JPH02172370A - Image pickup device - Google Patents

Abstract

PURPOSE:To suppress the spread of an image due to the movement of an object during the storage period of a signal charge by devising the device such that a relative speed of an image formed on a photodetecting face with respect to the photodetecting face is decreasing while a signal charge is stored or the image is made nearly standstill on the photodetecting face even if the object is moving. CONSTITUTION:The signal charge is stored while moving an optical system such as a lens 1 and an image pickup element 2 or either of them in matching with the movement of an object so that a relative speed of a noted image being at least part of the image formed on the photodetecting face of an image pickup element 2 with respect to the photodetecting face of the image pickup element 2 is small or nearly at a standstill for a period being nearly an integral number of multiple of a signal charge storage period or a signal charge readout period. Thus, the spread of the image due to a moving object for the signal charge storage period is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a structure of a television camera and a method for driving the same, which can reduce deterioration in resolution that occurs when the television camera is moved slowly from side to side or up and down.

[Conventional technology]

Image sensors used in television cameras accumulate open signal charges during a frame period or field period, and then read out the signal charges all at once. ? Karyotype imaging devices are widely used.

However, in this camera, if the subject moves during the signal charge accumulation period, the image is expanded and accumulated, and the resolution of the moving part (hereinafter referred to as dynamic resolution) deteriorates.

This deterioration in dynamic resolution can also cause a deterioration in the resolution of some moving subjects within the screen, but when photographing a wide distant scene while slowly moving the camera left and right or up and down, the image quality will noticeably deteriorate as the focus will seem to have shifted. deteriorate.

Conventionally, a method to prevent this resolution deterioration was to provide the image sensor with a shutter function (Japanese Patent Laid-Open No. 6252988).
A method is adopted in which the period for accumulating signal charges is made shorter than the frame period or field period. In this method, since the signal charge accumulation period is short, the movement of the subject during this period is small, and it is possible to suppress the spread of the image due to movement of the subject during the signal charge accumulation period. As a result, deterioration in resolution of moving parts can be reduced.

[Problem to be solved by the invention]

Incidentally, the longer the accumulation time, the more signal charges will be present. Therefore, from the viewpoint of S/H of the video signal, it is desirable that the storage time be long. However, this conventional method conversely shortens the signal charge accumulation period, resulting in deterioration of the S/N ratio of the video signal.

The present invention does not cause such deterioration of the S/H of the video signal, and prevents deterioration of the dynamic resolution of the entire screen, such as when rezooming by slowly moving the camera left and right or up and down, or when the subject of interest is moving. The purpose of the present invention is to provide resolution improvement means that can reduce deterioration in resolution.

[Means to solve the problem]

In order to achieve the above object, in the present invention, the relative velocity of at least a part of the image portion of interest formed on the light receiving surface of the image sensor with respect to the light receiving surface of the image sensor is determined by the signal charge accumulation period or The optical system, such as a lens, and the image sensor
Alternatively, signal charges may be accumulated while moving one of them.

[Effect]

According to the present invention, even if the subject is moving, the relative velocity of the image formed on the light receiving surface with respect to the light receiving surface becomes small or remains almost stationary on the light receiving surface while signal charges are accumulated. Therefore, it is possible to suppress the spread of the image due to movement of the subject during the signal charge accumulation period.

In addition, in this method, the signal accumulation time can be set to approximately the frame period or field period, so it is possible to obtain a good image with a high S/N ratio and little deterioration in resolution of the image portion of interest.

〔Example〕

A first embodiment of the invention is shown in FIG. This embodiment is an example of a circuit configuration for improving the dynamic resolution when a television camera is slowly moved left and right and up and down.

In FIG. 1, the imaging position moving device 3 is a device that moves the imaging position of an image formed by light passing through the optical lens 1 on the light receiving surface of the image sensor 2 at a substantially constant speed V1. There are two ways to configure the device: one is to move the image sensor, and the other is to shift the imaging position by shaking the optical path. The figure shows the latter method by shaking a glass plate inserted between the lens and the image sensor laterally. An example was given.

Further, the moving speed detection and discrimination circuit 4 detects the moving speed amount or direction of the subject on the screen from the video signal of at least a part of the image obtained by the image sensor, and forms an image according to the detected value. This circuit outputs a moving speed change amount Δvz for changing the moving speed v of the entire image. Various configurations are possible for this circuit, but it can be broadly divided into the following three circuits. That is, a detection window designation circuit 5 that specifies the position on the screen for detecting the speed, a movement speed determination circuit 6 that determines the movement state from the detected value obtained within the detection window, and a movement speed determination circuit 6 that determines the movement state from the detected value obtained within the detection window. This is a moving speed change amount calculation circuit 7 that calculates the amount of change in speed.

The moving speed control circuit 8 sets the entire image to be formed on the light receiving surface at a moving speed v2=vi+Δv1, which is the sum of the moving speed change amount ΔV1 outputted from the moving speed detection and discrimination circuit 4 and the stored moving speed v1. This is a circuit that controls the imaging position moving device 3 to move above.

The circuit of FIG. 1 operates as follows.

First, the imaging position moving device 3 is moved to the moving speed control circuit 8.
It is driven as follows by the control signal.

That is, as shown in FIG. 2(b), the period for accumulating signal charges, that is, the sign], 1.13; 1.5. As shown in FIG. 2(a), the imaging position of the image formed by the light passing through the optical lens is set on the light-receiving surface of the image sensor 2 at approximately constant speeds Vl, V2. ... (rightward in FIG. 2(a)), and the signal charge accumulated during this period is read out. Then, at time 12, 1.4, immediately after reading out the signal charge (or just before the start of signal charge accumulation for the next field).・
- Then, the imaging position is returned to the original position within a sufficiently short fixed period at a faster movement speed -vr, -Vl, -Vz, .

The imaging position moving device 3 is driven so that the above operation is repeated every 1-field period.

Under this driving state, the video signal accumulated during the accumulation period 1]- and read out from the image sensor 2 during the signal readout period 13 (also the signal charge accumulation period of the next field signal) is
First, the detection window designation circuit 5 extracts a portion of interest in the video and outputs it to the movement speed determination circuit 6.

The moving speed discrimination circuit 6 divides the amplitude Hp of the high frequency component of the video signal by the amplitude [Sp] of the video signal, which is the amplitude ratio Hp/S.
p (the amplitude Hp itself may be used),
When the amplitude ratio is a certain amount P], the moving speed change amount Δv1-0 is outputted through the moving speed change amount calculation circuit 7 so as not to change the moving speed.

However, if the moving speed change amount continues to be 0, the moving speed is readjusted at regular intervals as described below.

On the other hand, when the amplitude ratio Hp/Sp suddenly changes beyond the constant #:P1, the moving speed is readjusted as follows.

First, in order to change the moving speed v1 by a constant speed Δvo,
The moving speed change amount Δv1=ΔVQ is outputted through the moving speed change amount calculation circuit 7, and the moving speed v1 of the imaging area by the imaging position moving device 3 is changed to the moving speed V2''V1+Δvo.

As a result of this change in movement speed, when the value of the amplitude ratio Hp,/Sp becomes larger than the value in the previous field by more than a certain amount P1, as shown in Fig. 3(a), the movement in the same direction is continued. The speed change amount ΔV2=Δvo is output to change the moving speed v2 to VδFVz+Δv0.

Then, similar operations are repeated until the amount of change in the amplitude ratio becomes equal to or less than a certain amount P1.

On the other hand, by changing the moving speed V1, v2==v1+Δvo
, the value of the amplitude ratio becomes a constant amount P1 as shown in Figure 3(b).
- or when the amount of change is small, output the moving speed change amount Δv22×Δvo in the opposite direction and change the moving speed to v3=v1Δvo, then -ΔvO in the opposite direction to Δvo. Repeat the operation shown in FIG. 3(a).

Also, even if you change the movement speed to V2:V1+Δvo, v3=V
If the amplitude ratio becomes smaller or does not change even if the amplitude ratio is changed to 1-Δv0, the moving speed change amount Δv3=Δvo is output, and the moving speed is returned to the original value v4=v3+Δvo=v.

As described above, the moving speed is changed in one frame period, and the state after adjusting the moving speed is schematically shown in FIG.

If the speed at which the image part of interest (for example, the part of the image of a tree) moves within the imaging area is Vs, then the imaging area moves at a speed Vl that is approximately equal in size to Vs and in the opposite direction relative to the light-receiving surface.
``The object moves at FVS. Therefore, the relative speed of the image part of interest (for example, the part of the image of a tree) to the light receiving surface during the period of accumulating signal charges becomes extremely small.

By the way, when the imaging position moving device 3 is operated as described above, the position of the imaging area periodically returns to its original position on the light receiving surface. As a result of this operation, the image part of interest (for example, the part of the image of a tree) moves on the light-receiving surface by Vs x (
1 field cycle) (towards the left in Figure 4)
I'll go. Therefore, the window position determined by the detection window designation circuit 5 is
At least while adjusting the moving speed, move by -vl This is desirable.

In this way, in this circuit, even if the object is moving, the relative velocity of the image formed on the light receiving surface with respect to the light receiving surface becomes small or remains almost stationary on the light receiving surface while signal charges are accumulated.

Therefore, it is possible to suppress the spread of the image due to movement of the subject during the signal charge accumulation period. In addition, in this method, the signal accumulation time can be taken to be approximately the same as the field period, so it is possible to obtain a good image with a high S/N ratio and little deterioration in resolution of the image portion of interest.

The structure of the imaging position moving device 3 includes a structure in which two mirrors Ml and M2 are moved around different axes as shown in FIG. Although many structures are possible, such as a structure in which 2 is directly vibrated using a piezo element or the like (not shown), it is desirable to have a structure in which the direction of movement can be selected two-dimensionally.

Furthermore, as a driving method for the imaging position moving device 3, the operation of returning the imaging position to the original position is not carried out every few accumulation periods (every Eufield period) as shown in FIG. It may also be performed every multiple (every several field periods). However, in this case, the image signal of several fields in which the image part of interest is almost stationary with respect to the light-receiving surface is adjusted to the image output position shown in Figure 1 according to the moving speed of the image part of interest within the imaging area. It is necessary to shift the output using the moving circuit 9. Also, the movement speed can be changed every accumulation period (
It is desirable to perform this every one field period).

In addition, when returning the imaging position in the opposite direction, the returning position is not a fixed position, but when the moving speed is fast, it is moved far away, and when the moving speed is slow, it is returned to near the center of the light receiving area, and when the moving speed is
In this case, it is desirable to drive the image forming area so that it is located approximately at the center of the light receiving area.

In addition, the speed at which the imaging position is returned in the opposite direction is reduced, and the imaging position is returned in a period of one field or an integral multiple thereof. As for the video signal during that time, the video signal before starting to move in the opposite direction is stored, and the stored video signal is output while being shifted in accordance with the moving speed of the video part of interest. Also good.

Furthermore, in order to increase the adjustment speed and accuracy of the moving speed, it is desirable to change the magnitude of the moving speed change amount Δvo in accordance with the magnitude of the amplitude ratio in the previous two fields and the value of the moving speed change amount.

Similarly, in order to increase the adjustment speed of the moving speed, the moving speed change amount calculating circuit 7 calculates the moving speed of the next field from the amount of change in the amplitude ratio of the video signal output in the past two fields by changing the moving speed for each field. It is desirable to use a circuit that calculates and outputs the amount of change.

Furthermore, when the maximum moving speed is V II a x, the image output area that is output as a television signal is always within the light receiving area of the image sensor and the image forming area of the optical lens even if the image forming area is moved. In addition, the size of the image forming area must be larger than the size of the image output area by more than Vmax x (moving period), and the size of the light receiving area must be larger than the size of the image output area by more than Vmax x (moving period - 1 field period). be.

FIG. 6 shows a second embodiment of the invention. The device shown in FIG. 6 is an example of a device configuration that improves the resolution of an image portion by tracking a moving subject. The circuit configuration is essentially the same as that in FIG. 1 except for the changes.

The circuit of FIG. 6 operates as follows.

First, the lens direction moving device 23 is controlled by a control signal from the movement speed control circuit 8', and the camera lens direction is moved at a substantially constant speed 1 (for example, to the right) for a certain period of time while signal charges are being accumulated. The accumulated signal charges are then read out. The video signal obtained from the television camera 21 is input to the moving speed detection/discrimination circuit 4', and the moving speed is adjusted in the same manner as the operation of the moving speed detection/discrimination circuit 4 of the first embodiment. When this movement speed is adjusted, the movement speed (1) in the direction of the lens becomes a speed Vs, ``'; The relative velocity of the imaging position of the object of interest with respect to the light receiving surface can be made very small.

In this way, with this device, even if the subject is moving, the lens of the television camera follows it, and the relative speed of the image formed on the light receiving surface to the light receiving surface is reduced or the image can be kept almost stationary on the light receiving surface. Therefore, it is possible to suppress the spread of the image due to movement of the subject during the signal charge accumulation period.

In addition, in this method, the signal accumulation time can be set to almost the same as the field period, so it is possible to obtain a good image with a high S/N ratio and little deterioration in the resolution of the image portion of interest.

As shown in FIG. 7, it is preferable to change the moving speed immediately after reading out the signal charges for each field period or immediately before starting to accumulate the signal charges, as in the first embodiment. . Also, when adjusting the movement speed, the image formation position of the subject of interest shifts, or when you want to change the relative position of the subject to the lens direction, such as when changing the image output position to the center of the screen, or when changing the subject of interest. It is desirable to drive and adjust the moving speed so as to temporarily speed up or slow down in accordance with the change in the moving speed, as shown in FIG. 7, 20.

In addition, the position of the window designated by the detection window designation circuit 5' is also moved in accordance with the amount of change in movement speed corresponding to the tracking speed difference, thereby reducing the possibility that the subject of interest will deviate from the detection window position. things are desirable.

FIG. 8 shows a third embodiment of the present invention. The device shown in FIG. 8 is an example of the configuration of a device that reduces deterioration in resolution when changing the zoom ratio of a lens, and the zoom ratio is changed by this device in the following manner.

First, the synchronization signal generated by the synchronization signal generation circuit 25 is input to the zoom ratio change amount control circuit 26.

Then, in response to the signal instructing the change of the zoom ratio, the zoom ratio change amount control circuit 26 generates a control signal for changing the zoom ratio, as shown in FIG. This signal changes the zoom ratio only for a sufficiently short period immediately after the signal charges are read out. The signal charge accumulation period is maintained at a substantially constant zoom ratio.

When the zoom ratio changing device is driven by this control signal,
Even if a signal instructing to change the zoom ratio is applied from the outside, the actual zoom ratio hardly changes during the signal charge accumulation period. Then, the relative velocity of the image formed on the light-receiving surface to the light-receiving surface is reduced or the image is made to remain almost stationary on the light-receiving surface. Therefore, when the zoom ratio is changed during the signal charge accumulation period, it is possible to suppress the spread of the image due to the movement of the object image size <711. In addition, with this method, the signal accumulation time can be taken almost at the same time as the field period, so
It is possible to obtain a good video with a high S/N ratio and little deterioration in resolution of the video portion of interest.

It goes without saying that the speed of movement in the direction of the imaging area or the lens may be adjusted to an arbitrary speed such as an average speed within a certain area of the image rather than the image portion of interest.

In addition, instead of detecting the image movement speed from the video signal, a new circuit is installed on the tripod of a TV camera to detect the movement of the optical lens, and the image movement speed is calculated based on the output signal from that circuit. It's okay. Alternatively, detection from a video signal as shown in the above embodiment may be used in combination.

Further, in the above embodiments, only the case where the image or lens is moved left and right is described, but it is obvious that the invention can be similarly applied to the case where the image or lens is moved in any direction such as up and down.

In addition, although all of the moving speed detection and discrimination circuits have been explained above using a method that uses amplitude ratios, the moving speed of the video portion of interest is directly detected from two consecutive fields or two frames of video signals, and the moving speed is adjusted to match the detected moving speed. Needless to say, it is desirable to adjust the moving speed of the imaging position or the directional moving speed of the lens.

Further, noise in the video portion of interest that moves on the screen cannot be reduced by a normal noise reducer such as a cyclic additive noise reducer alone, but it can be reduced by using it in conjunction with the present invention. In other words, for example, in a cyclic addition type noise reducer, the cyclically added average signal is moved in accordance with the moving speed of the video part of interest within the imaging area, and this moved average signal (when changing the zoom ratio, signal processing average signal scaled by )
By performing cyclic addition of the newly manually generated video signals, it is possible to reduce the noise in the video parts that move on the screen. It is preferable that the noise reducer used at this time is a motion adaptive noise reducer that detects the relative motion of the video signals to be added and averages them only when there is little motion.

Further, by utilizing the present invention, it is possible to reduce image shaking due to camera shake or the like. In other words, move the lens so that the position of the image you are looking at on the light-receiving surface does not move too much, or move the position of the image so that the position of the image you are looking at on the screen does not move too much. By outputting the image in such a manner, it is possible to reduce image shaking due to hand shake or the like.

〔Effect of the invention〕

According to the present invention, even if the object is moving, the relative velocity of the image formed on the light receiving surface with respect to the light receiving surface decreases or remains almost stationary on the light receiving surface while signal charges are accumulated.

Therefore, it is possible to suppress the spread of the image due to movement of the subject during the signal charge accumulation period.

In addition, in this method, the signal accumulation time can be set to approximately the frame period or field period, so it is possible to obtain a good image with a high S/N ratio and little deterioration in resolution of the image portion of interest.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of an apparatus according to an embodiment of the present invention, Figs. 2 to 4 are explanatory diagrams of the operation of the above embodiment, and Fig. 5 shows how the imaging position is moved according to the embodiment. 6 is a block diagram showing the device configuration of the second embodiment of the present invention, FIG. 7 is an explanatory diagram of the operation of the second embodiment, and FIG. 8 is a diagram of the third embodiment of the present invention. FIG. 9 is an explanatory diagram of the operation of changing the zoom ratio in the third embodiment. 1. Optical lens, 2. Imaging element, 3. Imaging position movement device, 4. Movement speed detection and discrimination circuit, 8. Movement speed control circuit, 23. Lens direction movement device, 26. Zoom ratio change amount control. circuit. ``Sagi Seven Rainbows'', Resis No. 5, Acetic Candle, No. 2

Claims (1)

[Scope of Claims] 1. In an imaging device having an optical lens and an imaging device (such as an imaging tube or a fixed body imaging device) that converts light passing through the optical lens into an electrical signal, a light-receiving surface of the imaging device is Imaging is carried out so that the velocity of at least a part of the image portion of the image to be formed with respect to the light-receiving surface or the average velocity of a certain area is within a predetermined range of approximately 0 relative to the light-receiving surface of the image sensor for a certain period of time. An imaging device having a structure that 2. Claim 1, further comprising means for making the fixed period for maintaining the average speed at a predetermined speed range of approximately 0 approximately an integral multiple of the signal charge accumulation period or the signal charge readout cycle. Imaging device described in Section 2. 3. An imaging position moving device capable of moving the position of the entire image formed on the light receiving surface of the image sensor on the light receiving surface of the image sensor at a constant speed v_1; Detect or predict the speed or direction of movement at
Movement speed change amount Δv_ for changing the movement speed v_1 of the entire image to be formed according to the detected value or expected value
A moving speed detection/discrimination circuit that outputs 1, a moving speed change amount Δv_1 output from the moving speed detection/discrimination circuit, and a moving speed v_2=v, which is the sum of the stored moving speed v_1.
2. The imaging device according to claim 1, further comprising a movement speed control circuit that controls the imaging position moving device so that the entire image to be formed moves relative to the light receiving surface by _1+Δv_1. 4. The movement speed detection and discrimination circuit is a circuit that detects the amount of movement speed or its direction from a video signal of one area or multiple areas of at least a part of the image obtained by the image sensor, or a separately provided optical lens direction. 4. The imaging device according to claim 3, wherein the circuit calculates the amount of movement speed or its direction based on a signal from a movement detection circuit. 5. Moving the position of the formed overall image on the light receiving surface of the image sensor in a constant direction θ at a constant speed v_1,
After a certain period of time τ, the imaging position moving device is driven so as to move in the opposite direction at a speed v_r greater than or equal to the certain speed v_1, and return the position of the entire image to be formed to the original position on the light receiving surface of the imaging element. The imaging device according to claim 3 or 4, further comprising the moving speed control circuit. 6. While moving at a constant speed, the position of the image based on the video signal obtained by the image sensor is moved on the screen at the same average relative speed as the moving speed v_1 of the image to output the image. 6. The imaging apparatus according to claim 5, further comprising an image output position moving circuit. 7. The imaging device according to claim 3, further comprising a moving speed detection/discrimination circuit for detecting the moving speed amount or direction of the object image on the light-receiving surface from the video signal of at least a part of the image obtained by the image sensor. In the above, the moving speed detection and discrimination circuit moves an image area for which a detected value used in determining the amount of change in moving speed is to be moved together with the position of the image based on the image signal, so that the area of the image to be detected is the area of the image sensor. An imaging device that returns to its original screen position when certain conditions are met, such as going outside a light receiving area. 8. A lens direction moving device capable of changing the direction of the optical lens and the image sensor with respect to the object at a constant speed v_1; A moving speed detection device that detects the amount of moving speed or the direction thereof, and outputs a moving speed change amount Δv_1 for changing the moving speed v_1 of the optical lens and the alignment element in the direction relative to the subject according to the detected value. Movement speed v_2 = v_1 + Δv_1 which is the sum of the movement speed change amount Δv_1 output from the discrimination circuit and the movement speed detection and discrimination circuit and the stored movement speed V_1
2. The imaging device according to claim 1, further comprising a movement speed control circuit that controls the lens direction moving device so that the directions of the optical lens and the imaging device relative to the subject change. 9. The movement speed control circuit speeds up or slows down the movement speed for changing the direction of the optical lens and the image sensor for a certain period of time, and drives the lens direction movement device so that the position of the image of interest on the screen moves. 9. The imaging device according to claim 8, further comprising: 10. Claim 1 or 9, further comprising a moving speed control circuit that drives the lens direction moving device so that the target image moves to approximately the center of the screen. The imaging device described. 11. The moving speed detection and discrimination circuit calculates the amplitude Hp of a high frequency component in the video signal of at least a part of the image obtained by the image sensor, or the amplitude ratio Hp/ which is obtained by further dividing this amplitude Hp by the amplitude Sp of the video signal. A circuit that detects Sp, and a movement speed change that changes the movement speed v_1 to speed V_2 = v_1 + Δv_0 when the amplitude amount or amplitude ratio of the high frequency component suddenly changes by a certain amount P1 or more, or every fixed period. After that, when the amplitude amount or amplitude ratio of the high frequency component becomes large, the moving speed change amount Δv_0 that changes the moving speed to v_3=v_2+Δv_0 is output, and the amplitude amount or amplitude ratio of the high frequency component is output. becomes smaller, or when the amount of change is small, outputs the amount of change in moving speed (-2 x Δv_0) that changes the moving speed in the opposite direction v_3 = v_1 - Δv_0, and even if the moving speed is changed to v_2 = v_1 + Δv_0. v_3
If the amplitude amount or amplitude ratio of the high frequency component decreases or does not change even if it is changed to = v_1 - Δv_0, the moving speed change amount Δv_0 is output so that the moving speed is returned to the original value v_4 = v_3 + Δv_0 = v_1. The imaging device according to any one of claims 2 to 9, wherein the imaging device is a circuit. 12. The position of the image formed on the light-receiving surface at the cycle of accumulating and reading signal charges or at a cycle that is an integral multiple thereof, and approximately at the time when accumulation of signal charges starts or when the signal charges are read out. Claims 1 to 11 characterized in that the movement speed is controlled to change.
The imaging device according to any one of paragraphs.