JP2537350B2 - Imaging device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus, and in particular, to a photoelectric conversion type image pickup apparatus which is often used together with a subject illumination apparatus.

[Conventional technology]

The sensitivity of the image sensor used in this type of conventional image pickup device is not sufficient for all image pickup conditions, and when shooting in a dark place, the image is taken by illuminating the subject with a lighting device. It compensated for the lack of sensitivity of the element. Furthermore, to soften the shadows on the subject,
Illumination light has also been used as auxiliary light.

[Problems to be solved by the invention]

However, in the case where the illumination light for photographing is particularly prepared as described above, the following precautions are required. That is, if the hue of the prepared illumination light is significantly different from the hue of the ambient light that illuminates the subject other than that, it is not possible to adjust the white balance (white balance) suitable for both, and as a result, There is a drawback that the hue of the image becomes unnatural.

In order to deal with such a problem, it is sufficient to prepare a light source that matches the hue of the illumination light of the subject.
In general, the types of light sources that can be practically prepared are quite limited, so not all of them have excellent portability and good emission efficiency, and in some cases, they can be effectively applied. There was a problem that there were not many.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides an image pickup apparatus capable of obtaining an appropriate white balance for both the ambient light of a subject and the illumination of an auxiliary lighting device. Has an aim.

[Means for solving problems]

Therefore, in the present invention, a light source capable of continuously varying the hue and a colorimetric circuit are provided to measure the hue of ambient light without a lighting device, and light of the same hue is generated in the lighting device. It is intended to achieve the above object by illuminating an object.

[Action]

With the above-described configuration, it is possible to obtain a reproduced image that reproduces a natural color that has a proper white balance with respect to the original ambient light of the subject and the illumination light of both the illumination devices used.

〔Example〕

 Hereinafter, the present invention will be described based on examples.

(Circuit Configuration) FIG. 1 shows an electric circuit block diagram showing an embodiment of the photoelectric conversion image pickup device according to the present invention. Reference numeral 1 denotes an optical system for forming a subject image on the image sensor 4 and includes an optical lens and the like. 2a and 2b are the aperture and its driver, 3
Reference numerals a and 3b are a shutter and its driver, respectively. Reference numeral 4 denotes an image pickup element for converting a subject image into an electric signal, which may be, for example, an image pickup tube, a CCD (charge coupled device), a MOS solid-state image sensor, or the like.

Reference numeral 5 is a driver for driving the image sensor 4, and 6 is a driver.
A signal processing circuit for converting an electric signal read from the image pickup device 4 into a prescribed video signal, and 7 is a recording circuit for recording the video signal on a recording medium (for example, a magnetic tape, a magnetic disk or the like). is there. Further, 8 is a photometric circuit for measuring the brightness of the subject, and 9 is a colorimetric circuit for measuring the hue of the light illuminating the subject. No. 10 has insufficient subject brightness, and as described later, this light source can adjust the hue (color temperature). Reference numeral 11 denotes an arithmetic / control circuit for inputting a signal from each part of the image pickup apparatus, performing various calculations and determinations, and controlling each part. Also, 12
Is a clock circuit that determines the operation timing of each part, 13
Is a power switch, and 14 is a release switch for the photographer to specify the photographing timing.

The photometric circuit 8 can be easily configured by a known circuit as shown in FIG. In FIG. 2, 21 is an operational amplifier (op-amp), 22 is a light receiving element such as a silicon photodiode whose short-circuit current is proportional to the intensity of light illuminating itself, and 23 is a diode.
In this circuit, the voltage V ₀ generated at the output terminal O of the operational amplifier 21 is Where k: Boltzmann constant T: ambient temperature (absolute temperature) q: charge of one electron I _S : reverse saturation current of diode 23 I _SPC : forward current flowing in diode 23 (= light flowing in light receiving element 22) Current ∝ received light intensity) That is, the photometric output voltage V ₀ is proportional to the natural logarithm of the received light intensity, Therefore, every time the brightness of the subject (the light receiving intensity of the ∝ light metering circuit 8) doubles, it increases by 18 mV. Therefore, the subject brightness can be known by measuring the output voltage.

As shown in FIG. 3, the colorimetric circuit 9 in FIG.
It can be realized by a known circuit configuration. In FIG. 3, 31
Is a diffusion plate, 32, 33, 34 are color filters for transmitting only red (R), green (G), and blue (B), respectively, and 35, 36, 37 are respectively The respective photometric circuits are the same as those shown in FIG.

In this circuit, if you take the difference between the outputs of both photometry circuits 35 and 36, Therefore, the ratio of the line (G) component of the light incident on the colorimetric circuit 9 and the red (R) component is known.

Similarly, if the output difference of both photometric circuits 36 and 37 is taken, Therefore, the ratio of the line (G) component of the light incident on the colorimetric circuit 9 and the blue (B) component is known.

Thus, the red (R) component of the incident light: the green (G) component: the blue (B) component ...
Since the ratio of (5) is required, the hue of incident light can be known.

(Imaging Operation) Next, the case of imaging using an illumination device that generates temporally continuous light, such as an illumination lamp, will be described based on the imaging operation sequence flowchart of FIG.

First, when the power switch 13 (FIG. 1) is turned on, the image pickup device starts operating (step S1), and the photometric circuit 8 measures the brightness of the subject (step S2). Then, in step S3, it is determined whether or not the brightness of the subject is less than or equal to a specified value. If it is less than or equal to the specified value (YES), the light illuminating the subject from the surroundings is dark enough to be ignored. Therefore, the photographing is performed by the illumination of the light source 10.

Therefore, the white balance is set to a color temperature at which the light emission efficiency of the light source 10 is maximized, the light source 10 is set to a mode in which the light emission efficiency is maximized (step S4), and the light source 10 is turned on (step S5). Next, the photometric circuit 8 is again used to measure the subject brightness (step S6), and the imaging device
It is determined whether or not it is within the shooting range (step S
7). At this time, if the photographing range of the image pickup device is exceeded (too bright / too dark), the light intensity of the light source 10 is adjusted (step S8), and the process returns to step S6 to determine the brightness of the illumination. When the illumination of the light source 10 on the subject becomes appropriate (step S7, YES), the operation of the release switch 14 (FIG. 1) is awaited (step S17).

When the release switch 14 is operated (step S17, Y
ES), first, the arithmetic / control circuit 11 narrows down the diaphragm 2a via the diaphragm driver 2b (step S18). After that, the arithmetic / control circuit 11 drives the shutter 3a via the shutter driver 3b to open the shutter 3a for a predetermined time to expose the image sensor 4 (step S19).
The aperture value of the aperture 2a and the shutter 3a here
The exposure time is calculated by the calculation / control circuit 11 in step S6 based on the subject brightness information input via the photometry circuit 8.

After the exposure is completed as described above, the subject image of the image pickup device 4 is read out as an electric signal at an appropriate timing, converted into a prescribed video signal by the signal processing circuit 6 (step S20), and then the recording circuit. 7, the image is recorded on the recording medium (step S21), and the photographing operation is ended (step S22).

Next, in FIG. 4, step S3, the case where the ambient light around the subject is not so weak as to be negligible as a result of the photometry in step S2 (step S3, NO) will be described. In this case, since the influence of the color of the light illuminating the subject cannot be ignored, the arithmetic / control circuit 11 measures the hue of the light illuminating the subject via the photometric circuit 9 (step S10). Then,
Based on this colorimetric value, the arithmetic / control circuit 11 sets the white balance of the signal processing circuit 6 and the color temperature (absolute temperature) of the light source 10 (step S11).

Next, based on the photometric value in step S2,
It is determined whether shooting can be performed without the help of 10 (step S12). If the image cannot be taken without the help of the light source 10 (NO), the light source 10 is turned on (step S13).
Then, in the loop of steps S14 to S16, the brightness of the light source 10 is changed by the same process as steps S5 to S7.
The adjustment is performed until the image pickup apparatus is within the image pickup range, and then the image pickup operation is executed in steps S17 to S21. In this case, the parameter values of the aperture 2a and shutter 3a are
The value is calculated by the arithmetic / control circuit 11 together with the photometric value in S14.

If the result of determination in step S12 is as bright as (NO) where image capture is possible without the aid of the light source 10, the process immediately jumps to step S17, and the image capture operation is executed in steps S17 to S21. In this case, the parameter values of the diaphragm 2a and the shutter 3a are values calculated by the calculation / control circuit 11 based on the photometric value in step S2.

(Method of Setting Color Temperature of Light Source) Next, a method of setting the color temperature of the light source 10 will be described.
FIG. 5 and FIG. 6 are detailed diagrams of the hue (color temperature) variable light source.

In FIG. 5, reference numeral 41 denotes a light source whose brightness (luminance) is changed by the voltage applied between the electrodes A and B.
Reference numerals 2, 43, and 44 are, for example, red (R), green (G), and blue (B) color filters, and 45, 46, and
47 is each filter of the colorless phase whose transmittance changes according to the electric signal applied to each electrode C, D, E.

In the light source shown in FIG. 5 having the above-described configuration, the color temperature of the light source 10 is adapted to the colorimetric value of the ambient light of the subject by adjusting the transmittance ratio of each filter 45, 46, 47. By adjusting the intensity ratio of the red, green, and blue light, the intensity of the light of the color temperature is determined (each dimming step S8 and S1 in FIG. 4).
6) is adjusted by the voltage applied between the electrodes A and B.

When the intensity of ambient light is weak, as in step S3 of FIG. 4, each of the filters 42, 43 in front of the light source 41,
If all the 47 are removed and the subject is directly illuminated by the light source 41, the light is not attenuated by the filters 42 to 47, so that the efficiency is extremely improved. In this case, the white balance of the image pickup device is adjusted to that of the light source 41. This data may be input from the light source 10 to the arithmetic / control circuit 11 in the memory area of the arithmetic / control unit 11 (FIG. 1).

Next, FIG. 6 is an explanatory diagram of another method for changing the hue of the light source 10. In the figure, 51, 52 and 53 are independent light sources whose light emission brightness is changed by changing the voltages applied to the electrodes A, B and C, respectively, and 54 and 5
Reference numerals 5 and 56 are, for example, red (R), green (G), and blue (B) color filters, respectively. In the case of the light source shown in FIG. 6 having the above-described configuration, the red, green, and blue colors of the light transmitted through the color filters 54, 55, 56 are adjusted depending on the ratio of the voltages applied to the electrodes A, B, C, respectively. The light is adjusted by adjusting the component ratio (color temperature) and increasing the absolute value of the voltage applied to each of the electrodes A, B, and C.

In the two examples of FIGS. 5 and 6 described above, in the case of FIG. 5, both filters 43 and 46 are omitted, and the filters 42, 44, 45, and 47 mainly illuminate through light. Then, if you adjust the hue (color temperature) using two colors,
The filters 43 and 46 reduce light attenuation and also allow hue adjustment.

Regarding this point, the same effect can be obtained by omitting the color filter 55 from FIG.

If you want to further simplify the light source, for example light source 41 or
The color of 52 may be closer to cyan, and the transmittance or brightness of the filter 45 or the light source 51 may be adjusted. In this case, the color filters 43 and 44 in FIG. 5 can be omitted, and the filters 46 and 47 can be one. Moreover, in FIG.
The color filters 55, 56 and the light source 53 can be omitted.

Further, the color filters 42 and 54 are not shown in FIGS.
It is also possible to use 43 and 55 as cyan filters and omit the color filters 44 and 56 and the light source 53.

Further, in the case of FIG. 6, when light sources of color quality are used as the light sources 51, 52, the light source 53 and the color filters 54, 55, 56
May be omitted.

(Other Imaging Operation) Next, a case of imaging using an illumination device that generates pulsed light, such as a strobe, will be described. FIG. 7 shows an example of a photographing operation sequence flowchart in such a case. Also in this case, the electric circuit and the like can be realized by the one shown in FIG. That is, first, when the power switch 13 is turned on, the image pickup apparatus starts its operation (FIG. 7, step S61), and the photometric circuit 8 measures the subject brightness (step S62). Then, it is determined whether or not the brightness of the subject is below a predetermined value (step S63). As a result, if the value is equal to or less than the predetermined value (YES), the light illuminating the subject from the surroundings is so dark that it can be ignored, so that the shooting may be performed under the condition in which the light emission efficiency of the light source 10 is the best. The arithmetic / control circuit 11 sets the white balance of the signal processing circuit 6 to a value assumed to be illuminated under the conditions (step S6).
Four). Then, the parameter X for discriminating the case is set to 0 (step S65).

Then, it waits until the series switch 14 (Fig. 1) is operated (step S66, NO). Then, when the release switch 14 is operated (step S66, YES),
Next, the case determination parameter is determined (step S67).
In this case, since X = 0, the process jumps to step S68, and the color temperature of the light source 10 is set to be the maximum efficiency of the light source 10. Then, for example, stop 2a to the value specified by the light source 10.
(Step S69), the shutter 3a is opened (step S70), the light source 10 is made to emit light (step S71), and after the light emission is stopped, the shutter 3a is closed (step S72). The subject image information is read in the form of, and converted into a predetermined video signal by the signal processing circuit 6 (step S73), and recorded on the recording medium by the recording circuit 7 (step S74), and a series of photographing operations is completed.

If the ambient light has an intensity that cannot be ignored in step S63 (step S63, NO), the color temperature of the ambient light is first measured by the color measurement circuit 9 (step S7).
6). The white balance of the signal processing circuit 6 is set based on this colorimetric value (step S77).

Next, based on the colorimetric value in step S62, it is determined whether or not it is possible to shoot without the aid of the light source 10 (step S78).
When it is determined that the image cannot be captured without the assistance of the light source 10 (NO), the case determination parameter X is set to 1 (step S79), and when it is determined that the image cannot be captured without the assistance of the light source 10 (NO). ), The value of the case determination parameter X is set to 1 (step S79), the release switch 14 is expected to be operated (step S66), and when the release operation is performed,
The next operation is determined by the value of the discrimination parameter X.

In this case, since the influence of ambient light cannot be ignored when X = 1, the color temperature of the light source 10 is set according to the color temperature of ambient light (step S80). From then on, steps S69 to S75 are executed just as in the case of X = 0.

When it is determined in step S78 that the image can be taken without the assistance of the light source 10 (YES), the case determination pararotor X is set to 2 (step S81), and the release switch 14 is expected to be operated (step S66). Then, some of the case determination parameters X are determined (step S6
7).

In this case, since X = 2, the flow jumps to step S83, and the aperture 2a is narrowed down to the parameter value calculated by the calculation / control circuit 11 by the photometric value of step S62 (step S8).
3) After driving the shutter 3a (step S84) to perform exposure, the photographing operation is executed in steps S73 to S75 just as in the case of X = 0,1.

Here, as the configuration of the light source 10, each light source 41, 5
By changing 1, 52, 53 from a continuously lit light source such as a lamp to a flash discharge tube, the configuration shown in FIGS. 5 and 6 can be applied.

Further, the efficiency is improved by omitting the filters 46, 53, 55, as in the case of the continuous lighting light source.

〔The invention's effect〕

As described above in detail, according to the present invention, when there is no ambient light of the subject, the illumination light source for the image pickup device can be used with maximum efficiency, so that there is little waste and the ambient light is ignored. If it is not possible, by using the hue variable light source attached to the image pickup device that matches the ambient light, the photographer does not need any extra operation, and both the ambient light and the light source attached to the image pickup device have a hue with a white balance. It is now possible to obtain replayed images with good reproducibility.

[Brief description of drawings]

FIG. 1 is a block diagram of an electric circuit of an embodiment of an image pickup apparatus according to the present invention, FIG. 2 is a photometric circuit diagram thereof, FIG. 3 is a colorimetric circuit diagram, and FIG. 4 is a photographing operation sequence of the present embodiment. Flowcharts, FIGS. 5 and 6 are two examples of the light source of the present invention, and FIG. 7 is a sequence flowchart of another imaging operation. 8: Photometric circuit 9: Color measuring circuit 10, 41, 51, 52, 53 ... Light source (light emitting part) 32, 33, 34:42, 43, 44: 54, 55, 56 ... Color filter 45, 46, 47 ... Filter

Claims (6)

(57) [Claims] 1. An image pickup apparatus using a subject illuminating device, comprising color measurement means for measuring the hue of the ambient light of the subject other than the illuminating light of the illuminating device, and adjusting the hue of the light source of the illuminating device. An image pickup device comprising means for adjusting the hue of the illumination light generated from the illumination device light source to the hue of the ambient light on the basis of the colorimetric value obtained by the colorimetric means. . 2. The image pickup device according to claim 1, wherein the white balance of the image pickup device is adjusted to match the hues of the ambient light and the illumination light adapted to the ambient light. apparatus. 3. The operation for adjusting the hue of the illumination light of the illuminating device to the ambient light is performed only when the intensity of the ambient light is equal to or more than a predetermined value, and the intensity of the ambient light is When it is less than or equal to a predetermined value, the lighting efficiency of the lighting device is set to the best condition, and the white balance of the imaging device is adapted to match the emission hue of the lighting device under the above conditions. The image pickup device according to claim 1 or 2. 4. The illuminating device is composed of a plurality of light emitting parts having different hues, and the emission color from the illuminating device is changed by changing the relative light emission intensity of each light emitting body of each light emitting part. The image pickup apparatus according to claim 1, wherein the image pickup apparatus is configured. 5. The means for changing the color of light emitted from each of the light emitting units changes the hue of each of the light emitting bodies, or changes the spectral transmission characteristics of each color filter arranged in front of each of the light emitting bodies. The image pickup apparatus according to claim 4, wherein the image pickup apparatus is configured to be changed. 6. The image pickup device according to claim 1, wherein the lighting device is composed of a single light emitting portion whose hue can be varied from the outside.