JP2694620B2 - Imaging device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging device, and more particularly to an imaging device having a white balance adjusting unit.

[Prior Art] Conventionally, as a white balance adjusting device for an image pickup device,
An external measurement method that adjusts the white balance by the output signal of the external colorimetric sensor as shown in Fig. 11 and a through-the-lens method (hereinafter TTL that adjusts the white balance by the output signal of the image sensor as shown in Fig. 12). Method) is known. The conventional example will be described below with reference to FIGS. 11 and 12.

FIG. 11 is a block diagram of a conventional example of the external measurement method.
Is a solid-state image sensor that is an image sensor that converts optical information into electrical signals. Reference numeral 2 denotes a luminance signal processing unit that performs appropriate processing on the output of the image sensor 1 to derive a luminance signal Y. 3 is an image sensor 1
Saturation signal processing unit (hereinafter referred to as "chroma signal processing unit") that performs appropriate processing on the output of the above to derive low-frequency luminance signal Y _L and color signals R and B. Reference numerals 4 and 5 denote an R gain control unit and B for controlling the levels of outputs R and B of the chroma signal processing unit 3 and outputting R ₁ and B ₁ , respectively.
Gain control section. Differential amplifier for deriving the color difference signal R-Y from 6 Y _L and R _1. Differential amplifier for deriving the color difference signal B-Y from the Y _L and B ₁ is 7. 8 is NTS from color difference signals RY and BY
Modulator that derives the modulated signal specified by C, PAL, etc. 9
Is an adder for deriving a predetermined video signal from the output Y of the luminance signal processing unit 2 and the output of the modulation unit 8. 10 is a color temperature sensor that is a colorimetric sensor other than the image sensor that measures the color temperature of the light source illuminating the subject, and 11 is the color temperature sensor.
A control voltage derivation unit that derives a voltage for controlling the amplifier gain of the R gain control unit 4 and the B gain control unit 5 from the output of 10.

 The operation will be described below with reference to FIG.

The luminance signal processing unit 2 derives a Y signal from the output of the imaging device 1 and the chroma signal processing unit 3 obtains Y _L , R, and B. And
The control voltage deriving unit 11 measures the color temperature of the light source light illuminating the subject with the 10 color temperature sensors, and the control voltage to be given to the R gain control unit 4 and the B gain control unit 5 to correct the white balance by the control voltage deriving unit Is derived, and the R gain control unit 4
Then, color signals R ₁ and B ₁ whose white balance has been adjusted by the B gain control unit 5 are obtained. Hereinafter, the differential amplifiers 6 and 7, the modulation unit 8,
Then the adder 9, Y, Y _L, which derives a predetermined video signal adjusted in the white balance from R _1, B _1.

Next, FIG. 12 is a block diagram of a conventional example of the TTL system, blocks 1 to 9 correspond to blocks of the same number in the conventional example of FIG. 11, and 12 and 13 are R- Y, BY
An averaging unit such as a low-pass filter that averages a signal and converts the signal into a DC potential. Reference numeral 14 is a control voltage derivation unit that derives a control voltage to be given to the gain control unit 4 and the B gain control unit 5 in order to correct the white balance from the signals averaged by the averaging units 12 and 13.

 Hereinafter, the operation will be described.

The operations of blocks 1 to 9 are similar to those of the conventional example shown in FIG. Then, the RY and BY signals averaged over one screen or several screens by the averaging units 12 and 13 are compared with the specific potential corresponding to the zero level of the color difference signal by the control voltage deriving unit 14. , Determine whether the level is lower or higher than zero level,
A control voltage for causing the RY and BY levels to be the level closest to the zero level is derived. Then, the control voltage is input to the RB gain control units 4 and 5 to perform white balance adjustment.

As described above, in addition to the two methods, an example of an addition method combining the external measurement method and the TTL method is known.

 FIG. 13 is a block diagram showing an example of the addition method.

In the figure, blocks 1 to 14 are shown in FIG.
This corresponds to the block with the same number in the conventional example of FIG. Hereinafter, 14 is referred to as a first control voltage deriving unit, and 11 is referred to as a second control voltage deriving unit. Reference numerals 27 and 28 denote adders for adding the control voltage obtained by the first control voltage deriving unit 14 and the control voltage obtained by the second control voltage deriving unit 11 at a constant rate.
Then, white balance adjustment is performed with the added voltage.

That is, in this conventional example, the control voltage obtained from the signal obtained from the image sensor 1 and the control voltage obtained from the signal of the color temperature sensor which is the colorimetric sensor 10 other than the image sensor 10 are added at a fixed ratio, so that It is configured to perform good white balance adjustment.

Japanese Patent Application Laid-Open No. 63-314424, filed by the applicant of the present application, detects the amount of light incident on a colorimetric sensor and selects one of two colorimetric methods based on the detection output to adjust white balance. There is also description to do.

[Problems to be solved by the invention]

However. In the above-mentioned conventional example, in the external measurement method of FIG. 11, the accuracy of white balance adjustment is used when the light source illuminating each is different due to the distance between the imaging device body and the subject, or when the evening glow occurs. Will be significantly reduced.

In the TTL method of Fig. 12, when the subject is a large area of chromatic color and most of the screen is occupied by a single color, the white balance adjustment accuracy is also degraded. I will end up.

On the other hand, in the addition method of FIG. 13, in order to make up for the drawbacks of the above two conventional examples, the accuracy is improved by simply adding the control voltages derived by the external measurement method and the TTL method. However, there is a drawback in that the accuracy of the white balance adjustment for each of the strong scenes is deteriorated by adding the values in reverse. Further, JP-A-63-
The example shown in Japanese Patent Publication No. 314424 is a remedy only when the surroundings are dark, and is not suitable for white balance adjustment in a scene where it is not good when the surroundings are bright.

This invention solves the above-mentioned problems of the prior art, and the distant view which is not good at the external measurement method, the variation of the lighting condition, the back light, the image pickup under the dark background, and the image pickup screen which the TTL method is not good at have a single color. Appropriate white balance adjustment can be performed even with such image pickup. Moreover, it is an object of the present invention to provide an image pickup apparatus capable of obtaining an appropriate effect, which is different from the adjustment in which the characteristics of both the above-mentioned methods are thinned, which tends to occur in the addition method.

[Means for solving the problem]

Therefore, the image pickup apparatus according to the present invention is an image pickup apparatus that performs white balance adjustment using the image pickup output obtained from the image pickup element, and the image pickup outputs at a plurality of positions on the screen obtained by sampling the image pickup output. An object of the present invention is to achieve the above-mentioned object by a configuration characterized by having switching means for comparing each other and switching a control signal for controlling the white balance according to the comparison result.

Furthermore, the first white balance adjusting means for generating a white balance control signal for white balance adjustment using the signal obtained from the image sensor, and the white balance using the signal obtained from the colorimetric sensor other than the image sensor. Second white balance adjusting means for generating a white balance control signal for adjustment is compared with at least a signal at a predetermined position on the screen obtained by sampling the signal output from the image sensor, and the comparison result is shown. According to the above 2
It is an object of the present invention to achieve the above-mentioned object with a configuration characterized in that it has a synthesizing means for mixing respective white balance control signals from one white balance adjusting means at a predetermined ratio.

[Action]

With the above configuration, the control means compares the image pickup outputs at a plurality of positions on the screen obtained by sampling the image pickup output obtained from the image pickup device, and adjusts the white balance according to the comparison result to perform image pickup.

Then, the first white balance adjusting means generates a white balance control signal for white balance adjustment using the signal obtained from the image sensor, and the second white balance adjusting means obtains from the colorimetric sensor other than the image sensor. The generated signal is used to generate a white balance control signal for white balance adjustment. Then, the synthesizing means compares signals at a plurality of positions on the screen obtained by sampling at least the signal output from the image pickup device, and each white balance control from the two white balance adjusting means according to the comparison result. The signals are mixed and output at a predetermined ratio, and white balance adjustment is performed according to this output to capture an image.

By the above white balance adjustment, it is possible to capture an image with appropriate white balance.

If a warning device for generating a shooting warning signal is provided, the shooting warning signal is generated according to shooting conditions.

Furthermore, when a storage unit for storing the white balance control voltage is provided, appropriate white balance adjustment is performed by the stored white balance control voltage according to the imaging condition, and an image is captured.

〔Example〕

(First Embodiment) FIG. 1 is a block diagram showing a first embodiment of the image pickup apparatus according to the present invention. In this embodiment, the control signal in the present invention is controlled by the first and second white balance adjusting means. It is used for switching. In FIG. 1, books 1 to 14 are blocks corresponding to the blocks having the same numbers shown in the conventional example. In addition, 15 and 16 select the white balance control voltage obtained from the control voltage deriving units 11 and 14,
Is a switch for sending to the R and B gain control units of the above, and 17 is an output of the differential amplifiers 6 and 7, RY and BY signals and (RY) signals at a plurality of positions in the screen by a predetermined pulse. A switch control signal derivation unit that generates and derives a control signal for switching the switches 15 and 16 by comparing and (BY) signals, and 18 is a predetermined pulse sent to the switch control signal derivation unit 17, That is, it is a pulse generator that generates sampling pulses. The image sensor 1, the averaging units 12 and 13,
The control voltage deriving unit 14 constitutes the first white balance adjusting means, and the color temperature sensor 10 which is a colorimetric sensor other than the image sensor and the control voltage deriving unit 11 constitute the second white balance adjusting means. Switch control signal derivation unit 17,
The switches 15 and 16 and the pulse generator 18 constitute a combining means which is a control means.

The synthesizing means in the present embodiment selectively outputs the white balance control signal from each of the white balance adjusting means, that is, switches the synthesizing ratio between 0 and 100%.

FIG. 2 is a partially omitted explanatory view showing an example of the switch control signal derivation unit 17 of FIG. AD1 to AD8 are adders, CP
1 to CP8 are comparators, ND1 to ND6 are NAND gates, and NR1 to NR3 are NOR gates.
Is a standard voltage source, and 19-1 is a sample and hold circuit (hereinafter referred to as S.H circuit). The BY signal from the differential amplifier 7 is input to another SH circuit 19-2 and output to the NAND gate ND6 until the RY signal is processed and input to ND5. The illustration is omitted because it is similar to the configuration.

Further, FIGS. 3 and 4 are a timing diagram and an in-screen sampling point diagram for explaining this embodiment.

Next, the operation of the first embodiment will be described with reference to FIGS.

First, in FIG. 1, the operation of blocks 1 to 14 is as follows.
It operates in the same way as the same code blocks in FIG. 11, FIG. 12, and FIG. Then, one of the white balance control voltages derived by the control voltage deriving units 11 and 14 is selected by the switches 15 and 16, and the selected white balance control voltage is sent to the R and B gain control units 4,5. The switching control signal of the switches 15 and 16 is generated by the switch control signal deriving unit 17 from the outputs RY and BY of the differential amplifiers 6 and 7 and the pulse from the pulse generator 18.

The operation of the switch control signal deriving unit 17 will be described in more detail below with reference to FIGS. 2 and 3.

The output signal RY (FIG. 3a) from the differential amplifier 6 is
It is input to the SH circuit of 19-1. In the S / H circuit 19-1, R- is supplied during a high level period of the sample hold pulses SHP1 to SHP1 to SHP4 (FIGS. 3C to 3H) sent from the pulse generator 18.
The Y signal is sampled, and the signals SH1 to 4 (i to l in FIG. 3) whose levels are held are derived during the other periods.

As shown in FIG. 4 (A), the SHPs 1 and 2 in this embodiment sample the RY signals on the left and right sides in the figure on the upper scanning line in the predetermined screen, and the SHPs 3 and 4 are the same. The R-Y signals on the left and right sides in the drawing on the lower scanning line in the screen are sampled, and the S-Y signals SHP1 to SHP4 sample the R-Y signals near the corners in the screen.

Further, SHP1 and 2 and SHP3 and 4 are located on the front side and the rear side on one scanning line, as illustrated in FIGS.
SHP1 and SHP3 and SHP3 and SHP4 may be located on different scanning lines.

Further, the derived signals SH1 to SH4 are extracted two by two and their magnitudes are compared. For example, SH1 and SH2 are drawn out as a set, SH1 is guided to adders AD1 and AD2, and a positive potential E and a negative potential −E are applied to AD1 and AD2. The outputs of the adders AD1 and AD2 are the positive terminal and CP of the comparator CP1, respectively.
SH2 is connected to the negative terminal of CP1 and the positive terminal of CP2. As a result, the output of CP1 becomes high level if SH1 + E> SH2, and the output of CP2 becomes high level if SH1−E <SH2. The outputs of CP1 and CP2 are led to the NAND gate ND1. Therefore, the output of ND1 becomes low level only when SH1−E <SH2 <SH1 + E. That is, with SH1
Only when the level difference of SH2 is smaller than the constant level E, the ND1 output becomes low level.

Similarly, the outputs of the NAND gates ND2, ND3, ND4 are S.
Only when the level difference between SH3 and SH4, SH2 and SH4, SH1 and SH3 of the H circuit is smaller than the constant level E, the level becomes low.

Further, the output of NR1 becomes high level only when both outputs of ND1 and ND2 are low level, and the output of NR2 becomes high level only when both outputs of ND3 and ND4 are low level. The output of ND5 becomes low level only when the outputs of NR1 and NR2 are both high level.

That is, the output of the NAND gate ND5 becomes low level only when SH1 to SH4 have the following relationship.

SH1−E <SH2 <SH1 + E and SH4−E <SH3 <SH4 + E and SH2−E <SH4 <SH2 + E and SH3−E <SH1 <SH3 + E and the sample hold pulse SHP1 ～ shown in FIG.
Since SHP4 corresponds to the upper left, upper right, lower left, and lower right in order on the screen shown in FIG. 4, respectively, in this embodiment, the magnitudes of the RY signals at the four corners of the screen are compared, and the relationship between left and right and up and down is obtained. The output of the NAND gate ND5 becomes low level only when the difference in a certain portion is smaller than E and the difference between the sums of the diagonal portions is smaller than 2E.

Further, the same processing is performed for the output BY of the differential amplifier 7 so that the difference between left and right and up and down portions is smaller than E, and the difference between the sums of diagonal portions is smaller than 2E. Only when it is small, the output of the NAND gate ND6 becomes low level.

The output of the NOR gate NR3 becomes high level only when both outputs of the NAND gates ND5 and ND6 become low level, that is, when both the RY and BY signals satisfy the above conditions.

With the above configuration and operation, when the output of the NOR gate NR3, that is, the output of the switch control signal deriving unit 17 becomes a high level, the difference between the color signals at each sampling point as described above is smaller than the predetermined value E. It is estimated that most of the screen is occupied by a single color, which is estimated to be a scene where the TTL method is not good, as shown above, so the switches 15 and 16 are set to the second position. If the output of NR3, that is, the output of the switch control signal deriving unit 17 is at a low level, connect it to the TTL method side that is the first white balance adjusting means. This allows more accurate white balance adjustment.

Further, particularly in the present embodiment, by slightly increasing the threshold value (threshold level) for detecting the color difference between the portions that are diagonally related to the upper and lower sides and the left and right sides, the same object has a different color level difference due to the intensity of light such as a shadow. There is no erroneous detection in the diagonal direction, which is the easiest to attach.

As described above, by always selecting the first white balance adjusting means of the TTL method and the second white balance adjusting means of the external measurement method by comparing the color signals at a plurality of sampling points on the screen, It is possible to perform imaging with appropriate white balance adjustment.

Although the sampling point in the above embodiment is near the corner of the screen, it may be at the center of the screen.

The sampling point can be changed according to the subject. For example, when shooting a person, the sampling point should be on the center side, and when shooting a landscape, the sampling point should be on the corner section. May be.

Second Embodiment As a second embodiment, the switch control signal derivation unit 7 shown in FIG. 1 of the first embodiment may be composed of an A / D converter and a microcomputer (hereinafter referred to as a microcomputer).

FIG. 5 is a block diagram showing such a second embodiment. Reference numeral 19 is a microcomputer, 20 is an A / D converter, and the same or corresponding blocks as those of the other first embodiment are denoted by the same reference numerals.

The configuration of the first white balance adjusting means and the second white balance adjusting means is the same as that of the first embodiment, and the A / D converter 20, the microcomputer 19, and the switches 15 and 16 constitute the selecting means. ing.

FIG. 6 is a flow chart showing the operation of this embodiment. In step (a), the A / D converter 20 samples the RY and BY signals by a command from the microcomputer 19 for a predetermined period corresponding to SH1 to SH4 of the first embodiment, and A / D conversion,
The digital signal is taken into the microcomputer 19. In steps (b) to (e), RY, B-
Check whether SH1 to SH4 are within a certain level range by comparing the magnitude of SH1 to SH4 with Y. If yes, proceed to step (to), output a high level, and switch.
By switching 15 and 16 to the control voltage deriving unit 11 side, the external measurement method, which is the second white balance adjusting means, is selected and imaged.

If it is not within the certain level range, proceed to step (g), output low level, and switch 15,1
It is possible to switch 6 to the control voltage deriving unit 14 side and select the TTL method that is the first white balance adjusting means to perform appropriate white balance adjustment imaging.

(Third Embodiment) In the above embodiments, the number of samples of each of the RY and BY color signals and the sample period are four-point sample hold SH1 to SH4 shown in FIG. 4 (A). , The number of samples, and the sample points may be changed. For example, as shown in FIGS. 4 (B) and 4 (C), whether or not the screen is a single-color screen by appropriately switching the switches 15 and 16 by setting a large number of samples and effectively setting the sample points. Can be detected more accurately, which enables accurate white balance correction, and conversely reduces the number of samples to save circuits and microcomputer programs. Appropriate design is possible within the degree and integration with other requirements.

Fourth Embodiment In the above embodiments, weighting may be performed when comparing the sampling values. That is, FIG. 4 (C)
For SH5, each for determining the size of each SH1-9
Threshold level of difference from SH value (E shown in Fig. 2)
And the threshold level for determining the magnitude of SH1 and SH9 is increased, and the threshold level is changed according to the difference in the points to be compared, and the white balance adjustment means is selected and determined. as a result,
For example, when a single-color screen is photographed, erroneous detection due to the distance between sampling points can be prevented and a more appropriate white balance adjusting means can be selected.

(Fifth Embodiment) In the above embodiments, the size of one sampling value of SH1 to SH4 is compared, but the average value of the values sampled for several fields for each SH point may be compared. .

Further, even in the one-field period, several points may be sampled as shown in FIG. 4 (B) with respect to the proximity portion of each SH1 to SH4 on the screen, and the average value may be compared.

With the above configuration, it is possible to select more stable and appropriate white balance adjusting means from which the influence of random noise or the like is removed.

Sixth Embodiment For the number of samples, sample points, and weighting in the above embodiments, color temperature information, automatic exposure control (AE) information, distance information from an automatic focus control (AF) sensor, zoom lens, etc. are used. It may be switched based on the focal length information in this case. For example, when the subject is distant and the focal length is long, the light source illuminating the external colorimetric sensor and the light source illuminating the subject are often different. The number of samples is increased so that the white balance adjusting unit 1 is selected, and the sample points are set closer to the four corners on the screen than the position shown in FIG. 4 (A).

In addition, the subject is far, the focal length is long, and the fourth
Even if the conditions of the number of samples and the sample period are changed as shown in FIG. 6C, if the second white balance adjusting means that is the external colorimetric method is selected, the white balance cannot be corrected well in many cases. Therefore, by adopting a configuration in which the shooting warning signal is output according to the control signal in the present invention, it is possible to select a more appropriate white balance adjusting means, and particularly, in a bad condition, the shooting warning signal is used. It is possible to respond because it is possible to know.

A block diagram of a sixth embodiment as an example of this configuration is shown in FIG. It should be noted that blocks that are the same as or correspond to the blocks described above are denoted by the same symbols. Reference numeral 21 is a distance measuring sensor, 22 is a zoom lens, 23 is a counter, 24 is an AND gate, and 25 is a warning device.

In FIG. 7, when it is transmitted to the pulse generator 18 that the distance to the subject is short from the distance measuring sensor 21 and the focal length is long from the zoom lens 22, it is sent from the pulse generator 18 to the switch control signal deriving unit 17. The generated pulse is changed to the outer side on the screen and the number of pulses is changed from 4 to 9 so as to correspond to FIG. 4 (C). The switch control signal derivation unit 17 is configured to send a comparison result to the 15 and 16 switch units by configuring a comparison circuit corresponding to the number of pulses. In addition, the total number of pulses sent from the pulse generator 18 is measured by 23 counters, and the number is 1
When it exceeds the constant level, a high level signal is sent to the AND gate 24. At this time, if the switch control pulse from the switch control signal deriving unit 17 is at high level, the AND gate
The output of 24 becomes high level, and the high level signal causes the warning device 25 to generate a shooting warning signal.

(Seventh Embodiment) In the sixth embodiment, in addition to outputting the warning signal, the white balance control voltage of the previous scene that does not satisfy the warning condition may be stored and used.

FIG. 8 is a block diagram showing the seventh embodiment,
The same or corresponding blocks as described above are designated by the same reference numerals.

26 and 27 are switches that enable a high impedance output state, and 28 and 29 are memories that store the white balance control voltage. FIG. 9 is an explanatory view of the memories 28 and 29, where 30 is a buffer in the memories 28 and 29, 31 is a switch, 32 is a logic gate for generating signals for controlling the switches 26 and 27, and the switches of the memories 28 and 29. Circuit.

A signal indicating a situation in which it is difficult to adjust the white balance as described in the sixth embodiment is generated by the logic gate circuit 32 and sent to the switches 26 and 27 and the memories 28 and 29. The switches 26 and 27 are normally switched to the TTL side or the external measurement side by the output signal of the logic gate circuit 32, but when the white balance adjustment is difficult, the output of the logic gate circuit 32 causes a high impedance output state. On the other hand, the memories 28 and 29 are constructed as shown in FIG. 9, and during normal photographing, the switch 31 is switched from the output side of the buffer 30 to the input side at the same time when the power is turned on. The switch is connected to the output side when the power is turned off.
However, when a signal indicating that adjustment is difficult is sent from the logic gate circuit 32, the switch 31 remains connected to the output side even when the power is turned on. Therefore, normally, the white balance control signal derived by the TTL method or the external measurement method is sent to the R and B gain control units 4 and 5, and when the white balance adjustment is difficult, it is stored in the capacitors C of the memories 28 and 29. Therefore, the white balance control voltage based on the above voltage, that is, the white balance control voltage in the scene where the correction is easy before is sent.

With the above configuration and operation, it is possible to employ the white balance adjustment data of the previous scene to capture an image even under conditions where white balance adjustment is difficult.

(Eighth Embodiment) Although the white balance adjustment processing is directly performed on the output of the image sensor 1 in the above embodiments, the output of the image sensor 1 may be temporarily stored in the image memory and may be performed on the output. . FIG. 10 is a block diagram showing the embodiment, and 33 is a frame memory.

In this case, processing for each screen unit can be facilitated, and improvement in white balance adjustment accuracy can be expected.

(Ninth Embodiment) Although the RY and BY signals are used as the color signals used in the first white balance adjusting means in the above embodiments, the R, G and B signals may be used as the color signals. good.

In this case, the white balance adjustment effect can be further improved.

(Tenth Embodiment) In the above embodiments, the white balance control signal is obtained by averaging the color signals of the entire screen as the signals used in the first white balance adjusting means. Other methods such as obtaining a control signal by using may be used.

(Eleventh Embodiment) In the second embodiment, as shown in FIG. 5, the switch control signal deriving unit 17 in FIG. 1 of the first embodiment is replaced with the A / D converter 20 and the microcomputer 19. , Control voltage derivation unit 11,1
4, all switches 15, 16 are A / D converter, microcomputer and D
It may be configured with an / A converter.

In this case, the components can be rationalized and the function of the microcomputer can be effectively used.

(Twelfth Embodiment) In the above embodiments, the control voltage is switched to select one of the first and second white balance adjusting means. However, in the vicinity of the switching threshold (threshold), the control voltage of both means is changed. It is also possible to mix both control voltages such as an average value or an approximate value thereof at a predetermined ratio and use them as the white balance control voltage to switch the control voltage continuously or stepwise.

In this case, more stable and preferable imaging can be performed even near the threshold value.

Note that the control voltages of both means may be mixed at a predetermined ratio over the entire range of the signal level without being limited to the vicinity of the threshold value.

(Thirteenth Embodiment) Further, in the above embodiments, the comparator of the optical system information level determination means and the microcomputer comparison calculation may have a hysteresis characteristic in order to prevent instability near the threshold level. good.

In this case, more stable and preferable imaging can be performed even near the threshold value.

(Fourteenth Embodiment) The control signals in the present invention may be used to variably control the time constants of the averaging units (integrator circuits) 12 and 13.

That is, the integrating circuits forming the averaging units 12 and 13 in FIG. 1 may be configured to use a personal computer and / or a volume, and these may be appropriately variably controlled by the output of the switch control signal deriving unit 17.

Then, for example, when the subject does not change, by increasing the time constant, the accuracy of the control signal output from the control voltage deriving unit 14 in the TTL can be increased, and the subject changes quickly. In this case, by shortening the time constant, it is possible to reduce the disturbance of the white balance due to the change of the subject.

〔The invention's effect〕

As described above, according to the present invention, the control means compares the image pickup outputs at a plurality of positions on the screen obtained by sampling the image pickup output obtained from the image pickup device, and the white output is performed according to the comparison result. The balance adjustment is performed, that is, the white balance control signal for white balance adjustment generated by the first white balance adjusting means using the signal obtained from the image sensor, and the second white balance adjusting means other than the image sensor. The white balance control signal for white balance adjustment generated using the signal obtained from the colorimetric sensor, and the synthesizing means sample the signal output from at least the image sensor to obtain signals at a plurality of positions on the screen. Compare each other, mix and output at a predetermined ratio according to this comparison result, and perform white balance adjustment according to this output Since it is an image, it is suitable for distant scenes that are not good at external measurement, uneven lighting conditions, back light, imaging under a dark background, or even when the TTL method is not good at capturing an image with a single color. The balance can be adjusted. In addition, it is possible to provide an image pickup apparatus that can obtain an appropriate effect, which is different from the adjustment in which the characteristics of both the above-mentioned methods tend to occur, which is likely to occur in the addition method.

When a warning device for generating a shooting warning signal is provided and white balance adjustment is performed by issuing a shooting warning signal, the shooting warning signal is sent when the white balance adjustment is difficult. Can be issued to call attention.

Furthermore, in the case where the storage means for storing the white balance control voltage of the first white balance adjusting means and the second white balance adjusting means is provided and the white balance adjustment voltage is used to perform the white balance adjustment, When the white balance adjustment cannot be performed well, the white balance adjustment can be performed by the white balance control voltage stored in the storage means.

As described above, it is possible to provide an image pickup apparatus capable of performing appropriate white balance adjustment even under various conditions.

Further, in the present invention, since the control is performed according to the difference in sampling data, not the color or the brightness itself, it is determined whether or not the screen is a single color screen, especially when used for the switching control of the white balance control. The influence can be removed and the detection can be accurately performed, and more accurate white balance control can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention, and FIG.
FIG. 4 is a block diagram of a switch control signal deriving unit, FIG. 3 is a timing diagram, FIG. 4 is an explanatory diagram of sampling points on the screen, FIG. 5 is a block diagram showing a second embodiment, and FIG. FIG. 7 is a block diagram showing a sixth embodiment, FIG. 8 is a block diagram showing a seventh embodiment, FIG. 9 is an explanatory diagram of a memory, and FIG. 10 is an eighth embodiment. The block diagram shown in FIGS. 11 to 13 is a block diagram showing a conventional example. 1 ... Image sensor 2 ... Luminance signal processing unit 3 ... Chroma signal processing unit 4 ... R gain control unit 5 ... B gain control unit 6, 7 ... Differential amplifier 8 ... Modulation unit 9 ... Addition Instrument 10 …… Colorimetric sensor 11 …… Control signal deriving unit 12,13 …… Averaging unit 14 …… Control signal deriving unit 15,16 …… Switch 17 …… Switch Control signal deriving unit 18 …… Pulse signal generator 19 …… Microcomputer 20 …… A / D converter 21 …… Distance measuring sensor 22 …… Zoom lens system 23 …… Counter 24 …… AND gate 25 …… Warning device 26,27 …… 3-state switch 28, 29 …… Memory 30 …… Buffer 31 …… Switch 32 …… Logic gate circuit 33 …… Frame memory 34,35 …… Adder

Claims (4)

(57) [Claims] 1. An image pickup apparatus for performing white balance adjustment using an image pickup output obtained from an image pickup device, wherein image pickup outputs at a plurality of positions on a screen obtained by sampling the image pickup output are compared, An image pickup apparatus comprising: a switching unit that switches a control signal for controlling white balance according to a comparison result. 2. A first white balance adjusting means for generating a white balance control signal for white balance adjustment using a signal obtained from an image sensor, and a signal obtained from a colorimetric sensor other than the image sensor. A second white balance adjusting means for generating a white balance control signal for white balance adjustment is compared with signals at a plurality of positions on the screen obtained by sampling at least the signal output from the image sensor, The image pickup apparatus according to claim 1, further comprising a combining unit that mixes the white balance control signals from the two white balance adjusting units according to a comparison result at a predetermined ratio. 3. An image pickup apparatus comprising a warning device for generating a shooting warning signal in addition to the structure according to claim 2. 4. An image pickup apparatus according to claim 2, further comprising storage means for storing a white balance control voltage, wherein white balance adjustment is performed by the stored white balance control voltage.