JPH0961913A - Camera system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the control accuracy of main emitted light quantity by starting the integration of the output of the emitted light quantity of a preliminary light emission time prescribed time after a light pre-emitting action is started when the main emitted light quantity is calculated by integrating the output of the emitted light quantity of the preliminary light emission time. SOLUTION: The preliminary light emission is attained by emitting flat light by a prescribed wave-light value extending over a long time. At this time, photometry of the light emitting luminance of a xenon tube 19 is executed by a sensor 31. Besides, the start of the integration is instructed with respect to an integration circuit 221 by a light emission control circuit 200 Then the integration for the preliminary light emission started by the integration circuit 221 based on an output from a monitor 210. The wave-height value is not stabilized at the preliminary emission start time of the flat light and it is stabilized after the prescribed time elapses. Then, the integration of the direct photometry of the tube 19 is executed by delaying time (10μS-20μS, for example). By preventing the photometry from being executed when the wave-hight value is unstable and executing the photometry and the integration after the wage- height value is stabilized in such a way, unnecessary noise is prevented from being integrated and the accuracy of the photometry output is drastically improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera system that automatically adjusts the amount of light emission so that proper exposure can be obtained when light is emitted toward a subject.

[0002]

2. Description of the Related Art Conventionally, light is emitted toward a subject,
Various camera systems have been proposed that automatically control the light emission amount so as to obtain a proper exposure. Exposure, especially so-called TTL (Th
rough The Lens) Light control is generally performed.

FIG. 10 is a schematic block diagram showing an optical system for TTL light control.

The subject image is formed on the film surface 9 by the taking lens 32 and is exposed. The main mirror 2 is retracted upward from the illustrated position during exposure. And
Before exposure, the optical path is obliquely positioned as shown in the figure, and the optical path is changed so that the object image formed on the focusing plate 3 looks like a normal positional relationship when viewed from the viewfinder.

Denoted at 23 and 24 are an imaging lens for measuring the light reflected on the film surface during exposure, and a dimming sensor.
The light emission from the flash during exposure is measured by the light control sensor 24, and based on this, the light emission amount control is performed to stop the light emission when the light emission amount reaches a predetermined value.

[0006]

However, the above-mentioned TT
Since L dimming uses diffused reflected light from the film surface,
The reflectance varies depending on the type of film, and the exposure becomes unstable. Further, since the subject indirectly and dimly measures the exposure, the exposure becomes unstable depending on the size of the subject.

For example, in Japanese Unexamined Patent Publication No. 4-331935, the flash is pre-emitted (pre-emitted) before exposure,
A method of correcting TTL dimming during main light emission has been proposed. However, this method does not show any means for solving the above problem.

Further, Japanese Patent Laid-Open No. 6-250255 proposes a method of preliminarily emitting light from a flash before exposure to control the amount of light emitted during main light emission. However, in this method, if the preliminary light emission amount is a certain value, for example, the charging pressure of the capacitor for light emission is different or the preliminary light emission amount is different from the planned value and the actual value, If the predetermined preliminary light emission is performed when the charge capacity is small, the light emission amount may be different, and sufficient light emission energy for the main light emission may not be obtained. In addition, since a predetermined amount of preliminary light emission is performed regardless of the state of the subject, when the subject is a person in a dark place, and the subject is a person, the preliminary light emission feels dazzling, and for the person taking the picture, There is the inconvenience of being unfriendly.

As a solution to this problem, the present applicant has previously stated that "preliminary light emission toward the subject is performed, and the reflected light of the subject of the preliminary light emission is measured by the first photometric means, and at the same time, the preliminary light emission is directly performed. A strobe control camera system which has a second photometric means for photometry and calculates and controls the preliminary light emission amount measured by the second photometric means according to the photometric value by the first photometric means " ing.

In this strobe control camera system, as one of the embodiments, the preliminary light emission is controlled by a flat light emission which lasts for a predetermined time at a peak value of a predetermined light emission intensity, and the first light measuring means is not an integral type but a steady light emitting means. A photometric type is used,
A configuration using an integral type for the second photometric means has been proposed.

However, in the flat light emission control circuit, the discharge arc in the flash discharge tube does not spread throughout the discharge tube in the initial stage of light emission, and the preliminary light emission intensity becomes unstable, resulting in a waveform as shown in FIG. It has been known.

Therefore, although the preliminary light emission is directly measured by the second photometric means to perform integration, the photometric output is not stable. In addition, since the integrating circuit integrates even noise, the accuracy of the integration result is poor, and as a result, there is a problem that the control of the amount of light for main emission becomes poor.

SUMMARY OF THE INVENTION An object of the present invention is to provide a camera system which can improve the accuracy of controlling the amount of main light emission.

[0014]

SUMMARY OF THE INVENTION According to the present invention, when the output of the photometric means for measuring the amount of light emitted during preliminary light emission is integrated by the integrating means to calculate the amount of main light emission, a predetermined time has elapsed since the preliminary light emission was started. The integration is started after the passage of.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A structure for realizing the object of the invention according to the present application is, as described in claim 1, a flat light emitting means for keeping light emission with a constant light emission amount for a predetermined time, and a flat light emitting means. First light emission control means for performing preliminary light emission, photometric means for measuring the amount of light emitted during preliminary light emission by this control means, integrating means for integrating the photometric output by this photometric means, and based on the integration result by this integrating means. In the camera system including the calculating means for calculating the light emission amount of the main light emission and the second light emitting control means for performing the main light emission so as to obtain the light emission amount by the calculating means, the integration by the integrating means is started. A predetermined time has elapsed after the preliminary light emission was started.

With this configuration, the integration can be performed in a region where the intensity of the flat light emission is stable by starting the integration after a predetermined time has elapsed from the start of the preliminary light emission, and controlling the light emission amount of the main light emission. Accuracy can be improved, and light emission control with little variation can be performed under optimal exposure.

A specific configuration for realizing the object of the invention according to the present application is, as described in claim 2, the arithmetic means,
Based on the subject brightness photometric value obtained by measuring the reflected light from the subject at the time of the preliminary light emission, the proper amount of main light emission for the preliminary light emission is calculated.

According to this structure, it is possible to obtain the optimum exposure by taking the subject brightness photometric value into consideration of the brightness under the flash light with respect to the brightness under the natural light.

A specific configuration for achieving the object of the invention according to the present application is such that the integrating means is
The light reflected from the subject at the time of preliminary light emission is measured.

According to this structure, not the output of the monitor provided on the light emitting device side near the xenon tube but the reflected light from the object is measured and integrated, so that the object under natural light is integrated. The amount of exposure that is insufficient with respect to the luminance can be obtained, and proper exposure can be obtained.

As a specific configuration for achieving the object of the invention according to the present application, as described in claim 4, photometry of the reflected light is performed by a photometric sensor on the camera side.

According to this structure, recent cameras perform photometry by multi-division photometry, and if the photometry output of the multi-division photometry sensor is used as the photometry output of reflected light, a plurality of areas of the multi-division photometry sensor can be used. A weighted average can be obtained, and optimum main light emission control can be performed.

As a more specific configuration for realizing the object of the invention according to the present application, as described in claim 5, the photometric means measures the light reflected from the subject during preliminary light emission.

According to this structure, the exposure is stable.

A further specific configuration for achieving the object of the invention according to the present application is that, as described in claim 6, the photometric means is for photometrically measuring the light emitting portion.

According to this structure, the proper exposure can be accurately obtained.

[0027]

Embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment] FIG. 1 is a block diagram (partially shown in a circuit diagram) showing a configuration of an electric system in a camera system of the present invention, and FIG. 2 shows a camera system of the present invention. It is a side sectional view showing a schematic structure of an optical system.

First, FIG. 2 will be described. In FIG. 2, reference numeral 1 denotes a camera body, which has optical parts, mechanical parts, electric circuits, and the like, and can store a film. Reference numeral 2 denotes a main mirror, which is driven to a photographing optical path at an oblique position or a retracted position depending on a visual recognition state and a photographing state.
Further, the main mirror 2 is a half mirror, and a small sub-mirror 25 is attached to the back surface thereof. Even when the main mirror 2 is in the oblique position, about 50% of the light quantity from the subject is reflected by the focus detection optical system described later. It is transparent so as to lead to. Reference numeral 3 denotes a focusing plate (focus plate) 3 arranged on the planned image forming planes of the taking lenses 12 to 14, and 4 denotes a pentaprism for changing the finder optical path. 5 is a finder,
The photographer can see the photographing screen by visually observing the focusing plate 3 through the window of the finder 5. 6 is an imaging lens for measuring the brightness of the subject in the shooting screen,
Reference numeral 7 is a multi-division photometric sensor that receives the light that has passed through the imaging lens 6. Further, 8 is a focal-plane type shutter, and 9 is a film as a photosensitive member.

The electrical connection between the camera body 1 and the photographing lens is a mount contact 10 which functions as an interface.
Done through. The shooting lens is the lens barrel 1.
1, first lens group 12, second lens group 13, third lens group fixed lens 14, second lens group 13 and third lens group fixed lens 14
It is configured to include each of the diaphragms 15 arranged between the two.
The first group lens 12 is a focusing lens that moves back and forth on the optical axis, and with this, the focus position of the shooting screen can be adjusted. Similarly, the second group lens 13 can also be moved back and forth on the optical axis, and the zooming of the photographing screen is performed according to this movement. The first lens group 12 is driven by a motor 16, and the diaphragm 15 is driven by a motor 17.

An accessory shoe 22 is provided on the upper surface of the accommodating portion of the pentaprism 4, and an external flash 18 can be attached to the accessory shoe 22. The external flash 18 includes a xenon tube 19, a reflection plate 20 installed on the back surface of the xenon tube 19, and a Fresnel lens 21 installed in front of the xenon tube 19. Further, one end of the glass fiber 30 is inserted into a part of the reflection plate 20, and a sensor 31 (PD1) for monitoring the light emitted from the xenon tube 19 is connected to the other end. Also, the reflection plate 2
Similarly, 0 is a sensor 32 (PD
2) is connected. The sensor 32 is used to limit the light emission current of the xenon tube 19 to perform flat light emission.

A focus detection unit 26 is installed near the bottom of the camera body 1 on the exit optical path of the sub mirror 25. The focus detection unit 26 includes the secondary imaging mirror 2
The secondary imaging lens 28, the focus detection line sensor 29, and the like are provided. This focus detection line sensor 2
The optical system is adjusted so that the secondary imaging plane comes to the detection surface of 9. The focus detection unit 26 is used to detect the focus state of the subject in the photographic screen by a known phase difference detection method by processing of an electric circuit described later, and to control the focus adjustment mechanism of the photographic lens.

Here, the function of the multi-division photometric sensor 7 will be described.

FIG. 3 shows a photometric area division diagram on the photographing screen. In the figure, reference numeral 40 represents the entire shooting screen, and reference numeral 41 represents the area division on the shooting screen of the multi-division photometric sensor 7 for photometry. In FIG. 3, the photographing screens E0 (left side), E1 (center), E2 (right side) E3 (E0, E1,
It is divided into six areas: the left half outside E2), E4 (right half outside E0, E1, E2), and E5 (outside E3 and E4). Distance measuring points P0, P1 and P2 are set at the centers of the three areas E0, E1 and E2, respectively. LC in the viewfinder at the bottom of the shooting screen 40
D24 is provided to digitally display the shutter speed and the aperture value.

Next, the configuration of FIG. 1 will be described. Note that, in FIG. 1, the same reference numerals are used for the same members as the members shown in FIG. 2, and thus duplicated description will be omitted.

An MPU (microprocessor unit) 100 operates in synchronization with a clock signal generated by an oscillator 101. E built in MPU100
The EPROM 102 is a semiconductor memory for storing film counter and other shooting information. Also, A / D
The converter 103 A / D-converts the analog signal from the focus detection circuit 105 and the multi-division photometric sensor 7, and converts the analog signal into an MP signal.
Various states are set by processing in U100.

The MPU 100 has a focus detection circuit 105,
Photometric circuit 106, shutter control circuit 107, motor control circuit 108, film running detection circuit 109, switch sense circuit 110 for detecting the operating state, LCD 24
Each of the LCD drive circuits 111 for driving the is connected.

The focus detection circuit 105 performs accumulation control and read control of the focus detection line sensor 29 according to the signal of the MPU 100, and outputs each pixel information to the MPU 100. The photometric circuit 106 outputs the output from the multi-segment photometric sensor 7 to the MPU 100 as a luminance signal of each area on the screen. The MPU 100 performs A / D conversion of the luminance signal and executes exposure adjustment for shooting.

The shutter control circuit 107 uses the MPU 100.
The shutter magnet (MG-
1) and the exposure operation for leading the shutter magnet (MG-2) of the rear curtain. Motor control circuit 108
Controls the motor 104 in accordance with a signal from the MPU 100 to perform up / down of the main mirror 2, charging of the shutter 8 and feeding control of the film 9. The film running detection circuit 109 detects whether or not one frame of the film 9 has been wound up during film feeding,
The result is sent to the MPU 100 as a signal.

Further, the focus detection line sensor 29 is connected to the focus detection circuit 105, the focus detection line sensor 29 is connected to the photometric circuit 106, and the shutter control circuit 10 is connected.
7, shutter magnets MG-1 and MG-2 are connected, and a motor control circuit 108 is connected to a motor 104 serving as a drive source for film winding. The switch sense circuit 110 is connected with switches SW1 and SW2. SW1 is a switch that is turned on by the first stroke of the release button (not shown) to start photometry and AF (autofocus), and SW2 is a switch that is turned on by the second stroke of the release button to start the exposure operation. . Then, the ON operation of SW1 and SW2 is detected by the switch sense circuit 110 and further sent to the MPU 100.

Further, the line sensor 29 includes three sets of line sensors Line-L (left), Line-C (center) and L corresponding to the three distance measuring points on the finder as described above.
It is a known CCD line sensor composed of ine-R (right). Further, the LCD drive circuit 111 is connected to the in-finder LCD 24 and the monitor LCD 42.

The lens barrel 11 is connected to the camera body having the above-mentioned configuration through the mount contact 104. The lens barrel 11 incorporates a lens control circuit 112, and signals are exchanged between the lens control circuit 112 and the MPU 100. The lens control circuit 112 includes
The motors 16 and 17 and the photodetector 35 are connected.

The photodetector 35 is used in combination with a pulse plate 36 having a disc shape and slits provided at regular intervals, and the pulse plate 36 is moved according to the movement of the first group lens 12.
Is rotated and the slits are counted to obtain position information of the first lens group 12, which is used for focus adjustment of the lens.

Further, an external flash 18 is connected to the camera body 1 via an accessory shoe 22. The external flash 18 includes a light emission control circuit 200,
Each circuit in the external flash 18 is controlled. The light emission control circuit 200 is a circuit that emits a flash light toward a subject based on a signal from the MPU 100.

Reference numeral 201 denotes a DC which boosts the voltage of the battery 215.
/ DC converter, which boosts the battery voltage according to an instruction from the light emission control circuit 200, and
A voltage of about 300V can be stored in (C1). The resistors 211 and 212 (R1, R2) are the main capacitors 2
The voltage dividing resistor is provided to monitor the voltage of 08 by the light emission control circuit 200.

The light-emission control circuit 200 can monitor the voltage of the main capacitor 208 by A / D converting the voltage divided by the voltage dividing resistor by the A / D converter 202.
The / DC converter 201 can be stopped to stop boosting, or the current charging voltage can be monitored and the result can be transmitted to the MPU 100 on the camera body 1 side. Reference numeral 203 denotes a trigger circuit, which outputs a trigger through the light emission control circuit 200 in response to an instruction from the MPU 100 during exposure to generate a high voltage in the xenon tube 19 serving as an arc tube, and the charge energy stored in the main capacitor 208 becomes xenon. Tube 1
Emission is initiated by discharging via 9.

Reference numeral 204 denotes a light emission stop circuit, which is in an ON operation state at the time of trigger output and starts light emission. Then, an off operation is performed by the output of the comparator 205 or 206 and a signal from the light emission control circuit 200, and the light emission of the xenon tube 19 is stopped. Further, when off, the xenon tube 19, the diode 213 (D1), the coil 214
A reflux loop is formed by (L1) so that the light emission amount does not immediately decrease. For this reason, the light emission stop circuit 2
04 is connected in series to the xenon tube 19, and the light emission stop circuit 2
By turning ON / OFF 04 in a short cycle continuously, flat light emission becomes possible.

Reference numeral 207 is a D / A converter connected between the light emission control circuit 200 and the comparators 205 and 206. Reference numeral 209 is a second monitor connected to the sensor 32 (PD2), and 210 is a first monitor connected to the sensor 31 (PD1). Reference numeral 221 denotes an integrating circuit, which integrates the output voltage of the monitor 210 and applies the value to the comparator 205.

Next, various operations of the external flash 18 will be individually described.

[Flat light emission] The light emission control circuit 200 is
A predetermined value is set in the D / A converter 207. At this time, since the xenon tube 19 has not yet started to emit light, the sensor 3
2 (PD2) has a small photocurrent, and the output of the monitor 209 input to the inverting input terminal of the comparator 206 is low.
Therefore, the comparator 206 outputs the “H” level output to the light emission stop circuit 204. Trigger circuit 20
When the trigger is output from 3, the xenon tube 19 starts emitting light, the peak value of the emitted light immediately increases, the photocurrent of the sensor 32 increases, the output of the monitor 209 increases, and the output of the comparator 206 increases. It goes to "L" level.

When the output of the comparator 206 becomes "L" level, the light emission stop circuit 204 operates and the xenon tube 1
Although the discharge loop of 9 is broken, the diode 213 (D
1) and the coil 214 (L1) form a return loop, and the peak value does not drop instantaneously but gradually drops. As the peak value decreases, the photocurrent of the sensor 32 decreases,
The output of the comparator 206 turns to "H" level again,
A discharge loop of the xenon tube 19 is formed, and the peak value is in the rising direction.

As described above, the output of the comparator 206 makes it possible to perform the flat emission control in which the peak value is repeatedly increased and decreased in a short cycle, and as a result, the light emission is continued at a substantially constant peak value. To end the flat flash,
This is performed by the light emission control circuit 200 directly outputting a signal to the light emission stop circuit 204. Further, the peak value of the flat light emission changes the operating point of the photocurrent of the sensor 32 by changing the voltage input to the non-inverting input terminal of the comparator 206 according to the digital value given to the D / A converter 207, It can be controlled to a desired value.

[Preliminary Light Emission and Integration Processing] Preliminary light emission is achieved by performing flat light emission at a predetermined crest value for a predetermined time. At this time, the sensor 31 (PD1) measures the light emission luminance of the xenon tube 19, and the light emission control circuit 200 instructs the integration circuit 221 to start integration. The integrating circuit 221 starts integration for preliminary light emission based on the output from the monitor 210, and is configured to integrate a value obtained by compressing the photometric amount. The light emission stop circuit 2
The output of the comparator 205 is input to 04, which is set to be ignored by the signal from the light emission control circuit 200, so that the control of the flat light emission is not disturbed. The details of the integration timing of the preliminary light emission will be described later.

When the preliminary light emission is performed for a predetermined time, the output of the integrating circuit 221 is converted by the A / D converter 202,
The digital signal is read by the light emission control circuit 200.

[Main Light Emission Control] The MPU 100 obtains an appropriate integral value of the main light emission amount based on the integrated value of the preliminary light emission and the subject reflected light luminance value during the preliminary light emission (output of the multi-division photometric sensor 7), and emits light. D / A converter 2 via control circuit 200
The proper integration value is set to 07. After that, the integration circuit 2
21 is set to the initial state, and the trigger circuit 203 starts the light emission. The brightness at the time of light emission is measured by the sensor 31, integrated by the integration circuit 221, and when the value reaches the set proper integration value, the comparator 2
The output of 05 is switched from the “H” level to the “L” level, and the light emission stop circuit 204 performs the light emission stop processing. At this time, the output of the comparator 206 is set to be ignored by the signal from the light emission control circuit 200. As described above, in the main light emission subsequent to the preliminary light emission, the light emission amount is controlled to the proper light emission amount calculated.

Next, FIG. 4 is a flowchart focusing on the processing in the MPU 100. Note that S in the figure means a step.

The MPU 100 has a release button (not shown).
ON of the switch SW1 that operates in the first stroke of is detected (S401). When SW1 is detected to be on, the switch sense circuit 110 reads the states of other operation switches (not shown), and various shooting modes such as shutter speed determination and aperture determination are set (S40).
2). Then, the focus detection operation by the phase difference detection method and the lens drive associated therewith are executed (S403).

As described with reference to FIG. 3, there are three points for focus detection on the screen, and which of the objects to focus on may be arbitrarily set by the photographer. A well-known automatic selection algorithm method based on a concept based on near point priority may be used.

Next, photometry is performed by the photometry circuit 106 (S404), and the subject brightness values of the six areas on the screen are obtained. Further, the MPU 100 determines the exposure amount from a well-known algorithm based on the subject brightness values in the six areas, and determines the shutter speed value and the aperture value according to the set shooting mode (S405). Further, it is determined whether or not the switch SW2 that operates with the second stroke of the release button is turned on (S406). If SW2 is off, the process returns to S401, and the subsequent processes are repeatedly executed.
If SW2 is on, the MPU 100 obtains the charging pressure information of the current flash capacitor 208 by transmitting information from the light emission control circuit 200. Further, information on the absolute distance of the subject from the camera is obtained by transmitting information from the lens control circuit 112, and further subject luminance information is obtained from the photometric circuit 106 (S407).

Next, the MPU 100 determines the light emission amount of preliminary light emission based on the obtained charging pressure information, absolute distance information and subject brightness information (S408). The MPU 100 issues a command to the light emission control circuit 200 so that the determined value is obtained, and controls the preliminary light emission (S409). Furthermore, MPU1
00 causes the multi-division photometric sensor 7 to perform photometry at the same time as the preliminary light emission (S410). At this time, the brightness of the subject is measured by the multi-division photometric sensor 7 immediately before the preliminary light emission is performed. This is because the difference in the photometric value immediately before the preliminary light emission is calculated based on the photometric value of the preliminary light emission to obtain the reflected light from the subject only for the light emission of the preliminary light emission. Also, when performing preliminary flash,
The light emission control circuit 200 measures the direct light of the xenon tube 19 with the sensor 31, integrates it with the integration circuit 221, and A / D-converts the integrated value at the end of preliminary light emission, and reads this. The integration timing of this preliminary light emission will be described later.

Further, the MPU 100 calculates the proper integral value of the main light emission from the integral value of the preliminary light emission, the subject reflection photometric value of the preliminary light emission, the exposure value, etc. (S411). Next, prior to the exposure operation, the main mirror 2 is raised and the sub mirror 2
It is moved out of the photographing optical path together with 5 so that the subject image can reach the film 9 without any trouble (S412). After that, the MPU 100 issues a command to the lens control circuit 112 so that the aperture value is based on the determined exposure amount, and the shutter control circuit 10 is controlled so that the shutter speed value is determined.
7 is driven (S413).

Then, the light emission control circuit 200 operates so that the main light emission is performed during the exposure in accordance with the driving of the shutter 8. This main light emission is controlled to the light emission amount obtained by the calculation of S411 (414). When the exposure operation is completed in this way, the main mirror 2 and the sub-mirror 25 that have retreated from the photographing optical path are restored, and further, the MPU 100 operates the motor control circuit 108 and the film running detection circuit 109 to operate the film 9 for one frame. When only winding up, the light emission control ends (S415).

FIG. 5 is a flow chart showing a calculation process for determining the light emission amount. Here, the calculation of the proper main light emission amount and the calculation of the preliminary light emission amount will be described.

First, in step S404 of FIG. 4, the subject brightness is measured under natural light, and the weighted average E of the six areas is calculated.
Take Vb (S501). Equation (1) shown in Equation 1 is used for this calculation. Here, W (i) is a weighting coefficient, which changes depending on the photometry mode of main light emission control and the distance measurement point of automatic focus detection. FIG. 6 shows an example of the setting of W (i). Here, when the photometry mode of the main light emission control is the weighted average photometry, the weighted average is taken at the distance measurement points for automatic focus detection. Further, when the light metering mode is partial light metering, the weighting coefficient is applied only to the area including the distance measuring points, and the weighted average is calculated with all other areas set to zero. Therefore, EVb (i) in one area becomes EVb as it is.

When the weighted average is calculated, the logarithmically compressed value EVb (i) of the brightness value of each area is expanded by taking a power of 2 and expanded to obtain a weighted average, and finally the logarithm at the base of 2. It is compressed. The value EVb obtained by the above calculation is the proper emission ratio calculation (S50
Used in 9).

Then, the processing corresponding to S402 in FIG. 4 is performed in S502, and the shooting mode such as the shutter speed priority mode and the aperture priority mode and the input of the control value are performed according to the intention of the photographer. Further, the exposure value (EVs = TV + AV) based on the shutter speed (TV) and the aperture value (AV) is determined from EVb (i) of the input shooting mode and subject brightness (S503). When determining the exposure value, the EVb described above may be used, or a known division photometric calculation algorithm may be used. Further, the subject brightness immediately before the preliminary light emission is measured, and the weighted average EVa is calculated using the equation (2) shown in Equation 2 (S504).

Here, the reason why S504 performs the same photometry and calculation as S501 will be described. The switch SW
It is possible that the photographer changes the framing under the condition that 1 is turned on or when the switch SW2 that is about to start the exposure operation is turned on, and the condition of the subject is changing. There is. In addition, the subsequent preliminary light emission needs to be performed in a short time in order to prevent energy waste and to reduce glare on the captured side,
Similarly, it is necessary to perform photometry in a short time.

Therefore, as shown in FIG.
Considering the case of shooting with a light source of a fluorescent lamp, in order to reduce the influence of flicker as much as possible, the light measurement of S501 is repeated for a relatively long time, and the average of the light measurement values is taken. On the other hand, the photometry in S504 needs to be as short as the photometry during the subsequent preliminary light emission, and the time interval between the photometry during the preliminary light emission needs to be as short as possible.
The EVa calculated in S504 is used in the main light emission proper ratio calculation in S509, which will be described later, in order to calculate the subject reflected light of only the preliminary light emission.

Next, the preliminary light emission is controlled (S50).
7). The amount of light emission at this time is determined in S505 and S506. The process of S505 corresponds to S406 of FIG. 4, and the charging voltage Vc of the capacitor 208 and the subject brightness EV
a and the subject distance information Dist are input, and the preliminary light emission amount Q is calculated by the following equation in S506 (where k is a constant such that the preliminary light emission amount Q is appropriate, F1, F2, F3).
Is a function).

Q = k × F1 (Vc) × F2 (EVb) × F3 (D _ist ) (3) FIG. 8 is an explanatory diagram of the functions F1, F2, F3. FIG. 8A shows the characteristic of the function F1 and shows that the higher the charging voltage Vc of the capacitor 208, the larger the light emission amount Q of the preliminary light emission. This is advantageous because the larger the preliminary light emission amount Q is, the larger the dynamic range of photometry of the reflected light of the object is, which is advantageous, but when the charging voltage Vc of the capacitor 208 is low, the preliminary light emission does not deprive the energy of the final light emission. be able to.

FIG. 8B shows the characteristic of the function F2.
If the subject brightness EVa under natural light is high, the reflected light from the subject due to the preliminary light emission may be buried under the natural light, so the preliminary light emission amount Q needs to be increased. On the contrary, if the subject brightness EVa under natural light is low, the photographed side suddenly emits light. Therefore, it is necessary to reduce the preliminary light emission amount Q in order to suppress the glare. Further, when the brightness is higher than a certain level and when it is low, it is difficult to increase or decrease the preliminary light emission amount Q in terms of hardware, so that it is kept constant.

FIG. 8C shows the characteristic of the function F3.
If the absolute distance of the subject to the camera is short, the photographed side feels dazzling. To avoid this, the preliminary light emission amount Q
Need to be less. On the other hand, when the distance is far, the preliminary light emission does not reach the subject and the reflected light photometry from the subject cannot be performed. Therefore, the preliminary light emission amount Q needs to be increased. When the absolute distance is close to or beyond a certain distance, the preliminary light emission amount Q is kept constant as in the case of the function F2. The increase / decrease in the amount Q of preliminary light emission is performed by changing the peak value of the flat light emission by the D / A converter 2.
It is achieved by controlling by setting (by the light emission control circuit 200) to 07.

After the processing of S507, the brightness of the reflected light from the subject at the time of preliminary light emission is measured, and the weighted average EVf is given by
It is calculated using the equation (4) shown in (S508). The timing is the position of S508 shown in FIG. Next, the light emission amount of the main light emission that is appropriate for the preliminary light emission is calculated (S509). This process is S in FIG.
This is equivalent to the processing of 411 and is calculated by the following equation (ratio r).

R = LN ₂ (2 ^EVs −2 ^EVb ) − (LN ₂ 2 ^EVf −2 ^EVa ) ... (5) The first term of the equation (5) is the exposure value (EVs) to the subject brightness measurement value. (EVb) is a power of 2 and expanded to obtain a difference, and finally logarithmically compressed at the base of 2. By this calculation, the amount of insufficient exposure amount with respect to the subject brightness under natural light is calculated. In other words, the total exposure of the subject is based on the idea that the brightness under the flash light is added to the brightness under the natural light to obtain the proper exposure.

The second term of the equation (5) is obtained by similarly expanding the subject brightness (EVa) immediately before the preliminary light emission from the subject reflected light brightness (EVf) at the time of the preliminary light emission to obtain a difference and perform compression. ing. In this calculation, the subject reflected light of only the preliminary light emission is obtained by subtracting the subject brightness under natural light. Then, since it is the operation of the compression system, the first of the equation (5)
By subtracting the second term from the term, the ratio r of how much the main light emission should be increased (or should be reduced) with respect to the preliminary light emission can be obtained in order to obtain appropriate total exposure.

On the other hand, in S510, the integrated value obtained by directly measuring the light emission of the xenon tube 19 during the preliminary light emission is "pre in
t ”. The timing relationship between S508 and S510 is as shown in FIG. The peak value is not stable at the start of light emission of flat light emission, and becomes stable after a certain period of time. Therefore, the measurement of the reflected light of the subject at S508 and the integration of the direct photometry of the xenon tube at S510 are:
A delay time (for example, 10 μS to 20 μS) is provided. As described above, when the peak value is unstable, the photometry is not performed, and after the photometry and the integration are stabilized, unnecessary noise is not integrated, and the accuracy of the photometric output can be significantly improved.

When the processing of S509 or S510 is completed, the processing for calculating the proper integral value of the main light emission is performed (S
511). This process is a process corresponding to S411 of FIG. 4, and is performed using the following equation (6) (where the variables in the equation are all compression system variables, pre int is an integral value, and r is a ratio). , TV is the shutter speed, t pre is the pre-flash duration,
c is a correction coefficient such as a dimming correction amount).

Main int = pre int + r + TV−t pre + c (6) The peak value of the preliminary light emission is added with the ratio r calculated in S 509, and the flat light emission is performed only while the shutter 8 is open. This may be performed, but since this is converted into an integral value, a factor of time of shutter speed (TV) -preliminary light emission duration (t pre) may be added. To be exact, the preliminary light emission duration time (t pre) at this time is an integration time as shown in FIG. In addition, a correction coefficient c is added as a dimming correction amount set by the photographer.

When the processing of S511 ends, the amount of main light emission is controlled based on the result obtained by the equation (6) (S5).
12). This process is a process corresponding to S414 in FIG.

As described above, in the present invention, the preliminary light emission is performed by the flat light emission, and the light emission amount of the main light emission is arithmetically controlled by the value obtained by the photometry and integration. However, the preliminary light emission is started for a predetermined time. Since photometric integration is performed after the lapse of time, stable and proper exposure can always be obtained.

[Second Embodiment] FIG. 9 is a circuit diagram showing another embodiment of the camera system according to the present invention. The light emitting system according to this embodiment has the configuration shown in FIG.
5, the monitor 210 and the integrating circuit 221 are removed. This is because the main light emission can also be made flat. In addition, the photometric circuit 106 and MPU1
An integrating circuit 120 is connected between 00. Others (detection system, drive system, display system, lens system, etc.)
Since it is the same as FIG. 1, the illustration is omitted here.

The integrating circuit 120 integrates the output of the photometric circuit 106 (the photometric integrated value of each area of the multi-division photometric sensor 7). The integrating circuit 120 is of the type that integrates while compressing the photometric output, and has a wide dynamic range. I am trying. Even if the flat light emission is stable, there is some variation in the peak value due to ripple. However, by using the integral type photometry, it is possible to perform more accurate photometry than the type in which the constant light is measured a plurality of times and the average is taken.

The operation of this embodiment will be described below with reference to the flow chart of FIG. In this embodiment, the process of direct light emission and integration of the xenon tube in S510 becomes unnecessary. Then, in S511, the calculation by the following equation is performed in place of the calculation of the proper peak value of the main light emission. In the following equation, main hight is the flat emission peak value of main emission, and pre hight is the flat emission value of preliminary emission.

Main hight = pre hight + r + c (7) As described above, the embodiment of FIG. 9 differs from the embodiment of FIG.
Since both the preliminary light emission and the main light emission are flat light emission, a factor related to time is not used for calculation, and only S50 is used.
The calculation can be performed only with the ratio r obtained in 9.

Further, the embodiment of FIG. 9 will be described with reference to FIG. Subject metering is integrated circuit 12
Although it is an integration type based on 0, in this case as well, as shown in FIG. 7B, the start of integration is delayed by a predetermined time from the start of flat light emission.

According to the embodiment of FIG. 9, stable and proper exposure is always obtained by performing photometric integration after a lapse of a predetermined time from the start of preliminary light emission.

In the description of the above embodiments, the single-lens reflex camera is taken as an example, but the present invention is not limited to this, and can be applied to a lens shutter camera and other cameras.

Correspondence between Invention and Embodiment In the above embodiments, the light emission control circuit 200 corresponds to the first and second light emission control means, and the integration circuit 221 or the integration circuit 120 corresponds to the integration means. Further, the MPU 100 corresponds to an arithmetic unit, and the multi-division photometric sensor 7 and the photometric circuit 106 correspond to a photometric unit.

[0089]

As described above, according to the present invention as set forth in claim 1, when the output of the photometric means for photometrically measuring the light emission amount during the preliminary light emission is integrated by the integrating means to calculate the main light emission amount, the preliminary light emission amount is calculated. Since the integration is started after the elapse of a predetermined time from the start of the light emission, the integration can be performed in the region where the intensity of the flat light emission is stable, and the accuracy of the light emission amount control of the main light emission can be improved. Therefore, it is possible to control light emission with little variation under the optimum exposure.

The present invention as set forth in claim 2 is a book which is appropriate for the preliminary light emission based on an object brightness photometric value obtained by measuring the reflected light from the object during the preliminary light emission by the arithmetic means. Since the light emission amount is calculated, it is possible to obtain the optimum exposure by taking the subject brightness photometric value into consideration of the brightness under the flash light with respect to the brightness under the natural light.

According to the third aspect of the present invention, the integrating means measures the light reflected from the subject during preliminary light emission. Therefore, the amount of exposure is insufficient with respect to the subject brightness under natural light. Can be obtained and proper exposure can be obtained.

According to the present invention as set forth in claim 4, since the photometry of the reflected light is performed by the photometry sensor on the camera side, it is possible to take a weighted average of a plurality of areas of the multi-division photometry sensor, which is optimum. The main emission control can be performed.

According to the fifth aspect of the present invention, since the reflected light from the subject is measured during the preliminary light emission, the exposure is stable.

According to the present invention as set forth in claim 6, since the light emitting portion is directly metered, the proper exposure can be accurately obtained.

[0095]

[Equation 1]

[0096]

[Equation 2]

[0097]

(Equation 3)

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an electric system in a camera system of the present invention.

FIG. 2 is a side sectional view showing a schematic configuration of an optical system of a camera system according to the present invention.

FIG. 3 is an explanatory diagram showing a metering area division diagram on a shooting screen.

FIG. 4 is a flowchart focusing on processing in the MPU 100.

FIG. 5 is a flowchart showing a calculation process for determining a light emission amount.

FIG. 6 is a table showing calculation contents and setting contents of weighted average.

FIG. 7 is a timing chart showing the timing of light emission and photometry in the present invention.

FIG. 8 is a timing chart showing the timing of preliminary light emission and photometry in the present invention.

FIG. 9 is a circuit diagram showing another embodiment of the camera system according to the present invention.

FIG. 10 is a schematic configuration diagram showing an optical system for TTL dimming.

FIG. 11 is a waveform diagram showing peak value characteristics in flat light emission.

[Explanation of symbols]

 1 Camera body 7 Multi-division photometric sensor 19 Xenon tube 100 MPU 106 Photometric circuit 120,221 Integration circuit 200 Light emission control circuit 202 A / D converter 203 Trigger circuit 204 Light emission stop circuit 205,206 Comparator 207 D / A converter 209, 210 monitor

Claims (6)

[Claims] 1. A flat light emission means for maintaining light emission with a constant light emission amount for a predetermined time, a first light emission control means for performing preliminary light emission by this flat light emission means, and a light emission amount for preliminary light emission by this control means. Measuring means, integrating means for integrating the photometric output by the photometric means, computing means for computing the amount of main light emission based on the result of integration by the integrating means, and the main light emission quantity by the computing means. In the camera system including a second light emission control unit that emits light, the integration unit starts integration after a predetermined time has elapsed from the start of the preliminary light emission. 2. The calculating means calculates a proper main light emission amount for the preliminary light emission based on a subject brightness photometric value obtained by measuring reflected light from a subject during the preliminary light emission. The camera system according to claim 1, which is characterized in that. 3. The integrating means measures the reflected light reflected from the subject during preliminary light emission.
Or the camera system according to 2. 4. The camera system according to claim 2, wherein the photometry of the reflected light is performed by a photometric sensor on the camera side. 5. The camera system according to claim 1, wherein the photometric unit measures the reflected light from the subject during preliminary light emission. 6. The camera system according to claim 1, wherein the photometric means measures the light emitting portion.