JPS63123281A - Image pickup device - Google Patents

Abstract

PURPOSE:To prevent the deterioration of a picture quality due to the generation of a false signal by using a correlation between two adjoining rows and obtaining a luminance signal and a chrominance signal. CONSTITUTION:The charge pattern of a solid-state image pick-up element 2 is successively scanned by an image pickup element driving circuit 15, namely, respective horizontal rows of ...(N-2) row, (N-1) row, ...(N+2) row, (N+3) row ... are scanned in the sequence, they are A/D converted by an A/D converter 3, and thereafter, they are written through a first switch 4 changed over for one frame to first and second buffer memories 5 and 6 for one frame. The accumulating contents are read from the memory of the row not in the writing condition through switches 7 and 8. The signal of two adjoining read rows is added by an adder 9, processed by a luminance signal processing circuit 10 and comes to be a luminance signal Y. On the other hand, the above- mentioned signal of two rows is inputted respectively to first and second chrominance signals processing circuits 11 and 12, processed and comes to be a B-G signal an R-G signal. These signals are encoded to a standard television signal with an encoder 13.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an imaging device such as a video camera or an electronic still camera, and provides an imaging device with good image quality and less generation of false signals.

7 shows a typical conventional configuration of a color video camera using a solid-state image pickup device, and FIG. 8 shows a color filter arrangement of the solid-state image pickup device used in FIG. 7. In FIG. 7, a subject image (not shown) is guided by a lens 201 to a solid-state image sensor 202 and converted into a charge image. This charge image is then read out by the image sensor drive circuit 203 in synchronization with a synchronization signal generated by the synchronization signal generator 215. This charge image can be read out from the television
As shown in the solid line arrow in Figure 8, in the first vertical scan (odd field), the (N-2)th line, N The data is read out every other line in the order of row 1 and (N+2) row, and in the second vertical scan (even field), as shown by the dotted line arrow in Figure 8, the data left unread in the first vertical scan...
...(N-1)th line, (N-4-1)th line, (N+
3) The charge images are read every other row in the same order as the rows, and the readout of the charge image of the entire screen is completed.

The electric signal read out in this way is amplified by an amplifier 204, and then guided to a low frequency filter (LPF) 205 and a band pass filter (BPF) 208, where it is divided into a luminance component which is a low frequency component, It is separated into a color signal component which is a high frequency modulation acid component. For example, during the first vertical scan, the output signal components of the LPF 205 are (G + B) components, (R+G
) component and (G+B) component, and even if a negative image is captured in the vertical direction, the (R+G) component and (B+G) component will be different signals for each horizontal scanning period. The signals of two horizontal scanning periods are averaged by the horizontal period delay circuit 206 and the adder 207, and a signal of the (R+2G+B) component is constantly outputted as a luminance (1) signal. Also, BPF20
The components detected by the detection circuit 209 of the output of 8 become the (B-G) component and (R-G) component for each -horizontal scanning period, and the Y
As with the signal components, the necessary three primary color components cannot be obtained with only the signal components of one horizontal scanning period, so the second one horizontal scanning period delay circuit 210 and the two input terminals are alternately connected every -horizontal scanning period. The first thing to do is to switch. Second changeover switch 211
, 212, the (R-G) signal and the (B-G) signal are obtained simultaneously by using the signals from one horizontal scanning period ago. The Y signal, (R-G) signal, and (B-G) signal are guided to an encoder 213, converted into a standard television signal, and outputted from an output terminal 214. The above signal relationship is exactly the same during the second vertical scan because the color filter array in Figure 8 is exactly the same in the rows scanned during the first and second vertical scan periods. It is clear from

However, the conventional example with the above configuration has the following problems.

In other words, in the above example, both the brightness signal and the 9 sudden signals are obtained by using the correlation in one horizontal scanning period, so the image changes in the vertical direction and there is no correlation in the signals in one period. There is a fundamental problem in that false signals sometimes occur, and furthermore, in the above example, temporally the correlation is used for one horizontal scanning period, but spatially, the correlation between two adjacent rows is used. Instead, the correlation between two rows every other row is used, so there is a high probability that a false signal will occur due to lack of correlation, and the false signal will also become large, making it impossible to obtain a satisfactory image quality.

FIGS. 9 and 10 are diagrams showing examples of conventional configurations of color video cameras of other types and the arrangement of color filters of the solid-state image sensor 216 used therein, respectively. The scanning method and order are the same as the examples in Figures 7 and 8, using the interlaced scanning method, and as shown by the solid and dotted arrows in Figure 10, 1
In the second (odd field) vertical scan, charges are read out every other row, and in the second (even field) vertical scan, the remaining rows are similarly read out every other row. Therefore, the signal obtained by one horizontal scan is -(Cy+Cy+
Mg+Ye+G) and -(Cy+G+Ye+Mg), and the same signal of R+B+ and G is obtained, which is taken as a luminance signal.

On the other hand, the output of the detection circuit 209 has the following information for each horizontal scanning period:
? ((Cy+Mcy) −(Ye+G) )=(B
−G7′2) signal, −((Cy×G) −(Ye+
Mq) )=-(R-Cv″2) signal is obtained (because C7=B+G, Mq=R+B.

Substitute Ye=R-1-G).

Therefore, the two types of color difference signals obtained for each horizontal scanning period are transferred to the horizontal scanning period delay circuit 210, the first . Second
The four signals Y, R-G/2, and B-(4) are simultaneously led to the encoder 216 and sent to the output terminal 214.
You get a standard television signal.

Even in the video camera with the above configuration, the color signal is obtained by using the correlation between the horizontal scanning periods, that is, the correlation between two horizontal lines located every other row spatially, so there is no correlation between images in the vertical direction. As in the first example, the probability is high that a large false signal (in this example, only the color component) will occur in this part, which is an obstacle to obtaining high image quality.

Problems to be Solved by the Invention As mentioned above, in an imaging device typified by a conventional video camera, interlaced scanning is performed and the necessary information is obtained by utilizing the correlation between two spatially every other row. Since the signal is obtained, there is a high probability that the correlation will disappear, and therefore a high probability that a false signal will occur.Furthermore, since the false signal spatially spans between two lines, it becomes a false signal that is large in area, resulting in deterioration of image quality. There was a problem that it was easy to occur.

In view of the above, an object of the present invention is to provide an electronic still camera in which the probability of false signals occurring is low and the area of false signals is small.

Means for Solving the Problems In order to solve the above problems, the present invention provides an image sensor that photoelectrically converts an image for one frame, a scanning circuit that reads out an image signal for this one frame, and an image that has been read out. This imaging device is equipped with a buffer memory for one frame for temporarily storing signals, and means for calculating the signals in this buffer memory and extracting a video signal for one frame of interlaced scanning.

According to the above-described configuration, the present invention utilizes the correlation between two adjacent rows to obtain a necessary signal, so that the probability of generating a false signal is low, and the false signal is small in area, so that the image quality is improved. A good imaging device can be provided.

Embodiment FIG. 1 shows the basic configuration of the first embodiment of the present invention.
The figure is a diagram showing the arrangement of color filters of the solid-state image sensor used in FIG. 1.

In FIG. 1, a subject image (not shown) is guided by a lens 1 to a solid-state image sensor 2 shown in FIG. 2 on which a color filter is pasted, and is converted into a charge image. Then, this charge image is transmitted to the synchronizing signal generator 1 by the image sensor driving circuit 15.
For example, it is read out by sequential scanning in synchronization with a synchronization signal from 7. This sequential scanning will be further explained using FIG. 2.

Sequential scanning refers to line (Nf2) in Fig. 2.

(N-1) line...(N+2) line, (N+3) line...This method sequentially scans each horizontal row in that order, and is different from conventional interlaced scanning. is different. After the charge image read out in this manner is converted into a digital signal by the A/D converter 3.

Each frame is written into the first buffer memory 6 and the second buffer memory 8 via the first changeover switch 4, which is switched every frame (in the case of FIG. 1, the first
The data is being written to the buffer memory 6 of. )
. Then, of the backup memory 5 or 6, the buffer memory that is not in the write state (in the case of FIG. 1, the second buffer memory
The buffer memory 6) is selected by the second changeover switch 7 and the third changeover switch 8, and the stored signals are read out. This signal is read out in the first order.
In the field, first, during the (n-1)H horizontal scanning period, the signals corresponding to the (N-2) and (N-1) rows in the color filter array in FIG. 2 are simultaneously output from the backup memory 6, respectively. It is read from terminals 6-1 and 6-2. The signals of the two rows are first added together by an adder 9, and then processed by a luminance signal processing circuit 1o to obtain a luminance signal (=R+23+B). On the other hand, among the two rows of signals, the signal at the output terminal 6-1 is processed by the second color signal processing circuit 12, and the signal at the output terminal 6-2 is processed by the first color signal processing circuit 11. -G signal, B-G
It is considered a signal. These luminance signals, R-G signals, and B-G signals are encoded into standard television signals by an encoder 13 and output from an output terminal 14. Similarly, during the nH horizontal scanning period, signals corresponding to the N rows and (N+1) rows, and during the (n+1)H horizontal scanning period, the signals corresponding to the (N+2)
The signals corresponding to the rows and (N+3) rows are read out from the buffer memory 6 at the same time, and similar processing is performed. Next, in the second field.

During the (n-1)'H horizontal scanning period, signals corresponding to rows N and (N-1) are sent to terminals 6-1. f3-2, and during the n'H horizontal scanning period, (N+2
) and (N+1) rows are (n-)-1
)'H horizontal scanning period, (N+4) rows and (N+s
) rows are simultaneously read out to terminals 6-1 and 6-2, signal processing is performed in the same manner as in the first field, and a standard television signal is output to terminal 14. . Note that among the signal readouts described above, at least the first field is read out non-destructively, and the same signal is sent to the second field in a pair of two lines shifted by one line from the first field. It needs to be readable. When reading the second field, either destructive reading or non-destructive reading may be used.However, in non-destructive reading, when the reading of the entire screen for one frame is completed, the buffer is read in preparation for writing the signal in the next frame. It is natural that the contents of memory need to be reset. And in the next frame,
The same operation is performed by simply switching between the write operation and the read operation of the first buffer memory 6 and the second buffer memory 6, and a continuous standard television signal is output.

Note that the writing and writing of the buffer memories 6 and 6 described above
Read and reset operations are performed by the memory drive circuit 16 in synchronization with a synchronization signal from a synchronization signal generator 17, and other circuit operations are also performed in synchronization with the synchronization signal.

The signal outputted to the terminal 14 as described above will be considered. First, the relationship between the signals of the first field and the second field is such that the bears in two adjacent rows that are correlated are shifted vertically by one row in each field, which means that the center of scanning is shifted. , has an interlaced relationship, and an image with good vertical resolution can be obtained. Also, two horizontal lines that are correlated are always spatially closest to each other,
Since the rows overlap each other, the correlation is higher than that of the conventional example where there is one row.
Compared to the correlation between two rows, the probability of false signals occurring is small, and false signals that occur with a small probability are less noticeable because the vertical spread is small, resulting in good image quality. will be obtained. Or, among the vertical spatial frequency components of the optical image incident on the image sensor,
This false signal can be completely removed by removing high-frequency components with a spatial low-frequency F wave filter to ensure that there is a correlation between two adjacent lines. Since the component may be a frequency component higher than the frequency corresponding to one pitch of repeated pixels in the vertical direction, the degradation in resolution in the vertical direction caused by this is also small, and this method is also sufficient for practical use. As such a spatial low-pass filter, one that utilizes the birefringence of crystals such as quartz is well known, and in this case, optical images are separated by a distance equivalent to one vertical pixel pitch. A thick crystal plate may be placed in front of the image sensor.

Next, other embodiments of the present invention will be described.

FIG. 3 is a diagram showing another embodiment of the imaging device of the present invention, and FIG. 4 is a diagram showing the arrangement of color filters of the imaging device used in this embodiment. This is an example in which the present invention is applied to the video camera shown in FIG.

The description of the same parts denoted by the same reference numerals as in FIG. 1 will be omitted. The readout of charges from the image sensor 18 is performed by sequential scanning as shown by the arrows in FIG. Write every frame period. FIG. 3 shows the state in which the first buffer 1 memory 5 is being filled. Then, the buffer memory that is not in the writing state (second buffer 1 memory 6 in Figure 3)
The signals stored in the first . The 20th sudden signal processing circuit 11.12 and the 4th signal processing circuit whose input terminals are switched every field. A standard television signal is output to the output terminal 14 via the sixth changeover switch 19, 20 and the encoder 21. First, in the first field, (
During the n-1)H horizontal scanning period, signals corresponding to the (N-2) and (N-1) rows in the color filter array in FIG. 8-2. Then, the signal corresponding to the (N-2) row is processed by the luminance signal processing circuit 10 to produce a luminance signal (R+B+gG) as in the conventional example. The signal corresponding to this (N-2) row is then led to the second color signal processing circuit 12, and the signal corresponding to the ((Ye+Mg)-(C7''G)
) signal, that is, an RG/2 signal. On the other hand (N-1)
The signal corresponding to the row is led to the first color signal processing circuit 11 and is converted into T((Ye+G) −(Cy+Mq)), that is, B−
It is assumed to be a G/2 signal. Similarly, nH horizontal scanning period and (n
-1-1) During the H horizontal scanning period, signals corresponding to the Nth row and (N+2)th row are sent to terminals 6-1 and 6-1, respectively.
2, signals corresponding to the (N-1-1)th and (N+3)th rows are read out, and the same signals as in the (n-1)H horizontal scanning period are guided to the encoder.

Next, in the second field, during the (n-1)'H horizontal scanning period, the signal corresponding to the (N-1)th row is sent to the terminal 6-1, and the signal corresponding to the Nth row is sent to the terminal 6-2. The corresponding signal is read out, and the signal corresponding to the (N-1)th row is processed by the luminance signal processing circuit 1o. -(Ye+G)+-! -(Cy
+Mg) = (R+B+gG) luminance signal. The signal corresponding to this (N-1)th row is the second
The color signal processing circuit 12 converts it into a (B-Q/2) signal,
The encoder 21 is connected to the encoder 21 via a fourth changeover switch 19 that selects one of the two input terminals for each field.
(In Fig. 3, this fourth changeover switch 1
The selection of the input terminals of the 9 and 6th changeover switches 2o corresponds to the signals in the first field. ). On the other hand, the signal corresponding to the Nth row is converted into a (RG/2) signal by the first color signal processing circuit 11.

Encoder 21 via the sixth changeover switch 20
guided by.

Note that whether the above signal reading is destructive or non-destructive is the same as in the first embodiment.

Consider the signal outputted to the terminal 14 in this manner. First, regarding the luminance signal, the first and second fields
It is a completely different signal that is shifted by one line in the vertical direction from the field signal, and has a perfect interlaced relationship. Regarding the color signal, the first field and the second field
This also has an interlace relationship because two adjacent horizontal bears that are correlated in the field are shifted by one line in the vertical direction, and the center of the scan is shifted in each field. Images with good vertical resolution can be obtained. In addition, the two horizontal rows that are correlated in color signals are always the spatially closest adjacent rows, so the correlation is strong and the probability of false signals occurring is small, and the false signals that occur with a small probability are also As in the first embodiment, the vertical spread is small and noticeable, and good image quality can be obtained.

Also.

Similar to the first embodiment, by installing a spatial low-frequency F wave filter, this false signal can be removed with a slight deterioration of vertical resolution.

Next, the third aspect of the present invention. A fourth example will be described. FIG. 5 shows an example in which the first embodiment shown in FIG. 1 is applied to an electronic still camera, and the image sensor used is the same as that shown in FIG. Since they have many things in common, I will briefly explain them.

In FIG. 5, subject light is guided to the image sensor 2 only at a certain moment by the shutter 23, and is converted into a charge image. This charge image is read out using the same scanning method as in the first embodiment and
It is written to the buffer 1 memory 6 via the converter 3.

Then, at an arbitrary time after this writing is completed, this signal is read out in the same reading order as in the first embodiment, and similarly the luminance signal, (R-G) signal, and (B-G) signal are read out. This signal is converted into a signal suitable for recording by the recording signal processing circuit 26, and is recorded on the electronic still camera body 22 (the area surrounded by the dotted line in the figure) and on the removable recording medium 26. Shooting of still images is completed. The above operations are controlled by the system control circuit 27, and the shutter 23 and the recording medium 26 are controlled by the system control circuit 27, and the shutter 23 and the recording medium 26 are controlled by the drive circuit 24. It is driven by a drive circuit 28.

When the present invention is applied to an electronic still camera as described above,
Unlike a video camera, there is no need to constantly write images, so only one buffer memory is required, and the switch 1.2.3 required in Figure 1 is no longer required, simplifying the configuration. There are advantages. And regarding image quality,
The same high image quality as the video camera of the first embodiment shown in FIG. 1 can be obtained.

Next, FIG. 6 shows an example in which the second embodiment shown in FIGS. 3 and 4 is applied to an electronic still camera. All of the components are the same as those already explained in FIGS. 3 and 5, and the scanning method of the image sensor 18 and the driving method of the buffer 1 memory 6 are also the same as in the second embodiment, so their explanation will be omitted. However, it is similar to the second embodiment in that it has high image quality, and it is similar to the third embodiment in that the configuration can be simplified by applying it to a still camera.

In the above explanation, the signals of the image sensor are read out by sequential scanning, but although this method has the advantage of simplifying the addressing of the scanning circuit and buffer memory, it is not limited to this method, and in short, the method is not limited to this method. It is clear that the present invention can be implemented using any method that can move the signal for one screen of the image sensor to the buffer memory in one frame period.

Furthermore, although the above explanation has been made using a digital memory as the buffer 1 memory, there is no need to limit it to this configuration, and it is also possible to use an analog type memory configured integrally with the image sensor. it is obvious.

Furthermore, it is clear that the present invention is not limited to the color filter arrays of the embodiments described above, and that various color filter arrays are possible.

Effects of the Invention As described above, according to the present invention, a high-quality imaging device with less generation of false signals can be obtained.Furthermore, when the present invention is applied to an electronic still camera, an electronic still camera with a simple configuration and high image quality can be obtained. is obtained.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a first embodiment of the present invention, FIG. 2 is a color filter arrangement diagram of a solid-state image sensor used in the same embodiment, and FIG.
Figure 4 is a configuration diagram of a second embodiment of the present invention, Figure 4 is a color filter arrangement diagram of a solid-state image sensor used in the same embodiment, Figure 6 is a configuration diagram of a third embodiment of the invention, Figure 6 shows the fourth aspect of the present invention.
FIG. 7 is a configuration diagram of the first conventional example, FIG. 8 is a color filter arrangement diagram of the solid-state image sensor used in the conventional example, and FIG. 9 is a configuration diagram of the second conventional example. 10 are color filter arrangement diagrams of the solid-state image sensor used in the conventional example. 1...Lens, 2, 18...Image sensor, 3...A/D converter, 4, 7, 8, 1
9, 20---changeover switch, 6, 6...
... Buffer memory, 10 ... Luminance signal processing circuit, 11.12 ... Color signal processing circuit, 13
．． 21...Encoder, 15...Mountain/image sensor drive circuit, 16...Memory drive circuit, 17...
... Synchronization signal generator, 23 ... Shutter, 24 ... Shutter drive circuit, 26 ...
...recording signal processing circuit, 26...recording medium, 2
7...System control circuit, 28;...
...Drive circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure Scanning sequence Figure 4 Scanning mechanism direction 1 Figure 8 Figure 10 CY: B + 6 Ye: R + e 1%: R + B Scan term

Claims (2)

[Claims] (1) An image sensor that photoelectrically converts an image for one frame,
A scanning circuit that reads out the image signal for one frame, a buffer memory for one frame that temporarily stores the read image signal, and a video signal for one frame of interlaced scanning that calculates the signals in this buffer memory. An imaging device characterized by comprising: means for taking out. (2) The imaging device according to claim 1, wherein the color filter of the imaging element is arranged such that horizontal rows having the same dye arrangement in the horizontal direction are arranged every other row in the vertical direction. .