JP2529578B2 - Imaging device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image pickup apparatus configured to obtain a color difference line sequential signal from a color image pickup element.

[Prior Art] FIG. 4 is a block diagram showing a schematic configuration of a main part of a color image pickup apparatus which obtains color difference line sequential signals from a conventional color image pickup element, and 1 is an image pickup element.

FIG. 5 is a diagram showing an example of a color filter array applicable to the color image pickup apparatus shown in FIG. 4. From the image pickup device 1 shown in FIG. 4, in the first field, from the second N line to red ( R) and green (G) signals are obtained in time series,
Blue (B) and green (G) signals are obtained from the (2N + 1) th line. S / H 2 and 3 are sampling and holding circuits (hereinafter referred to as S / H circuits) for separating these color signals.
The G signal is output from the circuit 2, and the second Nth signal is output from the S / H circuit 3.
The R signal is output from the line and the B signal is output from the (2N + 1) th line. An amplifier 4 amplifies the G signal to a predetermined signal level. Reference numerals 10 and 11 are white balance gain control circuits.
Gain control is performed by two white balance control voltages RWB and BWB. The gain-controlled R and B signals are switched in the switch circuit 12 for each horizontal line, and in the subtractor 6 G
The signals are subtracted to obtain line-sequential signals of R-G signals and B-G signals.

[Problems to be Solved by the Invention] In the conventional image pickup apparatus as described above, since the gain control circuit is required for each of R and B, there is a problem that the circuit scale increases. In addition, the switch circuit for switching the R and B signals also needs to be a switch circuit that fully considers the band and the dynamic range because it is necessary to switch the signal itself, and the circuit scale tends to increase. There was a problem.

The present invention has been made in order to solve the conventional problems, and an object thereof is to provide an image pickup apparatus capable of obtaining color difference line sequential signals with a simple circuit configuration.

[Means for Solving the Problems] In order to achieve the above object, the present invention is characterized by a gain control circuit for alternately controlling the gains of different color signals for each horizontal line, and a direct color control at its output. A subtractor for subtracting the signal is provided.

[Operation] With the above configuration, the color signal amplified by the amplifier is subtracted from the line-sequential signals of different color signals whose gains are controlled, and the color difference line-sequential signal is formed with a simple circuit configuration. .

[Embodiment] FIG. 1 is a block diagram showing an embodiment of an image pickup apparatus of the present invention, 5 is a gain control circuit, 7 is a switch circuit, and the same reference numerals as those in FIG. 4 denote the same or corresponding portions. .

When the color filter shown in FIG. 5 is applied to the image pickup device 1 in the configuration of FIG. 1, the image pickup device 1 displays R, R 2
G time series signals are obtained, and B and G time series signals are obtained from the (2N + 1) th line. The S / H circuits 2 and 3 perform sampling and holding, and the S / H circuit 2 outputs the G signal and the S / H circuit 3
From, the R signal on the 2nd N line and the B signal on the 2H + 1th line
The signal is obtained.

The gain control circuit 5 is for controlling the gain of each of the R and B signals for white balance, and is controlled by the white balance control voltages RWB and BWB through the switch circuit 7 that switches for each horizontal line.

The amplifier 4 from the line sequential signals of the R and B signals whose gain is controlled
According to this embodiment, the G signal amplified at is subtracted to form the color difference line sequential signal. In this embodiment, the switch circuit 7 simply needs to switch the DC voltage. Since it is not necessary to consider the dynamic range, the circuit can be configured with a simple circuit scale.

FIG. 2 is a diagram showing another example of the color filter array applicable to the present invention.
In the field, yellow (Y _e ) + magenta (M _g ) and cyan (C _y ) + green (G) signals are obtained in time series on the 2nd N line, and C _y + M _g , y _e + G on the 2nd N + 1 line. Each signal of is obtained in time series.

These color signals are separated in the S / H circuit 2 and the S / H circuit 3, respectively, and from the S / H circuit 2 in the second N line, C _y + G, the second N +
One line gives Y _e + G. The second from the S / H circuit 3
The N line Y _e + M _g, the C _y + M _g resulting in the 2N + 1 lines. These subtractions are performed in the subtractor 6, but the spectral characteristics of the color filter are adjusted so that M _g = R + B, y _e = R + G, C _y =
If it is set to B + G, the output of the subtractor 6 is (Y _e + M _g ) − (C _y + G) = (2R + G + B) − (2G + B) = 2R−G in the 2Nth line, and (C _y + M) in the 2N + 1th line. _g )-( _Ye + G) = (2B + G + R)-(2G + R) = 2B-G.

As described above, the present invention can be effectively applied to the color filter array shown in FIG.

In addition, color filter arrays other than the above can be applied to any array as long as it is an array that can obtain color difference line sequential signals.

Next, FIG. 3 is a block diagram showing another embodiment of the image pickup apparatus according to the present invention, in which a different method is used for the white balance control method.

As the output of the color measurement sensor (not shown), data for white balance R / G, B / G is obtained, and these data R / G,
B / G is selected by the switch circuit 20. This selection control is for taking in data in a time-division manner and may be performed at any timing. However, according to the present invention, the switch circuit 20 can control a signal alternating every horizontal line. It is possible. 21 is an A / D that converts these data R / G, B / G into A / D
The converter 22 converts data from R / G and B / G so that an appropriate white balance is obtained, or RO
It is a microcomputer for selecting a predetermined control value from M. Reference numeral 23 is a D / A converter whose output controls the gain of the gain control circuit 5.

According to the above configuration, the micro-computer 22 needs only to output the control data for controlling the white balance of the 2R-G and 2B-G signals for each horizontal line.
U capacity is half. Moreover, the D / A converter can also be configured with one circuit.

[Effects of the Invention] As described above, according to the present invention, the color difference line sequential signal can be obtained with a simple configuration by providing the gain control circuit for controlling the gain of different color signals for each horizontal line. effective.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of an image pickup device of the present invention, FIG. 2 is a diagram showing another example of a color filter array applicable to the present invention, and FIG. FIG. 4 is a block diagram showing another embodiment of the image pickup device according to the present invention, and FIG. 4 is a block diagram showing a schematic configuration of a main part of a color image pickup device for obtaining a color difference line sequential signal from a conventional color image pickup device. The figure is a diagram showing an example of a color filter array applicable to the color image pickup apparatus shown in FIG. In the figure. 1: Image sensor, 2, 3: Sampling hold circuit, 5: Gain control circuit, 6: Subtractor, 7: Switch circuit

Claims (1)

(57) [Claims] 1. An image sensor capable of obtaining first and second color signals from a 2N-th horizontal line and third and fourth color signals from a (2N + 1) -th horizontal line; A subtractor that alternately subtracts the second color signal and the third and fourth color signals for each horizontal line, and a first and third color signal or a second color signal that is arranged in front of this subtractor. And the gain of the fourth color signal is 1
An image pickup apparatus comprising: a gain control circuit that alternately controls each horizontal line.