JPH04105493A - Automatic white balance adjustment device - Google Patents

Abstract

PURPOSE:To prevent white balance adjustment from being unstable even when a distance up to an object is close by adopting the configuration such that a means detecting the distance up to the object is provided and reverse count of a reverse count means is executed only when number of times of count decided depending on the detected distance is identical. CONSTITUTION:The above device is provided with a distance detector 16 and a microcomputer 12 executes a reversible count based on the detected distance signal. A signal representing the distance up to an object is fetched by the microcomputer 12. A coefficient N is decided depending on the distance up to the object. When the distance up to the object is close, the N is larger and when the distance up to the object is remote, the N gets smaller. Through the operation above, only when the outputs N from comparator circuits 10, 11 are identical, the result of reverse count is changed. Thus, when the distance up to the object is close and the output of the comparator circuit 10 or 11 changes frequency, the result of reverse count is not change but fixed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for automatically adjusting the self-balance of a color video camera.

[Conventional technology]

FIG. 3 is a block circuit diagram of a conventional automatic mill balance adjustment device to which the technical concept disclosed in, for example, Japanese Patent Publication No. 9-43872 is applied.

In I, (1) is a lens, (2) is an image sensor, and (3
) is the color separation circuit, (4) is the Rch gain control circuit, (
5) is +(ch gain control circuit, (6) is a process circuit, (7) is an encoder circuit, (13), (9) is an integration circuit, (10), (+11 is a comparison circuit, (12)
is a microcomputer, (131, +14) is I)
/Δ conversion circuit, (15) is a reference voltage generation circuit.

Next, the operation will be explained. The light image incident from the lens (1) is photoelectrically converted by the image sensor (2) and sent to the color separation circuit (
In step 3), the signals are separated into three color signals: R, G, and H. Next, the gain control circuit (4) controls the gain of the R signal, and the gain control circuit (5) controls the gain of the 13 signal.
By adjusting the gain of ,, -; This R-Y color difference transmission, 11-Y color Z signal is
Integration circuit (8+, (91 respectively integrates, comparison [[z1 path +10+, +11+ respectively reference voltage 1F]
A signal indicating the comparison result is input to the microcoscipulator (12).

Figure 4 is a flowchart of the software-based reversible counting means in the microcomputer (12), in which each clock pulse is reversibly counted based on the comparison result manually inputted from the comparator circuit (+01i11), and this reversible counting result is /A conversion circuits +13+ and (+41) perform D/A conversion, respectively, and use these analog signals to control the gains of gain control circuits +41 and +5+, respectively.

The gain control characteristics of the comparison circuit (911101 polarity, [increase/decrease direction of reversible counting means, gain control circuit +4), 15) are such that when an achromatic subject is imaged, the R-Y color difference signal and the B-Y color difference C1 'to' where each signal becomes ()
r Creates a return loop and integrates the entire screen with f
By integrating by 81i9+, it can be assumed that the same line 1'l as when an achromatic object is imaged. Note that a normal subject can be considered to have an achromatic color by integrating the entire screen.

From the following operation 1, it is possible to automatically adjust the white balance even if the light source illuminating the subject changes.

Next, the operation of the reversible counting means will be explained based on the flowchart of FIG.

Reversible counting result of Sl, Rch Rch [J l) C
The initial value of : and the initial value Hc of the ijJ inverse counting result of Bch
Set the initial value of h LJDC.

S 2 , Rch [J D C, B ch I
J T') Outputs C.

S3. The output value of the Rch comparator (10) is expressed as Rch [
Compare with J D C, if it is low, proceed to S4 and Hc h
[J D C+ 1, if high, go to S5 and R
chUDC-1 and proceed to S6.

S6. The output value of the Bch comparator (11))1ch h
11 Compare with D C, if it is low, proceed to S7 and t3
c h If DC+ I l25. - When the mountain is high, proceed to S8i H<: h IJ l) (Set knee to 1 and proceed to S8.

S8. When the clock pulse is manually applied, it becomes 82.7 As a result, the gain of the gain control circuit [41, (5) is always set to
111)C.

It is controlled to approach Hc b U I) C.

[Problems to be Solved by the Invention] Since the conventional automatic white balance adjustment device is configured as shown below, when the distance to the subject is long, the number of subjects increases, and the number of subjects is large. White balance adjustment is stable because the color difference signal can be integrated, but when the distance to the subject is short, only the color difference signal from a specific subject can be integrated, so the comparison circuit fl(
1) There was a problem in that the output level of (IJ) frequently changed between high and low levels, making white balance adjustment unstable.

This invention was made in order to solve the above-mentioned problems, and aims to provide an automatic self-balance adjustment device that does not cause unstable self-balance adjustment even when the distance to the subject is close. purpose.

[First step to solve the problem] The automatic self-balance adjustment device according to the present invention detects the distance to the subject, stores the output of the comparison circuit (1/i) for the same number determined by the distance to the subject, The present invention is characterized in that, only when the output values of the plurality of times are the same value, the reversible count fQ is inversely counted by Lebel + iJ in the direction of iF and fl of that value.

[Function] The reversible counting means in this invention changes the count ψ only when the comparator circuit output is a stable value determined by the distance to the subject, so automatic white balance adjustment is possible when the distance to the subject is short. The hypersensitive reaction of the device is suppressed and self-balance adjustment is stabilized.

〔Example〕

Son, one embodiment of this invention will be described with reference to the drawings.

FIG. 1 is a block circuit diagram of this embodiment. (16 is a distance detection device 7t for detecting the distance to the object to be photographed, and its distance detection signal is input manually to a micrometer (12).

FIG. 2 is a flowchart of the reversible counting means in the microcomputer (12) of this embodiment.

The difference between this embodiment and the conventional example shown in FIG. 3 is that it is equipped with a distance detection device (16) and has reversible counting means that is performed by a microcomputer (12) based on the detected distance signal. Since the operations of the parts are similar, the operation of the reversible divisor means will be explained below based on the flowchart of FIG.

In FIG. 2, Sl, Rch reversible counting results Rc h II D (':
and Rch reversible old number result B c h Ll [,) C
Set the initial value of

S 2 , Rch (J D C, B ch U
Output DC.

S:3. The distance to the subject is taken into the small XI-(, bow is \Soikro:) pinpointer (12).

S4. Determine the value of N from the distance to the object. If it is far away, the value of N will be small. S5. Set A111 of I to 1.

56-R (Let It be the output of the comparison circuit (10) of It ch. S7.8 (Let 11 be the output of the comparison circuit (11) of tl c.h).

Increase the value of S8.1 by 1.

S9. When the clock pulse is input, the process advances to S10.

If SIO, is N+1, proceed to Sl+, and if 1≠N+1, return to S6.

Here, until the clock pulse is manually inputted N times, 86~S1
Repeat 0, each time ノR (11~R(NIB (11~F
3FN).

S l 1. R(11-R(21...=l
−? (If Nl, proceed to S+2.R(1)~F?(N
If even one of l has a different II'I, S+
Proceed to step 5.

SI2. R (11 is Rc h U D C: higher [
1 (If j, then S I 3 and Rc h IJ D C 1
Lower it and proceed to Sl5, if) 111 is low rL, J then S
At I4, increase Rc h LJ DC by 11 degrees and proceed to Sl5.

SI 5.8fl) =Bf21...=B
+N), the process advances to S16, and if there is a different value in even one of B(1) to BIN+, the process returns to S2.

Sl6. B (If 11 is rHJ, proceed to Sl7 and tl
C h U D C, return to S2, B (1
) is “L,” then proceed to 318 and calculate B c h [J
Decrease DC by 1 and return to 82.

The reversible counting result changes only when the output of the comparator circuit (+01. Circuit (10) or (II
) changes frequently, the reversible counting result is identified without changing, so self-balance adjustment does not become unstable.

In addition, in the 1-memory loss example, the case where the reversible +il several stages are configured by a microcomputer is reduced, but the
It may be realized by hardware using several circuits, memory, etc.

In addition, the NoJ method, which determines the placement of N based on the distance to the subject,
Any method may be used, such as a calculation method such as linear conversion, or a table conversion method.

Further, the device for detecting the distance to the subject may be any method such as a method of detecting from the 0 position of a focus adjustment lens or a method of detecting with a distance measuring device separate from the imaging optical system.

Furthermore, in the embodiment described above, the color difference signal RY.

Although the value obtained by integrating B-Y was compared with the reference E, it is also possible to compare the value obtained by integrating the signal obtained by matrixing the color difference signals R-Y, I'3-Y and the luminance signal with the reference value. good.

〔Effect of the invention〕

As described above, according to this invention, the distance to the subject is short, the influence of changes in the subject is large, and comparison 11J1 road (1
11) Even if the high and low levels of the fl++ output are unstable, the self-balance adjustment will not change vibrationally, and the distance to the subject is far and the influence of changes in the subject will not be affected. If the amount is small, an automatic self-balance adjustment device that can quickly respond to changes in the light source can be obtained.

[Brief explanation of drawings]

Fig. 1 is a small block circuit diagram of an automatic self-balancing device according to an embodiment of the present invention, Fig. 2 is a flow chart of the software of this embodiment, and Fig. 3 is a program diagram of a conventional automatic self-balancing device. Circuit diagrams 1 and 4 are flowcharts for software air in this conventional example. (2)...Image sensor, (3)...Color # [[il
(4), (5)...gain control circuit, (6)...
...Process circuit, (81, +91... Integral circuit, i
lO+, (ll+...comparison circuit, (12)...microcomputer, (131, (+41...D/
Δ conversion circuit, (15)...Reference voltage generation circuit, (1st)...Distance detection device. In addition, in each figure, the same reference numerals are the same or equivalent parts are indicated by -4.

Claims (1)

[Claims] (1) A gain control circuit that controls the gain of a color signal, means for integrating an output signal of this gain control circuit or a signal obtained by matrixing the output color signal and luminance signal of this gain control circuit, and the integration level and reference. a comparator circuit for comparing the clock pulses with the level; a means for reversibly counting clock pulses in accordance with the polarity of the output signal of the comparator circuit;
In an automatic white balance adjustment device configured to adjust the white balance by controlling the gain of the gain control circuit using the D/A converted analog signal and the D/A converted analog signal, the distance to the subject is detected. automatic white balance, characterized in that the reversible counting operation in the reversible counting means is configured to perform reversible counting only when the values of the number of times determined corresponding to the detected distance are the same. Adjustment device.