JPH0528037B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates in particular to a color television camera having a solid-state imaging device. The present invention relates to a single imager type color camera combined with a line transfer type imager.

[Conventional technology]

In order to realize a single image sensor type color camera, a solid-state image sensor, a mosaic of color filters,
It is necessary to combine it with a processing circuit for video signals from a solid-state imaging device. In fact, many structures have been proposed for solid-state imagers for single-imager color cameras.

For example, in one of the structures actually used, a line transfer type imaging device is configured as follows. A photosensitive area containing m p photocells is coupled to two control registers with logical delays, which select the even and odd rows and place the even columns of the matrix of photocells in the first and the odd columns of the matrix are connected to a second line memory. The two charge transfer delay registers each contain a half line of video.

The operating principle of such an imaging device can be summarized as follows. That is, a line of m photocells is selected by the first delay register if the line belongs to an even row, and if the line belongs to an odd row.
selected by the second delay register. Therefore, when one line is selected, the charges accumulated in that photocell are transferred to the line memory, but at this time, the charges of the even-numbered photocells belonging to the same horizontal scanning line are transferred to the first line memory. This is because the charges of the photocells in odd-numbered columns are sent toward the second line memory.

The contents of the memory are then transferred to the output delay registers and these two registers are read in time with the television to provide one video line. With this configuration, pixel information can be extracted from each photocell at high speed.

[Problem to be solved by the invention]

Although the imager is read frame-by-frame or field-by-frame, the storage capacity of each delay register is equal to half a line of video, so only a single video line with its respective line period is seen by the imager. You can get it. These types of imaging devices are not compatible with line-to-line coupling.

For this reason, the mosaic of color filters combined with the imaging device preferably has a Bayer type structure, in which the same color filters are combined on two consecutive lines. That is, the same color filters are included, such as alternating green and red for the first group of lines, then blue and green for the second group of lines.

The processing circuitry that is combined with the imager and the color filter can take many forms;
To obtain color and luminance information, two consecutive lines of the same frame are combined in a processing circuit to calculate the chrominance (green, red and blue).
It is necessary to obtain all sample signals and brightness of

Therefore, in order to obtain these sample signals and create color difference signals, a line with a delay of one horizontal scanning period is required. Such a combination of two consecutive lines of the same frame (thus these two lines being separated by one line of the other frame) results in a loss of vertical resolution;
For this reason, lines in diagonal directions cannot be reproduced well. Furthermore, such a structure requires a delay line.

The object of the present invention is to realize a new color television camera with a solid-state imaging device that does not have the disadvantages of the prior art mentioned above without affecting the other properties of the camera, namely sensitivity and horizontal resolution. It is in.

[Means to solve the problem]

A color television camera having a line transfer type solid-state imaging device according to the present invention has the following features. That is, the line transfer type imaging device includes means for selecting successive lines of a matrix for transferring charges accumulated in photocells of a photocell matrix, and even columns and rows of one line of said photocell matrix. The odd numbered rows of photocells are each connected to one of two memories by a conductive column, each of said two memories having:
The conductive columns associated with the even points of one line are associated at the same time with the odd points of the next line, which are associated with a delay register at the output having a storage capacity equal to one line of the photocell matrix. The electric charge generated from the entire two five-dot pattern photocells is transferred to two of the output sections.
The charges accumulated in the even-column photocells of one line and the odd-column photocells of its adjacent preceding or subsequent line are transferred to each of the two delay registers during the same retrace interval and a matrix of complementary color filters of yellow, cyan and magenta is placed in the photocell matrix, and one of the photocells in a quincunx pattern is entirely covered with a yellow filter; , the entire photocell of the other five-point pattern is covered alternately line by line, with a cyan filter on one line and a magenta filter on the next line, and the processing circuitry The signals output from the two delay registers of the output section resulting from the combination of two consecutive lines of the photocell matrix are directly combined to output a chrominance signal and a luminance signal.

[Effect]

In order to solve the above-mentioned problems, as mentioned above, the color television camera according to the present invention uses a special line-transfer type imaging device in which a matrix of photocells and conductive cells connecting these photocells to a memory are used. The sex column is composed of two independent structures.

In these independent structures, the photocells are arranged in a quincunx pattern. This allows even-numbered points on one line and odd-numbered points on the line following it to be transferred to the same line memory. Furthermore, a complementary color filter and a particularly simply combined processing circuit are combined.

The invention will be better understood, and other features of the invention will become clear, from the following description of the embodiments, which refers to the accompanying drawings.

〔Example〕

FIG. 1 schematically shows a camera having a solid-state imaging device. The camera thus includes a color filter 10 placed in front of a single imager 20 of line transfer type. The line transfer imaging device used in the camera of the invention includes two line memories connected to a photosensitive matrix, each of which is connected to an output register.

To this end, the illustrated line transfer imaging device has two output parts emitting signals S ₁ and S ₂ , which are applied to the input part of the processing circuit 30 . The processing circuit converts the color television signal into three components: luminance Y and two different color difference components D _R and D _B.

FIG. 2 is a schematic diagram of a line transfer type imaging device used in the camera of the present invention. The imaging device includes a photosensitive area 1 forming a matrix of m lines (for example m=576), each line consisting of p photocells, for example from index i=1 to p (for example p=576). The photocell is connected to two line selection delay registers 2 and 3. That is, the first line selection delay register 2 is connected to the lines of odd columns of the matrix,
The second line selection delay register is connected to the even column lines of the matrix.

The charge stored in the photocell is transferred by the conductive column as follows. That is, the conductive column C _i connects the odd line photocells located in the i column on the one hand, and the even line photocells located in the i+1 column of the matrix on the other hand. One of the two adjacent conductive columns is connected to a first line memory 4 and the other conductive column is connected to a second line memory 5. These line memories 4 and 5 each have p/2 memory elements.

The parallel output parts of line memories 4 and 5 are
It is connected to p/2 parallel inputs of delay registers 6 and 7 of the charge transfer output. Two independent structures are thus defined, and in each structure the pixels are arranged in a quincunx pattern.

The selection of lines carried out by either register 2 or 3 is done so as to simultaneously select the pixels associated with one quincunx pattern structure and the pixels associated with the other quincunx pattern structure.
The number of conductive columns connected to each line memory is equal to half the number p of pixels in one line, but the complete output of the information of delay registers 6 and 7 has a duration of one line. However, these delay registers include, for example, p stages.

In such a structure, selection registers 2 and 3 are both active during the readout of one frame, and for each frame the imagers are all readout. That is, this imaging device as a whole is read out every 20 milliseconds, which is because the odd lines ln and even lines of the matrix are read out every 20 milliseconds to form the odd horizontal scanning lines Ln of the image, as shown in FIG. Lines ln' are combined, while even lines ln' and odd lines ln+1 of the matrix are combined to form even horizontal scan lines Ln' of the image.

The storage period in the photocell is therefore reduced by half compared to the storage period of the photocell in the conventional structure shown at the beginning. In this way, the structure of the color filter and the combined processing circuit are
If similar to the processing circuit described above, a camera using such an imaging device would have half the sensitivity.

In order to avoid these inconveniences, a color filter 10 combined with this line transfer type imaging device is used.
takes a special configuration. This color filter is made up of a filter mosaic of complementary colors. This color filter is shown in FIG. This color filter is used for odd lines of the matrix, for example, yellow filter J.
and cyan (turquoise blue) filters C are arranged alternately. All odd-numbered lines have a similar alternating arrangement. The color filters on the even-numbered lines are a magenta filter M and a yellow filter J, which are arranged alternately, and a similar alternating arrangement is made on all the even-numbered lines.

For this reason, the yellow filter J covers the photocells located in a quincunx pattern. Here, in this specification, the term "five-point pattern" refers to a pattern where the basic pattern is made up of the four corners and the center point of a square, like the five numbers of a die. Use as meaning. In Figure 3, it can be seen that ``J'' is exactly in this ``quincunx pattern''.

That is, all sample signals of the yellow filter J correspond to one of the two quincunx pattern structures of the imaging device.

This mosaic is not broken down into frames, since all imaging devices are read to create the television frame. Such a reading method is illustrated by the waveform of the control signal shown in FIG.

During the line retrace period of the video signal, reading of two consecutive lines is commanded. Therefore, the selection command signals C _S2 and C _S3 applied to the selection registers 2 and 3 are signals shown on this waveform. The pulse of C _S2 transfers the charges stored in the photocells of line n to the two line memories 4 and 5. The C _S3 pulse then commands the reading of the charge stored in the photocells belonging to column n' of the matrix.

Both pulses occur during the same retrace interval. By changing the state of the voltage applied to the transfer command input part φ _C of the line memories 4 and 5, it is possible to transfer the contents of these memories in the output registers 6, 7, after which each new charge Transfer takes place.

As mentioned above, each output register has a length comparable to a video line, so that one half line belongs to line n of the matrix and the other half line belongs to the next line n' of the matrix of photocells. Because it contains a quincunx pattern of photocells, the contents of one line are stored in each output register twice as long. The transfer and delay clock signals H _T and _HD in the output registers command charge output to the output portions S ₁ and S ₂ of these output registers.

Thus, after reading out two successive lines n and n' with the sample signals obtained as a result of the filtering performed by the color filters shown in FIG. , has the contents shown in FIG.

The signal S ₁ is formed by sample signals that all correspond to the yellow component of the image, the yellow sample signals of two consecutive lines n and n' of the quincunx pattern in the matrix being transmitted in a continuous manner; They are combined at the output portion of the delay register 6. Signal S ₂
is formed by sample signals corresponding alternately to the magenta and cyan components of the image, each previously taken out on a quincunx pattern of sample signals in two successive lines of the photocell matrix. The two components are combined.

The processing circuit shown in FIG. 6 allows the components of the video signal to be obtained simultaneously by means of these two signals S ₁ and S ₂ . The output of register 6 is connected to the input of sample circuit 31, which is commanded by clock signal _H2 . The output part of the delay register 7 which provides the signal _S2 is connected to the clock signal S2.
Connected to the input parts of two sample circuits 32 and 33 commanded by H ₂ and H ₃ .

The clock signals H ₁ , H ₂ , H ₃ and the output signals S _J , S _C , S _M of the sample circuits 31, 32, 33) are shown in FIG. These three sample circuits are connected to a filter circuit and a matrix circuit 34, which is
Pseudo luminance S _MF signal and red R, by three color signals corresponding to yellow, cyan and magenta components.
Generates green V and blue B color signals.

These signals are obtained in the following form.

S _J +S _M -S _C =2R aS _J +bS _C +cS _M =S _HF (However, a, b, c are equilibrium coefficients) S _J +S _C -S _M =2V S _M +S _C -S _J =2B For this purpose, the signals R, V, B resulting from such a combination are filtered in low-pass filters 35, 36, 37 with a cut-off frequency F _C =750 KHz.

Therefore, the luminance signal Y _BF with low frequency is
It is obtained by linear summation of the above three signals.

Furthermore, _{the cutoff frequency F C =}
The two consecutive _lines n and
Eliminates the noise resulting from multiplexing n′. The outputs of filters 35, 36, 37 and 39 are provided by known matrixing, encoding and video processing circuits 4.
0, and this circuit, by the components R, B, Y _BF , after normal processing,
In other words, after adjusting the white level and black level, adjusting constant brightness, and correcting gag, the color difference component _DR and
D _B and brightness Y, D _R = R−Y _BF , D _B = B−
Y _BF , Y=Y _BF +KY _HF is generated.

The treatments described above are not the only treatments that can be taken from components S _J , _SC and _SM .

In fact, in this first case, we perform spatial averaging over several pixels to obtain the signal S _HF ,
Camera sensitivity is prioritized at the expense of horizontal resolution. On the contrary, in the first aspect described below, the pseudo luminance is obtained exclusively from the yellow sample signal, so horizontal resolution is prioritized at the expense of sensitivity.

In this first aspect, the high frequency luminance signal
Y _HF is obtained exclusively from the signal S _HF , which is derived exclusively from the series of yellow sample signals, by high-pass filtering with a cutoff frequency Fc = 750 KHz. Other processing circuits are the same as above.

In a second aspect of the invention, the green component is Y _BF ,R
and B by dematrices, Y _BF
is obtained by low-pass filtering the pseudo-luminance signal Y at 750 KHz. The signal Y _HF is a pseudo-luminance signal Y of 750K, as in the first case detailed above.
Obtained by filtering with a Hz high-pass filter.

The invention is not limited to the embodiments described above. In particular, two selection registers 2 and 3 are shown, one selection register connected to the even lines of the matrix and the other selection register connected to the odd lines of the matrix. actually,
Since the mosaic is read completely for each frame of the image, the selection means for successive lines of the matrix may consist of only one delay register, which is It is commanded by a signal C _S that includes two delayed pulses and is equivalent to the sum of signals C _S2 and C _S3 .

The camera described above guarantees a good compromise between resolution and sensitivity and, as mentioned above, allows the use of particularly simple processing circuits; This is because the camera does not require a delay line.

Furthermore, the principles adopted for reading the imager (reading a quincunx pattern of the sample signal of two successive lines), e.g.
Defects such as FPN noise and "smearing" can be corrected.

A commonly employed device to reduce these defects is to memorize one line during retrace time;
It then consists of processing the information collected on this line into a useful signal.

For this reason, it must be possible to carry out such a neutralization process at a frequency point, and such a task requires the implementation of very fast processing techniques, for example bipolar. However, these techniques present the disadvantages that are consuming and make the integration of such modifications extremely difficult, at least in bipolar areas. On the contrary, these corrections are at frequency points (≒
2F _SC = 8.86MHz),
It is possible to correct these defects with integrated circuits implemented in MOS technology.

The applied reading method confirms that such corrections can be made at half the frequency of the above frequency point (f _SC =4.43MHz). In fact, at outputs S ₁ and S ₂ of the imager, two sample signals are
Can be grouped individually. That is 2
This is because each of the two sample signals passes along the same path and therefore undergoes the same changes as the congeners of the same column (but belonging to different selected lines).

[Effects of the Invention] As explained above, in the color television camera according to the present invention, the line transfer type imaging device has the following features:
The conductive columns connecting the photocells of the matrix to the memory are composed of two independent structures, while
The photocells are arranged in a quincunx pattern so that the even points of one line and the odd points of the following line can be transferred to the same line memory.
Furthermore, the photocells of the matrix are combined with complementary color filters.

Such a configuration eliminates the need to combine two consecutive lines of the same frame in the processing circuit to obtain all the sample signals of chrominance (green, red and blue) and luminance, and it is possible to obtain these sample signals and also to obtain the color difference signal. To create, 1
A delay line with a horizontal scan period delay is also no longer needed. Therefore, the configuration of the processing circuit can be simplified and the cost can be reduced.

And by combining two consecutive lines of the same frame, vertical resolution is lost,
Therefore, it is possible to solve the problem of the prior art in which lines in diagonal directions cannot be reproduced well.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a color television camera having a solid-state imaging device, FIG. 2 is a schematic diagram of a solid-state imaging device having a five-dot pattern structure used in the camera of the present invention, and FIG. FIG. 4 is a diagram showing a mosaic of color filters used in the camera of the invention, FIG. 4 is a diagram showing the waveform of a command signal applied to the imaging device, and FIG. 5 is a diagram showing the output after transfer of two consecutive lines. FIG. 6 is a schematic diagram of the processing circuit, and FIG. 7 is a waveform diagram of characteristic signals of the operation of the processing circuit. Main reference numbers: 1... photosensitive area, 2, 3... register, 4, 5... line memory, 6, 7... register, 10... color filter, 30... processing circuit.

Claims (1)

[Scope of Claims] 1. A color television camera having a line transfer type solid-state image pickup device, wherein the line transfer type image pickup device includes continuous lines of a matrix for transferring charges accumulated in photocells of a photocell matrix. means for selecting, wherein photocells in even and odd columns of one line of said photocell matrix are respectively connected to one of two memories by a conductive column; Each,
The conductive columns associated with the even points of one line are associated at the same time with the odd points of the next line, which are associated with a delay register at the output having a storage capacity equal to one line of the photocell matrix. The electric charge generated from the entire two five-dot pattern photocells is transferred to two of the output sections.
The charges accumulated in the even-column photocells of one line and the odd-column photocells of its adjacent preceding or subsequent line are transferred to each of the two delay registers during the same retrace interval and a matrix of complementary color filters of yellow, cyan and magenta is placed in the photocell matrix, and one of the photocells in a quincunx pattern is entirely covered with a yellow filter; , the entire photocell of the other five-point pattern is covered alternately line by line, with a cyan filter on one line and a magenta filter on the next line, and the processing circuitry A color television, characterized in that the signals output from the two delay registers of the output section resulting from the combination of two consecutive lines of the photocell matrix are directly combined to output a color signal and a luminance signal. camera. 2 pairs ln of successive lines combined to form the first horizontal line of the image to form an image composed of two combined rows,
ln' is delayed relative to the pair of successive lines ln', ln+1' which are combined to form a second horizontal line, and this delay is effected by the selection means 2, 3, respectively, at the beginning of a horizontal scan line of the image. A color television camera according to claim 1, characterized in that: 3. The processing circuit is connected to receive the output S ₁ of said delay register associated with the whole photocell covered by the yellow filter, and the sample circuit controlled by the sample frequency of one line and the whole other photocell. and two further sample circuits connected to receive the output S ₂ of said delay register associated with said delay register and controlled at half the frequency of said sample frequency, the outputs of these sample circuits being coupled to said matrix circuit. , filter circuit, and color difference component
3. Color television camera according to claim 1, characterized in that it is connected to an input of a processing circuit which provides D _R and D _B and a luminance component Y.