JPS5838027B2 - Color Kotai Satsuzou Sochi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color solid-state imaging device that uses a solid-state imaging plate to extract color image signals.

Camera tubes such as planpicon and videocon are generally used to convert the image of the subject into television signals, but recently solid-state recording plates have been attracting attention.

Solid-state imaging plates include a combination of a charge transfer element coupled to a photosensitive element such as a photodiode, a structure in which the light receiving section also serves as a charge transfer element, or a structure in which a large number of photosensitive elements are arranged in a lattice pattern. There are things like photodiode arrays that read sequentially to obtain a continuous video signal.

Regarding charge transfer devices, as explained in Japanese Patent Application Laid-Open No. 46-1211 and elsewhere as a charge-coupled device (hereinafter referred to as CCD), two-phase, three-phase, three-phase, Alternatively, an electrode wired in a four-phase structure is provided, and if the semiconductor substrate is an N-type semiconductor, a negative potential is applied to this electrode to create a depletion layer in the semiconductor, and the potential of this electrode is By sequentially moving, the depletion layer is also moved.

If charges are injected into this depletion layer, the charges can be sequentially moved as the depletion layer moves.

An example of a solid-state imaging board using this principle is shown in FIG.

In Figure 1, 1-1, 1-2, 1-3, 1-4,
. . . 1 -N are vertical CCDs that each transfer charges in the direction of the vertical arrow.

The transfer pulse for vertical transfer is synchronized with the horizontal synchronizing pulse of the television signal.

2 is a photosensitive element such as a photodiode, and vertical C
It is provided along the CD, and charges are accumulated depending on the intensity of light.

Then, after a certain period of time has elapsed, this accumulated charge is simultaneously injected into the vertical CCD.

The injected charges are sequentially transferred in the direction of the horizontal arrow by pulses synchronized with the horizontal synchronization signal.

3 is a horizontal CCD which horizontally transfers charges transferred to corresponding positions from a plurality of vertical CCDs.

Then, the charge is transferred using a horizontal transfer pulse having a frequency such that the charge is completely transferred in the direction of the arrow within the horizontal period, and a signal for one line is obtained from the output terminal 4.

After repeating this process and reading out all the charges on the vertical CCD 1 from the output terminal 4, the charges accumulated in the photosensitive element 2 are injected again.

The same reading is repeated to obtain a continuous television signal.

5 is a horizontal transfer pulse generator, and 6 is a vertical transfer pulse generator, which may be two-phase, three-phase, or four-phase.

When obtaining a color television signal, three such imaging plates are generally used, each receiving light separated by a dichroic mirror to obtain a signal for each color.

This corresponds to the imaging method of a three-tube color television camera that uses three imaging tubes.

However, unlike the three-tube type using three imaging tubes, very fine precision is required for positioning each imaging plate.

As is well known, imaging tubes generally deflect electron beams using a magnetic field, and after the optical axes are approximately aligned, the fine images are superimposed on each other by passing a direct current through the deflection coil to create the entire image. The position of can be moved.

On the other hand, a camera plate cannot be aligned like a camera tube, and its swing width cannot be adjusted.

Therefore, there is no other choice but to do all of this mechanically.

In order to reduce or omit the number of adjustment points, a two-plate system or a single-plate system can be considered.

Are Figures 2 and 3 one of the ones that have already been proposed? This is an example of a single-plate color solid-state imaging device that generates color signals using a imaging board.

Figure 2 shows a striped color filter.
, 8 and 9 are color filter elements that pass red, blue and green spectral light, respectively.

By placing this color filter on the solid-state imaging board shown in Figure 1, an output signal containing red, green, and green signals can be obtained point-sequentially. , the three primary colors can be extracted by sampling and separating as shown in FIG.

In FIG. 3, reference numeral 11 denotes a solid-state imaging board provided with a stripe filter as shown in FIG.

A point-sequential output signal obtained from the solid-state imaging board 11 is applied to a sampling circuit 15 via an amplifier 12.

On the other hand, the horizontal transfer pulse from the signal generator 13 is waveform-shaped through a waveform shaping circuit 14 to the phase and width of each color component signal, and is applied to a sampling circuit 15 to separate each color component signal from the output signal. used.

A standard color signal 17, which is applied to an encoder 16, is extracted from the separated color signal.

In addition, without sampling separation, the output signal obtained from the solid-state sensing plate is passed through a band-pass filter whose center frequency is the repetition frequency of red, blue, and green of the stripe filter, and is then used to generate a horizontal transfer pulse or the like. It is also possible to perform synchronous detection using a reference signal obtained by processing a horizontal drive pulse to obtain a color difference signal.

However, according to these color signal separation methods,
Since stripe filters of three colors are used and corresponding photosensitive elements must be provided, three times the number of elements is required to obtain the same degree of disassembly as a black and white photographic plate.

This means that three times the imaging area is required for colorization, but increasing the imaging area is extremely difficult in manufacturing, and a colorization method that requires as small an area as possible is required.

SUMMARY OF THE INVENTION An object of the present invention is to propose a color solid-state imaging device that can generate a color image signal by using one or two solid-state imaging plates, and can reduce the area of the required imaging section.

The invention basically consists of a set of substantially different color sensitive photosensitive elements along a horizontal line (e.g. a photosensitive element itself having spectral sensitivity characteristics or a combination of a color filter and a photosensitive element). A first example of a photosensitive element in which a plurality of sets of photosensitive elements that are substantially sensitive to different colors are repeatedly provided along a horizontal line is alternately arranged in the direction of vertical readout. At the same time, in continuous horizontal scanning, a first color signal is transmitted from the first photosensitive element column, and a second color signal is transmitted from the second photosensitive element column.
The color signals of By ensuring that the resulting color signals are each subjected to predetermined processing, two
This method obtains two different color difference signals.

Although the luminance signal can be extracted using another solid-state imaging board, it can also be obtained from the low-frequency component of the output signal.

Therefore, for example, it can be used as a single-cover type color solid-state imaging device using only one solid-state imaging board as shown in Fig. 1, and the area of the imaging part can be reduced as shown in Figs. 2 and 3. This makes it possible to make the device even smaller than conventional devices.

The present invention will be described below using actual winding examples.

4 to 6 are diagrams showing an actual case of a color solid-state imaging device according to the present invention. In FIG. 4, a mosaic color filter as shown is superimposed on the solid-state imaging plate shown in FIG. 1. This shows the camera team that was set up.

In the figure, the photosensitive element group and the vertical transfer stage are omitted to simplify the drawing.

In the figure, 21 is a color filter element that passes red (auto), 22 is a color filter element that passes each color spectrum of cyan 0, and these elements are arranged alternately along the horizontal line (horizontal readout direction) 25 shown by a dotted line in FIG. are arranged repeatedly.

Further, 23 is a color filter element, and 24 is a color filter element that passes each color light of yellow (Ye), which are similarly arranged alternately along a horizontal line 26 shown by a dotted line.

As is clear from Figure 4, the color filter is horizontal line 2.
The rows of color filter elements along 6 and 26 are
They have a structure in which they are alternately and repeatedly arranged in the vertical reading direction.

In the area under each color filter, a photosensitive element corresponding to one pit, or two bits in the case of interlaced scanning, is provided corresponding to each color filter element.

The amount of signal charge corresponding to the strength of the light that has passed through each color filament element accumulated in the photosensitive element group is transferred to the corresponding position of each vertical transfer stage every fixed period (1 frame or 1 field). .

This signal charge is transferred line by line in the vertical read direction shown by the arrow 27 by a vertical transfer pulse generated during the horizontal blanking period, and read into the corresponding position of the horizontal transfer stage 281.

Furthermore, the signal charge is transferred in the horizontal readout direction shown by an arrow 282 by a horizontal transfer pulse generated during the horizontal scanning period, and an output signal 29 is obtained via a signal charge detection section 283.

FIG. 5 shows one horizontal scanning signal obtained when equal white light is projected onto all the color filters arranged as described above.

4A shows the output signal obtained by one horizontal scan k corresponding to the position 25 shown in FIG. 4 as E,(t) with respect to the time axis t.

Now, when the horizontal transfer pulse applied to the horizontal transfer stage is a two-phase type, this horizontal transfer pulse frequency fH is twice the fundamental frequency of E1(t).

In addition, the opening in the same figure shows the output signal E2(t) from the horizontal scan that follows the horizontal scan that provides the above output signal E1(t), for example, the output signal E2(t) obtained by one horizontal scan corresponding to the position 26 in FIG.
This is what is shown.

Since cyan C is a color obtained by adding green G and center color B, and yellow Ye is a color obtained by adding green G and red R, a signal having a center value as shown in FIG. 3 is obtained.

When the repetition angular frequency of the color filter in the horizontal direction is ω, if the output signals obtained by each horizontal scan of E, (t), and E2 (t) shown in Fig. 5A are subjected to Fourier expansion, the following is obtained. It is expressed as

E1(t) and E2(t) are obtained alternately for each successive horizontal scan.

An example of a configuration for generating color signals from these output signals is shown in FIG.

In FIG. 6, a color difference signal is obtained using a synchronous detection method, and 41 is a color solid-state imaging plate provided with a color filter array as described above, which corresponds to that in FIG.

Reference numeral 42 denotes a transfer clock generation circuit for driving the color imaging board 41, and the horizontal transfer clock pulse generated here is applied to the color solid-state imaging board 41 and is simultaneously applied to the pulse processing circuit 4.
I am guided by 3.

43 is a pulse processing circuit that divides the horizontal transfer pulse frequency fH into 1/2, assuming that the horizontal transfer pulse is of a two-phase type as described above.

44 is obtained by adding the output signals E1(t) and E2(t) obtained from the output terminal 441 of the color solid-state imaging board 41 to form the equation (1)? (2) is the signal E 1 (t) t
E2( tΦ Each fundamental wave E'l(t), Bi2(
t).

Here, Et(t)+tE2(t) is expressed as follows.

E'1(t)={R (G+B))cosωtE'2
(t)-{B-(G+R)} cos ωt Output E'i (t) of the bandpass filter 44 (where i =
1,2) is the delay line (referred to as LH) for one horizontal scanning period (LH).
It is led to an IH delay line 145 and input terminals a and d of a switch circuit 50 shown in the figure.

On the other hand, the output of the IH delay line 45 is output to the switch circuit 50.
is led to input terminals b and C of.

Output terminals e and f of the switch circuit 50 are connected to a and b, respectively, during the IH period in conjunction with each other, and are connected to input terminals C and d during the next IH period.

This switch circuit 50 is shown here in a simplified manner for operation explanation, but for example, by a pulse synchronized with the vertical transfer pulse φ. It can be constructed by a switch circuit that is controlled to connect to either one.

The signals obtained from the output terminals e and f through such a switch circuit 50 correspond to E'1(t) and E'2(t), respectively.

46 and 47 are signals E '1 (t) t E '2 (t
) is added and synchronous detection is performed using the pulses obtained from the pulse processing circuit 43, and two types of color difference signals R C ,
This is a synchronous detector that obtains B Ye.

Here, C is a cyan signal (G+B), and Ye is a yellow signal (G+R).

48 is a low-pass filter, and the signal extracted through this filter is R+G+B as seen from equations (1) and (2).
becomes.

49 is a color encoder to which the outputs of the synchronous detectors 46, 47 and the low-pass filter 48 are applied to create a decoded color signal.

Now, when a signal is read out from the photosensitive element array along the horizontal line 25 in a certain horizontal scan, the bandpass filter 44
The output of the IH delay line 45 is E 1 (t), and the output of the IH delay line 45 is E 2
(t), but it is reversed in the next horizontal scan.

The switch circuit 50 serves to internally connect the output terminal eyf to the input terminals a, b and cod for each IH,
As a result, the synchronous detector 46 always detects the f-R-C signal, and the synchronous detector 47 always detects the B-Ye signal.

As is clear from the above practical example, the color solid-state imaging device according to the present invention includes a first photosensitive element array that is sensitive to a plurality of different colored lights, and a second photosensitive element array that is different from the first photosensitive element array. Using imaging means provided alternately in the vertical direction,
A color solid-state imaging device that generates line-sequential color signals through continuous horizontal scanning, converts and demodulates these line-sequential signals simultaneously, and generates simultaneous color signals, and uses a single imaging plate with a small imaging area. becomes possible.

Furthermore, in the present invention, the obtained first and second color signals are synchronously detected using a reference signal obtained by frequency-dividing the horizontal readout pulse, thereby detecting the first and second baseband color signals. Since simultaneous color difference signals are obtained and used to convert them into carrier color signals for standard color television signals, signal processing such as color temperature correction and white balance correction during shooting can be performed at the baseband color difference signal stage. It is something that can be done easily and yields something that is easy to handle.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional solid-state imaging board that combines a photosensitive element and a charge transfer element, Figure 2 is a diagram showing a three-color striped color filter, and Figure 3 is the color filter shown in Figure 2. FIG. 1 is a block diagram of a conventional color solid-state imaging device that obtains color signals by overlaying a color signal on a solid-state imaging board shown in FIG. The block diagram shown in Fig. 5A,
The mouths are diagrams showing the output signals of the imaging board in Figure 4 and Figure 6, respectively.
The figure is a block diagram of a signal processing circuit for generating color signals in the same case. 21-24...Color filter element,
41...Color image pickup plate, 42...Transfer clock generation circuit, 44...Band filter, 4
5... IH day line, 46, 47...
...Synchronous detector, 50...Switching circuit.

Claims (1)

[Claims] 1. A first photosensitive element row in which a plurality of sets of photosensitive elements sensitive to light of substantially different colors are repeatedly provided along a horizontal line; The first
an imaging means for repeatedly arranging a row of photosensitive elements and a different second row of photosensitive elements in a vertical readout direction; a means for generating a pulse for driving the imaging means; means for alternately reading out a first color signal from the l-th photosensitive element column and a second color signal from the second photosensitive element column as output signals in a horizontal scan; a delay means for delaying by a period; means for obtaining simultaneous signals of the first color signal and the second color signal from the output of the delay means and the output signal; and frequency division of the horizontal read pulse in the drive pulse. a first synchronous detection circuit that obtains a first color difference signal by synchronously detecting only the first color signal in the simultaneous signal using the reference signal; By synchronously detecting only the color signal of
1. A color solid-state imaging device comprising: a second synchronous detection circuit for obtaining a color difference signal; and means for converting the first and second color difference signals into a carrier color signal.