JPS62104294A - Multi-board type image pickup device - Google Patents

Abstract

PURPOSE:To reduce the cost by increasing the size of a picture element of at least a solid-state image pickup element more than the size of a picture element of other solid-state image pickup element so as to decrease number of picture elements of a CCD with simplified optical system without decreasing the sensitivity. CONSTITUTION:The 1st sensor CCD 1a consists of a full color transmission color signal filter and number of horizontal picture elements is, e.g., 570 picture elements, and the 2nd sensor CCD 2a consists of a color separation filter transmitting red and blue color, and the difference between the CCD 2a and the CCD 1a resides in that the number of horizontal picture elements of the CCD 2a is 285 picture elements, which a half of that of the CCD 1a. Thus, a luminance signal of a nearly 5.4MHz band is obtained from the sensor CCD 1a and a color signal of nearly 1MHz band is obtained from the sensor CCD 2a. When a half mirror 20 has the transmitivity of 50%, the CCD 2a has a higher sensitivity than that of the CCD 1a by the size of the picture element area, but the CCD 2a is of R, B transmission type, the S/N is nearly the same practically.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a multi-plate imaging device with improved sensitivity and dynamic range.

[Conventional technology]

In conventional sensors, the light-receiving areas of pixels for obtaining complementary colors and pixels for obtaining pure colors are the same, so the sensitivity of the solid-state image sensor is limited by the pure color signal. For example, when comparing a complementary color transmitted through a gold transmission filter and a pure color transmitted through a pure color transmission filter, the former has lower sensitivity as an image sensor than the latter, with a sensitivity difference of about 3 to 4 times. There is. Therefore, even in a multi-chip imaging device having a plurality of solid-state imaging devices, its sensitivity is limited by the solid-state imaging device for obtaining pure color signals.

[Problem that the invention seeks to solve]

The conventional imaging device as described above has the following problems.

Generally, the bands of luminance signals and chrominance signals are different, but even taking this into consideration, there is a problem with the S/H of luminance signals and chrominance signals. Now, the luminance signal band is approximately 4MH2°, and the color signal band is approximately IMH.
2, the S/N of the color signal to the luminance signal is approximately 6d.
Although this is an improvement in B, even taking this into consideration, the S/N of the chrominance signal is about 3 to 5 dB worse than the S/N of the luminance signal.

The second problem is the dark current unevenness of the sensor caused by the difference in sensitivity between pixels for obtaining pure colors and pixels for obtaining complementary colors. In particular, dark current unevenness that exists within the color signal band cannot be expected to be reduced by reducing the sensitivity difference caused by the band limitation described above.

The third problem is that the dynamic range of the sensor is limited due to the difference in S/N between the color signal and the luminance signal.

Another problem with multi-plate imaging devices is that there is a problem with the accuracy of positioning of each sensor.

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to provide a multi-plate imaging device with high sensitivity and high resolution.

[Means for solving problems]

In the multi-chip imaging device according to the present invention, the size of the pixel of at least one solid-state image sensor has a different shape compared to the size of the pixel of the other solid-state image sensor.

[For production]

In this invention, since the pixel size of each solid-state image sensor is different compared to the pixel size of other solid-state image sensors, the light-receiving area of each element is different. Adjusts the sensitivity difference between the signal and color signal.

〔Example〕

FIG. 1 is a layout diagram of a sensor and a color separation filter showing an embodiment of the present invention. The first sensor CCD 1a is composed of a color separation filter that transmits all colors, and the number of horizontal pixels is, for example, 5.
It has 70 pixels, and the second sensor CCD2a consists of a color separation filter that transmits red and blue.
The difference from CD1a is that the number of horizontal pixels of the sensor is CCDI&
The number of pixels is 285 pixels, which is half of the total number of pixels.

Therefore, a luminance signal with a band of about 5.4 MH2 is obtained from the sensor CCD1a, and a luminance signal with a band of about IM2 is obtained from the sensor CCD2a.
A color signal in the H2 band is obtained.

FIG. 2 is a schematic diagram of the optical system of the imaging device, in which 10 is a photographing lens, 20 is a half mirror, 130 is a reflecting mirror, and 40
is CCD1a in FIG. 1, and 50 is C0D2a in FIG. Assuming that the half mirror 20 has a transmission characteristic of 50 inches, the CCD 2a has a higher sensitivity than the CCD 1a due to its larger pixel area. However, in reality CCD
1a is transparent for all colors, and CCD 2a is transparent for R and B, so if you take that into account, the S/N will be great! It can be said that they are close to being the same.

1g 3 is a signal processing block diagram for the signals obtained from the apparatus in FIG. 2, 60 is a drive circuit for each image sensor, 70 is a clock generator, 80 is a band pass filter (BPF), 90.100° 110 120 is a matrix circuit, 130 is a process circuit M, 14U is an adder, and 150 is an encoder.

In the device constructed as shown in FIG.
Color No. 15 B' via color signal RsLPFtto with 00
4 is obtained, and the color No. 11 R and B are subtracted in a matrix from the brightness No. 100 Y to generate the G1 g signal. Low I in the process circuit 130 from these R, G, and H numbers.
tc luminance signal Y1 is formed, and this low-range luminance signal YL is applied to the low-range luminance signal YL from CCL) lan) through BPF8U.
The signal Y□ is multiplied by the square U calculator 140 to obtain the NTSC j4 degree signal Y.

FIG. 4, FIG. 5, and FIG. 6 are layout diagrams of sensors and color separation filters showing other embodiments of the present invention.

In FIG. 4, when the CCD 1b is provided with a half mirror 20 with a reflection of 67 and a transmission of 33%, the sensitivities of the G, R, and B signals become almost the same. In this example, the sensitivity is further improved by using a prism, but as shown in Fig. 2, a half mirror is used.
20 has the advantage of simplifying the optical system. In this method, the signal processing circuit shown in Figure 3 is
20 is unnecessary. For the high-frequency luminance component, the G signal obtained from the R and B signals is used.

The CCD 2C in FIG. 5 is different from the embodiments in FIGS. 1 and 4. In FIG. 5, the number of pixels in the vertical direction of pixel B for obtaining color signals is reduced. This is a color arrangement that takes advantage of the fact that the spectral sensitivity of the eye may be coarse for the color signal B.

FIG. 6 shows the arrangement of pixels of each image sensor by applying the color difference line sequential recording method to each horizontal scanning line.

〔Effect of the invention〕

As explained above, this invention allows the use of a COD with a smaller number of pixels without reducing the sensitivity of the camera even if the optical system is simplified, thereby reducing costs and lowering the horizontal transfer frequency. Further, there are effects such as being able to reduce power consumption.

[Brief explanation of drawings]

Fig. 1 is a layout diagram of a sensor and color separation filter showing an embodiment of the present invention, Fig. 2 is a schematic diagram of an optical system of an imaging device, and Fig. 3 is a signal processing block for the signals obtained from Fig. 2. 4, 5, and 6 are layout diagrams of sensors and color separation filters showing other embodiments of the present invention. In the figure, 60 is a drive circuit, 70 is a clock generator, 80 is a BPF, 90, 100, 110 are LPFs,
120 is a matrix circuit, 130 is a process circuit, 14
0 is an adder, and 150 is an encoder. Agent Patent Attorney 1) Haru Kitatake Figure 5 Figure 6

Claims (1)

[Claims] In a multi-chip imaging device consisting of a plurality of solid-state image sensors for obtaining a luminance signal, the size of the pixel of at least one solid-state image sensor for obtaining a color signal is determined by the size of the pixel of the solid-state image sensor for obtaining a luminance signal. A multi-plate imaging device characterized by being larger than the size of.