JP2623083B2 - Imaging device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging apparatus suitable for a color difference line sequential recording method.

[Conventional technology]

FIG. 11 (a) shows a conventional striped color separation filter, in which m1, m2, m3... Indicate odd-field horizontal scanning lines, and e1, e2, e3. Indicates horizontal scanning lines constituting an even field. Generally, in each horizontal scanning line, the read R _i , G _i , B _i
Signal (i indicates what row of pixels) than the luminance signal Y _i and the color difference signals _{R i -Y i, B i -Y} i is formed (e.g., Y _i = 0.3R _i +
0.59G _i + 0.11B _i ). And, in the color difference line sequential recording method,
The color difference signals R _i -Y _i and B _i -Y _i are transmitted line-sequentially be recorded. Table 1 shows the luminance signal, color difference line-sequential signal, etc. of each odd-numbered scanning line in this case.

Also, in a color separation filter as shown in FIG. 11 (b), when a luminance signal and a color difference line-sequential signal are represented corresponding to the odd fields, the result is as shown in Table 1. Then, it is necessary to restore the original R, G, B signals by receiving the above signal on the receiving end side (reproduction system). In this case, restored signals as shown in Table 1 are obtained. .

[Problems to be Solved by the Invention] In the above-described conventional color separation filter, if the color difference signal missing in each horizontal scanning line is correlated with the color difference signal one horizontal scanning line before and substituted, the following Table 1 is used. As shown in the "Synchronization" column, the R and B signals (G is omitted) restored are naturally not restored, and a false color signal corresponding to the luminance difference of each horizontal scanning line is generated. is there.

This is due to the television interlace system, and in synchronizing the color difference signals, a correlation error of two pixels occurs on the solid-state device between the color difference signal and the luminance signal.

The present invention has been made in order to solve such a problem, and forms a color difference signal from another horizontal scanning line adjacent to a main horizontal line forming a luminance signal to reduce a correlation error, thereby reducing a false color signal. It is an object to provide a small number of imaging devices.

[Means for solving the problem]

An imaging apparatus according to the present invention includes a solid-state imaging device including a plurality of pixels, a first color separation filter arranged in a checkered pattern on the pixels of the solid-state imaging device, a second color separation filter, and a third color separation filter. A color filter in which filters are arranged line-sequentially every two pixels between the first color separation filters; and a signal for one of the upper and lower main horizontal lines when reading two horizontal lines from the solid-state imaging device and the other. The horizontal scanning is performed by simultaneously reading out the signals of the sub-horizontal lines of
Forming a low-frequency luminance signal from the signal of the main horizontal line,
Color difference signal processing means for forming a color difference signal from a sub-horizontal line.

[Action]

According to the present invention, signals of a plurality of horizontal lines are read out at the same time, so that not only a high-quality image signal can be obtained without using a 1H delay line or the like, but also when forming a color difference signal, Therefore, when the color difference signals are synchronized, the influence of the vertical correlation of the luminance signal is dispersed, and the variation of a specific color in each horizontal scan is reduced.

〔Example〕

Table 2 shows the concept of the present invention in terms of a luminance signal and a color difference signal.

The difference between the signals in Table 2 and Table 1 is that one horizontal scanning line is composed of two horizontal lines (main and sub), the color difference signal is formed from sub-horizontal lines, and a low-frequency luminance signal is formed from the main horizontal line. It is about to be formed. As shown in Table 2, when the transmitted chrominance line-sequential signals are synchronized by delaying one horizontal scanning line and restoring the R and B signals, a luminance error of one pixel occurs for both the R signal and the B signal. However, it has been confirmed that this error is considerably smaller than the luminance error of two pixels, and that this error can be considerably reduced by a vertical quartz low-pass filter.

FIG. 1 is a color separation filter for explaining an arrangement of color separation filters according to an embodiment of the present invention and a method for reading a signal for each field. In the drawing, n1, n2,. ..., and odd fields 01, 02, ... indicate horizontal scanning lines in odd fields.For example, in horizontal scanning line 01, horizontal lines n1 and n2 are processed at the same time, and luminance and chrominance signals are processed. It shows that it can be obtained.
Similarly, the even fields e1, e2,... Also mean each horizontal scanning line in the even field.

The color filter in this embodiment is an all-color transmission filter (W).
Are arranged in a checkered pattern, and a red transmission filter (R) and a blue transmission filter (B) are line-sequentially arranged every two pixels.

By the above-described simultaneous processing of each horizontal line and the color filter arrangement, the high-frequency luminance signal is formed from the W signals of two horizontal lines, and the low-frequency luminance signal is formed on one horizontal line (in this embodiment, the upper side of each horizontal scanning line). , And a color difference signal is formed from the color signal of the other horizontal line of each horizontal scanning line (the lower horizontal line in each horizontal scanning line in this embodiment) and the W signal.

FIG. 2 is a driving schematic diagram of a non-destructive readout image sensor (hereinafter abbreviated as SIT) to which the filter of the present invention can be applied. In the figure, R, B, and W represent each pixel combined with the R, B, and W filters, respectively. V · SR is a vertical shift register, H · SR is a horizontal shift register, φV · RS, φ
H · RS indicates a charge refresh pulse for each vertical and each bit.

In the signal wiring method of this embodiment, the R and B color signals are read from the output S2, and the W signal is read from S1.

FIG. 3 is a waveform diagram showing signals read from the SIT and sample timings of sample-and-hold circuits 40a, 40b, and 70 described later. FIG. 4 is a block diagram of a signal processing circuit of an image pickup apparatus using the SIT shown in FIG. is there.

In FIG. 4, reference numeral 10 denotes a SIT in which a vertical crystal low-pass filter is inserted in the incident optical path, reference numeral 20 denotes a clock generator, reference numeral 30 denotes a system controller, reference numerals 40a, 40b, and 70 denote sample and hold circuits (S / H), and reference numeral 50a. Reference numerals 50b and 80 denote low-pass filters (LPF), 60 denotes a band-pass filter (BPF), 90 denotes a white balance circuit, 100 denotes a process circuit, 111 denotes a 1H delay circuit, and 112 denotes a matrix circuit. 110, 120, 140 are adders, 130 is FM modulator, 150 is amplifier, 160 is head, 1
70 is a motor for driving the recording medium.

In the device configured as described above, when two adjacent horizontal lines are simultaneously read as horizontal scanning signals,
Now, the W signals of two horizontal lines are alternately and sequentially read out from the output line S1 of the SIT 10, and the R and B point sequential signals and the B and R points are output from the output line S2 every horizontal scanning line. The signals are sequentially read out alternately. The luminance signal is formed from the above-mentioned SIT output S1. First, since the high-frequency luminance signal uses the SIT output S1 as it is, a high-resolution band is secured. That is, the repetition frequency of the W signal from S1 is, for example, if the number of horizontal pixels of SIT10 is 510 pixels, the readout frequency is about 9.5 MHz, and if it is the Nyquist frequency, about 4.7 MHz is the luminance band. . In this case, the band of the BPF 60 has a band pass characteristic of about 1 MHz to 4.7 MHz.

Next, the low-frequency component Y _L1 and the low-frequency component Y _L2 for color difference for the luminance sampling timing offset sample and hold circuit
The chrominance signals are separated from the SIT outputs S1 and S2 by the sample and hold circuit 70, respectively. Referring to FIG. 1, the odd field 01
In the horizontal scanning line, the W signal corresponding to the horizontal line n2 and the B signal
A color difference signal is formed from the signals. In the next 02 horizontal scanning lines, a color difference signal is formed from the W signal and the R signal corresponding to the horizontal line n4. That is, in the odd field, a low-frequency luminance signal is formed from an odd-numbered horizontal line among the horizontal lines, and a color difference signal is formed from an even-numbered horizontal line. In the even field, a low-frequency luminance signal is formed from even-numbered horizontal lines of each horizontal line, and a color difference signal is formed from odd-numbered horizontal lines. Further, as shown in FIG. 3, the color difference luminance signal Y _L2 is separated by shifting the sampling time from the low frequency luminance signal (degree low frequency luminance signal Y _L1 ).

Vertical resolution of the two field signals is close correlation distance low-frequency luminance signal Y _L and the color component in this order were interlaced with each other relationship is sufficiently maintained.

On the other hand, the horizontal resolution because it uses connexion form two horizontal lines for high-frequency luminance signal Y _H becomes extremely high.

The low-frequency luminance signal for luminance, the low-frequency luminance signal for color difference, and the color signal obtained as described above are respectively band-limited to about 1 MHz by the LPFs 50a, 50b, and 80 at the next stage. The color signal is further subjected to white balance operation by a control voltage (not shown) which is controlled line-sequentially by a white balance circuit 90 at the next stage. The white-balanced R and B line-sequential color signals, the luminance low-frequency luminance signal Y _L1 and the color difference low-frequency luminance signal Y _L2 are subjected to γ processing in the process circuit 100, and the low-frequency luminance signal ▲ Y
^' _L1 ▼ and line-sequential color difference signals R'- ▲ Y ^' _L2 ▼, B'- ▲ Y ^'
_L2 ▼ is output. The low-frequency luminance signal ▲ Y _^'L1 ▼ are added by the adder 110 and the high band luminance signal Y _H and the pseudo luminance signal Y
Becomes The Y signal is added to the synchronizing signal by the adder 120 and input to the FM modulator 130. Further, a line-sequential color difference signal is also input to the FM modulator 130, and these signals are FM-modulated by different carriers, respectively, and added by the adder 140,
The data is recorded on the recording medium 171 via the amplifier 150 and the head 160.

R'- ▲ Y ^' _L2 ▼ and B'- ▲ Y
The line-sequential signal of ^' _L2 ▼ is directly and indirectly input to the matrix circuit via the 1H delay circuit 111. The matrix circuit 112 low-frequency luminance signal ▲ Y _^'L1 ▼ also input, in the matrix circuit 112 Is performed to form the respective color signals R ", G", B ".

Although the first embodiment has been described above centering on the color separation filter shown in FIG. 1, it is characterized by the fact that a high-band luminance signal is obtained from two horizontal lines, whereby a high resolution can be obtained, and the vertical correlation distance is short. Less occurrence of moiré etc.

Also, since the low-frequency luminance signal is formed from one horizontal line, the vertical resolution is good. Further, since the color difference signal is formed by one horizontal line, there is an advantage that generation of a false signal is very small.

Also, the color separation filter is convenient for SV (still image capturing) application. That is, it is possible to generate a color difference line-sequential signal from a horizontal line that forms a low-frequency luminance signal in both odd and even fields.

If a nondestructive readable sensor such as SIT is used, the same signal as the odd / even field is read and processed a plurality of times in a single photographing (exposure) using the shutter as in the above-described embodiment. There is a great advantage that a frame image can be obtained in addition to the effects described above. Further, since the vertical correlation distance between the line-sequential color difference signal and the low-frequency luminance signal is short, a false color signal caused by the luminance difference can be reduced. Further, by inserting a crystal low-pass filter in the vertical direction of the pixel in order to increase the vertical correlation, the false color signal can be improved to a negligible level.

Figure 5 is a color separation filter arrangement view of a second embodiment of the present invention, first shown R, G, instead of element Y _e B filter,
It uses W and C _Y filters respectively. In the figure,
Yotsute B signal is obtained that from the W signal subtracting Y _e signal, also obtain Yotsute R signal by subtracting the C _Y signal from the W signal. The block diagram of the signal processing circuit at that time is
A circuit configuration as shown in FIG. 6 is obtained by adding 0 to the signal processing circuit block diagram of FIG. That is, the high-frequency luminance signal Y _H , the low-frequency luminance signal Y _L1 for luminance, and the low-frequency luminance signal Y _L2 for color difference are obtained from the W signal from the output line S1 of the SIT ₁₀ , as shown in FIG. it is the same, R, and B color signals are obtained by subtracting from W signal from Y _e, a line sequential color signal C _Y S1.

In the case of the second embodiment, since the complementary color filter is introduced as compared with the configuration of the first embodiment, the transmittance is improved and the sensitivity is increased. Moreover, by using complementary colors, MTF (Modulat
ion transfer function) is improved in the vertical direction, and moire is less likely to occur.

FIG. 7 is a diagram showing a third embodiment, in which the wiring method of the signal output lines of the SIT is different from that of the embodiment of FIG. That is, according to this method, the W signal of two horizontal lines is obtained from the SIT output S1, but the color signal is set so that the horizontal switches (181, 185...) Corresponding to the even horizontal lines are kept off in the odd field. I have.
As a result, the R and B color signals are output line-sequentially from the SIT output S2 for each horizontal scanning line, so that the color separation sample and hold circuit 70 shown in FIG. 4 can be omitted.

FIG. 8 shows the timing of the drive pulse of the horizontal drive shift register of the SIT of FIG. In the figure
S1 (W / W) in the driving pulse W _n, φRS1 is bit reflation tool Shiyu pulse S1 (W / W). On the other hand, S2 (R /
B) is o _n, to 1/2 of the repetitive pulse S1 is driving pulse e _n (W / W), it can be seen that the switch for each horizontal two pixels. In addition, the bit refresh pulse at that time is a half repetitive pulse φRS2. During odd fields, as described above, the driving pulses of the above the line of o _n is applied, lines of e _n is the voltage turned off is applied. In the case of an even field, the driving conditions are reversed.

Next, FIG. 9 is a schematic diagram of the configuration of an SIT showing a fourth embodiment of the present invention. In FIG. 9, the relationship of the W signal is the same as in the above-described embodiment, and the wiring of the color signal output line is changed. is there. That is,
The output line for the odd field and the output line for the even field of the color signal are separated as S2 and S3, respectively, and the R signal and the B signal of the two horizontal lines which are simultaneously read out, for example, S2 to R, It is separated so that B is output from S3. Fig. 10 is a block diagram of the signal processing circuit at that time. If S2 and S3 of the SIT output are switched for each field, the color signal
R and B are obtained line by line for each field. As described above, according to this embodiment, the sample and hold circuit 70 shown in FIG. 4 becomes unnecessary.

〔The invention's effect〕

As described above, according to the present invention, signals of a plurality of horizontal lines are simultaneously read, so that not only can a high-quality image signal be obtained without using a 1H delay line or the like, but also when a color difference signal is formed. Is formed from the signals of the sub-horizontal lines, so that when synchronizing the color difference signals, the effect due to the vertical correlation of the luminance signal is dispersed, and the fluctuation of a specific color is reduced every horizontal scanning. Having.

[Brief description of the drawings]

FIG. 1 is a layout diagram of a color separation filter showing an embodiment of the present invention, FIG. 2 is a schematic diagram of driving of an SIT, FIG. 3 is a waveform diagram showing a sample timing of a signal read from the SIT, and FIG.
The figure is a block diagram of the signal processing circuit using the SIT of FIG. 2,
FIG. 5 is a layout diagram of a color separation filter according to a second embodiment of the present invention, FIG. 6 is a block diagram showing a main part of the signal processing circuit of FIG. 5, and FIG. FIG. 8 is a waveform diagram showing the timing of the drive pulse of the drive shift register of the SIT in FIG. 7, FIG. 9 is a schematic view of the SIT drive showing the third embodiment, and FIG. Figure 11 is a block diagram of the signal processing circuit, Figure 11 is a layout diagram of a conventional striped color separation filter, and in the figure, 10 is a SIT, 20 is a clock generator, 30 is a system controller, and 40a, 40b, and 70 are sample and hold. Circuits, 50a, 50b, 80 are low-pass filters (LP
F), 60 is a band pass filter (BPF), 90 is a white balance circuit, 100 is a process circuit, 110 is an adder, 110, 120, 140 are adders, 130 is an FM modulator, 150 is an amplifier, 160 is a head, 170 is a motor, and 190 is a subtractor. It is.

Claims (1)

(57) [Claims] 1. A solid-state image pickup device comprising a plurality of pixels, and first color separation filters arranged in a checkered pattern on the pixels of the solid-state image pickup device, wherein a second color separation filter and a third color separation filter are arranged. A color filter arranged line-sequentially every two pixels between the first color separation filters, a signal of one of upper and lower main horizontal lines and a signal of another sub line when reading two horizontal lines from the solid-state imaging device; A color difference signal processing means for performing horizontal scanning by simultaneously reading out signals of horizontal lines, forming a low-frequency luminance signal from the signal of the main horizontal line, and forming a color difference signal from a sub-horizontal line. An imaging device characterized by the above-mentioned.