JP2003087630A - Moving picture imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continuously vary a frame rate according to environment wherein an imaging apparatus used of an image measurement field is used. SOLUTION: Cycles in which signal charges are outputted is varied according to specific variation associated with an optical image to be picked up.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a moving image pickup apparatus for picking up an optical image from a subject to obtain a video signal, and more particularly to a moving image pickup in which a signal charge output cycle of a solid-state image pickup device is variable. Involved in the device.

[0002]

2. Description of the Related Art As an image pickup apparatus using conventional technology,
A certain fixed video signal output cycle, for example, NTSC (Nati
onal Television System Committee) method,
There is an imaging device that outputs a moving image video signal in a cycle in which a video signal for 30 frames is output per second.

Further, as an image pickup apparatus for picking up and outputting a still image video signal for picking up and outputting for each frame video signal such as a digital still camera, there is disclosed in Japanese Patent Laid-Open No. 2001-863.
There is known an image pickup device capable of changing the charge accumulation period as described in Japanese Patent Laid-Open No. 97. However, in the conventional technique disclosed in this publication, preliminary imaging is first performed in a predetermined charge accumulation period that is an initial charge accumulation period to determine the charge accumulation period, and the charge accumulation period is adjusted after the preliminary image pickup. However, it is not easy to apply such a technique to an imaging device for outputting a moving image signal that needs to be continuously imaged.

[0004]

The image pickup device using the above-mentioned conventional technique is an image pickup device which outputs a video signal only in a predetermined cycle, or even if the charge accumulation period is variable, It was a still image pickup device such as a digital still camera. Therefore, for example, as a moving image capturing apparatus used as a measuring unit in the field of image measurement, one image capturing apparatus can be used in accordance with various situations, particularly if the video signal output cycles are continuously different so as to eliminate a joint. It was not intended to be imaged.

An object of the present invention is to realize a moving image pickup apparatus capable of picking up an image while switching a video signal output cycle for various situations.

[0006]

In order to solve the above-mentioned problems, the present invention receives an optical lens for forming an optical image from a subject, receives the formed optical image, and receives the received optical image. A solid-state image sensor that photoelectrically converts an optical image by a plurality of light receiving pixels for each predetermined charge accumulation period and outputs a signal charge obtained by the photoelectric conversion, and a moving image based on the output signal charge In a moving image pickup device which outputs a video signal, the period of the signal charge accumulation period of the solid-state image pickup device is changed according to a predetermined change relating to the optical image to obtain the signal charge, and the signal charge is transferred to the moving image. The image signal is output at a predetermined rate.

The present invention is further directed to changing the signal charge output cycle in accordance with the temporal change of the external trigger signal relating to the optical image. In addition, depending on the timing when the external trigger signal changes, the signal charge output cycle may be set to a shorter cycle or a longer cycle (a buffer memory is unnecessary) in a predetermined period after the timing.

Further, the present invention is to sequentially change the signal charge output cycle in accordance with the change in brightness of the optical image. The charge accumulation period is changed so that the amount of signal charges obtained by the photoelectric conversion becomes a predetermined value according to the change of the brightness of the optical image, and the charge accumulation period is changed according to the change of the charge accumulation period. The signal charge output cycle may be changed sequentially.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an embodiment of a moving image capturing apparatus according to the present invention. 1 is subject 7
An optical lens 2 that collects the imaging light from the optical lens to obtain an optical image, and 2 receives the optical image formed by the optical lens 1, photoelectrically converts the optical image according to the optical image, and obtains a signal charge obtained by the conversion. Is a solid-state image sensor including a plurality of light-receiving pixels that store the charge in each predetermined charge storage period. In particular, a CMOS solid-state image sensor is used. Reference numeral 3 denotes correlated double sampling of the signal charge output from the image sensor 2.
CDS & A / D conversion circuit for converting the sampled signal into a digital video signal
A memory for recording the digital video signal obtained by the A / D conversion circuit 3, and a digital signal processing circuit 6 for performing various signal processes on the video signal from the memory 4, for example, gamma correction, contour compensation, white balance adjustment, etc. DS
P) and 5 are CPUs for controlling operation timings and operation frequencies of the image pickup device 2, the CDS & A / D conversion circuit 3, the memory 4 and the DSP 6, and have a timing generator function. The CPU 5 can also input a trigger signal from the outside and control the operation timing and the operation frequency of each block described above according to the input trigger signal.

Here, as the above-mentioned solid-state image pickup device 2,
The light receiving pixels arranged in a two-dimensional matrix are divided into a plurality of parts in the horizontal direction, and the A / D for each divided group
A digital image signal obtained by A / D conversion by a converter can be output, which can be operated at higher speed and whose charge accumulation period can be significantly changed. For example, by using a CMOS type image sensor, The effect of the invention can be further increased. Needless to say, the effect of the present invention can be obtained even if a CCD type image pickup element which is widely used in conventional image pickup apparatuses is used.

Next, in the moving image pickup apparatus of FIG. 1, when there is any change in the optical image being picked up, the operation of changing the signal charge output cycle of the image pickup element in accordance with the change will be described. 2 and FIG. 3.

First, the operation of changing the frame rate in association with the change of the optical image picked up by the image pickup device will be described with reference to FIG. To change the frame rate,
This is performed by inputting a trigger signal from the outside as a precursor signal of the change in the optical image. FIG. 2 illustrates an example of the operation of the moving image capturing apparatus when the frame rate of the image capturing element is increased by the input trigger signal. For example, a substance that is hard against the windshield of a car
A case is shown in which a moving image is captured at a relatively high-speed collision, the windshield is cracked, and the degree of the crack is analyzed.

In this figure, the video signal (c ') is shown by compressing the time axis of the video signal (c). That is, in FIG. 2, the trigger signal (a), the charge accumulation period (b), and the video signal (c) input to the memory 4 are shown.
Are both represented on the first time axis, and the same signal as the video signal (c ′) and the memory 4 output signal (d)
The display image content sequence (e) is represented by the second time axis which is smaller than the first time axis. Further, in the charge accumulation period (b), A ₀ , A ₁ , and A ₂ are frame rates of normal operation, and B _{0 to} B ₁₀ are high-speed frame rates.

Here, during the normal operation before the trigger signal is input, the timing control of the CPU 6 causes a charge accumulation period of about 33 mS as shown in FIG. 2, for example, the period A ₀ of FIG. 2B. During (X = A ₀ period), the signal charge is obtained from the image sensor 2 according to the optical image from the subject,
Via the CDS & A / D conversion circuit 3, a video signal based on the obtained signal charge (1 in FIGS. 2C and 2C ') is used.
The first video signal in the video signal of 0 continuous) is recorded in the memory 4. Further, the video signal in the period A ₀ is output from the memory 4 in the period a ₀ of the memory output (d). The video signal at this time is output every period of about 33 mS, which is the same as the period A _0, and 30 frame images are output per second.

When the substance is ejected toward the windshield of the vehicle and a trigger signal ((a) is input from the outside at an appropriate timing in accordance with the timing of collision between the substance and the windshield, the signal is output. Entered C
The PU 6 immediately changes the operation of the image pickup apparatus from the normal operation to the high-speed image pickup operation, and performs timing control according to the high-speed image pickup operation, so that a predetermined number of frame images with a frame rate of 2 mS, here, 10 frame images. Enable to take images. By doing so, it will be possible to obtain a moving image suitable for the observation purpose by the high-speed imaging operation within 20 mS.

Further, the operation when a trigger signal is input from the outside will be described. The moving image capturing apparatus of this embodiment shifts to the high-speed image capturing operation mode due to the input of the external trigger signal. In this example, in order to obtain a video signal for 10 frame images, an image is picked up by an optical image from a subject in a charge accumulation period of 2 mS, that is, in each of the periods B ₁ to B _{10 in} the example of FIG. A signal charge is obtained from the element 2, and via the CDS & A / D conversion circuit 3,
A video signal based on the obtained signal charge is recorded in the memory 4. Furthermore, the period b ₁ ~ period b ₁₀ to about 33 of the video signal 2 for each period of the periods B ₁ ~ period B ₁₀
It is output every mS period. By doing so, the moving image video imaged in the high-speed imaging operation mode is output at the same frame rate of 30 frames per second as in the normal operation. Then, after the video signal related to the period B ₁₀ is output, the imaging in the normal imaging operation mode starts from the period after the period B ₁₀ , and the image related to A ₁ which is the period next to the period B ₁₀ is started. The signal is output at a frame rate of 30 fps.

As described above, according to this embodiment,
Although not shown, in the image processing circuit in the subsequent stage, for example, the operation speed cannot catch up with a video signal having a frame rate of 500 frames per second as in the period B, and normal image processing operation cannot be performed. Even if
In this embodiment, since the output is performed at a slower rate, for example, a frame rate of 30 frames per second, it is possible to perform a normal image processing operation. Furthermore, the video signal output frame rate obtained during the normal operation and the video signal output frame rate obtained during the high-speed image pickup operation can be continuously and continuously set to the same frame rate.

Next, referring to FIG. 3, when it is desired to use the full dynamic range of the image sensor, the illuminance level of the optical image captured by the image sensor changes, and
An example of the operation of the moving image pickup apparatus when changing the frame rate of the image pickup device in association with the change will be described. Such a configuration is effective for obtaining a video signal intended to be used in an image processing field where S / N ratio is important.

Here, the illuminance by the optical image can be detected by various methods. For example, the illuminance may be measured from the transition of the amount of signal charges picked up by the image pickup device, or the illuminance of the image pickup device may be measured. The illuminance may be calculated by detecting the reflected light from the optical image incident on the light receiving surface,
In the following description, the case where measurement is performed from the transition of the signal charge amount imaged by the image sensor will be described as an example.

As shown in the graph of illuminance change in FIG. 3, when the reference illuminance is 1, the illuminance of the optical image to be captured is initially in the range of ⅔ or more (hereinafter referred to as range 1).
Referred to), from which a range of 2/3 to 1/3 (hereinafter referred to as range m) is reached to a range of 1/3 to 0 (hereinafter referred to as range n), and further range m Change to come to.

[0021] illuminance of the optical image is detected to be in the range l, about with the charge accumulation period of each 17 mS, for example, signal charges obtained from the image pickup element 2 in the period C ₁ by an optical image from a subject, CDS & A A video signal based on the obtained signal charge is recorded in the memory 4 via the / D conversion circuit 3. Similarly, video signals based on the signal charges accumulated in the periods C ₂ to C ₄ are sequentially recorded in the memory 4.
Here, the signal charge in each period is obtained by being accumulated about every 17 mS, that is, the image is picked up at a frame rate of 1 frame image in 1/60 seconds.

Then, the period D ₁ which is the period next to the period C ₄
When it is detected that the illuminance of the optical image is within the range m, the signal charge is obtained from the image sensor 2 by the optical image from the subject in the charge accumulation period of about 33 mS, and the CDS & A / D
A video signal based on the obtained signal charge is recorded in the memory 4 via the conversion circuit 3. Here, the signal charge in this period is obtained by being accumulated at about 33 mS, that is, the image is picked up at a frame rate of 1 frame image for 1/30 second.

[0023] Then, the period E _1, which is the next period of the period D ₁
After that, when it is detected that the illuminance of the optical image is in the range n until the period E ₃ , the signal charge from the image sensor 2 is generated by the optical image from the subject in the period E ₁ , for example, in the charge accumulation period of about 67 mS. Is obtained, and the CDS & A / D conversion circuit 3
A video signal based on the obtained signal charge is recorded in the memory 4 via the. Similarly, video signals based on the signal charges accumulated in the periods E ₂ to E ₃ are sequentially recorded in the memory 4. Here, the signal charge in each period is obtained by being accumulated about every 67 mS, that is, 1/15.
The image is captured at a frame rate of 1 frame image per second.

Then, the period D ₂ which is the period next to the period E ₃
In the following, the illuminance of the optical image is detected to be in the range m, with the charge accumulation period of about every 33 mS, the signal charges from the image pickup element 2 is obtained, for example, in the period D ₂ by an optical image from a subject, CDS & A A video signal based on the obtained signal charge is recorded in the memory 4 via the / D conversion circuit 3. Similarly, video signals based on the signal charges accumulated in the period after the period D ₃ are sequentially recorded in the memory 4. Here, as in the case of the period D ₁ described above, 1/3
The image is captured at a frame rate of 1 frame image in 0 seconds.

The signal levels of the video signals sequentially recorded in the memory 4 as described above have a smaller variation in the signal charge storage amount of each engine as compared with the case where the charge storage period is made constant. The difference can be made as small as possible, and it is possible to perform moving image capturing that makes more effective use of the dynamic range of the image sensor.
It should be noted that the illuminance of the optical image incident on the image pickup device 2 can be set within a predetermined value range by the operation of the diaphragm provided in the optical lens 1 of the image pickup device. However, in the present invention, adjustment of the diaphragm mechanism is performed. When the illuminance range exceeds the range, it is possible to further respond to the illuminance, and the dynamic range of the image sensor can be more effectively utilized, which is extremely effective in such a case.

The video signals sequentially recorded in the memory 4 are output from the memory 4 at a frame rate in which one frame image is output in 1/30 second of a constant rate in this example, and the rate is further increased. It will be output from the image pickup device. Therefore, when outputting a video signal related to the period C ₁ to the period C ₄ in which 1 frame image is captured in 1/60 seconds, it is necessary to output as 1 frame image from the memory contents of 2 frame images. There, in this example, for example, from a video signal related respectively to the period C ₁ and period C _2, without outputting a video signal related to the period C _1, selectively outputs the video signal related to the period C ₂ The output is thinned out so that

When outputting a video signal related to the period E ₁ to period E ₃ in which one frame image is picked up in 1/15 second, it is output as a two frame image from the memory contents for one frame image. This is necessary, and in this example, the video signals related to the periods E ₁ to E ₃ are output in duplicate so that the same video signal is output twice by repeating each.

[0028]

As described above, according to the present invention,
It is possible to realize a moving image capturing apparatus capable of responding to various situations while continuously switching the video signal output cycle without interruption.

[Brief description of drawings]

FIG. 1 is a diagram showing a block configuration of a moving image capturing apparatus according to the present invention.

FIG. 2 is a timing chart illustrating an example of the operation of the moving image capturing apparatus according to the present invention.

FIG. 3 is a timing chart explaining another example of the operation of the moving image capturing apparatus according to the present invention.

[Explanation of symbols]

1: Optical lens, 2: Solid-state image sensor, 3: CDS &
A / D conversion circuit, 4: memory, 5: CPU, 6: digital signal processing circuit (DSP), 7: subject.

Claims (5)

[Claims] 1. An optical lens for forming an optical image from a subject, and the received optical image, and the received optical image is photoelectrically converted by a plurality of light receiving pixels for each predetermined charge accumulation period. A solid-state image pickup device for converting and outputting a signal charge obtained by the photoelectric conversion, and a moving image pickup device for outputting a moving image video signal based on the output signal charge. A moving image characterized by changing the cycle of the signal charge accumulation period of the solid-state imaging device according to a predetermined change to obtain the signal charge and outputting the signal charge as the moving image video signal at a predetermined rate. Imaging device. 2. The moving image pickup device according to claim 1, wherein the signal charge output cycle is changed in accordance with a change in an external trigger signal related to the optical image. 3. The moving image pickup device according to claim 2, wherein the signal charge output cycle is shorter or longer in a predetermined period after the external trigger signal in accordance with the timing of the change of the external trigger signal. A moving image capturing apparatus characterized by: 4. The moving image pickup device according to claim 1, wherein the signal charge output cycle is sequentially changed according to a change in illuminance of the optical image. 5. The moving image pickup device according to claim 4, wherein the charge accumulation period is set so that a signal charge amount obtained by the photoelectric conversion according to a change in illuminance of the optical image becomes a predetermined value. A moving image pickup device, characterized in that it is changed and the signal charge output cycle is sequentially changed according to the change of the charge accumulation period.