JP3320868B2 - Strobe device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strobe device for controlling the color temperature of strobe light to obtain a more natural color image.

[0002]

2. Description of the Related Art In a conventional still video camera, white balance is adjusted so that a white object is photographed white regardless of the color temperature of illumination light on the object.
For example, in a still video camera equipped with a strobe device, by adjusting the gain of a color difference signal (RY, BY) or the like of a captured image output from a solid-state imaging device,
White balance adjustment is performed. When the light amount from the subject is insufficient, photographing with flash emission is performed, and the white balance adjustment in that case is controlled according to the color temperature of the flash light.

[0003]

However, when the color temperature of the ambient light of the subject is different from the color temperature of the strobe light, an unnatural color may be reproduced in the photographed image. As a configuration for solving such a problem, the present applicant has already disclosed in Japanese Patent Application No. 5-235518 that a xenon tube emits light with a color temperature conversion filter arranged in front of the xenon tube, and a strobe light irradiated to a subject is provided. It proposes a configuration that adjusts the color temperature of light to ambient light.

However, as the arc tube and the color temperature conversion filter change over time, the emission color temperature and the color temperature conversion capability tend to change. Therefore, if the light emission time or the color temperature conversion ability is always controlled in the same manner with respect to the color temperature of the ambient light, an error occurs in the color temperature of the light applied to the subject, and it is difficult to obtain a desired combined color temperature. It may be. Further, the white balance adjustment of the imaging system is performed so that the color temperature of the strobe irradiation light is adjusted to the ambient light. Therefore, if there is an error or a change with time in the color temperature of the strobe irradiation light, the white balance of the image will be lost.

The present invention has been made in view of such a problem, and adjusts the color temperature of the strobe irradiation light even if an error or a change with time occurs in the color temperature of the strobe irradiation light to the subject. An object of the present invention is to provide a strobe device capable of improving the white balance of a captured image.

[0006]

According to the first aspect of the present invention, there is provided a first strobe device comprising: a light emitting tube; a light emitting color temperature converting means capable of converting a light emitting color temperature of the light emitting tube; and a first color temperature detecting means for detecting the color temperature of the illumination light, a second color temperature detecting means for detecting the color temperature of the ambient light of the object and the color temperature detected by the first color temperature detecting means
Based on the detected color temperature by the second color temperature detecting means, the irradiation light color temperature control means color temperature of the illumination light emission color temperature conversion unit is controlled to be substantially equal to the color temperature of the ambient light of the subject It is characterized by having. Further, a second strobe device according to the present invention comprises: a light emitting tube; first color temperature detecting means for detecting a color temperature of light emitted to the object or light reflected from the object with the light emitting tube being emitted; A second color temperature detecting means for detecting a color temperature of ambient light of the first color temperature, a color temperature detected by the first color temperature detecting means, and a second color temperature.
An illumination light color temperature control unit that controls the color temperature of the illumination light to be substantially equal to the color temperature of the ambient light of the subject based on the color temperature detected by the detection unit .

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a block diagram of a still video camera to which a strobe device according to a first embodiment of the present invention is applied. In the first embodiment, two luminous tubes are made to emit light simultaneously through a monochrome liquid crystal filter, the color temperature of the reflected light from the object is detected, and the light emission amount is controlled by changing the density ratio between the filters. .

A stop 12 is provided in front of the light receiving surface of the solid-state image sensor 11.
Is provided, whereby the amount of incident light from the subject SB to the solid-state imaging device 11 is adjusted. The image pickup device 11 is driven by a shift pulse or the like generated by the image pickup device driving circuit 13, whereby an image signal (R signal, G signal, and B signal) generated in accordance with the light incident on the light receiving surface of the image pickup device 11. ) Are sequentially read from the image sensor 11. R
The signal and the B signal are amplified by the amplifiers 14 and 15, respectively, and input to the signal processing circuit 16, and the G signal is directly input to the signal processing circuit 16. The amplifiers 14 and 15 are connected to a control circuit 23, and the control circuit 23 performs gain adjustment of the amplifiers 14 and 15, that is, white balance adjustment.

The image signal is converted by a signal processing circuit 16 into a recording signal of a predetermined format,
And recorded by a recording circuit 17 on a recording medium such as a magnetic disk (not shown).

The photometric sensor 21 is composed of a photoelectric conversion element such as a photodiode, for example, and receives the reflected light F1 from the subject SB and performs photoelectric conversion, thereby measuring the luminance of the subject SB. The colorimetric sensor 22 includes a plurality of photoelectric conversion elements having different spectral sensitivities of visible light. As described later, before the xenon tubes 51 and 52 emit light,
The colorimetric sensor 22 measures the color temperature of the ambient light E1,
When the xenon tubes 51 and 52 emit light, the colorimetric sensor 2
2, the color temperature of the reflected light F1 from the subject SB is measured. The color temperature information from the colorimetric sensor 22 is input to the control circuit 23 via the color temperature calculation circuit 20, and the emission color temperature of the strobe device 50 is determined based on the color temperature information as described later.

The photometric sensor 21 is connected to an integrating circuit 24. The signal photoelectrically converted by the photometric sensor 21 is integrated according to an integration start signal S1 input from a control circuit 23. The integration circuit 24 is connected to the control circuit 23 via a comparison circuit 25.
The A converter 26 is connected. In the comparison circuit 25, D
A voltage value (signal S2) input from the / A converter 26;
The integration value input from the integration circuit 24 is compared, and the comparison result is output to the control circuit 23 as a quench signal S3. The xenon tubes 51 and 52 stop emitting light based on the quench signal S3.

A flash device 50 is connected to the control circuit 23, and the xenon tubes 51 and 52 of the flash device 50 are connected.
The start and stop of light emission are controlled by the control circuit 23.
A blue filter 53 and a monochrome liquid crystal filter 54 are provided in front of the xenon tube 51, and an amber filter 55 and a monochrome liquid crystal filter 56 are provided in front of the xenon tube 52. The voltages applied to the monochrome liquid crystal filters 54 and 56 are controlled by liquid crystal filter application voltage control circuits 57 and 58, respectively, and the shading of each of the liquid crystal filters 54 and 56 is controlled by the amplitude value of the voltage. For example, when a voltage is applied, the density of the liquid crystal filters 54 and 56 increases and the amount of light from the xenon tubes 51 and 52 decreases.
4 and 56 become transparent, respectively, whereby the amount of light from the xenon tubes 51 and 52 increases. The liquid crystal filter applied voltage control circuits 57 and 58 both operate based on a control signal output from the control circuit 23.

A signal line A1 extending from the charging circuit 61
The positive electrode of the main capacitor 62, the resistor 63, and the anode terminals of the xenon tubes 51 and 52 are connected to each other.
2 and the common terminal of the trigger transformer 64 and the emitter terminal of the insulated gate bipolar transistor (IGBT) 65 are connected. The main capacitor 62
An impulse voltage is applied by the charging circuit 61 via the signal line A1, and charges are accumulated. The low voltage side coil of the trigger transformer 64 is connected to one end of the resistor 63 via the trigger capacitor 66. One end of the resistor 63 is connected to the cathode terminals of the xenon tubes 51 and 52 and the IGB
It is connected to the collector terminal of T65.

The base terminal of the IGBT 65 is connected to the control circuit 23
The IGBT 65 is turned on by the light emission trigger signal S4 output from the control circuit 23, and the IGB
A current flows from the collector terminal of T65 to the emitter terminal. As a result, the charge of the trigger capacitor 66 is discharged, a current flows through the low voltage side coil of the trigger transformer 64, and a trigger pulse is induced in the high voltage side coil. The trigger pulse is applied to the trigger electrodes of the xenon tubes 51 and 52, thereby discharging the electric charge of the main capacitor 62, and the xenon tubes 51 and 52 emit strobe light F2.

The control circuit 23 includes a release switch 27 provided on the still video camera main body and a timer circuit 2.
8 are connected, and various controls are performed according to the operation of the release switch 27. The memory 29 provided in the control circuit 23 stores various information such as data indicating the relationship between the output signal of the color temperature calculation circuit 20 and the actual color temperature.

FIG. 2 shows a connection state of the photometric sensor 21, the integrating circuit 24, the comparing circuit 25, and the D / A converter 26. The integration circuit 24 has an operational amplifier 24a, an integration capacitor 24b, and a reset switch 24c.
The photometric sensor 21 includes a photodiode, and is connected between an inverted signal input terminal and a non-inverted input terminal of the operational amplifier 24a. A non-inverting input terminal of the operational amplifier 24a has a reference power supply 24d for applying a reference voltage value before the start of integration.
Is connected.

An integration capacitor 24b and a reset switch 24c are connected in parallel between the inverting input terminal and the output terminal of the operational amplifier 24a. The integration switch 24c is connected to the reset switch 24c by the integration start signal S1 input from the control circuit 23. Opening and closing are controlled. When the reset switch 24c is opened, the photocurrent generated in the photometric sensor 21 is integrated by the operational amplifier 24a. The output terminal of the operational amplifier 24a is connected to the inverting input terminal of the comparison circuit 25.

The non-inverting input terminal of the comparison circuit 25 has a D / A
A converter 26 is connected.
The voltage value of the output signal S2 of the A converter 26 and the operational amplifier 24
The voltage value of the output signal S5 of FIG. When the voltage value of the signal S5 becomes lower than the voltage value of the signal S2, the quench signal S3 is output from the comparison circuit 25 to the control circuit 23. It should be noted that the voltage value of the signal S2 is
The voltage value of the signal S2 is determined by digital data given to the converter 26, and is set by a proper integration value setting process described later.

FIG. 3 shows a colorimetric sensor 22 and a color temperature calculating circuit 2.
FIG. 3 is a block diagram showing a configuration of a 0. The colorimetric sensor 22 includes filters 22a and 22 for extracting R, G, and B components of external light.
b, 22c, and photometric sensors 22d, 22e, 22f for converting these R, G, B components into electric signals, respectively. The R, G, and B signals output from the photometric sensors 22d, 22e, and 22f are input to logarithmic compression circuits 20a, 20b, and 20c of the color temperature calculation circuit 20, and are logarithmically compressed. In the subtraction circuit 20d, the logarithmic compression circuit 20a, 2
The difference between the R signal and the G signal output from 0b is obtained, and this difference (RG) is logarithmically expanded in a logarithmic expansion circuit 20f and output to the control circuit 23 as an R / G signal. Similarly, in the subtraction circuit 20e, the logarithmic compression circuits 20c and 20c
The difference between the B signal and the G signal output from b is obtained. This difference (BG) is logarithmically expanded by the logarithmic expansion circuit 20g and output to the control circuit 23 as a B / G signal. The control circuit 23 detects the color temperature of the light input to the colorimetric sensor 22 based on the R / G signal and the B / G signal, and controls the liquid crystal filters 54 and 56 for synthesizing the light of this color temperature. Density data is determined.

FIG. 4 shows a liquid crystal filter applied voltage control circuit 57.
Is shown. The oscillator 54a is configured by combining an inverter, a resistor, and a capacitor, and this configuration is conventionally known. A signal line 57b connected to the output terminal of the oscillator 57a is connected to a transistor 5 via a resistor 57c.
It is connected to the base terminal of the transistor 7g via the inverter 57e and the resistor 57f. The D / A converter 57h is connected to the constant voltage power supply 57i, and outputs a signal having an amplitude corresponding to the density data signal input from the control circuit 23. A signal line 57j extending from the D / A converter 57h includes resistors 57k and 57m.
Are connected to the collector terminals of the transistors 57d and 57g, respectively, and these collector terminals are connected to the liquid crystal filter 54 via signal lines 57n and 57p.

To the base terminals of the transistors 57d and 57g, a rectangular wave voltage signal that changes at a predetermined cycle is applied from the transmitter 57a, and a rectangular liquid crystal drive signal that changes at the same cycle as the rectangular wave signal is applied. The signal is output to the liquid crystal filter 54 via the signal lines 57n and 57p. The amplitude of the liquid crystal driving signal is determined by the amplitude of the output signal of the D / A converter 57h, and the density of the monochrome liquid crystal filter 54 is controlled by the amplitude of the liquid crystal driving signal. Since voltages having opposite phases are applied to the respective base terminals of the transistors 57d and 57g, the phases of the rectangular wave signals output from the signal lines 57n and 57p are also opposite to each other. The liquid crystal filter applied voltage control circuit 58 has the same configuration, and the density of the monochrome liquid crystal filter 56 is similarly controlled.

FIG. 5 is a sequence diagram showing an outline of the photographing operation in this embodiment.

When the release switch 27 is half-pressed (step D20), the control circuit 23 causes the photometric sensor 2
The light amount of the subject SB is measured based on photometric data by a photometric sensor (not shown) different from 1 and an exposure calculation process is performed according to the photometric value (step D2).
1).

In the exposure calculation processing, the operation time of the electronic shutter of the image pickup device 11 and whether or not the flash device 50 needs to emit light are determined. The charging process of the main capacitor 62 by the charging circuit 61 is performed when a main switch (not shown) is turned on or when a flash shooting instruction switch (not shown) is operated. The charging process is started by outputting a charging start signal S6 from the control circuit 23 to the charging circuit 61, and is also started at the time when the strobe light emission control described later ends.

In the charging circuit 61, in response to the input of the charging start signal S6, a pulsed high voltage signal is output to the main capacitor 62, and the electric charge for strobe light emission is stored in the main capacitor 62. Main capacitor 6
When the predetermined charge is stored in the second circuit 2, the potential of the signal line A1 reaches a predetermined value, whereby the charge storage in the main capacitor 62 by the charging circuit 61 ends. Next, the charging circuit 61 outputs a charge completion signal S7 to the control circuit 23, that is, a signal indicating that the charge accumulation of the main capacitor 62 is completed. As a result, the control circuit 23 recognizes that flash photography has become possible.

Photometry and exposure calculation processing (step D2)
After the end of 1), when the release switch 27 is fully pressed (step D22), the control circuit 23 controls the color temperature K of the ambient light E1 from around the subject SB according to the signal input from the colorimetric sensor 22. _C is determined (step D2
3).

The colorimetric sensor 22 is composed of photometric sensors 22d, 22e, and 22f having filters 22a, 22b, and 22c having different spectral sensitivity characteristics in the visible light region. And there is a one-to-one relationship with the color temperature. In the color temperature calculation circuit 20, the ratio of the output signals is calculated and output, and based on this, the control circuit 23 calculates the color temperature K _C of the ambient light E1.
The memory 29 of the control circuit 23 stores a data table indicating the correspondence between the input signal from the color temperature calculation circuit 20 and the color temperature information in this signal. The color temperature K _C of the ambient light E1 is calculated based on the input signal. The memory 29 is referred to based on the color temperature information, and the amplifiers 14, 1
A gain of 5 is set (step D24).

Next, the amount of opening of the aperture 12 is adjusted based on the photometric value, and the amount of light from the subject SB incident on the image sensor 11 is adjusted (step D25). Then, based on the photometry result, the charge accumulation time of the photoelectric conversion signal in the image sensor 11, that is, the electronic shutter time is determined, and charge accumulation (main exposure) is started (step D2).
6). At the same time as the start of the accumulation of the signal charges, if the strobe light emission is necessary according to the photometry result, the strobe light emission control is started (step D27).

[0029] In flash emission control start almost synchronism with the control circuit 23, a color temperature K _M of the reflected light F1 from the subject SB is determined in response to a signal input from the color measurement sensor 22 (step D28). Also, as the color temperature K _M becomes equal to the color temperature K _C of ambient light E1, a predetermined voltage is applied to the electrodes of the monochrome liquid crystal filters 54, 56,
These monochrome liquid crystal filters 54 and 56 are controlled to a predetermined density. That is, during the main exposure period, an operation of monitoring the actual emission color temperature and correcting the color temperature error is performed. When the amount of light reflected from the subject SB reaches a predetermined value, the flash emission stops (step D29).

When the photographing operation is completed in this way, under the control of the control circuit 23, a control signal is output from the image sensor driving circuit 13 to the image sensor 11, and the charge accumulation of the image sensor 11 is completed (step D30). Then, the aperture 12 is closed (step D31). At the same time, the control voltage applied to the electrodes of the liquid crystal filters 54 and 56 is released to return to the inactive state. Thereafter, the imaging device driving circuit 1
3 outputs a signal charge readout control signal such as a transfer pulse to the image pickup device 11, reads out the signal charges accumulated in the image pickup device 11 as an image signal and inputs the read out signal charge to the signal processing circuit 16, and outputs an image signal of a predetermined format. After that, the data is recorded on a recording medium (not shown) by the recording circuit 17 (step D32).

FIG. 6 shows a flowchart of the operation of the control circuit 23 in the flash emission control of this embodiment. In step 100, the density data of the monochrome liquid crystal filters 54 and 56 corresponding to the reciprocal (1 / K _C ) of the ambient light color temperature K _C stored in the memory 29 of the control circuit 23 is read from the memory 29, and It is set in the filter application voltage control circuits 57 and 58. That is, the ambient light E1
As the color temperature becomes higher, the density of the monochrome liquid crystal filter 54 disposed in front of the blue filter 53 decreases, and the density of the monochrome liquid crystal filter 56 disposed in front of the amber filter 55 increases. Conversely, the ambient light E1
As the color temperature becomes lower, the density of the monochrome liquid crystal filter 54 increases and the density of the monochrome liquid crystal filter 56 decreases. In step 101, the proper integration value (exposure level) is read from the memory 29, and the D / A converter 2
6 is set.

In step 102, the integration value output of the integration circuit 24 is reset. In step 103, the operation of the operational amplifier 2 in the integration circuit 24 is performed by the action of the integration start signal S1.
The integration of 4a is started. Along with the start of this integration, in step 104, the maximum light emission time T1 is
Is set in step 105, and the timer operation of the timer is started in step 105. In step 106, the light emission trigger signal S4 is output to the IGBT 65, and the
65 is turned on. As a result, a trigger voltage is applied to the trigger electrodes of the xenon tubes 51 and 52,
Strobe light is emitted from 52.

[0033] At step 107, the color temperature K _M of the reflected light F1 from the subject SB is detected by the color measurement sensor 22, in step 108, the ambient light E stored in advance
The memory 29 is referred to based on the reciprocal 1 / K _C of the color temperature of 1 to calculate the value of (1 / K _M ) − (1 / K _C ).
This value will be zero when the color temperature K _M of the reflected light F1 from the strobe illumination light ie subject SB is equal to the color temperature K _C of ambient light E1, changes according to the difference between the color temperature K _M, K _C I do.

In step 109, 1 / K _C and (1 / K _C
The liquid crystal filter density correction data corresponding to each value of ( _M )-(1 / K _C ) is read from the memory 29, and the correction data is set in the liquid crystal filter application voltage control circuits 57 and 58, respectively. For example, when K _M <K _C , the color temperature of the reflected light F1 from the subject SB is lower than that of the ambient light E1, so that the density of the liquid crystal filter 54 before the blue filter 53 is increased in order to increase the strobe emission color temperature. Is lowered, and conversely, K
_{When M} > K _C , the color temperature of the reflected light F1 from the subject SB is higher than that of the ambient light E1, so that the density of the liquid crystal filter 56 before the amber filter 55 is low in order to lower the strobe emission color temperature. Be killed. This step 109
In the case of the memory read out by setting various control amounts so that the reciprocal of the color temperature is equally spaced according to the visual sense, the memory can be used effectively.

When the reflected light F1 from the subject SB increases due to the strobe light, and the integrated value output from the integrating circuit 24 reaches the value of the signal S2 (appropriate integrated value), the comparing circuit 2
5 outputs the quench signal S3. Step 11
When the output of the quench signal S3 is confirmed at 0, the output of the light emission trigger signal S4 stops at step 112, and the light emission of the xenon tubes 51 and 52 stops. If the output of the quench signal S3 is not confirmed in step 110, it is determined in step 111 whether or not the time counted by the timer circuit 28 has timed out. If not, the process returns to step 107 and quench again. The output of the signal S3 is determined. On the other hand, if the time is over, step 11
In step 2, the output of the light emission trigger signal S4 is forcibly stopped. Then, the IGBT 65 turns off and the xenon tube 5
The strobe light emission of 1, 52 stops. Next, in step 113, the timer circuit 28 is stopped, and this program ends.

[0036] In this embodiment as described above, always detects the color temperature K _M of the reflected light from the object SB at the time of flash emission, based on the difference between the color temperature K _C of the color temperature K _M and ambient light E1 Thus, the densities of the liquid crystal filters 54 and 56 are adjusted to control the color temperatures K _M and K _{C to} be equal. Therefore, for example, even if the emission color temperature of the xenon tubes 51 and 52 and the color temperature conversion capability of the filters 53 and 55 change over time,
The color temperature of the strobe light is always accurately controlled, and the white balance of the captured image can be improved. In the present embodiment, the detection of the color temperature K _C of the ambient light E1 and the detection of the subject S
To cover the color temperature K _M detection of the reflected light F1 from B by one colorimetric sensor 22, there is an advantage that cost and space, the weight is not changed from the conventional.

FIG. 7 is a block diagram of a still video camera to which a strobe device according to a second embodiment of the present invention is applied. In this figure, the same components as those in the first embodiment are denoted by the same reference numerals. The circuit configuration of FIGS. 2 to 4 is common to the first embodiment, and the photographing operation and the strobe light emission control operation are basically the same as those shown in FIGS.

While the first embodiment is a two-light simultaneous emission type flash device, the second embodiment is a single-light type flash device having a single light emission. , A white tailored liquid crystal filter 59 capable of controlling the color temperature of the filter itself in accordance with the ambient light E1. The voltage applied to the liquid crystal filter 59 is controlled by a liquid crystal filter applied voltage control circuit 57, and the color temperature of the liquid crystal filter 59 is controlled by the amplitude value of the voltage. Other configurations of the strobe device are exactly the same as those of the first embodiment. However, in the liquid crystal filter applied voltage control circuit 57, a hue data signal indicating the hue of the liquid crystal filter 59 is input to the D / A converter 57h.

The flash emission control in the second embodiment is basically the same as the flowchart (FIG. 6) in the first embodiment, and only different points will be described. That is, step 10
At 0, the hue data of the liquid crystal filter 59 is read from the memory 29, and at step 109, the hue correction data of the liquid crystal filter 59 is read from the memory 29. Further, the hue of the liquid crystal filter 59 in the correction of this hue, K _M
<When K _C is adjusted so that the light emission color temperature increases, K _M Conversely> When the K _C is adjusted so that the light emission color temperature decreases.

According to the second embodiment, the same effects as those of the first embodiment can be obtained.

FIG. 8 is a block diagram of a still video camera to which a strobe device according to a third embodiment of the present invention is applied. In this figure, the same components as those in the first and second embodiments are denoted by the same reference numerals. Note that the circuit configurations in FIGS. 2 and 3 are also common to the first embodiment, and the photographing operation is basically the same as that shown in FIG.

In the third embodiment, two xenon tubes 51,
52 emit light sequentially, and this strobe light is
The light is radiated on the subject SB via the third and amber filters 55. The color temperatures K _A and K _{B of} the strobe light transmitted through the filters 53 and 55 are detected, and the xenon tubes 51 and 52 are detected.
By changing the ratio of the minute light emission time, the composite emission color temperature applied to the subject SB is controlled. Xenon tube 5
The minute light emission of 1, 52 is performed by alternately switching the IGBTs 33, 34 at high speed.

Blue filter 53 and amber filter 5
5 shows the color temperature K _A of the strobe light transmitted through the filter,
Colorimetric sensor 30 and 31 for detecting the K _B are respectively provided. The output of each colorimetric sensor 30, 31 is
2, the selector 32 selects a signal input to the color temperature calculation circuit 20 by a select signal from the control circuit 23. For emission time control, the emitter terminals of the IGBTs 33 and 34 corresponding to the xenon tubes 51 and 52 are connected to a signal line A2 extending from the charging circuit 61. The low-voltage coil of the trigger transformer 64 is connected to one end of a resistor 63 via a trigger capacitor 66, and one end of the resistor 63 is connected to the cathode terminals of the xenon tubes 51 and 52 and the IGBT 3 via diodes 35 and 36, respectively.
3, 34 are connected to the collector terminals.

FIGS. 9 and 10 show a flowchart of the operation of the control circuit 23 in the flash emission control of the third embodiment. Referring to FIG. 9, the process from the proper integration value setting process in step 200 to the start of the timer clocking operation in step 204 is the same as the process in steps 101 to 105 in FIG.

In step 205, the colorimetric sensor 30 provided in front of the blue filter 53 is selected under the control of the selector 32, and the signal from the colorimetric sensor 30 is taken into the color temperature calculation circuit 20. In step 206, a light emission trigger signal is output to the IGBT 33, whereby the IGBT 33 is turned on. As a result, a trigger voltage is applied to the trigger electrode of the xenon tube 51, and strobe light is emitted from the xenon tube 51.

After the strobe light is emitted in this manner, in step 207, the colorimetric sensor 30 detects the color temperature K _A of the irradiation light F2 to the subject SB. Step 20
In FIG. 8, the difference between the reciprocal of the actual color temperature K _A of the strobe light transmitted through the xenon tube 51 and the reciprocal of the designed emission color temperature K _AO of the strobe light is (1 / K _A ) − ( _1/1 ). K _AO ) is calculated, and a change with time or an error from the designed color temperature is obtained.

Next, in step 209, the memory 29 is referred to based on the reciprocal 1 / K _C of the color temperature of the ambient light E1 stored in advance, and the value of (1 / K _A ) ─ (1 / K _AO ) is obtained. Is read out from the xenon tube 51 and set in the timer circuit 28. In step 210, the timer counting operation starts, and the xenon tube 51 emits light until it is determined in step 211 that the emission time A has elapsed. When the light emission time A has elapsed, step 212 is executed, and the output of the light emission trigger signal is forcibly stopped. As a result, the IGBT 33 is turned off,
At the same time as the flash emission of the xenon tube 51 stops, the timer circuit 28 is stopped in step 213, and the micro emission of the xenon tube 51 ends.

The above-described minute light emission processing is similarly performed for the xenon tube 52 that transmits and irradiates the light through the amber filter 55. That is, in the flowchart of FIG. 10 following step 213, in steps 214 to 222,
The same processes as those in steps 205 to 213 are performed on the colorimetric sensor 31 and the xenon tube 52. Here, the color temperature of the irradiation light F2 detected by the colorimetric sensor 31 is K _B , and the designed emission color temperature of the xenon tube 52 transmitted through the amber filter 55 is K _B
BO and the light emission time are indicated by B. That is, in this embodiment, the synthetic emission color temperature increases as the emission time A increases,
The longer the emission time B is, the lower the emission time becomes.

In step 223 after the micro emission from the xenon tube 52 has been completed, the presence or absence of the quench signal S3 is determined. If the output of the quench signal S3 is confirmed here, in step 225, start in step 204 The set timer stops and the program ends. On the other hand, if the output of the quench signal S3 is not confirmed in step 223, it is determined in step 224 whether or not the time counted by the timer circuit 28 has exceeded the maximum flash emission time T1. Returning to step 205, the minute light emission processing of the xenon tube 51 is continued again. On the other hand, if the maximum flash emission time T1 has elapsed, this program ends after the timer circuit 28 is stopped in step 225.

As described above, in the third embodiment, the xenon tube 5
In the 1, 52 alternately one which weak light emission, radiation detected color temperature K _A of the irradiation light F2 on the subject SB, a K _B directly controls the ratio of the weak light emission time by the information on the subject SB Is set equal to the color temperature of the ambient light E1 of the subject SB. FIG. 11 shows the emission control timings of the xenon tubes 51 and 52 of the third embodiment, that is, the timings of the detection of the color temperatures K _A and K _B and the timing operations of the timers A and B. In this figure, until the quench signal S3 is output, each of the xenon tubes 51 and 52 alternately emits a small amount of light, and the ratio of the total light emission time is different.

As described above, the same effects as those of the first and second embodiments can be obtained by the third embodiment. In the third embodiment, the color temperature of the xenon tube is detected through the filter at the time of the main exposure, and the light emission time and the filter O are immediately detected.
This is fed back to the control of the N / OFF time and is repeated until the quench signal S3 is output.
If feedback control during the main exposure is difficult, the color temperature of the xenon tube may be detected before the main exposure.

FIG. 12 is a block diagram of a still video camera to which a strobe device according to a fourth embodiment of the present invention is applied. In the fourth embodiment, one xenon tube 51 is used as a light emitting unit.
The provided, the umber liquid crystal filter 37 capable of lowering the color temperature in front, in which the colorimetric sensor 38 for detecting the color temperature K _D of the irradiated light F2 transmitted through the filter 37 provided. The emission color temperature control is performed by the liquid crystal filter ON / OFF control circuit 39 controlling the time during which the filter 37 is colored and becomes transparent. Other configurations are the same as those of the third embodiment. That is, the circuit configurations in FIGS. 2 and 3 are the same as those in the first embodiment, and the photographing operation is basically the same as that shown in FIG.

FIG. 13 shows the configuration of the liquid crystal filter ON / OFF control circuit 39. The oscillator 39a includes an inverter, a resistor, and a capacitor. A signal line 39b connected to an output terminal of the oscillator 39a is connected to a base terminal of a transistor 39d via a resistor 39c.
It is connected to the base terminal of transistor 39g via 9e and resistor 39f. Signal line 39 extending from the power supply
h is connected to the transistor 39 via the resistors 39i and 39j.
d and 39g are connected to the collector terminals, respectively, and these collector terminals are connected to the liquid crystal filter 37 via signal lines 39k and 39m.

A first input terminal of the EXOR circuit 39e is supplied from the oscillator 39a with a rectangular wave signal changing at a predetermined cycle,
That is, "0" and "1" are input alternately. Also EX
A control signal of “0” or “1” is input from the control circuit 23 to a second input terminal of the OR circuit 39e. EXO
The R circuit 39e outputs a signal of the same level as the signal input to the first input terminal when the control signal input from the control circuit 23 is “0”, and outputs the first signal when the control signal is “1”. And outputs a signal having a level different from that of the signal input to the input terminal. Therefore, when the control signal is “0”, an in-phase rectangular wave signal is transmitted via the signal lines 39k and 39m,
As a result, no voltage is applied to the electrodes of the amber liquid crystal filter 37, so that the filter 37 becomes transparent.
On the other hand, when the control signal is “1”, the signal lines 39k, 3k
Since the opposite-phase rectangular wave signal is transmitted via 9m, a voltage is applied to the electrode of the filter 37, and the filter 37 becomes amber.

FIGS. 14 and 15 are flowcharts showing the operation of the control circuit 23 in the flash emission control of the fourth embodiment. Only parts different from those of the third embodiment will be described.

In step 305, the colorimetric sensor 38 provided in front of the filter 37 is controlled by the selector 32.
Is selected, and the signal from the colorimetric sensor 38 is taken into the color temperature calculation circuit 20. In step 306, IGB
A light emission trigger signal is output to T33, whereby a trigger voltage is applied to the trigger electrode of the xenon tube 51,
Strobe light is emitted from the xenon tube 51.

After the strobe light is thus emitted, in step 307, the control circuit 23 turns on / off the liquid crystal filter.
The control signal “1” is output to the OFF control circuit 39, and the liquid crystal filter 37 is colored amber. In step 308, the colorimetric sensor 38 detects the color temperature KD _(ON) of the irradiation light F2 to the subject SB via the liquid crystal filter 37. Then, in step 309, the color temperature K
_{The difference} between the reciprocal of _{D (ON) and} the reciprocal of the designed emission color temperature K _{DO (ON)} of the strobe light of the xenon tube 51 transmitted through the colored liquid crystal filter 37, (1 / KD _(ON) )-(1 / K
_{DO (ON)} ) is calculated, and a change with time or an error from the designed color temperature is obtained.

Next, in step 310, the memory 29 is referred to based on the reciprocal 1 / K _C of the color temperature of the ambient light E1 measured in advance, and (1 / K _{D (ON)} ) − (1 /
The filter ON time corresponding to the value of ₍ K _{DO (ON)} ) is read out and set in the timer circuit 28. In step 311, the timer counting operation starts, and the control signal “1” is continuously output until it is determined in step 312 that the filter ON time has elapsed. If it is determined in step 312 that the filter ON time has elapsed, the timer circuit 28 is stopped in step 313.

In step 314, the control circuit 23 outputs a control signal "0" to the liquid crystal filter ON / OFF control circuit 39, and the liquid crystal filter 37 is made transparent.
In step 315, the color temperature K _{D (OFF)} of the irradiation light F2 to the subject SB through the liquid crystal filter 37 is detected by the colorimetric sensor 38. In step 316, the color temperature K
The reciprocal of _{D (OFF)} and the designed emission color temperature K from the xenon tube 51 transmitted through the liquid crystal filter 37 in the transparent state.
Difference from the reciprocal of _{DO (OFF)} , (1 / KD _(OFF) )-(1 / K
_{DO (OFF)} ) is calculated, and a temporal change and an error from the designed color temperature are obtained.

Next, in step 317, the memory 29 is referred to based on the reciprocal 1 / K _C of the color temperature of the ambient light E1 which has been measured in advance, and (1 / K _{D (OFF)} ) − (1 / K
_The filter OFF time corresponding to the value of _{DO (OFF)} ) is read out and set in the timer circuit 28. Step 318
Then, the timer counting operation starts, and the control signal “0” is continuously output until it is determined in step 319 that the filter OFF time has elapsed. Step 319
If it is determined that the filter OFF time has elapsed, the timer circuit 28 is stopped in step 320.

Next, in step 321, the presence or absence of the quench signal S3 is determined. When the output is confirmed, the output of the light emission signal to the xenon tube 51 is stopped in step 323, and in step 324, step 30 is executed.
The timer which started timing at 4 stops, and the program ends. On the other hand, if the output of the quench signal S3 is not confirmed in step 321, it is determined in step 322 whether or not the time counted by the timer circuit 28 has exceeded the maximum flash emission time. If not, step 3
Returning to 07, the process of coloring the liquid crystal filter 37 is performed again. On the other hand, when the maximum flash emission time has elapsed, the emission signal output to the xenon tube 51 is stopped in step 323. Then, in step 324, the timer stops, and the program ends.

As described above, in the fourth embodiment, the xenon tube 51
Is converted by the amber liquid crystal filter 37, the color temperature K of the irradiation light F2 to the subject SB is changed.
_D is detected directly, and the information of O
By controlling the ratio of the N / OFF time, the combined emission color temperature for irradiating the subject SB is made equal to the color temperature of the ambient light E1 of the subject SB. FIG. 16 shows the ON / OFF timing of the xenon tube 51 and the liquid crystal filter 37.
As shown in this figure, ON / OFF of the liquid crystal filter 37 is repeated at a predetermined time ratio until the quench signal S3 is output.

In the fourth embodiment, similarly to the third embodiment, the color temperature of the xenon tube may be detected before the main exposure.

Next, a fifth embodiment will be described. This embodiment combines the pre-light emission processing for preventing the red-eye phenomenon and the color temperature detection. A block diagram of a still video camera to which the strobe device of the fifth embodiment is applied has the same configuration as the third embodiment shown in FIG. Photometric sensor 2
1, integration circuit 24, comparison circuit 25 and D / A converter 2
The configuration of the light control circuit composed of 6 and the like is the same as that of FIG. 2, and the configurations of the colorimetric sensor 22 and the color temperature calculation circuit 20 are the same as those of FIG.

FIG. 17 is a sequence diagram showing an outline of the photographing operation in the fifth embodiment. Release switch 27
The operation from the time when (FIG. 8) is half-pressed to the operation for adjusting the opening amount of the aperture 12 is the same as the timing chart shown in FIG. When the light amount from the subject SB is adjusted by the aperture 12,
Red-eye reduction pre-flash is started based on the photometric result (step D41). At the time of the red-eye reduction pre-emission, the color temperatures K _A and K _{B of} the irradiation light F2 passing through the filters 53 and 55
Are respectively detected. Then, the electronic shutter time is determined based on the photometry result, charge accumulation is started, and then main flash emission is started. The subsequent processing is exactly the same as the timing chart of FIG.

FIG. 18 shows a flowchart of the pre-emission control in the fifth embodiment. In step 400,
The pre-emission time PA by the first xenon tube 51 corresponding to the blue filter 53 is set in the timer circuit 28, and in step 401, the timer circuit 28 starts counting time. In step 402, the selector 32 is switched to take in the signal from the first colorimetric sensor 30 into the color temperature calculation circuit 20. Next, step 403
Then, a light emission trigger signal is output to the IGBT 33, whereby the IGBT 33 is turned on. As a result,
A trigger voltage is applied to the trigger electrode of the xenon tube 51,
Strobe light (pre-emission) is emitted from the xenon tube 51.

After pre-emission by the xenon tube 51,
In step 404, the color temperature K _A of the irradiation light F2 on the subject SB is detected by the colorimetric sensor 30 and stored in the memory 29. This pre-emission is continued until it is determined in step 405 that the pre-emission time PA has elapsed. That is, in step 405, the pre-emission time PA
Is determined, the output of the light emission trigger signal is forcibly stopped in step 406. As a result I
The GBT 33 is turned off, the strobe light emission of the first xenon tube 51 is stopped, and the timer circuit 28 is stopped in step 407.

The pre-emission processing described above is similarly performed for the second xenon tube 52 corresponding to the amber filter 55. That is, in Steps 408 to 415, the processes in Steps 400 to 407 are performed on the second colorimetric sensor 31 and the second xenon tube 52.
Here, it indicates the color temperature of the illumination light F2 detected by the colorimetric sensor 31 K _B, the pre-emission time PB.

After the pre-emission by the first and second xenon tubes 51 and 52 is stopped, in step 416,
The reciprocal 1 / K _C of the ambient light color temperature and the color temperatures K _A and K _B detected by each pre-emission are obtained (1/1).
K _A ) − (1 / K _AO ) and (1 / K _B ) − (1 /
K _BO ) corresponding to each value of the first and second xenon tubes 5
The maximum light emission times T _A , T _B and the proper exposure levels L _A , L _{B of} 1, 52 are read from the memory 29, and this program ends.

FIG. 19 is a flowchart of the main light emission control in the fifth embodiment. In step 500, the maximum light emission times T _A and T _B determined in the pre-light emission control routine shown in FIG. 18 are compared. If the maximum emission time T _A of the first of the xenon tube 51 is less than or equal to the maximum emission time T _B of the second xenon tube 52, step 501 to 511 is executed first, light emission by the first xenon tube 51 rows Will be Conversely if the maximum emission time T _A of the first of the xenon tube 51 is longer than the maximum emission time T _B of the second xenon tube 52, step 512-522 is executed first, light emission by the second xenon tube 52 Is performed.

[0071] proper integration value L _A read at pre-emission control routine at step 501 is set to the D / A converter 26. In step 502, the integration value output of the integration circuit 24 is reset, and in step 503, the integration start signal S
The action of 1 causes the integration circuit 24 to start integration. At the start of this integration, the maximum light emission time T _A is set in the timer circuit 28 in step 504, and the timer operation of the timer circuit 28 starts in step 505. In step 506, a light emission trigger signal S4 is output to the IGBT 33, and the xenon tube 51 emits strobe light.

After the strobe light is emitted in this manner, the presence or absence of the quench signal S3 is determined in step 507. If the output of the quench signal S3 is confirmed here, the output of the light emission trigger signal is stopped in step 509, that is, xenon. The main light emission of the tube 51 stops. In contrast,
If the output of the quench signal S3 is not confirmed in step 507, in step 508, whether time measured by the timer circuit 28 has not elapsed time T _A is determined, if not over time T _A, again In step 507, it is determined whether the quench signal S3 is output. If it is determined in step 508 that the time T _A has elapsed, then in step 509 the IGBT 33
The output of the light emission trigger signal is forcibly stopped, and in step 510, the timer circuit 28 is stopped. Thus, the main light emission processing of the first xenon tube 51 ends.

The main light emission processing of the second xenon tube 52 in steps 512 to 522 is the same as the main light emission processing of the first xenon tube 51 described above.
Steps 2 to 522 correspond to steps 501 to 511, respectively.

According to the fifth embodiment, the same effects as those of the above embodiments can be obtained, but the luminous energy can be further reduced.
The battery life of the strobe device can be extended.

Next, a sixth embodiment will be described. In this embodiment, in the same circuit configuration as that of the fourth embodiment shown in FIG. 12, the pre-emission processing for avoiding the red-eye effect and the color temperature detection are combined. That is, the block diagram of the still video camera to which the strobe device of the fourth embodiment is applied has the same configuration as that of FIG.

FIG. 20 shows the pre-emission control in the sixth embodiment. In step 600, the colorimetric sensor 38 provided in front of the filter 37 is selected by the control of the selector 32, and a signal from the colorimetric sensor 38 is taken into the color temperature calculation circuit 20. In step 601, the pre-emission time P by the xenon tube 51 is determined by the timer circuit 28.
Is set, and at step 602, the timer operation of the timer circuit 28 starts. In step 603, the IGBT 33
, An emission trigger signal is output, and the xenon tube 51 emits strobe light (pre-emission).

After the pre-emission by the xenon tube 51,
In step 604, the control circuit 23 sends the liquid crystal filter O
The control signal “1” is output to the N / OFF control circuit 39, and the liquid crystal filter 37 is colored amber. In step 605, the color temperature K _{D (ON)} of the irradiation light F2 to the subject SB via the liquid crystal filter 37 is
8 and stored in the memory 29.

At step 606, the control circuit 23 outputs a control signal "0" to the liquid crystal filter ON / OFF control circuit 39, and the liquid crystal filter 37 is made transparent.
In step 607, the color temperature KD _(OFF) of the irradiation light F2 to the subject SB via the liquid crystal filter 37 is detected and stored. In step 608, it is determined whether or not the pre-emission time P started in step 602 has elapsed, and the pre-emission is continued until the pre-emission time P elapses. Step 6 when the pre-emission time P has elapsed
09, the IGBT 33 is turned off and the xenon tube 5
The strobe light emission of 1 is stopped. And step 61
At 0, the operation of the timer circuit 28 is stopped.

At step 611, the reciprocal 1 / K _C of the ambient light color temperature and the color temperature K detected by each pre-emission
(1 / KD _(ON) ) obtained by _{D (ON)} and KD _(OFF )-
(1 / K _{DO (ON)} ) and (1 / KD _(OFF) )-(1 / K
_{DO (OFF)} ) ON / _{OFF of} the liquid crystal filter 37 corresponding to each value of
The maximum light emission time T _ON , T _OFF and the appropriate integral values L _ON , L OFF at the time of _OFF are read from the memory 29, and this program ends.

FIG. 21 shows a flowchart of the main light emission control of the sixth embodiment. This flowchart is almost the same as that of the fifth embodiment. That is, step 700
Then, instead of comparing the times T _A and T _B , the maximum emission times T _ON and T _OFF determined in the pre-emission control routine of FIG. 20 are compared. In step 700, the maximum light emission time T _ON
Is determined to be less than or equal to the maximum light emission time T _OFF , the liquid crystal filter 37 is first _turned on in step 701 to be in a colored state, and thereafter, in steps 702 to 711, FIG.
The same processing as in steps 501 to 510 of No. 9 is performed.

On the other hand, if it is determined in step 700 that the maximum light emission time T _ON is longer than the maximum light emission time T _OFF , the liquid crystal filter 37 is turned off in step 713 to be in a transparent state. 723
Then, the same processing as in steps 512 to 521 in FIG. 19 is performed.

According to the sixth embodiment, the same effects as those of the above embodiments can be obtained.

In each of the above embodiments, a colorimetric sensor is disposed outside the optical system to detect reflected light, illuminated light, and the like from a subject. However, the imaging device 11 is used as a colorimetric sensor, and a photographic lens is used. It may be one that detects the passed light. Further, the present invention is not limited to a still video camera, but can be applied to a strobe device of a general silver halide camera. In this case, when the characteristics of the ambient light and the film are different, a color temperature conversion filter is required separately before the taking lens.

[0084]

As described above, according to the present invention, even if an error or a change with time occurs in the color temperature conversion capability of the filter or the color temperature of the light emitted from the arc tube, the reflected light from the object or the irradiation light to the object can be obtained. Since the color temperature is detected and the color temperature of the strobe light is controlled based on the color temperature information, the color temperature of the strobe light can always be made equal to the color temperature of the ambient light, and the white balance of the captured image can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of a still video camera to which a strobe device according to a first embodiment of the present invention is applied.

FIG. 2 is a detailed diagram of a photometric sensor, an integration circuit, and a comparison circuit.

FIG. 3 is a block diagram illustrating a colorimetric sensor and a color temperature calculation circuit.

FIG. 4 is a block diagram illustrating a configuration of a liquid crystal filter applied voltage control circuit.

FIG. 5 is a sequence diagram illustrating an outline of a photographing operation.

FIG. 6 is a flowchart illustrating an operation of flash emission control according to the first embodiment.

FIG. 7 is a block diagram of a still video camera to which the strobe device of the second embodiment is applied.

FIG. 8 is a block diagram of a still video camera to which the strobe devices of the third and fifth embodiments are applied.

FIG. 9 is a flowchart showing the first half of the operation of the flash emission control of the third embodiment.

FIG. 10 is a flowchart showing the latter half of the operation of the flash emission control of the third embodiment.

FIG. 11 is a timing chart of a flash emission operation according to the third embodiment.

FIG. 12 is a block diagram of a still video camera to which the strobe devices of the fourth embodiment and the sixth embodiment are applied.

FIG. 13 is a block diagram showing a configuration of a liquid crystal filter ON / OFF control circuit.

FIG. 14 is a flowchart showing the first half of the operation of the flash emission control of the fourth embodiment.

FIG. 15 is a flowchart showing the latter half of the operation of the flash emission control of the fourth embodiment.

FIG. 16 is a timing chart of a flash emission operation according to the fourth embodiment.

FIG. 17 is a sequence diagram showing an outline of a photographing operation in the fifth embodiment.

FIG. 18 is a flowchart showing an operation of pre-emission control in the fifth embodiment.

FIG. 19 is a flowchart illustrating an operation of main light emission control in a fifth embodiment.

FIG. 20 is a flowchart showing the operation of pre-emission control in a sixth embodiment.

FIG. 21 is a flowchart showing an operation of main light emission control in a sixth embodiment.

[Explanation of symbols]

 Reference Signs List 20 color temperature calculation circuit 22 colorimetric sensor 23 control circuit 51, 52 xenon tube 53 blue filter 54, 56 monochrome liquid crystal filter 55 amber filter 57, 58 liquid crystal filter applied voltage control circuit 59 white tailored liquid crystal filter SB subject E1 ambient light F1 Reflected light F2 Irradiation light

Claims (10)

(57) [Claims] 1. An arc tube, an emission color temperature conversion unit capable of converting an emission color temperature of the arc tube, and a first color temperature detection unit for detecting a color temperature of irradiation light passing through the emission color temperature conversion unit. Second color temperature detecting means for detecting the color temperature of ambient light of the subject; color temperature detected by the first color temperature detecting means; and color temperature detected by the second color temperature detecting means
Based on the bets, strobe, characterized in that the color temperature of the emission color temperature converting means and the irradiation light is an illumination light color temperature control means for controlling so as to be substantially equal to the color temperature of the ambient light of the subject apparatus. 2. The strobe device according to claim 1, wherein the first color temperature detecting means and the second color temperature detecting means are the same colorimetric sensor. 3. A light emitting color temperature converting means for converting a light emitting color temperature of each of the light emitting tubes, a light emitting amount controlling means for controlling a light emitting amount from each of the light emitting tubes, and The strobe device according to claim 1 , wherein the irradiation light color temperature control means controls a combined light emission color temperature by controlling a light emission amount ratio from each light emitting tube that irradiates the subject. 4. The strobe apparatus according to claim 3, wherein the light emission amount control means controls the color temperature of the light irradiated to the subject by controlling the conversion rate of the light emission color temperature conversion means. 5. The apparatus according to claim 1, wherein said one light emitting tube is provided, and said irradiation light color temperature control means controls the color temperature of irradiation light to a subject by controlling the light emission color temperature of the light emitting tube. Item 2. The strobe device according to Item 1 . 6. A color temperature conversion unit for converting a color temperature of light emitted from each of the plurality of arc tubes, wherein the color temperature control unit for irradiating light emits light from each of the arc tubes for irradiating an object. The strobe device according to claim 1, wherein the combined emission color temperature is controlled by controlling the ratio. 7. An illuminating color temperature converting means provided with one luminous tube, and converting the illuminating color temperature into a plurality of illuminating color temperatures while each luminous tube emits light, wherein the illuminating color temperature controlling means is a luminous color temperature converting means. The strobe device according to claim 1, wherein a combined emission color temperature is controlled by controlling a time ratio of different emission color temperature conversions performed by the electronic device. 8. The flash device according to claim 1, wherein the first color temperature detecting means detects the color temperature before the main exposure. 9. The strobe device according to claim 1 , wherein the color temperature detection by the first color temperature detection means is performed at the time of pre-flash for red-eye reduction. 10. An arc tube, first color temperature detecting means for detecting a color temperature of light emitted to a subject or reflected light from the object in a state where the arc tube emits light, and a color temperature of ambient light of the subject. the bichromal temperature detecting means, the second color temperature sensing hand color temperature detected by the first color temperature detection means for detecting
An illumination light color temperature control means for controlling the color temperature of the illumination light to be substantially equal to the color temperature of ambient light of the subject based on the color temperature detected by the step. apparatus.