JP2002354492A - Multi-lens and multi-ccd type image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-lens and multi-CCD type image pickup device capable of realizing improvement of the performance of the whole image pickup device and a reduction in the cost. SOLUTION: The multi-lens and multi-CCD type image pickup device is provided with image pickup elements 4, 5, 6 for R, G, B each having a light- receiving surface of the same size and processing circuits 7, 8, 9 therefor. The number of pixels of the image pickup element 6 for B is reduced compared to the number of pixels of image pickup elements 4, 5 for R, G. Conventionally, a gain of a processing circuit of a B channel is much larger than that of a G channel, and this causes the deterioration in the S/N(signal to noise) ratio of a chroma signal. However, in the above-mentioned constitution, since the sensitivity of the image pickup element for B is larger than those of image pickup elements of R and G, the gain of the processing circuit of B can be made to be small, thereby improving the S/N ratio of the chroma signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-lens, multi-plate type image pickup apparatus having a plurality of photographing optical systems and image pickup elements, and more particularly to improvement of performance and cost reduction.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram showing the configuration of a conventional multi-view, multi-plate type imaging apparatus. Most of the configuration is the same as that of the embodiment shown in FIG.

The blue (B) channel imaging device 6 is the same product having the same specifications as the other red (R) and green (G) channel difference imaging devices. Also, the drive pulse 34 from the TG 23
Is the same for each channel and the same for each imaging element (C
CD). The R, G, and B signals are input to the contour correction signal generation circuit 51, and a contour correction signal that constitutes a fine detail of an image in the video signal is generated.

FIG. 6 is a diagram showing the frequency characteristics of each channel in the above-mentioned conventional example. In this case, output signals 24, 2 from the amplifying blocks 7, 8, 9 of each channel are shown.
5 and 26, the frequency characteristics of each channel are the same.

FIG. 7 is a diagram showing an example of a signal processing circuit total gain difference between colors of a general three-panel camera. The gain of the B channel is as large as 12 dB (4 times) of the G channel, and this is mainly the case. This greatly affects the deterioration of the S / N (signal to noise) ratio of the chroma signal.

[0006]

In the case of the above-mentioned conventional example, that is, when the same specification is used for each image sensor, the blue (B) channel usually has a small spectral transmittance, that is, a poor S / N ratio. This has an effect on the output signal and contributes to the deterioration of the S / N ratio of the chrominance signal and the luminance signal.

On the other hand, the image pickup device is generally one of the most expensive components in the image pickup device, and the cost reduction of the image pickup device is a great proposition because the multi-plate type image pickup device is expensive and therefore expensive as a product. is there.

The present invention has been made under such circumstances, and it is an object of the present invention to provide a multi-lens, multi-plate imaging apparatus capable of improving the performance of the entire imaging apparatus and reducing the cost. Things.

[0009]

In order to achieve the above object, according to the present invention, a multi-view, multi-plate type imaging apparatus is configured as in the following (1) to (4).

(1) A plurality of photographing optical systems for condensing light from a subject, and each of the plurality of photographing optical systems corresponds to the plurality of photographing optical systems.
A plurality of image sensors having substantially the same size and a plurality of filters of the three primary colors of light or their complementary colors, and a processing circuit for output signals of the plurality of image sensors; and one or more of the plurality of image sensors A multi-view multi-panel imaging apparatus, wherein the number of pixels of an imaging element is smaller than the number of pixels of another imaging element.

(2) In the multi-lens, multi-plate type imaging apparatus according to the above (1), the specification of the sampling frequency in the imaging element having a smaller number of pixels than the number of pixels of the other imaging element is set to the integer number of the other imaging elements. A multi-lens, multi-plate imaging device with an integer of

(3) In the multi-view multi-panel imaging device according to the above (1) or (2), the number of pixels of the blue imaging device is smaller than the number of pixels of the red and green imaging devices. Multi-eye multi-plate imaging device.

(4) In the multi-view multi-chip type imaging apparatus according to (3), the contour correction signal generating circuit for generating a contour correction signal receives two red and green signals and generates a contour correction signal. Characteristic multi-view multi-plate imaging device.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to examples of a video camera.

[0015]

FIG. 2 is a conceptual diagram of a multi-view, multi-plate type imaging apparatus which is the basis of a "video camera" according to an embodiment. In this imaging apparatus, light from a subject is parallel light, that is, the subject has an infinite distance. Basically, it is a premise (parallax of each optical system becomes a problem at a short distance).

Light from the subject enters a red (R) lens 2, a green (G) lens 32, and a blue (B) lens 33, each of which is an R filter 29, a G filter 30, and a B filter 31.
To select each band light, and thereafter, the image pickup devices 4, 5, 6
To each of the color signals R24, G25, B
26.

In this case, a photographing optical system (hereinafter abbreviated as an optical system) is required for each color. However, since only the primary color light beams need to be passed, simplification can be achieved without considering chromatic aberration. It becomes possible. Further, by applying the present invention, it is possible to further simplify and reduce the cost of an optical system corresponding to an image pickup device having a small number of pixels, mainly in terms of resolution.

Next, a description will be given of a video camera of this embodiment which employs this multi-lens, multi-plate imaging system.

FIG. 1 is a block diagram showing the configuration of the video camera of the present embodiment. In FIG. 1, reference numeral 1 denotes light from a subject to be imaged, and the light enters respective optical systems (lenses) 2, 32, and 33, and then each of the three primary colors of light, red, green, and blue ( Hereinafter, these components may be abbreviated as R, G, and B).

Next, each of the three primary colors is an image sensor 4, 5,
6 and is converted into an electric signal. Then, the electric signals from the respective image sensors are input to the amplifier circuits 7, 8, and 9,
The amplitude of the signal is expanded at a predetermined amplification factor.

Next, among the outputs of the respective colors, the signals of all the colors are input to the luminance signal matrix circuit 10, and in the case of the signal of the NTSC system, the luminance signals are synthesized at the following ratios as well known. Is done.

Y = 0.30R + 0.59G + 0.11B Band 4.2 MHz Y: Luminance signal, R: R (red) signal, G: G (green) signal,
B: B (blue) signal In addition, two signals of R and G are input to the contour correction signal generation circuit 11, and a contour correction signal constituting a fine detail of an image in a video signal is generated.

Incidentally, the contour correction signal generation circuit 11
Does not receive the signal of B, but the signal of B is usually
There is a lot of noise, and the composition ratio of the luminance signal is about 1/10 of the whole as shown in the above equation. Even if this is omitted, there is almost no effect on the image quality, and on the other hand, there is also a problem that the noise increases. This is to be improved.

The luminance signal synthesized by the luminance signal matrix circuit 10 and the contour correction signal generated by the contour correction signal generation circuit 11 are added by an addition circuit 12 and input to a luminance signal processing circuit 13 for gamma, knee, and white clipping. And the like, a Y (luminance) signal 14 is output.

On the other hand, the R, G, and B signals are input to the color difference signal matrix 15, and an I signal 21 and a Q signal 22 are formed by the following equations.

I = −0.27 (BY) +0.74 (RY) Band 1.3 MHz Q = 0.41 (BY) +0.48 (RY) Band 0. 5 MHz Each of these signals passes through low-pass filters (LPFs) 27 and 28 for band limiting, and is then input to the color encoder 16 together with the subcarrier 17, and quadrature-modulates the subcarrier with each color difference signal. , Chroma (C)
Output as signal 18.

It should be noted that what is shown in FIG. 1 is only a basic block diagram for explaining the present invention,
In an actual product, an aperture is inserted between the lens and each color filter, and the amplification factors of the amplification circuits 7, 8, and 9 can be varied, and these are often controlled by a separately provided microprocessor.

In the above-described embodiment, the signals are output separately from Y (luminance) and C (chroma). This is based on the assumption that the S terminal is output. Can be obtained by adding an adder circuit.

The essential point of this embodiment is that the number of pixels of the image pickup device is different for R, G, and B. As an example, consider a case where the R and G image sensors have an effective pixel of 380,000 pixels, and a case where B has an effective pixel of 250,000 pixels.

FIG. 3 shows an example of comparison between CCDs having the same light receiving size and different numbers of pixels. The sensitivity of a 250,000-pixel CCD is 1.5 times that of a 380,000-pixel CCD, that is, about 3 times. A noise level improvement of a decibel high, ie about 3 dB, is possible. This is because the image sensor, especially the CCD,
For the same light receiving size, the smaller the number of pixels, the more
The circuit for transferring the photoelectrically converted charge is simplified, and the PD
This is because the area of the (photodiode) increases accordingly, and as a result, the so-called aperture ratio increases, and the sensitivity naturally increases. Also, if the number of pixels is large, fine processing is required, and the circuit becomes complicated, so that the cost naturally increases.

FIG. 4 is a diagram for explaining a difference in frequency characteristics of an output signal when an image pickup device having the same size and a different number of pixels is used. The characteristics are different from those of other channels, and the expansion in the high range is insufficient, but the composition ratio of the B signal of the contour correction signal that affects the expression of the details of the image in the luminance signal processing is zero, and the luminance signal itself is composed. Do B
The ratio of the channels is about 10% as shown in the equation, and there is no problem in both cases.

On the other hand, for the color difference signal, the required bandwidth of the I color difference signal is 1.3 MHz /-according to the NTSC standard.
The required bandwidth of the 3 dB, Q color difference signal is also 0.5 MHz
/ -3 dB, and there is no problem in the frequency band of the B channel.

On the other hand, the structure of the TG (timing generator) 23 is slightly complicated due to the necessity of driving the image pickup devices having different numbers of pixels.
As a result, the increase in production cost can be made small.

If the sampling frequencies of the above-described R, G and B-channel image sensors are set to "integer integer", that is, 1/2, 1/3, 2/3, etc., the TG Is simplified, and the relationship between the signal processing and the sampling frequency is simplified when the signal processing is digitized. Therefore, the sampling frequency conversion and the like are not complicated, and the image quality and the cost are increased. It has the advantage of being minimized.

In addition to the above-mentioned effects, a channel having a small number of pixels of an image pickup element is not required to have a high performance such as the resolution of an optical system, so that it is possible to further reduce the cost. In this case, it is possible to prevent a false signal (moiré) generated in a channel having a small number of pixels, and there is an advantage that the image quality is further improved.

The signal of the B channel is artificially made high-definition by a known appropriate circuit so as to match the number of pixels with the other channels.

As described above, according to this embodiment,
By reducing the number of pixels of one image sensor among the used image sensors, or by setting the sampling frequency of the image sensor to be reduced to an integer equal to the integer of the sampling frequency of the other image sensor, It is possible to improve the performance of the entire apparatus and reduce costs.

[0038]

As described above, according to the present invention,
It is possible to provide a multi-view multi-panel imaging device capable of improving the performance of the entire imaging device and reducing the cost.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment.

FIG. 2 is a conceptual diagram of a multi-view multi-panel imaging apparatus.

FIG. 3 is a diagram showing a difference between CCDs having the same size and different numbers of pixels.

FIG. 4 is an explanatory diagram of a frequency characteristic of each channel in the embodiment.

FIG. 5 is a block diagram showing a configuration of a conventional example.

FIG. 6 is a diagram showing frequency characteristics of respective channels in a conventional example.

FIG. 7 is a diagram illustrating an example of a total gain difference of a signal processing circuit for each color of a three-chip camera.

[Explanation of symbols]

 Reference Signs List 1 light from subject 2 red (R) lens 4 red (R) image sensor 5 green (G) image sensor 6 blue (B) image sensor 29 red (R) color filter 30 green (G) color filter 31 blue (B) ) Color filter 32 Green (G) lens 33 Blue (B) lens

Claims (4)

[Claims] 1. A plurality of photographing optical systems for condensing light from a subject, a plurality of filters of three primary colors of light or their complementary colors and a light receiving surface size corresponding to each of the plurality of photographing optical systems being substantially the same. A plurality of image sensors, a processing circuit for output signals of the plurality of image sensors,
A multi-view multi-panel imaging apparatus, wherein the number of pixels of one or more imaging elements in the plurality of imaging elements is smaller than the number of pixels of other imaging elements. 2. The multi-view multi-panel imaging apparatus according to claim 1, wherein the specification of the sampling frequency in the image pickup device whose number of pixels is smaller than the number of pixels of the other image pickup device is an integer corresponding to an integer thereof in the other image pickup device. A multi-view, multi-plate imaging apparatus characterized by the following. 3. The multi-view multi-panel imaging device according to claim 1, wherein the number of pixels of the blue imaging device is smaller than the number of pixels of the red and green imaging devices. Imaging device. 4. A multi-view multi-panel imaging apparatus according to claim 3, wherein the contour correction signal generating circuit for generating the contour correction signal receives two red and green signals and generates a contour correction signal. Multi-lens image sensor.