JPH088692B2 - Color video camera - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-high-speed color image-capturing apparatus equipped with an optical intensifier, and more particularly to an ultra-high-speed moving object such as a rocket, explosion, destruction, turbulence, discharge phenomenon, chemical reaction It is preferably used for scientific measurement of phenomena and movement of microorganisms under a microscope.

[0002]

2. Description of the Related Art When photographing the above-mentioned scientific phenomenon,
It is necessary to shoot with an ultra-high speed camera. In ultra-high-speed shooting, the exposure time becomes very short, so the amount of light per screen may drop, and shooting may not be possible. A typical example is photographing a dynamic phenomenon under a microscope. Under a microscope, the higher the magnification, the lower the amount of light originally, and the smaller the movement, the faster the movement. If the number of shooting screens per unit time, that is, the frame rate is increased to cope with this movement, the exposure time is short and the light amount is limited.

Recently, a micro channel plate type image intensifier (hereinafter referred to as MCP type II) for amplifying weak light has been provided as a means for achieving high sensitivity when the light amount is small. There is.

The MCP type II has the structure shown in FIG. 12, and a photocathode 3 consisting of a cathode that emits electrons when light is incident on the rear surface of a fiber glass 2 which is an incident glass window attached to the front part of a vacuum tube 1. And a microchannel plate 4 having a large number of pores with a minute diameter of about 10 μm is installed behind the photocathode 3 with a required space. A fiber glass 5 is installed behind the microchannel plate 4 with a required space, and the front surface of the fiber glass 5 is a fluorescent screen 6 provided with a screen made of a substance that emits light when electrons collide. With respect to the MCP type II, the light receiving surface 9 of the image pickup element 8 is connected to the rear surface of the fiber glass 5 via a fiber coupling 7.

In the MCP type II described above, as shown by the arrow in the figure, the light incident from the front surface of the fiber glass serving as the incident glass window and hitting the photocathode is converted into electrons according to the amount of light, and The converted photoelectrons enter many holes of the microchannel plate 4. In the microchannel plate 4, one photoelectron collides with the wall of a small hole to generate an avalanche phenomenon in which a large number of secondary electrons are emitted. This is repeated to increase the number of electrons.
A large number of photoelectrons emitted from the microchannel plate 4 collide with the phosphor screen 6 while being accelerated by the electric field, and emit enhanced light.

According to the MCP type II having the above action,
Due to the effect of increasing the number of electrons by the microchannel plate and accelerating the electrons by the electric field, the amount of incident light can be increased to about tens of thousands of times. Therefore, an MC that has a light enhancement function of 10,000 times or more when shooting under weak light
The use of P-type II is extremely effective in ultra-high-speed photography.

[0007]

As described above, the MCP type II is a very powerful optical device, but in principle the image is black and white. This is because the photocathode on the front surface of the microchannel plate emits electrons not only for visible light but also for light of any frequency such as infrared rays, ultraviolet rays, and X-rays. This is because it will be information only.

Therefore, it is not easy to achieve colorization using the MCP type II, but in image processing, color information has a much larger amount of information than black and white information, which facilitates processing. For example, when tracking the movement trajectory of a rocket, in monochrome photography, only a bright spot corresponding to the trajectory of one target object is not affected by other bright spots among many bright spots existing on the screen. It's not easy to choose. In that case, when color information is obtained by color photography, the bright spot of the color to be traced can be easily identified.

For the above reason, it is desired to use the MCP type II in the ultra-high-speed image pickup apparatus and colorize the image. The following three methods can be considered. 3-plate type Shutter or method of sequentially inserting filters of three colors on the light source side Method of mounting color filter array on the front of MCP type II

First, as is well known, the above-mentioned three-plate type video camera has the structure shown in FIG.
A dichroic prism 12 is provided behind the dichroic prism 12 and a layer for transmitting or reflecting only the three primary colors (usually blue, red, and green) is provided in the prism 12 and the dichroic surfaces 13A and 13B are provided.
Is provided. Three image pickup devices 14A, 14B and 14C are arranged so as to face the three emission surfaces of the prism 12, and a color image is obtained by synchronizing the image pickup by the three image pickup devices.

The MCP is used in the color image pickup device of the three-plate type.
When the type II is attached, as shown in FIG. 13, the MCP is provided between the image pickup elements 14A, 14B, 14C and the prism, respectively.
Type II 16A, 16B and 16C are interposed, and only the light of a predetermined color that has been color separated in advance and passed through the color filter is MCP type I.
It is possible to adopt a method in which the amount of light is increased by I and each image sensor receives light. A red image, a green image, and a blue image respectively appear on the three image pickup devices, and a color image can be obtained by combining these.

However, when the above three-plate type is used,
There is a drawback that a positional shift is likely to occur when synthesizing three images. Further, since three image pickup devices and three MCP type II are used, there is a drawback that the device becomes large and the cost becomes high.

Next, the shutter or the light source side 3
Consider how to add color filters in sequence. In principle, if the three continuous screens that are shot at short intervals of 1 / 60th of a second or less capture the red, green, and blue light components, the movement (shift) between the three is sufficient. When small,
A color image can be obtained by combining the three images. This 3
As a method of changing the color of one continuous image, red on the light source side,
There are a method of outputting three colors of green and blue one after another, and a method of sequentially applying filters of three colors when entering a camera.

Specifically, for example, three strobes are prepared, and these are used as light sources of three colors and are synchronized with the shuttering of the camera. Alternatively, a rotary type three-color filter may be attached in front of one white light source or in front of the camera and rotated in synchronization with the shuttering of the camera.

The problem with the above method is that the synchronization technique and the outline are large. In addition, it is often impossible to change the color on the light source side or the shutter side depending on the type of photographing, and for example, the color on the light source side cannot be changed in photographing under a microscope or photographing in the daytime.

Next, the above color filter array
A method using (hereinafter, referred to as CFA) will be examined. In this case, as shown by the alternate long and short dash line in FIG. 12, the front surface of the photocathode 3 is used as an imaging position by a lens, and the CFA 10 is vapor-deposited and attached to that portion, or the incident light is converted into parallel light and then passed through the CAF. A method of making the light incident on the photocathode can be adopted. This method is in principle the same as the case where the CAF is mounted on the front surface of the image pickup element adopted in a normal color video camera.

When the CFA is mounted on the front surface of the above-mentioned normal image pickup device, the CFA is closely attached to the front surface of the image pickup device,
The pitch of A is the same as the pixel pitch of the image sensor.
Therefore, for example, the amount of light received by the pixel below the red filter is proportional to the amount of red light above the red filter. Therefore, consider four adjacent pixels,
(Red, green, blue, green (R, G, B, G)) or (blue, yellow,
When a filter such as green and white (without a filter) is attached, the brightness of each color component in the area covered by these four pixels can be known, and a color image can be reproduced.

On the other hand, the method of attaching the CFA to the front surface of the MCP type II photocathode has the following problems.
First, it is not easy to match the positional relationship between the CFA and the image sensor. CFA on the front surface of a normal image sensor
When mounting, the color filter should be overlaid on each pixel and baked, so the usual integrated circuit manufacturing method (usually 1
A color filter can be attached without any error on the extension of 0 to several tens of μm. However, CFA
When it is attached to the front surface of the I photocathode, as shown in FIG. 12, the photocathode 3 and the MC are provided between the CFA 10 and the image sensor 8.
P4, the fiber glass 5, and the fiber coupling 7 intervene, and there is a space between them. Therefore,
Since the distance between the CFA and the image pickup element is several cm and a plurality of optical device elements are interposed between them, it is very difficult to match the pitch of the CFA and the image pickup element. Even if they can be adjusted at the time of shipment from the factory, it is almost impossible to prevent the displacement caused by deformation due to thermal stress or mechanical stress.

Secondly, the light is dispersed from the CFA until it enters the image pickup device, causing color mixing in the image of the image pickup device. For example, as shown in FIG. 14, the red light passing through one red window of the CFA 10 collides with the photocathode 3 to become an electron corresponding to the light intensity, and the photoelectron diffuses before entering the MCP 4, and The electrons emitted from the MCP 4 are diffused even before they hit the fluorescent screen 6, and when they are incident on the fiber coupling 7 from the fluorescent screen 6, they are also diffused in the coupling process between the fiber coupling 7 and the image sensor 8. So, for example,
It is estimated that the total diffusion width of light transmitted through a 10 μm wide filter is about 40 μm.

On the other hand, as a matter of course, it is desirable that the mesh size of the CFA 10 on the front surface of the photocathode 3 and the pitch of the pixels 8a of the last image pickup device 8 are about the same. Since the total diffusion width is about 40 μm, these pixel pitches must be at least 40 μm or more. However, since the pixel pitch of an ordinary image pickup device is on the order of 10 to 40 μm, naturally, when an MCP type II is used and a color image is to be obtained, color overlaps inevitably occur in each pixel.

On the other hand, it is also possible to use an ordinary small pixel size of the image pickup element, consider several to several tens of pixels as one set of pixels, and adjust the width thereof to the mesh size of CFA. However, in the case of the above method, since the actual number of pixels is reduced, the resolution of photography using the MCP type II, which originally has a relatively low resolution, is further lowered, and practicality is almost lost. In addition, the pixel size of the image sensor is the same as the above, and a normal small one is used, and at the stage of processing the captured image, the pixel region is divided into each color later, and the pixel group of the red region and the blue region are divided. It is also possible to consider a method of eliminating the overlapping of colors as the pixel group of 1) and the pixel group of the green region. However, in the case of this method, it is necessary to set a color-coded section for each image, which has a drawback that the image processing becomes extremely complicated.

As described above, there are various problems in colorization using the MCP type II, but as described above, in image processing, color information has a much larger amount of information than black and white information, and various types of color information are required. M for easy and accurate processing
There is a strong demand to provide a video camera capable of ultra-high-speed shooting that uses both CP type II and color.

The present invention is intended to achieve the above-mentioned demand, and to achieve high-sensitivity colorization by a very simple structure in a video photographing apparatus for ultra-high-speed photographing using MCP type II.

[0024]

That is, according to the present invention, a light quantity intensifying device is installed in the front part of an image pickup device, and a photoelectric surface of the light quantity increasing device converts incident light into photoelectrons, and then the light amount is increased by a fluorescent surface. In an image pickup device in which the light is converted and emitted and received by each pixel of the image pickup device, a color filter of three colors (usually red, green, blue) is formed in front of the photocathode of the light intensifying device. The color filter array is installed, for example, with each color filter set at a pitch of about 1/3 of the pixel pitch of the image sensor, so that the transmitted light from the color filters of the same color is incident on the entire light receiving surface of the image sensor. In addition, each color filter is provided with an electrode, and the electrodes of the color filters of the same color are synchronized so that each color is turned on (conduction) and turned off (interruption) at different timings. One switching unit is provided, and a control unit for sequentially turning on these three switching units in synchronization with the shuttering of the image sensor is provided, and the light transmitted through the color filter of the same color is incident on all pixels of the image sensor. This is performed sequentially for three colors, that is, after the red light that has passed through the red filter is incident, the green light that has passed through the green filter is incident, and then the blue light that has passed through the blue filter is incident, The present invention provides a color video recording device equipped with a light intensity increasing device configured to sequentially capture images of three colors separated by sequentially entering → green → blue → red → green.

The above color filter arrays are red,
It suffices that the three primary colors of green and blue are sequentially arranged, but the stripe type is more preferable than the connection between the electrodes and the switching means.

The electrodes attached to each color filter may be any electrodes that can illuminate the entire surface of the color filter attached at the time of turning on, and the wire that runs along the entire length of the rear surface of the color filter or the rear surface of the color filter can be used. A transparent conductive film or the like attached to the whole is preferable.

The MCP type II described above is preferable as the light intensity increasing device used in the present invention, and the MCP type II is used to turn on / off each electrode of the color filters of the three colors.
It is shuttering (or gating).

When the image pickup device has an internal shutter mechanism, the color filters are sequentially turned on in synchronization with the shuttering of the image pickup device as described above. In any case, the frame rate is set to at least 1/60 second or less, and a set of three color-separated images is obtained every 1/20 second or less of the afterimage time of human eyes. Or three consecutive red, green and blue images, then 1
For example, three consecutive images are regarded as one image, such as three images of green, blue, and red, which are divided into sheets, and a composite image of these images is displayed. Good.

The above color filters are usually red, green,
Although it is composed of three colors of blue, it is not limited to this, and any color such as yellow, green, and blue that can be combined to obtain a color image may be used.

As the image pickup device used in the present invention, 256
It is preferable to use one having a high resolution of 40 μm pixel pitch or more in rows × 256 columns. Pixel pitch is 40
In the case of μm, the stripe width of one color of the color filter is set to 1/3, that is, about 10 μm in consideration of the diffusion width, and three color filters each having a width of 10 μm are juxtaposed side by side to obtain the same color. The filters are arranged with an interval of about 20 μm.

[0031]

As described above, in a photographing device capable of ultra-high-speed photographing under weak light by using the light amount enhancing device, a color filter is attached to the front surface of the photocathode of the light amount enhancing device. Only the color filters of the same color are turned on synchronously, all the pixels of the image sensor receive the light that has passed through the color filters of the same color, and this is repeated for each color of the color filter in order to mix the colors. It is possible to obtain a color image by synthesizing three colors of continuous three images without causing the occurrence of.

As described above, since light transmitted through the color filters of the same color is incident on all the pixels of the image pickup device at the time of shuttering, it is not necessary to align the pitch of the color filter and the image pickup device. Also, the colors do not mix at all. Moreover, because it is super high-speed shooting,
A color image is formed by three color images obtained by consecutive three times of shuttering, and there is no problem of positional displacement of the three color images due to displacement of mounting of the image pickup element which occurs when the three-plate type is used. In addition, it is possible to take a picture under a microscope or in the daytime, which is difficult to realize by the method of giving light of three colors to the light source side, and it is possible to eliminate the limitation of the object to be photographed due to colorization. As described above, according to the present invention, it is possible to achieve high-sensitivity colorization even in the case where the light amount enhancement device required for ultra-high-speed shooting is provided.

[0033]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. The entire configuration of the video apparatus according to the present invention is the same as the conventional one, and as shown in FIG. 1, a video camera main body 20 is provided with an image pickup unit 22 for converting light imaged by a lens 21 into an electric signal. The image signal of the image pickup device provided in the image pickup unit 22 is transferred to the video camera main body 2
It is configured to output to a signal processing unit 24 provided in a processing device 23 which is separate from 0 and to be sent from the signal processing unit 24 to a memory unit 25. An image forming computer 26, an image forming device 27, a display 28, and an external recording device 29 are connected to the memory section 25.

As shown in FIG. 2, the structure of the image pickup unit 22 is substantially the same as the structure shown in FIG. 12, so the same members are designated by the same reference numerals and the description thereof will be omitted. That is, the imaging unit 22 includes a micro channel plate type image intensifier (hereinafter referred to as M
(Referred to as CP type II) 31 is installed, and the MCP type II3
The stripe type color filter array 33 is attached to the front surface of the photocathode 32 of No. 1 so that the light quantity is increased by the MCP type II 31 and the color filter array 33
The color is set by installing the.

As in the case of FIG. 12, the MCP type II 31 converts incident light into electrons at the photocathode 32 on the rear surface of the fiber glass 2 serving as an incident glass window attached to the front portion of the vacuum tube 1 and converted. The photoelectrons are doubled through the microchannel plate 4, and the doubled electrons are converted into light by the fluorescent surface 6 on the front surface of the fiber glass 5 and emitted to the light receiving surface 30a of the image pickup device 30 through the fiber coupling 7.

As shown in the figure, the color filter array 33 has red, green and blue colors on the rear surface of the front fiberglass 2.
Color filter 40R consisting of three primary colors (R, G, B),
40G and 40B are sequentially baked in a stripe pattern.
On the rear surface of these color filters 40R, 40G, 40B, electrodes composed of electric wires 41, 42, 43 are wired over the entire length to form a cathode film (photoelectric surface 32).

In this embodiment, the image pickup device 30 has 256
The pixel pitch is 40 μm in rows × 256 columns, and the light transmitted through the color filters 40R, 40G, and 40B is diffused by about 40 μm on the light-receiving surface of the image pickup device 30 to correspond to the pixel pitch. The color filters 40R, 40G,
The width of 40B is set to 10 μm. Therefore, the pitch of the color filter array 33 is 10 μm, which is 1/3 or less of the pixel pitch of 40 μm, and the transmitted light from one color filter (or one or more color filters) is incident on the entire image pickup surface for one pixel. I am trying to do it. Color filter as shown 40R → 40G →
40B → 40R → 40G are sequentially arranged adjacent to each other in the vertical direction.

By configuring the color filter array 33 as described above, light transmitted through the color filters of the same color, for example, all the red color filters 40R is incident on the entire image pickup surface (light receiving surface) of the image pickup element 30 without leakage. It

In this embodiment, the light transmitted through the one color filter is incident on the entire surface of one pixel of the image pickup device, and the light transmitted through the color filter of the same color is supplied to all the pixels of the image pickup device 30. It is set so that the light is incident on all the light receiving surfaces without any leakage, but there is no problem even if the lights transmitted through the adjacent color filters of the same color are overlapped with each other as long as the requirement that all the light receiving surfaces are incident on the entire light receiving surface is satisfied.

Each of the above color filters 40R, 40G, 4
Wires 41, 42, 43 to be wired on the rear surface of 0B are connected to color filters of the same color and connected to switching means 44, 45, 46, respectively, and these switching means 44, 45, 46 are connected to the control section. Connected to 47.

The control section 47 controls the switching means 44, 45, 46 so as to be sequentially turned on in synchronization with the shuttering of the image pickup device 30. That is, the red filter 4 is synchronized with the shuttering of the image sensor 30.
Only the light transmitted through the 0R is emitted to the light receiving surface of the image sensor 30, only the light transmitted through the green filter 40G is emitted to the light receiving surface of the image sensor 30 at the next shuttering, and the blue filter 40B is emitted at the next shuttering. Only the transmitted light is emitted to the light receiving surface of the image sensor.

With the above configuration, first of all,
When the electrode 41 on the rear surface of the red filter 40R is turned on in synchronization with the shuttering of the image sensor 30, as shown in FIG. 4, the light transmitted through the red filter 40R is a pixel provided on the light receiving surface 30a of the image sensor 30. 50A, 50B, 50
It is incident on all of C ... without omission, and a red image is obtained. At the time of the next shuttering, the electrode 42 of the green filter 40G is turned on as shown in FIG.
The light transmitted through 0G is incident on all pixels without leakage, and a green image is obtained. Further, at the time of the next shuttering, the electrode 43 of the blue filter 40B is turned on as shown in FIG. 6, the light transmitted through the blue filter 40B is incident on all pixels without leakage, and a blue image is obtained.

As described above, a red image, a green image, and a blue image are sequentially obtained at the time of shuttering, and if the shuttering is set to 1/60 seconds or less, three images are combined and 20 minutes are combined. A color image is obtained every 1 second or less.

The present embodiment is not limited to the above configuration, and in the above embodiment, the light transmitted through one color filter is set to enter the entire surface of one pixel of the image pickup device. As shown in, the light from a plurality of color filters of the same color may be set to enter one pixel. Further, lights from the color filters of the same color may overlap each other on the pixel.

Further, as shown in FIGS. 8 and 9, transparent electrode films 60, 61 and 62 are used as electrodes to be attached to the rear surface of each color filter, and these electrode films can be attached to the rear surface of the color filter. . In that case, a gap 63 is provided between adjacent electrode films 60, 61, 62 so as to insulate the electrode films. Similar to the above embodiment, the electrode films attached to the rear surface of the same color are connected to the same switching means and are turned on in synchronization.

Further, although the color filter array 33 has the color filters arranged in the horizontal direction in the above embodiment, it may have a stripe shape in which the color filters are arranged in the vertical direction as shown in FIG. Furthermore, as shown in FIG. 11, a checkered Bayer array may be used. still,
In the case of the Bayer array, the wiring of the electrodes attached to the rear surface of each color filter becomes complicated as compared with the stripe array. In either case, there is no problem if the transmission light from the color filters of the same color is set to be incident on all the pixels of the image sensor.

Further, although the MCP type II is used as the light amount increasing device in the above-mentioned embodiment, another image intensifier, for example, a multi-tube image tube or a multi-stage image tube may be used. In any case, the color filter 8 may be attached to the front surface of the photocathode arranged on the front fiber glass of the image intensifier, as in the above-described embodiment.

[0048]

As is apparent from the above description, according to the present invention, in a photographing device using a light amount enhancing device suitable for ultra-high speed photographing, a stripe type color filter is provided in front of a photoelectric surface of the light amount enhancing device. Since the array is attached and the color filters of the same color are sequentially turned on in synchronization with the shutter ring and only the transmitted light of the color filter of the same color is received by the image sensor, there is a problem of color mixing.
The problem of alignment with the color filter is eliminated, and a color image with high resolution and high sensitivity can be obtained.

Therefore, there is an advantage that the amount of information is increased in various kinds of measurement photographing and the accuracy of measurement processing can be improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an entire imaging apparatus of the present invention.

FIG. 2 is a side view of essential parts showing a state in which a stripe type color filter is attached to the front surface of an MCP type II photocathode used in the present invention.

FIG. 3 is a schematic diagram showing a circuit of the stripe color filter and electrodes attached to the rear surface thereof.

FIG. 4 is a schematic diagram showing a relationship between a color filter and an image sensor.

[FIG. 5] Same as above

FIG. 6 Same as above

FIG. 7 is a schematic view showing a modified example of a color filter.

FIG. 8 is a schematic view showing a modified example of the electrodes attached to the rear surface of the color filter.

9 is a cross-sectional view of FIG.

FIG. 10 is a schematic view showing a modified example of a color filter.

FIG. 11 Same as above.

FIG. 12 is a view similar to FIG. 2 for explaining a conventional problem.

FIG. 13 is a view for explaining a problem in the case of using the conventional formula # 3.

FIG. 14 is a view for explaining a problem when a color filter is attached to the front surface of the photocathode.

[Explanation of symbols]

 2, 5 Fiber glass 4 Micro channel plate 30 Image sensor 31 MCP type II 32 Photocathode 33 Color filter 40R, 40G, 40B Color filter 41, 42, 43 Electrode 44, 45, 46 Switching means 47 Controller

Claims (1)

[Claims] 1. A light amount intensifying device is installed in front of an image pickup device, incident light is converted into photoelectrons by a photoelectric surface of the light amount intensifying device, and then converted into light having an increased light amount by a fluorescent surface and emitted. In the image pickup device in which each pixel of the element receives light, as the above-mentioned light amount intensifying device, fiber glass is attached to the front part and the rear part of the vacuum tube, and a microchannel plate having a large number of fine holes is arranged in the middle part. , Microchannel plate type image intensifier that converts incident light into electrons on the photocathode provided on the rear surface of the front fiberglass, passes through the microchannel plate, and then converts it to light on the fluorescent surface on the front of the rear fiberglass A color filter array is attached by baking onto the front surface of the photocathode. Together are sequentially stripe array of filters,
The stripe width of each color filter is set to ⅓ of the pixel pitch of the image sensor so that the transmitted light from the color filter of the same color can enter all the pixels of the image sensor, and each color filter is provided with an electrode. At the same time, the electrodes of the color filters of the same color are synchronized with each other, and three switching means are provided for each color to be turned on / off at different timings, and these three switching means are used as a shutter ring of the image sensor. A color video recording apparatus, which is provided with a control unit that is turned on in synchronization with each other.