JP2778737B2 - Electronic imaging device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic image pickup apparatus including means for adjusting a color tone of a subject image signal electronically picked up using an image pickup device.

[Related Art] In recent years, various electronic cameras have been developed which electronically image a subject using a solid-state imaging device such as a CCD and electronically record the image signal on a floppy disk, a memory card, or the like. This type of electronic camera reproduces a subject image signal captured and recorded as described above using a TV receiver or the like.
Because of its easy handling and the ability to use the image signal as it is for image communication, it has attracted attention as an alternative to a camera using a conventional silver halide film.

FIG. 6 shows an example of a basic configuration of an electronic camera of this type, wherein reference numeral 1 denotes a CCD as a solid-state imaging device for electronically imaging a subject. The CCD 1 is driven under the control of the control unit 2 including the synchronization signal generation unit 2a and the CCD drive control unit 2b to electronically image a subject, and outputs an image signal thereof to the imaging signal processing circuit unit 3. The imaging signal processing circuit unit 3 performs white balance adjustment on the image signal by a white balance (WB) control unit 4 provided therein, and adjusts its color tone. The image signal thus adjusted in color tone (white balance adjustment) is supplied to the recording unit 5 and recorded on the floppy disk 7 via the recording head 6, for example.

Normally, about 50 signal recording tracks are formed concentrically on the floppy disk 7, and one subject image signal is recorded for each track under the track access control by the recording head 6.

The system controller 8 controls the electronic imaging of the subject by the above-described CCD 1 and the recording of the image signal. The system controller 8 receives the imaging instruction by operating the release switch 9a and executes the imaging operation of the subject. At this time, the shooting mode information of “single / continuous shooting” is obtained from the switching state of the switch 9b, and the shooting mode information of “strobe auto / strobe off” is obtained from the switching state of the switch 9c, and the shooting operation mode is set. Switching is controlled.

The system controller 8 includes a photometric sensor 10.
The brightness information of the subject measured by the
11, which are input via the A / D converter 12. The drive of the CCD 1 by the control unit 2 is controlled in accordance with the brightness information of the subject, and the exposure amount (exposure amount) for the imaging signal is controlled to be constant. That is, according to the brightness of the subject detected by the photometric sensor 10, the CCD drive control unit 2b controls the CCD.
The imaging timing (accumulation period of signal charge) of 1 is controlled, and the exposure amount is adjusted by so-called element shutter control.

Note that, instead of adjusting the exposure amount by controlling the element shutter, it is of course possible to adopt a configuration in which the exposure amount is controlled by driving an aperture mechanism (not shown) incorporated in the imaging lens system.

Here, the WB control unit 4 in the imaging signal processing circuit unit 3
Are, for example, color difference signals (RY) and (BY) white-balance-adjusted from the color separation signals I and II obtained from the CCD1, for example.
, Which is configured to adjust the color tone according to a white balance adjustment value given according to the color temperature of the subject.

Thus, the white balance adjustment value given to the WB control unit 4 is conventionally manually selected and set generally by switching the switches 13a and 13b. That is, the variable resistor group 14 has a white balance adjustment value corresponding to the color temperature of the illumination light source of the object in advance, specifically, 5400K (Kelvin) which is a daylight color temperature, and 3200K which is a color temperature of indoor tungsten light. Then, white balance adjustment values corresponding to each of the color temperatures of the fluorescent light, 4800K, are set. The white balance adjustment value corresponding to the color temperature of various illumination light sources set in the variable resistor group 14 is
The selection is made by switching the switches 13a and 13b by the photographer's manual operation, and is given to the WB control unit 4. In other words, the photographer determines the illumination light condition of the subject and switches the switches 13a and 13b, thereby controlling the operation of the electronic camera so that the white balance is adjusted according to the photographing condition at that time.

In addition, the xenon lamp 15 in FIG. 6 is driven by flash light emission by a strobe circuit 16, and constitutes a so-called electric flash (strobe). The subject to be imaged is supplementarily illuminated with light (strobe light) emitted from the strobe (xenon lamp 15), and the lack of brightness is compensated. Generally, the color temperature of the strobe light is determined to be substantially equal to the color temperature of daylight. At the time of imaging a subject using the strobe light, the color balance is adjusted using the white balance adjustment value set for the daylight color temperature described above.

Also, as disclosed in Japanese Patent Publication No. 63-30612, a light emission command signal to a strobe circuit 16 associated with a shutter release operation at the time of shooting using a strobe light, a mounting detection signal of a strobe device mounted on a camera, or Since the brightness of the subject is low, it is determined that the flash is to be fired to perform the shooting, and the flash shooting operation is detected using the output auto flash signal, and the white balance adjustment value used at that time is used for the flash shooting described above. It has been proposed to force the value.

[Problems to be Solved by the Invention] However, in the conventional electronic camera which performs white balance setting by manual operation in this way, each time the shooting conditions change, the switches 13a and 13b described above must be switched and set. There is the complexity that it does not become. In addition, the user often forgets to switch the switches 13a and 13b or takes a picture in an erroneous operation state.

Conventionally, a colorimetric sensor for measuring the color temperature of an illumination light source of a subject is incorporated in an electronic camera, and the above-mentioned white balance adjustment value is automatically selected and switched according to color temperature information detected by the colorimetric sensor. Etc. are considered. However, measuring the color temperature of an illumination light source using a colorimetric sensor has a problem that a very complicated processing mechanism is required.

On the other hand, the flash shooting modes include a flash single-shot shooting mode in which flash shooting is performed with a sufficient shooting time interval, and a flash continuous shooting mode in which flash shooting is continuously performed at predetermined time intervals. . In the flash single-shot mode, the xenon lamp 15 can be caused to emit light each time the main capacitor in the flash circuit 16 is sufficiently charged, and the color temperature of the flash light can be kept substantially constant.

However, in the flash continuous shooting mode, it is necessary to repeatedly drive the xenon lamp 15 to emit light at predetermined time intervals, and it is generally not possible to secure a sufficient recharge time for the main capacitor. Therefore, conventionally, for example, a device has been devised such that the charging voltage of the main capacitor (light emission driving voltage for the xenon lamp 15) is reduced and the amount of strobe light emission per time is suppressed, so that strobe light emission can be repeatedly performed in a short time. . In other words, the operating conditions of the flash circuit 16 are switched and set, the charging voltage of the main capacitor is set high enough for single flash shooting, and the flash is fired spontaneously, and the charging voltage of the capacitor is low for continuous flash shooting. , So that the strobe can be repeatedly and continuously emitted.

For this reason, it cannot be denied that the color temperature of the strobe light changes depending on the light emission drive conditions (light emission drive voltage for the xenon lamp 15; charging voltage of the main capacitor), even with respect to the strobe light emitted from the same xenon lamp 15. Therefore, when the white balance adjustment is performed according to only a single white balance adjustment value for strobe shooting as described above, for example, the color tone of an electronic still image during strobe continuous shooting may be significantly distorted. The following trouble occurred.

The technique disclosed in Japanese Patent Publication No. Sho 63-30612 detects whether a single shooting mode or a continuous shooting mode is used during flash shooting, and sets a white balance adjustment value suitable for each mode. However, it is merely a matter of setting a single white balance adjustment value determined according to flash photography. For this reason, it is unavoidable that a problem such as a color balance collapse between the above-described strobe single shooting and strobe continuous shooting will occur.

The present invention has been made in view of such circumstances,
The purpose is to automatically and effectively switch the white balance adjustment value between single flash shooting and continuous flash shooting, and stably adjust the white balance according to the color temperature of the flash light. An object of the present invention is to provide an electronic imaging device that can perform the operation.

[Means for Solving the Problems] An electronic imaging apparatus according to the present invention includes white balance adjustment means for adjusting the color tone of a subject image signal electronically imaged using an imaging element according to a white balance adjustment value. In the electronic imaging apparatus, the white balance adjustment value under illumination conditions using the strobe means is set to a value corresponding to the first color temperature in the strobe single shooting mode, and the first balance temperature is set in the strobe continuous shooting mode. A value corresponding to a second color temperature lower than the color temperature is set, and the white balance adjustment value is switched and set according to each mode.

Another electronic imaging apparatus according to the present invention is an electronic imaging apparatus including a white balance adjustment unit that adjusts a color tone of a subject image signal electronically imaged using an imaging element according to a white balance adjustment value. The white balance adjustment value under lighting conditions using the strobe means is set according to the charging voltage of the strobe.

Hereinafter, an electronic imaging apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an electronic camera constructed by incorporating the apparatus of the embodiment, and the same parts as those of the conventional apparatus shown in FIG. 6 are denoted by the same reference numerals.

This embodiment is characterized by a variable resistor group.
A plurality of white balance adjustment values set in advance by 14, specifically, a color temperature of daylight of 5400 K (Kelvin), a color temperature of indoor tungsten light of 3200 K, and a strobe light in a strobe single shooting mode. A plurality of whites are set in advance corresponding to a color temperature (first color temperature) of 6400K and a color temperature (second color temperature) of strobe light in the continuous flash shooting mode (second color temperature) of 5900K. The point is that the balance adjustment value is automatically selected by the switching control of the switches 13a and 13b by the system controller unit 8, and is supplied to the WB control unit 4 in the imaging signal processing circuit unit 3.

Thus, the strobe circuit 16 in this embodiment device is
When the single shooting mode is set by switching the switch 9c and when the continuous shooting mode is set, different operations are performed, and the flash light is emitted according to the shooting mode. Specifically, for example, as shown schematically in FIG. 2, the operation mode of the strobe circuit 16, during single-shot shooting of the strobe, the strobe light is emitted spontaneously with its main capacitor charged to a sufficiently high voltage. Then, during continuous flash shooting, it is necessary to repeatedly and continuously emit strobe light in synchronization with the continuous shooting, so that the charging voltage of the main capacitor is suppressed to some extent and the charging time of the main capacitor is shortened. The strobe light is repeatedly emitted.

Due to the difference in the strobe driving voltage (operating condition of strobe light; discharge voltage of the xenon lamp 15) between the strobe single shooting mode in the strobe circuit 16 and the strobe continuous shooting mode, the flash circuit 16 There is a difference in the color temperature of the strobe light between the flash shooting and the flash shooting. The two types of white balance adjustment values for the strobe light set by the above-described variable resistor group 14 are:
In order to cope with such a difference in color temperature of strobe light,
These are set according to the respective color temperatures of the strobe light.

Then, the system controller 8 sets a white balance adjustment value as shown in FIG. 3 as one processing procedure in the imaging control. In the procedure for setting the white balance adjustment value, first, the photometric sensor 10 detects brightness information of the subject (step a), and determines whether or not the subject brightness is sufficiently bright, specifically, when the EV value is [10]. It is determined whether or not the brightness is not so high that the auxiliary lighting by the strobe light irradiation is unnecessary (step b).

If the brightness of the subject is sufficiently bright, it is determined that the subject is in a shooting state under daylight outdoors, and the flash drive of the strobe is prohibited. After a while, the aforementioned switch
The white balance adjustment value set for the color temperature of 5400 ± 500K is selected by the switching control between 13a and 13b, and is provided to the WB control unit 4 (step c). After setting the white balance adjustment value in this manner, the system controller unit 8 drives the control unit 2 described above to
The subject is electronically imaged (exposed) by D1. After the image signal obtained by this exposure is adjusted in color balance according to the above-mentioned white balance adjustment value, the image signal is used for recording.

On the other hand, when the subject brightness is lower than the above-mentioned [10 EV] (step b), the system controller 8 checks the shooting mode information of "strobe auto / strobe off" from the switching state of the switch 9c (step b). If the “strobe off” mode is set, it is determined that the shooting is performed indoors under the conditions of tungsten light illumination, and the emission drive of the strobe is prohibited. Then, by the switching control of the switches 13a and 13b described above, 320
A white balance adjustment value set for a color temperature of 0 ± 500K is selected and given to the WB control unit 4 (step e).

On the other hand, when "strobe auto" is set (step d), the shooting mode information of "single shooting / continuous shooting" is obtained from the switching state of the switch 9b, and the strobe single shooting shooting mode is set. It is checked whether the setting has been made or the flash continuous shooting mode has been set (step f). When it is confirmed that the strobe single-shot mode is set, the white balance adjustment value set for the color temperature of 6400 ± 500K is selected by the switching control of the switches 13a and 13b. Is given to the WB control unit 4 (step g). In this state, the flash circuit 16
The electronic still image signal captured at that time is given a flash command, and the electronic still image signal captured at that time is subjected to color balance adjustment using the above-mentioned white balance adjustment value set for 6400 ± 500K.

If it is confirmed that the flash continuous shooting mode is set, the white balance adjustment value set for the color temperature of 5900 ± 500K is selected by the switching control of the switches 13a and 13b. Is given to the WB controller 4 (step h). Then, a flash command is given to the flash circuit 16, and the flash is repeatedly fired in synchronization with the continuous shooting by the CCD 1, and the electronic still image signals sequentially shot under these flash lighting conditions are set to the above 5900 ± 500K. Color balance adjustment using the white balance adjustment value.

Thus, according to the present apparatus configured as described above, depending on whether the brightness of the subject is bright or dark, and if the brightness of the subject is dark, whether or not the strobe light is to be emitted, the lighting at that time is determined. A white balance adjustment value according to the color temperature of light is selectively set. Then, at the time of flash shooting, a white balance adjustment value corresponding to the color temperature of the flash light determined by the flash operating condition at that time is automatically selected and set according to the flash single shooting or the flash continuous shooting. In other words, during single-shot flash shooting, the color temperature of the strobe light that is emitted spontaneously is high,
A color balance adjustment is performed by selecting a white balance adjustment value set for the color temperature (6400K). In addition, during continuous flash shooting, the color temperature of the strobe light that is emitted repeatedly and continuously is low, so its color temperature (5900K)
The color balance adjustment is performed by selecting the white balance adjustment value set for.

Therefore, without using a colorimetric sensor to measure the color temperature of the object illumination light as in the prior art, a simple processing procedure of simply identifying the type of the illumination light source and examining the shooting mode at that time can be used. In this way, it is possible to automatically select and set the white balance adjustment value according to the shooting conditions (color temperature of the illumination light source) effectively, and perform the color balance adjustment on the electronic still image.

In particular, during flash shooting, the operating conditions of the flash circuit 16 differ depending on whether the camera is in single-shot shooting mode or continuous shooting mode.
Since the color temperature of the strobe light changes with this,
The white balance adjustment value is switched according to the shooting mode at that time. As a result, the color balance can be adjusted using the white balance adjustment value corresponding to the color temperature of the strobe light that is actually emitted. Moreover, appropriate color balance adjustment can be easily achieved simply by selecting and switching the white balance adjustment value according to the single-shot or continuous shooting mode of flash shooting.

In the above embodiment, the shooting mode information of “single shooting / continuous shooting” is obtained from the switching state of the switch 9b. However, the magnitude of the charging voltage of the main capacitor in the strobe circuit 16 is detected and the single shooting shooting mode is detected. Or the continuous shooting mode, and the shooting mode information of the “single shooting / continuous shooting” may be obtained.

Next, another embodiment of the present invention will be described. FIG. 4 is a schematic diagram of a main portion showing a second embodiment, in which the basic components are denoted by the same reference numerals as in the above-described embodiment.

The feature of this embodiment is that during the so-called strobe shooting using strobe light, the charging voltage of the main capacitor in the strobe circuit 16 is monitored by the system controller unit 8 via the A / D converter 17, and When the flash emission is confirmed from the change in the charging voltage, the white balance adjustment value corresponding to the color temperature of the flash light obtained according to the information on the flash drive voltage detected at this time is used.
The WB controller 4 is provided via the D / A converters 18a and 18b.

That is, when the strobe continuous shooting mode is set, the strobe circuit 16 in this embodiment intermittently discharges a predetermined amount of electric charge in the main capacitor of the strobe circuit 16 as illustrated in FIG. It is configured to drive strobe light emission. In other words, by discharging the charged charge of the fully charged main capacitor by a predetermined amount by so-called serial control, a constant amount of strobe light can be intermittently and repeatedly emitted. Thus, the charging voltage of the main capacitor is reduced stepwise by intermittently and repeatedly emitting the fixed amount of strobe light, and the strobe light emission driving voltage is also reduced stepwise. Although the amount of strobe light repeatedly emitted in this manner is kept constant by controlling the amount of discharged electric charge, its color temperature depends on its emission driving voltage (the charging voltage of the main capacitor). It decreases as the drive voltage decreases. The system controller 8 monitors the emission drive voltage of the strobe light to obtain the color temperature of the strobe light, and outputs the white balance adjustment value corresponding to the color temperature to the D / A converters 18a and 18b. Via the WB control unit 4

Specifically, in the case where the strobe light is repeatedly emitted with the change of the emission drive voltage as shown in FIG.
The strobe light emission is detected from the change in the charging voltage of the main capacitor detected via the converter 17, and further, from the charging voltage of the main capacitor at that time, the strobe light color temperature corresponding to the strobe emission driving voltage is set to 6400K, 6100K, 5900K, 5700
Obtained sequentially as K etc. Then, the white balance adjustment values corresponding to these color temperatures are sequentially set in the WB control unit 4 via the D / A converters 18a and 18b in synchronization with the imaging operation of the subject.

Further, at the time of single flash shooting, the strobe light color temperature corresponding to the charging voltage of the main capacitor detected at that time is determined spontaneously, and a white balance adjustment value is set according to the color temperature.

When the flash shooting mode is not set, the setting of the white balance adjustment value via the D / A converters 18a and 18b according to the brightness of the subject detected by the photometric sensor 10 described above is performed as described above. This is performed in the same manner as in the embodiment.

According to the present embodiment device in which the white balance adjustment value for the strobe light is automatically set,
The white balance adjustment value corresponding to the color temperature of the strobe light actually emitted can be set each time in synchronization with the shooting. As a result, even when the strobe continuous shooting mode is set and the color temperature of the strobe light emitted and emitted during continuous shooting changes every time shooting is performed, the strobe light color temperature at that time is changed. It is possible to give a good white balance adjustment value. Moreover, when it is detected that the strobe light has actually emitted,
The white balance adjustment value corresponding to the color temperature of the strobe light is set. Therefore, it is possible to always stably perform color balance adjustment for an electronic still image.

Note that the present invention is not limited to the above-described embodiment. For example, in the embodiment, the brightness of the subject is detected using the dedicated photometric sensor 10, but the brightness of the subject is detected from the luminance component of the output using, for example, a CCD1 that electronically captures the subject. It is also possible. In this case, for example, under the control of the CCD drive control unit 2b, prior to the start of imaging, only the image signal component in the central area of the imaging screen or a specific area is extracted, and the luminance component is extracted from the system controller unit. 8 should be given.

In addition, the white balance adjustment value corresponding to each illumination light source is not limited to the value shown in the above-described embodiment, and it is sufficient to determine the white balance adjustment value according to the color temperature of the illumination light source. That is, since the color temperature of the strobe light depends on the size of the arc tube and the driving voltage, the white balance adjustment value for the strobe light may be determined according to these specifications, and the white balance for other illumination light sources may be determined. It is sufficient to determine the adjustment value according to the color temperature. In addition, the present invention can be variously modified and implemented without departing from the gist thereof.

[Effects of the Invention] As described above, according to the present invention, the white balance adjustment value under the illumination condition using the strobe means is set to a value corresponding to the first color temperature in the strobe single shooting mode. In the flash continuous shooting mode, the color temperature of the strobe light is set to a value corresponding to the second color temperature lower than the first color temperature, and switching is performed according to each mode. Even if they differ, appropriate white balance adjustment corresponding to the difference can be performed, and there is no such trouble as when a white balance adjustment value is selectively set by manual operation as in the related art. Since the color temperature itself of the illumination light source is not measured using the colorimetric sensor, an image signal with a good color tone can be obtained with a very simple configuration.

Also, since the white balance adjustment value under lighting conditions using the strobe means is set according to the charging voltage of the strobe, even when the color temperature of the strobe light changes during continuous shooting, it is followed. Appropriate white balance adjustment can be performed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of an electronic camera according to an embodiment of the present invention, and FIG. 2 is charging in a strobe circuit in a single shooting mode and a continuous shooting mode in the embodiment apparatus. FIG. 3 is a diagram showing a change in voltage, and FIG. 3 is a diagram showing a procedure for selecting and setting a white balance adjustment value in the apparatus of the embodiment.
FIG. 5 is a schematic configuration diagram of an electronic camera according to another embodiment of the present invention, FIG. 5 is a diagram showing a form of change of a charging voltage in a strobe circuit in the embodiment device shown in FIG. 4, and FIG. Is a diagram showing a configuration example of a typical electronic camera. 1 ... CCD (imaging device), 2 ... Control unit, 2a ... Synchronization signal generation unit, 2b ... CCD drive control unit, 3 ... Imaging signal processing circuit unit, 4 ... White balance (WB) control unit , 5 ...
Recording section, 6 Recording head, 7 Floppy disk, 8 System controller section, 9a Release switch, 9b Switch (continuous / single-shot), 9c Switch (strobe auto / strobe off ), 10 Photometric sensor, 11 Signal processing unit, 12 A / D converter, 13a, 13b
Switch (selection of white balance adjustment value), 14 ... Variable resistor group (setting and holding of white balance adjustment value),
15 xenon lamp (strobe light arc tube), 16 strobe circuit (including main capacitor), 17 A / D converter (charge voltage detection), 18a, 18b D / A converter.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-62-274889 (JP, A) JP-A-64-58185 (JP, A) JP-A-61-128694 (JP, A) JP-A-61-128694 128694 (JP, A) JP-A-63-266437 (JP, A) JP-A-63-267091 (JP, A) JP-A-62-188991 (JP, A) JP-A-62-146089 (JP, A) JP-B-63-30612 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04N 9/73 H04N 9/04

Claims (2)

(57) [Claims] 1. An electronic image pickup apparatus comprising a white balance adjusting means for adjusting a color tone of a subject image signal electronically imaged using an image pickup element in accordance with a white balance adjustment value. Is set to a value corresponding to the first color temperature in the strobe single shooting mode, and to a value corresponding to the second color temperature lower than the first color temperature in the strobe continuous shooting mode. An electronic imaging apparatus, wherein the setting is made and the white balance adjustment value is switched and set according to each of the modes. 2. An electronic image pickup apparatus comprising a white balance adjusting means for adjusting a color tone of a subject image signal electronically imaged by using an image pickup element in accordance with a white balance adjustment value. An electronic image pickup apparatus, wherein the white balance adjustment value is set according to the charging voltage of a strobe.