JPH0279685A - Image pickup device - Google Patents

Abstract

PURPOSE:To dispense with high accuracy in the mounting of a solidstate image pickup element by correcting deviation in an image due to the mounting error of the image pickup element by applying constant computation on an output signal, CONSTITUTION:The light receiving area of the solid-state image pickup element to be used is widened, and the number of image elements are increased according to the above widening. Also, after the solid-state image pickup element 10 is fixed on an optical system 2, the position relation of the light receiving areas in the solid-state image pickup element and the optical axis of an optical lens 1 is measured in advance, and the information is recorded on a mounting error quantity recording arithmetic circuit 11. When the image is outputted, computation is applied on a video signal obtained from each image element of the solid-state image pickup element by a video signal arithmetic circuit 14 based on the quantity of deviation of an image element point found at an image element point travel quantity arithmetic circuit 12 from the information with respect to the mounting error recorded already, and the video level of each image element point in an effective image element area required for the output of the image is interpolated by anticipation, and a signal after interpolation is outputted. In such a way, it is not required to request high mounting accuracy for the solid-state image pickup element.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a correction circuit for image sensor mounting errors in a color solid-state imaging camera using a solid-state imaging cable, and a solid-state image sensor that enables correction of mounting errors. Regarding structure.

[Conventional technology]

Currently, three-tube television cameras are widely used in broadcasting stations and the like. However, with the rapid development of solid-state imaging devices in recent years, multi-disc television cameras that use solid-state imaging devices instead of image pickup tubes are also becoming popular.

FIG. 3 schematically shows a block diagram of a three-tube camera as an example. The incident light is divided into three color images by a lens 1 and a prism 2, and each image is converted into an electric signal by an image pickup tube 3.

Thereafter, this electric signal (video signal) is passed through a signal processing circuit 4 to obtain a television signal.

By the way, if the center of the color images separated by the prism in Figure 3 and the center of the light-receiving surface of the image pickup tube are different for each tube,
Because the position of the image included in the TV signal is different for each color, 2
This results in superimposed images, causing color blurring and a drop in resolution, which deteriorates image quality. This problem also occurs in multi-disc cameras. Therefore, in both the multi-tube type and the multi-plate type, it is necessary to accurately superimpose the images of each tube or each element.

In the case of an image pickup tube, the position of the light receiving area can be corrected to some extent by adjusting the deflection signal of the electron beam. In the conventional multi-tube type camera, this property of the image pickup tube is used to register the light-receiving areas of the three tubes by adjusting the amount of current of the deflection signal generator 6 shown in FIG. Figure 3 circuit 7
is a circuit that takes advantage of this property of the image pickup tube and eliminates image shift due to chromatic aberration of the lens. (For example, see TV Society Journal Vo 1.36.NG, 10 ('82) P40).

[Problem to be solved by the invention]

In this way, in a camera using an image pickup tube, the position of the light receiving area can be corrected to some extent by adjusting the deflection signal of the electron beam, so there is a margin for accuracy in mounting the image pickup tube.

However, in a solid-state imaging device, the position of the sub-cable is fixed on the light-receiving surface, and positional deviation cannot be corrected as freely as in the case of an image pickup tube.Therefore, in a multi-disc camera, it is difficult to align and fix each image sensor. High precision is required.

Furthermore, currently, studies are underway to improve the definition of the conventional NTSC television system. The pixel pitch of solid-state image sensing devices used in such systems has become even smaller than in the past, and as a result, the accuracy of mounting the devices has become even more demanding. This not only makes adjustment difficult, but also causes problems such as the adjustment device becoming expensive or the manufacturing cost increasing.

The present invention provides a screen positioning means that does not require high mounting accuracy even in cameras using solid-state image sensors.

[Means to solve the problem]

In order to achieve the above object, the present invention uses a solid-state image sensor so that even if the mounting position of the solid-state image sensor is shifted from the optical axis of the optical lens, the video signal of the pixel necessary for image output is obtained from near the optical axis. The solid-state imaging element has a wide light-receiving area, and the number of pixels is increased accordingly.

Further, after fixing the solid-state image sensor to the optical system, a total of 819 positional relationships between the light-receiving areas of the solid-state image sensor and the optical axis of the optical lens are determined in advance, and this information is stored in the camera.

When outputting an image, calculations are performed on the video signal obtained from each pixel of the solid-state image sensor based on the amount of deviation of pixel points obtained from information about mounting errors that has already been memorized, and the effective pixel area required for outputting the image is calculated. The image level of each pixel point in the image is predicted and interpolated, and the interpolated No. 48 is output.

[Effect]

According to the present invention, even if the mounting position bgL of the solid-state image sensor is shifted, the video signal of the necessary area can always be obtained from the solid-state image sensor, and the video signal without positional shift required for image output can be obtained from the solid-state image sensor. Since it is determined by interpolation from the output signal of the cable, there is no need to require very high mounting accuracy for the solid-state image sensor.

〔Example〕

A first embodiment of the invention is shown in FIG. In the conventional circuit shown in FIG. 3, a small amount of fil is added to the deflection signal to directly move the position of the light receiving area on the image pickup tube surface. On the other hand, the circuit shown in Figure 1 predicts and interpolates the video signal required for image output based on the information on the solid-state image sensor mounting error stored in advance and the video signal obtained from each pixel of the solid-state image sensor. It differs from conventional circuits in that it is made to do so.

In Fig. 1, the image divided by prism 2 is
Each solid-state image sensor 10 converts it into an electrical signal.

The number of pixels of the solid-state imaging element used at this time is usually only about 2 to 5 pixels in the upper, lower, left, and right directions, which is necessary to eliminate the influence of the peripheral areas of effective pixels. However, in the present invention, even if the mounting position of the solid-state image sensor is shifted from the light @20 of the optical lens as shown in Fig. 2, the effective pixel 2 required for image output from near the optical axis
In order to obtain all the video signals of 1, the light-receiving area 22, 24 of the solid-state image sensor used is widened, and the total number of light-receiving pixels is increased accordingly. show). In other words, the effective number of pixels required for image output is Nv pixels in the vertical direction and Nh pixels in the horizontal direction, and the conversion value of the installation error when configuring all pixels at the same pitch is Mv pixels in the vertical direction and Nh pixels in the horizontal direction. When using Mh pixels, the light-receiving area of the solid-state image sensing device used is made wide so that the number of pixels in the vertical direction is N v + Mv pixels and the horizontal direction is Nh + Mh pixels or more.

Further, after the solid-state imaging device is fixed to the optical system, the position 23,25 in the light-receiving region and the rotation angle 26 of the point where the light-receiving region of the solid-state imaging cable intersects with the optical axis of the optical lens are measured in advance. Then, the mounting error information itself or the displacement amount of each pixel point obtained from the mounting error information is stored in the mounting error amount storage calculation circuit 11.

The signal level of one pixel point of the video signal necessary for image output is determined as follows. First, the amount of movement of the image at the pixel point position of the output image is determined by the pixel point movement amount calculation circuit 12 based on the data of the mounting error amount storage calculation circuit 11. On the other hand, among the electric signals converted by the solid-state image sensor 10, at least the signals of a part of the screen near the moving position of the image are sequentially stored in the video storage circuit 13 in accordance with the pixel point positions of the output image. Then, from the amount of image movement determined by the pixel point movement amount calculation circuit 12 and the pixel signal stored in the video storage circuit 13, the signal level of the pixel point position of the output image is calculated by the video signal calculation circuit 4 using a method such as linear approximation. Predict and interpolate. The interpolated output signal of the video signal calculation circuit 14 is passed through a signal processing circuit to obtain a blur signal as in the conventional case.

In addition, in the circuit shown in FIG. 1, in order to suppress rounding errors during video signal calculation that predicts and interpolates the signal level at the pixel point position of the output image, the amount of deviation due to chromatic aberration of the optical lens determined by the lens registration deviation amount storage calculation circuit 7 is calculated. Including pixel point shift 11) The I amount calculating circuit 12 calculates the moving range of the image, and then calculates the video signal.

Furthermore, if the solid-state image sensing device is mounted poorly and the amount of image movement extends to several pixels, a large storage capacity will be required for the 13 video storage circuits. 1st E! The start pulse position calculation circuit 16 of I is inserted to keep the storage capacity of the video storage circuit 13 small. For this purpose, the circuit 16 outputs pixel signals near the optical axis at approximately the same time.

The pixel signal readout start pulse timing is calculated for each imaging probe and the drive pulse generation circuit is controlled.

As a result, the pixel signals required for interpolation are output from the imaging element at the same time as the pixel signals after interpolation are output, eliminating the need for extra buffer memory to match the timing of the output signals from each element. Become.

In this way, in this circuit, the image signal calculation circuit 14 can correct the positional deviation of the image on the solid-state image sensor. Therefore, even though the solid-state image sensor cannot freely move the position of the light-receiving area on the imaging surface like an image pickup tube, there is no need to require the solid-state image sensor to have very high mounting precision.

FIG. 4 shows a second embodiment of the invention. Generally, the resolution of an optical lens is high at the center and worsens as it approaches the periphery. Therefore, it is desirable to apply an enhancer that emphasizes the high-frequency components of the video signal at the periphery of the screen compared to the center.

The circuit in Figure 4 is the circuit in Figure 1 plus the enhancement amount calculation circuit 4.
1 and a matrix calculation circuit 42, it is possible to perform various two-dimensional filtering calculations including the above-mentioned enhancer.

Image deviation areas due to lens aberrations and element installation errors are determined by the lens registration deviation line storage calculation circuit 7, similar to the circuit shown in FIG.
．． It is determined by the mounting error amount storage calculation circuit 11 and the pixel point movement amount calculation circuit 12. On the other hand, the enhancement amount calculation circuit 41 calculates the enhancement amount and other amounts for each pixel point, and uses a 3 Find the coefficients of the matrix (generally 2x2 or more is sufficient). Then, in the matrix element calculation circuit 42, the coefficients of this matrix are modified based on the amount of image shift determined by the pixel point movement amount calculation circuit 12. Thereafter, the video signal calculation circuit 14 interpolates the pixel signal using the matrix coefficients obtained by the matrix element calculation circuit 42, taking into account everything such as the amount of image shift and enhancement.

The interpolated output signal of the video signal calculation circuit 14 is passed through a signal processing circuit to obtain a television signal as in the conventional case.

By the way, the matrix elements used for interpolation etc. are often fractional values made up of simple integers, and the matrix #
Arithmetic operations between elements are relatively easy. On the other hand, interpixel interpolation calculations and enhancer calculations associated with image movement handle video signals that require high precision, so repeating the same calculations has the disadvantage of accumulating rounding errors during calculations and deteriorating image quality. be.

This circuit handles various functions such as the amount of image movement and the enhancer.
Since the coefficients necessary for the dimensional filtering calculation are obtained in advance and the video signal calculations that require high accuracy are performed all at once, rounding errors during video signal calculations can be kept small.

Further, like the circuit shown in FIG. 1, this circuit can also correct the positional deviation of the image, so there is no need to require very high mounting precision for the solid-state image sensor.

FIG. 5 shows a third embodiment of the invention. A solid-state image sensor generally has a structure in which pixels are arranged in a two-dimensional manner as shown in Figure 6(a). The data are sequentially read out using drive pulses at the IV synchronous frequency. Signals from unnecessary pixels not required for image output shown in FIG. 2 can be read out and removed during periods corresponding to the horizontal retrace period and the vertical retrace period. However, if the mounting accuracy is poor, the number of unnecessary pixels to be prepared increases, and therefore it becomes impossible to remove the signals of unnecessary pixels only during a period corresponding to the horizontal retrace period and the vertical retrace period.

In order to remove such unnecessary pixel signals, the circuit shown in Figure 5 uses a horizontal clock frequency and horizontal synchronization frequency that are different from the horizontal clock frequency and horizontal synchronization frequency, which are determined by the number of effective pixels required for the television system used for image output. The solid-state image sensor is driven at the horizontal synchronous frequency. However, the field frequency is set to be the same as the field frequency of the television system used for image output.

That is, based on the vertical synchronization pulse (which determines the field frequency) output from the synchronization signal generator 15, the drive pulse generation circuit 53 generates a drive pulse having a horizontal clock frequency and a horizontal synchronization frequency higher than the frequency determined by the television system. Then, this driving pulse is used to drive circuits including the solid-state image sensor, the pixel point movement amount calculation circuit 12, and the video signal calculation circuit 14. Thereafter, the output signal of the video signal calculation circuit 14 is passed through a time adjustment buffer circuit 54 in order to match the frequency of the output signal, and then converted into a television signal by a signal processing circuit and output.

In this way, in this circuit, even if the mounting accuracy of the solid-state image sensor is poor and the signal of the prepared unused pixel cannot be removed by driving it at the normal clock frequency, it is possible to remove it and correct the image position shift. .

In FIG. 5, a case has been described in which signals are sequentially read out from the solid-state image sensor for each horizontal line.

The solid-state image sensor may be configured to be able to read several lines at the same time, and may be driven with drive pulses having a horizontal clock frequency and a horizontal synchronization frequency lower than the frequency determined by the television system.

In addition, in order to remove unnecessary pixel signals, instead of driving at a constant clock frequency as shown in Figure 6,
As shown in the figure, high-speed reading may be performed only during a period during which at least a portion of unnecessary pixel signals that cannot be removed only during periods corresponding to the horizontal retrace period and the vertical retrace period are removed.

Above we have described the case where all three plates are aligned with the optical axis, but 3
The position of the element on one of the plates (for example, for green light) may be taken as a reference, and the positions of the other elements may be determined as relative positions with respect to this reference element.

Further, although the above description has focused on a three-panel type camera, the present invention can be similarly applied to monochrome cameras such as a single-panel type and two-panel type that read out three colors separately.

Furthermore, it is clear that even in an imaging apparatus using an image pickup tube, the method according to the present invention, that is, the method of correcting image distortion by performing calculations on read signals, may be used, regardless of the deflection of the electron beam.

〔Effect of the invention〕

As described above, according to the present invention, even if the mounting position of the solid-state image sensor shifts, the video signal of the necessary area can always be obtained from the solid-state image sensor, and the video signal without positional shift required for image output can be obtained from the solid-state image sensor. Since it is determined by interpolation from the output signal of the element, there is no need to require very high mounting accuracy for the solid-state imaging cable.

Additionally, processing such as correction and enhancement of chromatic aberration of optical lenses can be easily performed at the same time.

[Brief explanation of the drawing]

1 and 2 are respectively a first embodiment of the present invention and an explanatory diagram thereof, and FIG. 3 is a conventional circuit block diagram. FIG. 4 shows a second embodiment of the present invention, and FIGS. 5 to 7 show a third embodiment of the present invention and explanatory diagrams thereof. ■, 2... Optical lens and prism, 3.10... Camera tube and solid-state image sensor, 4... Signal processing circuit, 11...
- Attachment error amount storage calculation circuit, 12... Pixel point movement amount calculation circuit, 13... Video signal storage circuit, 14...
Video signal calculation circuit, 16... Start pulse position calculation circuit, 42... Matrix element calculation circuit, 54...
Time adjustment buffer circuit.

Claims (1)

[Claims] 1. An optical lens and an imaging device (such as an imaging tube or solid-state imaging device) that converts the light passing through the optical lens into an electrical signal.
In an imaging device having an image sensor, an image shift caused by aberrations of the optical lens, mounting errors of the image sensor, etc. is corrected by adding a certain calculation to an output signal from the image sensor. Device. 2. In an imaging device that has an imaging device that converts light passing through an optical lens into an electrical signal, the vertical mounting error when fixing the imaging device behind the optical lens of the imaging device is Jv, and the horizontal mounting error is Jv. When the installation error is Jh, the vertical length of the effective light-receiving area required for image output is Lv, and the horizontal length is Lh, the size of the light-receiving area of the image sensor is (Lv x Jv) x (Lh×Jh) An imaging device characterized by the above. 3. In an imaging device that uses a solid-state image sensor having a two-dimensional arrangement of pixels consisting of a plurality of photoelectric conversion elements as an image sensor, installation error when fixing the solid-state image sensor behind an optical lens. The converted value of the number of pixels is Mv pixels in the vertical direction and Mh in the horizontal direction.
An imaging device characterized in that, when used as a pixel, the number of vertical and horizontal pixels included in the light receiving area of the solid-state image sensor is at least Mv+Nv pixels in the vertical direction and at least Mh+Nh pixels in the horizontal direction. 4. The field frequency when reading signals from the image sensor is the same as the field frequency of the television system used for image output, but the horizontal scanning speed (horizontal clock frequency for solid-state image sensors) or horizontal synchronization frequency is , the image sensor is set to a horizontal scanning speed (horizontal clock frequency for solid-state image sensors) determined by the area of the effective light-receiving area required by the television system used for image output or a frequency different from the horizontal synchronization frequency. An imaging device characterized by being driven. 5. In the imaging device according to claim 2 or 3, an effective light-receiving area for obtaining a signal used for image output within the light-receiving area of the image sensor (in a solid-state image sensor, Nv pixels in the vertical direction and Nv pixels in the horizontal direction).
The image sensor is driven to read out at least some of the signals accumulated in the area except the area (area consisting of h pixels) at a higher speed than the readout speed of the signals in the effective light receiving area. An imaging device that uses 6. In the imaging device according to claim 2 or 3, a memory for storing position information of a point where the optical axis of the optical lens intersects with a light receiving area of the fixed image sensor as installation error information of the fixed image sensor. Each point within the effective light-receiving area necessary for image output (in the case of a solid-state image sensor, a pixel an arithmetic circuit that calculates the amount of positional deviation between the fixed point on the image sensor (pixel point in the case of a solid-state image sensor); 1. An imaging device comprising a video signal calculation circuit that predicts and interpolates the video level of each point (pixel point in a solid-state imaging device) in an effective light-receiving area necessary for image output based on the amount of image output. 7. The imaging device according to claim 6, wherein each point (pixel point in a solid-state image sensor) within the effective light-receiving area necessary for the image output and each point (in the light-receiving area of the solid-state imaging element)
When predicting and interpolating the video level from the amount of deviation from the pixel point (with a solid-state image sensor), the matrix coefficients that also perform enhancement to reinforce the high-frequency components of the image are calculated, and then the effective An imaging device characterized by predicting and interpolating the image level of each point (pixel point in the case of a solid-state imaging device) within a light receiving area. 8. The imaging device according to claim 6, wherein the timing of starting reading in the vertical or horizontal direction when reading signals from the imaging device is such that the optical axis of the optical lens passes through the center of the light receiving area of the imaging device. The position correction amount for the mounting error of the image sensor is the start timing before and after the readout start timing assuming that the optical axis of the optical lens passes through the center of the light receiving area of the image sensor. An imaging device characterized in that the imaging device is smaller than the amount of light. 9. The imaging device according to any one of claims 6 to 8, which uses two or more imaging elements, comprising: installation error information of the one fixed imaging cord;
a memory circuit that stores mounting error information consisting of the position and rotation angle of an image sensor other than the one image sensor with respect to the one image sensor; A calculation circuit that calculates the amount of deviation between each point (pixel point in the case of a solid-state image sensor) and the fixed point of each image sensor (pixel point in the case of the solid-state image sensor), and a calculation circuit that calculates the amount of deviation between each point (pixel point in the case of a solid-state image sensor) and the amount of deviation required for the image output from the calculated amount of deviation. 1. An imaging device comprising an image interpolation circuit that predicts and interpolates the image level of each point (pixel point in the case of a solid-state image sensor) within an effective light-receiving area.