JPS6198087A - Automatic white balance controller - Google Patents

Abstract

PURPOSE:To constitute an automatic white balance controller at lower cost by sticking a filter of a specific color on a part corresponding to a blanking period where there is no influence upon a camera output, and adjusting white balance. CONSTITUTION:The signal of a specific-color filter which is outputted from an image pickup element 1a is inputted to an R/B separating circuit 6 through a preamplifier 1 and an AGC circuit 2. The signal processed by this R/B separating circuit 6 is sampled by a sampling circuit 9 with pulses in a horizontal blanking period or/and pulses of a vertical blanking period and compared by a comparing circuit 9 so that a predetermined rate is obtained. The gains of an R gain matrix circuit 7 and a B gain matrix circuit 8 are adjusted invariably automatically with the output of the comparing circuit 9.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an automatic white balance control device for a home video color camera.

Configuration of a conventional example and its problems FIG. 1 is a circuit block diagram of an automatic white balance control device for a conventional home video color camera, and FIG. 2 (A) is a front view showing an image sensor and a color separation filter.
FIG. 2(B) is a sectional view of the same.

In FIG. 1, 1 is a preamplifier that amplifies the signal of the image sensor 1a, 2 is an AGC circuit, 3 is an iris gamma correction circuit, 4 is a composite video signal creation circuit, 5 is a 1H delay circuit, and 6
is the R signal that separates the R signal (red light) and the B signal (green light).
/B separation circuit, 7°8 is an R gain matrix circuit that adjusts the gain of the separated R and B signals, a B gain matrix circuit, 9 is a comparison circuit that compares the outputs of the R or B gain matrix circuit 7.8 , 10 is a white balance circuit, 11 is an R gain matrix circuit 7. A digital memory holds the ratio adjusted so that the B gain matrix circuit 8 becomes a predetermined ratio, 12 is a switch for issuing an automatic adjustment control signal, and 13 is an R and B gain matrix 922 circuit.

A modulator 14 modulates the output of 8, and 14 is a comb filter. In FIG. 2, 15 is a photoelectric conversion surface of the image sensor 1a, 16 is a color separation filter inserted in the front surface of the photoelectric conversion surface 15, and 17 is an optical black.

The operation of the conventional automatic white balance control device configured as described above will be described below.

In conventional home video color cameras, as a means to automatically adjust the white balance of the image pickup output, a filter of a specific color (for example, white) is inserted in front of the image sensor 1a to capture an image. Switch 1 as shown
2, the comparator 9 compares the gains of the R gain somato 92 circuit 7 and the B gain button 92 circuit 8 to a predetermined ratio.
The gain of the gain control circuit 92 and the gain of the B gain control circuit 8 are automatically adjusted. The adjustment state at that time is stored and held in the digital memory 11 of the white balance circuit 10, and the adjustment state is maintained until the switch 12 is turned on, which is the next automatic adjustment command.

However, in the conventional configuration described above, it is necessary to insert a filter of a specific color and turn on the switch 12 every time the color temperature of the imaging state changes, such as when indoors or outdoors.
The disadvantage was that it was cumbersome to operate, and it was easy to forget to use it, resulting in poor white balance.

OBJECTS OF THE INVENTION It is an object of the present invention to provide an automatic white balance control device for a video color camera that eliminates the above-mentioned conventional drawbacks, has better operability, and is lower in cost.

Structure of the Invention The present invention provides a color separation filter of a video color camera's image pickup tube, which is superimposed on the color separation filter of the image pickup tube of a video color camera, to a portion corresponding to a horizontal blanking period or a vertical blanking period that does not affect the output to the camera.
For example, by pasting a filter of a specific color such as a white filter, this part is always extracted as a signal of a specific color, and in the white balance adjustment circuit, the signal part of this blanking period is sampled and compared, and the image is captured at any color temperature. Even if the signal is red or green.

Among the green signals, two types of gains are always automatically adjusted.

DESCRIPTION OF EMBODIMENTS An automatic white balance control device according to an embodiment of the present invention will be described below with reference to the drawings.

3(A) and 3(B) are a front view and a sectional view showing an image sensor and a color separation filter in an embodiment of the present invention, and the horizontal blanking on the optical black 17 and color separation filter 16 of the conventional example. A specific color filter 18 such as a white filter is attached to a portion corresponding to a rainy period, whether it is a period or a vertical blanking period. Next, FIG. 4 is a block diagram of an automatic white balance control device in one embodiment of the present invention.

In FIG. 4, the signal of the specific color filter 18 output from the image sensor 1a is input to the R/B separation circuit 6 via the preamplifier 1 and the 〇〇 circuit 2, where it is processed. The processed signal is extracted by a pulse within the horizontal blanking period, a pulse within the vertical blanking period, or both pulses in the sampling circuit 19, and is compared by a comparator circuit to obtain a predetermined ratio. The gain of the gain pad 92 circuit 8 and the gain of the B gain button 92 circuit 8 are as follows.
Always automatically adjusted.

Effects of the Invention As described above, in the present invention, a specific color filter is pasted on the image sensor of a video color camera during a period that does not affect the output of the video camera, so there is no need to insert a white filter as in the past. Moreover, since there is no need to operate a switch, operability is improved, and since no digital memory is required, costs can be reduced.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional automatic white balance control device, Figures 2 (A) and (B) are a front view and 411 side view showing a conventional image sensor and color separation filter, and Figure 3 (A). , (B) is a front view showing an image sensor and a color separation filter in an embodiment of the present invention, and 411
FIG. 4 is a block diagram of an automatic white balance control device according to an embodiment of the present invention. 1...Preamplifier, 1a...Image sensor, 2...
...AGC circuit, 3...Iris gamma correction circuit, 4...Composite video signal creation circuit, 5...1
H signal delay circuit, 6...R/B signal separation circuit,
7...R gain matrix circuit, 8...
B gain matrix circuit, 9... Comparison circuit, 13.
...Modulator, 14...Comb filter,
16...Photoelectric conversion surface, 16...Color separation filter, 17...Optical black, 18...
... White filter, 19... sampling circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] To adjust the white balance, a specified area on the color separation filter of the image sensor of a video color camera that corresponds to the horizontal blanking period, vertical blanking period, or both periods that does not affect the output to the camera is placed. An automatic white balance control device featuring a combination of color filters.