JPS6072383A - Image pickup device used together with illuminating device - Google Patents

Abstract

PURPOSE:To widen the dynamic range of an image pickup device and to obtain a video signal at the proper level by outputting signal corresponding to the light emitting capacity of an illuminating device by an indicating means, and controlling the gain of an electric signal obtained by an image pickup device responding to the light emission capacity signal indicated by the means. CONSTITUTION:An illuminating device 2 is combined to an image pickup device and the image of an object is converted to an electric signal by an image pickup element 7 as an image pickup means. A signal corresponding to light emission capacity of the device 2 is outputted from a guide number indicating circuit 18 that works as an indicating device. The output from the circuit 18 is added to an arithmetic circuit 12 to set the value of a potentiometer 6a that is interlocked with a distance ring 3, and at the same time, the output is added to a switching circuit 14. The gain of a gain controlling circuit 9 that works as a controlling means that makes output from the image pickup element 7 input responding to a light emission capacity signal of the device 1 indicated by the circuit 18. Thus, dynamic range of the image pickup device 2 is widened and video signals of proper level are outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an imaging device that is used together with an external lighting device.

[Description of prior art]

Conventionally, the dynamic range of the Jiu image element is narrow, and the dynamic range of the Jiu image element is narrow, and even a slight exposure deviation is
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In order to electrically correct this, an automatic gain control circuit (hereinafter referred to as AGC) using a negative feedback loop is used to compensate for this, regardless of the magnitude of the output from the image sensor. The level of the signal transmitted to the signal processing and recording circuits was always kept almost constant. However, such an apparatus has the drawback that it cannot cope with cases where the photometric conditions before photography and the exposure conditions during photography are completely different, such as in flash photography.

Therefore, in Japanese Patent Application No. 57-208920, the present applicant proposed an imaging device capable of eliminating such drawbacks.

That is, in the imaging device σ, the conventional drawbacks are eliminated by controlling the gain of the imaging signal to be a predetermined constant gain when performing imaging using a flash device such as a flash.

〔the purpose〕

The present invention improves on the imaging device described above and makes it more extensive.

[Explanation of actual rolling example]

Hereinafter, the inner world of the present invention will be explained in detail with reference to the accompanying drawings.

FIG. 1 is a diagram showing a first embodiment of the present invention, in which 1
The imaging device 6.2□ includes an artificial illumination light source 20, and is a lighting device that is detachable and replaceable for the imaging device i (i, lK).The light source 20 may be a continuous light source such as a lamp or a flash light source. Good. 3 is a distance ring that adjusts the distance between the lens and the imaging plane according to the distance to the subject. 10
0 is the subject 0, and as shown in the figure, let D be the distance between the imaging device 1 and the lighting device 2 and the subject 100. 5 is an imaging optical system, 6 is a potentiometer linked to the distance ring 3, and 7 is an imaging ISi! as an imaging means. 08 is a signal processing circuit for gamma conversion and contour correction, which converts the subject image into an electric signal using an element; 9 is a gain control circuit as a control means; 10 is a modulation circuit; and 11 is a recording device.
Further, 15 is a driver circuit for driving the image sensor 7, and causes the illumination device 2 to emit light in synchronization with this driving. 4 is an aperture as an aperture means for limiting the amount of light incident on the image sensor; 13 is an aperture stop lever circuit for driving the aperture 4;
12 is an arithmetic circuit, 14 is a switch circuit, and 116 is a light source circuit standby switch for putting peripheral circuits in the lighting device on standby, such as a switch for starting charging of a capacitor for storing and storing luminous energy. .

By turning on this switch, the peripheral circuits of the light source go into standby mode, and one switch 14 is switched from a to b in conjunction with the switch.

17 is a low pass filter provided in the feedback loop of the gain control circuit 9. □ Also, l:8 is a guiding circuit as an indicating means according to the present invention, and by adjusting the value of the setting resistor 19 to the guide number GN0, which is the light emitting capacity of the lighting device, the indicating circuit 18 can be controlled. A predetermined guide number 11+ is output as a light emitting power signal.

In addition, in this embodiment, the terminal' voltage 6a of the potentiometer 6
forms an output proportional to the logarithm of the distance.

That is, v6a=IsogD ・・・・・・・・・・・・・・・
(1) (where F is a constant) Next, the operation will be explained.

When illuminating a subject using the illumination device f2 in FIG. 1, the illumination device n2 is first attached to the imaging device 1. In conjunction with this, or by manual operation, switch 16 is turned ON.
Put the circuit in the camera gJl device into standby state.

Further, when a guide number GNo, which is a value corresponding to the light emitting ability of the attached lighting device α, is set by a setting resistor, guide number information proportional to the guide number GNo is outputted from the guide number instruction circuit 18. When the lens is adjusted using the distance ring 3, the voltage V6a at the terminal 6a of the potentiometer 6 changes in accordance with equation (1). 1. Based on this voltage, the arithmetic circuit 12 calculates an aperture value FNo that allows the exposure condition for the imaging device to be constant even if the subject distance changes. Specifically, in this embodiment, □FNo =-...
Kawa surface...Scream...(2): ・ 9 Perform calculations like Nitaryo1.

Here, 1C is the guide number and bar information which are the output signals of the instruction circuit 18 mentioned above.

The aperture driver circuit 13 is controlled so that the aperture value is determined by this calculation, and the illumination light source emits light at a predetermined timing, and the optical system 5. The light passes through the aperture 4 and is exposed to the image sensor 7. Signal □ Processing circuit, 8. Gain control circuit 9. Modulation circuit 1
The signal passing through 01 is transferred to a magnetic disk in the recording device 11 and recorded on a medium such as a magnetic tape, semiconductor memory, optical memory, etc., and the imaging operation is completed.

Here, the FNO output from the arithmetic circuit 12 is shown in FIG.
a) As shown in 211 and 22, if the open limit value 1 of the aperture 4 is Fb1 and the limit value of the aperture cut off is Fc, then 8. (Fb, ,F'NO:) l? At c, the aperture remains constant and does not change, so Ji'b≦FNO≦Pc
to I within the range of. The relationship indicated by - holds true. In addition, the songs and %121.22 are respectively (:' = C,, c = c
, the curve for the case is not shown. However, Ct>C+ holds true, and the arithmetic circuit according to this embodiment outputs a gain 4rJ control signal for dividing the gain of the gain control circuit by 11 outside the aperture interlocking range, as shown in FIG. 2(b). That is, in the case of C=C1, D(
In Db, the smaller D is, the more the gain control circuit 9
Also, ub≦1〕≦l) c
In ItG, the gain of gain control circuit 9 is constant;
The gain side (i1tl signal is output) for controlling the gain control circuit 9 so that the larger the gain, the greater the gain by the gain control circuit 9.

Father, in the case of C=C, D(] as shown by curve 22
) to b'? The smaller l) is, the lower the gain by the gain control circuit 9 is, and the gain of the l circuit 9 is constant, and when D>DC', D
A gain control signal is output for controlling the gain control circuit 9 so that the larger the gain, the greater the gain by the gain control circuit 9. Therefore, the signal that has passed through the gain control circuit 9 is always at an appropriate level and does not cause any deterioration in image quality.

That is, in the range of Fb≦l”No≦Fc, the gain is constant, but an appropriate exposure level can be obtained by adjusting the aperture, so the signal level is stable as a result, and F(Fb, ,F)
In the range of li''c, the aperture is fixed at the limit value and the curvature is corrected by gain adjustment, so the No. 1i level remains stable.

In addition, in the non-embodiment, when the switch 16 is set to (JFF), that is, when performing normal photography without using an illumination light source, the switch 14 is switched to the a side, so that the output of the gain control circuit 9 is passed through the low-pass filter 17. It is fed back to the gain control circuit 9 and automatic gain adjustment is performed. In this case, the low-pass filter 17 has an appropriate time constant, so it is in a state suitable for continuous J7iL switching.

In addition, in this embodiment, when imaging is performed using the illumination device N sound, the aperture is configured to be controlled according to the distance to the subject, and the signal is adjusted by correcting the gain while the aperture is at a constant value. In order to optimize the level, the gain correction characteristics are changed according to the guide number of the illumination light source, thereby always providing an appropriate video signal.
However, the present invention is not limited to this embodiment.

For example, in order to simplify the 41' configuration, it is possible to configure the subject distance and aperture to be linked, and even in such a case, the gain control signal can be set to a gain value that corresponds to the guide number. By forming this, the signal level can be stabilized.

In this embodiment, the gain is controlled according to the guide outside the interlocking range of the diaphragm, but the present invention also includes one in which the gain is controlled only according to the guide number.

Of course, in that case, there remains a possibility that the level of the video signal will include some error depending on the distance. According to the first embodiment of the present invention, if the lighting device is replaceable, Even if the light emitting ability of the lighting device changes, the appropriate level of projection □8 and E can be obtained. 5: 3 years ago. Yu2□1. ．． □Oh, 7 The same number as in Figure 1 is the same number:, it's a call.

In the figure, reference numeral 23 indicates a flash source, for example, a key □, , or hexanon tube.

Reference numeral 24 denotes a trigger circuit for supplying a trigger pulse to the trigger fic 4i of the flash source, and its control terminal CK receives a light emission trigger signal output from the image pickup device driver circuit 15.

As a result, light is emitted in synchronization with the driving timing of the image sensor. 25 ke mei conde/za? sPA exclusive possession 9 Electricity party 1 Lisi death - Md) Bond N℃ 100 rugi Mitsushige,
do. 26 is a booster circuit which increases the voltage of the DC power supply 27 and applies it to the capacitor 25. Reference numeral 16 is the stun switch which turns ON and starts charging the capacitor. 36 is a gain correction circuit according to 11 which divides the charging voltage of the capacitor 25. Resistors 34 and 35 output a light-emitting capability signal indicating the light-emitting capability of the xenon tube, and a squaring circuit 3 squares this divided potential Va.
It includes a reciprocal circuit that obtains the reciprocal of the output of the 0.2 power circuit 30, and the like. Here, the indicating means is constituted by resistors 34, 35, etc.

32 is a switch circuit, and 33 is a reference value output circuit, which outputs a reference value VCO.

A 38-digit comparator, 37 is a reference power supply connected to its inverting input, and from this voltage source 37, the reference 1
1 degree Celsius pressure Vt1t is outputted.

In addition, the comparator: lid 3 switches the switch 32 to c (14t1
It controls the switch 32 so that it connects to the d side when s is larger than tl+, and it has a slight internal time constant, so even if the main capacitor is instantaneously discharged, the output remains unchanged for a while. It is maintained.

FIG. 4 is a diagram showing the relationship between the voltage dividing type QVa and the voltage vG manually applied to the gain control circuit 9, as shown in the figure (Va
> In the range of vth, the switch 32 is connected to the d side, so ■. ” Next, the operation of this second embodiment will be explained.

Switch 16 is OFF during normal daylight shooting.
Therefore, similarly to the embodiment shown in the first diagram, the gain control circuit as a control means receives negative feedback from the output of the low-pass filter 17 and automatically performs gain control so that a signal at a predetermined level is always obtained. There is.

When the switch 16 is turned on to perform illumination photography, the switch 14 is switched to the b side in conjunction with this, and a high voltage is applied to the main capacitor 25 by the booster circuit 26, so that the main capacitor 25 is rapidly charged. During this charging period, the level of the divided potential Va is compared with the reference voltage Vth by the comparator 38, and the switch 32 is connected to the C side until the voltage exceeds the reference voltage Vth. Control is performed so that the lower the charging pressure is, the higher the gain of the cane control circuit 9 is, and as the charging pressure increases, the gain is lowered.

In general, the brightness of the lighting device 2 is equal to the square of the capacitor 25, which is the source of the light emitting energy, and the ratio is 1t.
11. Therefore, if the gain of the image signal is controlled by taking the square of the light voltage of the capacitor 25 and the value proportional to its reciprocal, the final image signal output will be the brightness due to the difference in the photoelectric voltage of the capacitor 25. The difference can be completely compensated for.

If the potential Va exceeds the voltage Vth, the switch 32 is switched to the d side, so the gain is controlled to a predetermined constant potential.

When a trigger button (not shown) is turned on at an arbitrary timing, the trigger circuit 24 is triggered in synchronization with the drive timing of the image sensor that has already been driven, and the xenon tube 2
A trigger pulse is applied to trigger electrode 3, causing the xenon tube to emit flash light.

As a result, the subject is illuminated and the reflected light is sent to the imaging optical system 5.
．． The light enters the image sensor through the aperture 4.

At this time, the output of the potentiometer 6 changes depending on the subject distance, and the aperture 4 is adjusted. The image incident on the image sensor 7 is photoelectrically converted, and then linearly scanned by the driver circuit 15 and read out. The signal is processed as a series signal in the signal processing circuit 8, and then sent to the recording device via the gain control circuit 9 and the modulation circuit IO.
1.

At this time, the gain of the gain control circuit 9 is determined by the light emitting ability of the charging voltage section before light emission, so a video signal of an appropriate level is always obtained at the output of the gain control circuit 9. It is something. Therefore, the charging capacitor's charge +(i, ``ilf's falling characteristic,
It is not affected by uneven light emitting ability of lighting/devices due to changes over time, etc.

In addition, in the above pH 1, second embodiment, the aperture value is changed in conjunction with the distance ring, or the imaging device having a distance measuring device:
In 6, the diaphragm is set to 1lill Ijiil according to the output of the fill I city device 4, and -C is also good.

Further, although an example of a lighting device using a real 111 f id gisenon tube is shown, the lighting device may be of any type, such as one using a tungsten lamp or the like.

〔effect〕

As described above, the present invention provides an imaging device used with a lighting device, which includes an imaging means for converting a photographic object image into an electrical signal, and an instruction means for outputting a signal according to the light emitting capability of the lighting device. and a control means for controlling the gain of the electric signal obtained by the imaging means in accordance with the light emission capability signal instructed by the instruction means, so that the light emission capability of the lighting device changes by replacing the lighting device. This has the effect of making it possible to always obtain an appropriate level and video signal when the lighting device's charging capacitor starts up or when its luminous ability changes due to changes over time. Therefore, it is possible to obtain a wide dynamic range against fluctuations in the light emitting capacity of the lighting device.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention, FIG. 2(a) is a diagram showing the relationship between subject distance and aperture p in one embodiment, and FIG. Figure 3 is a diagram showing the relationship between the object distance and gain; Figure 3 is a configuration diagram of the second embodiment of the present invention; Figure 4 is a diagram showing the relationship between charging pressure and gain in the same practical example; ...Imaging device 41.2...Lighting device, 7
...JL&FA element as a means of filming, 18...
Guide number indicating circuit as indicating means, 34.35
...Voltage dividing resistor for indicating charging pressure as a means of finger, 9.
...Gain control circuit as control means.

Claims (1)

[Claims] In an imaging device used with a lighting device, an imaging device that converts a subject image into an electrical signal, an instruction device that outputs a signal according to the light emission capability of the lighting device, and a light emission capability signal instructed by the instruction device. An imaging device for use with an illumination device, comprising: control means for controlling the gain of an electrical signal obtained by the imaging means according to the image pickup means.