion ROM 49 line address correction Data 50 Adder 51 Line counter 52 Line frame clock 53 Pitch correction video data

Claims (2)

[Claims] 1. An optical system mounted on a space stabilizing mount,
A line sensor, a roll rate sensor, an A / D converter for A / D converting the line sensor output after amplification, first and second line memories for recording the A / D converter output, Means for alternately switching between writing and reading of the first and second line memories, an integrating circuit for integrating the roll rate sensor output to generate a roll angle signal, and an A / D conversion of the integrating circuit output for the roll Means for outputting address correction data according to a corner, a first pixel counter for inputting a pixel clock and counting the line sensor pixel address, and a line sensor pixel for inputting a pixel clock and setting the address correction data as preset data A second pixel counter that counts an address, and the second pixel counter output as write address data, and the second pixel counter Imaging apparatus characterized by comprising a means for switching the address data of the first and second line memory as a read address data pixel counter output. 2. An optical system mounted on a space stabilizing mount,
A line sensor, a pitch rate sensor, an A / D converter for A / D converting the line sensor output after amplification, an area memory for recording the A / D converter output, and integrating the pitch rate sensor output. An integrator circuit for generating a pitch angle signal, a means for A / D converting the output of the integrator circuit to output line address correction data according to the pitch angle, and a line frame clock as an input to count the number of lines scanned by the line sensor. A line counter, an adder for adding the line counter output and the line address correction data, and a means for switching the line address data of the area memory using the line counter output as a read line address and the adder output as a write line address. An imaging device comprising: