JPH02278978A - Color image pickup device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to white balance adjustment in a color imaging device, particularly in a color imaging device having a flash light emitting device such as a strobe.

[Conventional technology]

A block diagram of an example of conventional white balance adjustment is shown in Figure 7.
As shown in the figure.

(Configuration) In the figure, 9 indicates the light source color for each color component (here, red (R
), blue (B), and green (G)) and converts them into electrical signals. 12 indicates G to each signal KR and G obtained by the colorimetric sensor 9.
, a control unit for deriving a white balance control signal based on B.

4 is an image sensor that separates the subject image into three primary colors and converts them into electrical signals. Reference numeral 6 indicates a B amplifier for amplifying the blue component signal B of the subject obtained from the image sensor 4, and reference numeral 6 indicates an R amplifier for amplifying the red component signal R. Also,
Reference numeral 7 denotes a signal processing section for deriving a predetermined signal based on the red signal R', the blue signal B' amplified by each amplifier 5.6, and the green signal G sent from the image pickup device 4.

Furthermore, 10 indicates a flashlight emitting circuit such as a strobe light.

(Operation) The operation of the conventional example will be explained below based on FIG. The color measurement circuit 9 exchanges signals KR for red, blue, and green components of the light source.
, G and KB are obtained, and from these signals R, KO and KB, the ratio of red to green and the ratio of blue to green of the light source light is determined by the control unit 1z.

On the other hand, the image sensor 4 converts the object into three types of signals R, G, and B of red, green, and blue.

Here, "white balance", as is well known, is to remove the influence of the light source from the reflected light of the subject so that when a white object is photographed, it can be reproduced as white, so the above R
, G, and B signals by G/by R1 and by G/KB, respectively, to perform white balance adjustment.

That is, a signal is sent out from the control section 12 so that the B amplifier 6 and the R amplifier 5 are controlled as described above.

The detailed operation of this control section 12 will be explained using the block diagram of FIG. 8. G to R1 for the output of each colorimetric sensor 9
, KB is the logarithmic compression circuit 3-1.3 included in the control unit 12
-2.3-3 are each manually operated, making effective use of the dynamic range and facilitating subsequent processing.

Output log of each logarithmic compression circuit 3-1.3-2.3-3
in R, log in G, log in KB, log
KR and log KG are applied to differential 3-4 and l
og B and log KG are respectively input to the differential unit 3-5, and the differential outputs are log (to G/to R),
Obtain log (to G/to B). Normally, the differential outputs are sent to the R amplifier 5°B amplifier 6 in FIG. 7 via switches 3-8 and 3-9, respectively, and the white balance is adjusted.

On the other hand, when photographing with a flash, a charging completion signal is sent from the flash light emitting device IO, each changeover switch 3-8, 3-9 comes into contact with the flash constant 3-6, 3-7, and each amplifier 5, 6
The constants for each flash, log SR and log SB, are sent to. That is, during flash photography, the camera is configured to always perform constant control, assuming that the color temperature is a preset, fixed color temperature.

[Problem to be Solved by the Invention 1] However, in the conventional example described above, white balance control is performed assuming a fixed color temperature during strobe photography, but the actual color temperature of the strobe light Since the color temperature depends on the light emission time, if # control is performed using a fixed constant, there is a possibility that the white balance adjustment will deviate depending on the light emission time.

The present invention has been made in consideration of the above-mentioned conventional examples, and it is an object of the present invention to provide a color imaging device that can obtain appropriate white balance adjustment during strobe photography regardless of the length of the flashing time. The purpose is

(Means for Solving the Problems) Therefore, in the present invention, there is provided a detection means for detecting the light emission time by the flashlight emitting device, and a white balance control signal that is converted into a plurality of white balance control signals according to the detected light emission time. The above object is achieved by providing a switching means for switching.

[Effect]

With the above configuration, the color imaging device of the present invention can perform appropriate white balance adjustment during strobe photography, regardless of the length of the light emission time.

(Example·) The present invention will be explained below based on examples.

FIG. 1 shows a block diagram of the overall configuration of an embodiment according to the present invention.

(Configuration) In FIG. 1, 1 is an optical system for focusing the subject image, 2a is an aperture for limiting the luminous flux of the subject, and 2b
is a driver for driving this aperture 2a, and 3a is
The shutter 3b for limiting the incident time of subject light is a driver for driving the shutter 3a.

Furthermore, numerals 4 to 7, 9, and 10 each have the same (equivalent) function as the constituent elements with the same numbers explained in FIGS. 7-8 of the prior art example.

8 is a photometry circuit for measuring the amount of light passing through the aperture 2a, and 13 is a distance measurement circuit for measuring the distance to the subject. Further, 11 is a photometric circuit 8.
Color measurement circuit 9. This is an arithmetic control circuit for controlling each driver 2b, 3b and each amplifier AR, A, 5.6 from each information of the flashlight emitting device 10.

FIG. 2 is a block diagram showing the detailed configuration of the photometric circuit 5, in which 8-1 is a photometric sensor for photoelectric conversion;
-2 is an integrator for integrating the output of the photometric sensor 8-1, 8-3 is a constant voltage source for outputting a constant voltage value Vref, and 8-4 is the output of the integrator 8-2. A comparator J8-5 for comparing the voltage value Vref of the constant voltage source 8-3 with the voltage value Vref of the constant voltage source 8-3 is a switch circuit for switching between the output of the photometric sensor 8-1 and the output of the comparator 8-4.

(Strobe Imaging Operation) The operation sequence during strobe photography in this embodiment will be described below based on the flowchart of FIG.

As shown in FIG. 5, when the power is turned on in step S1, the photometry circuit 8 is activated in step Sz,
The exposure amount EV is obtained.

Next, in step S3, if EV≧N (N is the lower limit EV value of the photometry interlocking range) (Yes),
In step S4, normal general photographing without using a flashlight is performed. On the other hand, if EVEN (No), distance measurement is performed in step S5 and an aperture value is set. Then, in step S6, the aperture 2a is stopped down to the given aperture value via the driver 2b, the shutter 3a is opened in step S7, and a flash is emitted in step S8. The emission start time at this time is 1
= 0, and at the same time the disconnection switch 8-5 is set to the comparator 8.
Connect to the output side of -4. Next, in step S9, it is checked whether the output of the photometric circuit 8 (output of the comparator 8-4) LtI is at a low level.

The operation of this photometric circuit 8 will be explained based on FIG.
The output of the photometric sensor 8-1 is input to the integrator 8-2 and integrated, and the integrated output S is compared with the constant voltage Vref of the constant voltage source 8-3, which is an appropriate photometric level, in the comparator 8-4. . At this time, the integrator 8-2 outputs the flash light emission start time 1=
Reset at 0, 1 = 0 to 1 for closing of shutter 3a
Integration is performed for up to =1s□. The integral value S is the constant voltage value Vr
When it is larger than ef, the output of the comparator 8-4 is high level, and when it is smaller, it is low level. (In addition,
As described above, the selector switch 8-5 is connected to the comparator 8-4 side during the integration period and to the photometric sensor 8-1 side during other periods. ) Also, when the above operations are shown in each timing chart of FIG. 4.5, (a) is the flash waveform of the flash light emitting device 10,
The flash start time is set to 1=0.

Further, the flash duration is t□ when full light is emitted.

(b) shows the state of shutter control, in which the shutter 3a opens when 1=0, closes when 1=1, and closes when H. (C) is a signal P sent from the arithmetic control circuit 1'1 to the integrator 8-2;
Then, the integral 9B-2 is reset with 1-0, and the signal L described later is
While s is at a low level, it is at a high level so as to be in an integral state. (d) is the output S of the integrator 8-2, 1=
It is reset at 0, and the photometric sensor output is integrated while the signal P is at a high level. (e) is the output of the switch 8-5, and the integration period is the output of the comparator 8-4, and if the integral value S in (d) is lower than the constant voltage value Vref, it is a low level, and if it is higher, it is a high level. . Other than the integration period, it is the photometric sensor output.

Now, in step S9 in FIG. 3, if the switch 8-5 outputs and 8 is at a low level (Yes), as can be seen from the above explanation, the integral output S is equal to the constant voltage value Vref.
Since the amount of light is smaller than that, the amount of light will not exceed the level.Therefore, it is checked in step 512 whether the signal Ps is at a high level, and if it is at a high level, the flash light is being emitted, so the light amount is not exceeded. In step S9, switch 8-5
Check whether the outputs t and s are low level. When L3 is at a low level and signal Pg is at a high level, it is a case of full light emission, and the flash duration is set to tr in step S13.
=tst, and the process advances to step S14.

Next, in step S9, the switch 8-5 outputs s
If is at a high level (NO), it means that the integral level S has exceeded the constant voltage value Vref, so step S10
In step Sll, the flash light emission time t1 is stored. In step S14, the shutter 3a is closed (step 514). In step 515, the arithmetic control circuit 11 executes the flash light emission time t1 according to the stored light emission time. The WB control voltage is calculated, the control voltage obtained as a result of the calculation is output in step S16, and the imaging signal is read out in step S17.

(Operation of Arithmetic Control Circuit) Next, the detailed operation of the arithmetic control circuit 11 will be explained based on the block diagram of FIG. Components with the same numbers as in the control unit 12 in FIG. 8 of the conventional example are the same (equivalent)
Since it has a function, repeated explanation will be omitted. Further, in the case of general photography without using a strobe, the operation is similar to that in the conventional example.

On the other hand, when photographing with the flash light emitting device 10, each changeover switch 3-8, 3-9 is set to each flash light constant 3-10.
．． Connect to 3-11 side. Further, 3-14 is a timer, and when the flash light emission starts in step S8 in FIG.
0, step Sll or step 51
Flash times up to 3 are memorized. Arithmetic IIJ control circuit 11
As shown in 3-10 and 3-11, it has multiple strobe WB constants, and a timer 3-14.
Flash duration stored in 1. For each switch 3
-12.3-13 is changed to a constant that provides an appropriate white balance.

By doing so, it is possible to solve the problem in the conventional example that the color temperature of the strobe light differs depending on the light emission time, so that an appropriate white balance cannot be achieved with fixed control.

[Other Examples]

In the above embodiment, the arithmetic control circuit 11 was configured as shown in FIG. 8, but it was replaced with a microcomputer capable of calculation, and
Each of the strobe WB constants may be written as a table in a read-only memory (ROM) in advance, and then read from the table written in the ROM based on the calculation result and output as a control o4 signal. The same effect can be obtained.

Further, in the above embodiment, 83 colors of R and G were detected as detection components of the colorimetric circuit 9, but white balance adjustment may be performed by detecting 82 colors of R and G and predicting the G component. .

Furthermore, as the output of the image sensor 4 and the colorimetric circuit 9,
Although the three primary colors R, G, and B are used, it goes without saying that a correction signal may also be used.

(Effects of the Invention) As described above, according to the present invention, when taking pictures using a flash light source, the flash light emission time is detected and the white balance control signal is switched depending on the light emission time. This makes it possible to perform appropriate white balance adjustment even if the color temperature of the strobe light differs.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the configuration of an embodiment of the present invention, FIG. 2 is a block diagram of the photometry circuit configuration of FIG. 1, FIG. 3 is a strobe photography operation sequence flowchart, and FIGS. 4 and 5 are , the timing chart of each of the above operations, FIG. 6, is as follows:
FIG. 7 is an operational block diagram of the arithmetic control circuit, FIG. 7 is a block diagram of a conventional white balance adjustment example, and FIG. 8 is an operational block diagram of the f#IIt11 section in FIG. 2am-Aperture 3a-4--Shutter-10, 3-11--Strobe WB constant-14
----1 Timer...Image sensor...Signal processing unit that obtains a predetermined signal...-Photometry circuit...Coloring circuit 0... Flashlight emitting device 1------- Arithmetic control circuit

Claims (1)

[Claims] an imaging device for converting subject light into an electrical signal and outputting a plurality of color signals; a flashlight emitting device; a detection device for detecting the flashlight emission time; and a device for storing a plurality of white balance control signals. and a switching means for switching the stored control signal, and is configured to switch the white balance control signal according to the detected light emission time.