JP2004013171A - Electronic flash system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that flat light emission is impossible in some cases due to peripheral circumstances, the accumulation state of light emission energy, or the like. <P>SOLUTION: An electronic flash system capable of performing flat light emission has: a means for measuring a flat light emission available time; a means for writing temporal information into a storage means wherein the flat light emission available time is to be stored; and a means for starting measurements. When the start of the measurements is indicated to the measurement start means, flat light emission is performed with a prescribed intensity of light emission, and the flat light emission available time measured by the measuring means is stored into the storage means by the write means. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a flash strobe system, and more particularly to a flash strobe system capable of emitting light for a long time (so-called flat light emission) for performing flash photography at high speed in a camera using a focal plane shutter.

In conventional cameras using focal plane shutters, when using a flash light emitting device, if the shutter speed is lower than the shutter speed at which the shutter curtain is fully opened, high-speed shutter that emits flash light while the shutter curtain is fully opened and the shutter curtain is not fully opened In the region, continuous light emission is performed in the same manner as the steady light.

In general, a focal plane shutter is composed of two or more shutter curtains composed of one or a plurality of shutters. According to a required shutter opening time, a predetermined shutter is called after a first shutter curtain called a front curtain runs. After a lapse of time, a second shutter curtain called a rear curtain runs to expose a predetermined amount of light to the film. Since the shutter curtain has a finite speed, when a shutter time faster than the traveling speed of the shutter curtain itself is required, the rear curtain runs before the traveling of the front curtain is completed. Therefore, when performing flash-like light emission, shooting is performed at a shutter speed equal to or lower than the shutter speed at which the shutter is fully opened (so-called strobe tuning speed or the like), and when performing flash shooting at a shutter speed higher than the flash tuning speed, The strobe light is continuously emitted in the same manner as the steady light, and is generally called flat emission or FD emission. When performing this flat light emission, it is necessary to continue emitting light with a substantially constant light amount from the time when the front curtain runs until the time when the rear curtain runs, but the product of the light emission time and the light emission intensity is used for light emission. When the charge amount is exceeded, light emission cannot be continued until the shutter travel is completed, and a problem that a part of the screen becomes dark occurs.

問題 This problem will be described with reference to FIG. In FIG. 14, the upper waveform diagram is a strobe light emission waveform during flat light emission, and shows a case where the light emission intensity is high and a case where the light emission intensity is low. The lower diagram of this waveform shows the state in which the focal plane shutter runs on the screen, together with the upper diagram and the time axis. When the shutter release is started, the front curtain of the shutter starts running at time t0 in the figure, and at time t1, the front curtain shows its face at the top of the screen and exposure starts. On the other hand, since the strobe needs to be in a steady light emission state before time t1, light emission is started before time t1. Next, after the front curtain starts running, the shutter rear curtain starts running at time t2 after a desired shutter opening time. Since the exposure of the film ends at time t5 when the rear curtain of the shutter completely shields the rear end of the screen, the strobe light needs to be emitted with a constant light until time t5. As shown in the above figure, when the light emission intensity is low, steady light emission can be performed until the end of light emission.However, when the light emission intensity is high, the remaining charge amount of the main capacitor that stores light emission energy during exposure is low. In this case, the amount of energy remaining to maintain flat light emission becomes lower than the remaining amount, and light emission ends, resulting in an insufficient exposure amount portion as shown in FIG.

For the purpose of alerting a photographer of this problem, a prior warning is issued when the shutter opening time is longer than the time during which the flash device can continuously emit light, as described in Patent Document 1. An electronic flash device that issues a post-warning warning when light emission stops before the end of the second curtain has been proposed (conventional example 1).

In order to avoid this problem, as described in Patent Document 2, a shutter time is transmitted from the camera to the flash device side, and a flash duration that can cover the shutter time is selected by the electronic flash device. What has been proposed has been proposed (conventional example 2).

Further, in Patent Document 2, a strobe system that performs FP test light emission before FP main light emission and determines the flat light emission intensity of the main light emission. The flat light emission of the main light emission according to the charging voltage of the main capacitor and the flat light emission time. A device for correcting the intensity has been proposed (conventional example 3).
JP-A-6-73748 JP-A-5-45706 JP-A-7-120813

However, in the above-described conventional example 1, although a warning can be given to the photographer before or after the photographing, it is against the automation of the photographing, and is not suitable for easy strobe photographing.

Further, in the above conventional example 2, the flat light emission intensity set in the flash device, the corresponding flat light emission time and the guide number are transmitted to the camera, and the camera side determines whether or not flat light emission is possible based on it, and at the same time, the flash device side There has been proposed a system in which an appropriate shooting distance is displayed based on a shutter speed set by a camera. However, basically, a flashing device is mainly used to perform a shooting operation by manually emitting a fixed guide number. However, it is not possible to avoid interruption during the emission of the flat light emission with respect to the emission time and the emission intensity of the flat emission corresponding to the shutter speed and the aperture arbitrarily selected for the appropriate exposure.

Further, in the above-mentioned conventional example 3, by correcting the emission intensity of the main light emission in consideration of the charging voltage of the main capacitor, it is possible to prevent the interruption of the flat light emission even during the charging of the main capacitor. There is a problem that the entire screen is underexposed halfway.

Further, in any of the above conventional examples, when the photographing temperature condition fluctuates, the actual guide number fluctuates due to the fluctuation of the accumulated charge amount of the main capacitor, and the sensitivity fluctuation of the light emission control system depending on the light emission irradiation angle of the flash light emitting device. No proposal has been made on how to determine the emission time during which flat emission can be performed, which serves as a reference when correcting the emission intensity of flat emission and fluctuation of emission intensity.

An object of the present invention has been made in view of the above, and a first object of the present invention according to the present application is to calibrate a maximum flat light emission available time required when obtaining an emission intensity for performing stable flat light emission. It is an object of the present invention to realize a strobe system in which means can be built in a strobe system and a high-precision calibration can be easily performed by itself.

A second object of the present invention is to realize a strobe system capable of accurately and at low cost obtaining temperature information required for obtaining emission intensity for performing stable flat emission.

A configuration for realizing the object of the first invention according to the present application includes a capacitor that stores electric energy, a light emitting unit that converts the electric energy of the capacitor into light energy, and a monitor that monitors the light emission intensity of the light emitting unit. Light emission control means for adjusting light emission intensity based on an output of the monitor means, controlling light emission of the light emission means at a predetermined light emission intensity and light emission time, and calculating light emission intensity for performing uniform flat light emission Storage means for storing at least a flat light emission possible time under a predetermined light emission condition, wherein the light emission control means controls light emission of the light emission means based on time information of the storage means, Measuring means for measuring the flat light emission possible time, time information writing means for storing in the storage means, and starting measurement for performing the measurement And the light emission control means, when the measurement start means is instructed to start measurement, performs flat light emission at a predetermined light emission intensity, and writes the flat light emission available time measured by the measurement means to the writing means. Is stored in the storage means.

The instruction for measurement to the measuring means is a specific serial communication via a connection terminal with the camera.

A configuration for realizing the object of the second invention according to the present application includes a capacitor that stores electric energy, a light emitting unit that converts the electric energy of the capacitor into light energy, and a monitor unit that monitors the light emission intensity of the light emitting unit. And light emission control means for adjusting the light emission intensity based on the output of the monitor means, and correction means for correcting the light emission intensity of the light emission means by the light emission control means based on the temperature information detected by the temperature detection means. And

In this configuration, the temperature detecting means includes a voltage detecting means for detecting a forward voltage of the PN junction semiconductor driven substantially at a constant current, information corresponding to the forward voltage at a predetermined time, and an ambient temperature at a predetermined time. Storage means for storing information; information indicating a forward voltage of the voltage detection means detected by the voltage detection means at the time of temperature detection; and indicating the forward voltage in the predetermined state stored in the storage means. Calculating means for calculating the temperature at the time of detection based on a difference from the information, information indicating the ambient temperature, and information indicating a predetermined temperature change of the forward voltage of the temperature detecting element; The junction semiconductor is a diode, and the predetermined time is an adjustment time point, when a specific serial communication is received via a connection terminal with the camera, and the voltage detecting means is an A / D converter.

In the first invention, the predetermined light emission condition of the flat light emission possible time stored in the storage means is a maximum light emission intensity that can be arbitrated by the light emission control means when the capacitor is in a fully charged state. In the second invention, the storage means is a writable or rewritable storage means.

As described above, according to the first aspect of the present application, the strobe system incorporates the maximum flat light emission available time calibration means, which is required when calculating the light emission intensity for performing stable flat light emission. By doing so, it became possible to easily perform high-precision adjustment with a single strobe without using a special measuring tool.

Further, according to the second aspect of the present invention, the temperature information required for obtaining the emission intensity for performing stable flat light emission is obtained by a simple method of obtaining the temperature information based on the change in the forward voltage of the diode, while performing the adjustment at the time of adjustment. The forward voltage of the diode is measured by an A / D converter, which is a voltage detecting means, and stored in a writable storage means together with information indicating the temperature at the time of adjustment. The forward voltage detected by the means, the forward voltage at the time of adjustment stored in the storage means, the temperature at the time of adjustment, and the temperature change rate of the temperature detection element set in advance, the temperature The temperature can be accurately measured by a simple method of calculating the strobe, and it is also possible to perform strobe photography stably with respect to temperature fluctuation.

FIG. 1 is a cross-sectional view mainly illustrating an optical configuration of a camera system implemented by applying the present invention to a single-lens reflex camera.

Reference numeral # 1 denotes a camera body, in which optical components, mechanical components, electric circuits, films, and the like are stored so that a photograph can be taken. Reference numeral 2 denotes a main mirror which is inclined or retreated to a photographing optical path according to an observation state and a photographing state. When the main mirror 2 is a half mirror and is inclined, the main mirror 2 transmits about half of the light from the subject to a focus detection optical system described later. Reference numeral 3 denotes a focusing plate arranged on a predetermined image forming plane of the photographing lenses 12 to 14, 4 denotes a pentaprism for changing a finder optical path, 5 denotes a finder, and a photographer observes the focusing plate 3 from this window to obtain a photographing screen. Can be observed. Reference numerals 6 and 7 denote an imaging lens and a photometric sensor for measuring the luminance of the subject in the observation screen. The imaging lens 6 associates the focusing plate 3 and the photometric sensor 7 via a reflection optical path in the penta roof prism 4 in a conjugate manner. ing. A shutter 8 and a photosensitive member 9 are made of a silver halide film or the like. Even when the main mirror 2 is inclined, about half of the light rays from the subject are transmitted. Reference numeral 25 denotes a sub-mirror which bends a light beam from a subject downward and guides it toward the focus detection unit 26. The focus detection unit 26 includes a secondary imaging mirror 27, a secondary imaging lens 28, a focus detection line sensor 29, and the like. A secondary imaging mirror 27 and a secondary imaging lens 28 constitute a focus detection optical system, and a secondary imaging surface of the imaging optical system is connected to a focus detection line sensor 29. The focus detection unit 26 realizes an automatic focus detection device by detecting the focus state of a subject in a shooting screen by a known phase difference detection method by processing of an electric circuit described later and controlling a focus adjustment mechanism of a shooting lens. ing.

# 10 is a mount contact group serving as an interface between the camera and the lens, and 11 is a lens barrel mounted on the camera body. Reference numerals 12 to 14 denote photographing lenses. Reference numeral 12 denotes a first group lens, which can adjust a focus position on a photographing screen by moving back and forth on the optical axis. Reference numeral 13 denotes a two-group lens, which moves right and left on the optical axis to change the magnification of the photographing screen and change the focal length of the photographing lens. Reference numeral 14 denotes a third-group fixed lens. Reference numeral 15 denotes a taking lens aperture.

# 16 is the first group lens drive motor, which can automatically adjust the focus position by moving the first group lens back and forth according to the automatic focus adjustment operation. Reference numeral 17 denotes a lens aperture drive motor, which can drive the photographic lens aperture to a desired aperture diameter.

Reference numeral 18 denotes an external strobe which is attached to the camera body 1 and controls light emission according to a signal from the camera. A xenon tube 19 converts current energy into luminescence energy. Reference numerals 20 and 21 denote a reflector and a Fresnel lens, respectively, which serve to efficiently condense light emission energy toward a subject. Reference numeral 22 denotes a group of flash contacts serving as an interface between the camera body 1 and the external flash 18. Reference numeral 30 denotes a glass fiber, which guides the light emitted from the xenon tube 19 to a light receiving element 31 such as a photodiode which is a light receiving means for monitoring light emitted from the xenon tube 19. Reference numeral 31 directly measures the light amounts of the preliminary light emission and the main light emission of the strobe. Numeral 32 denotes a light receiving element such as a photodiode which is a light receiving means for monitoring the light emitted from the xenon tube 19. The light emission current of the xenon tube 19 is limited by the output of the light receiving element 32 to control the flat light emission. 20a, 20b is a light guide integrated with the reflection shade 20, and guides the light of the xenon tube to the light receiving element 32 or the fiber 30 by reflecting the light.

Next, FIG. 2 shows an electric circuit block diagram of the camera system of the present embodiment. Members corresponding to those in FIG. 1 are denoted by the same reference numerals.

(4) The camera microcomputer 100 operates internally based on a clock generated by the oscillator 101. The EEPROM 100b can store a film counter and other photographing information. The A / D converter 100c performs A / D conversion of analog signals from the focus detection circuit 105 and the photometry circuit 106, and the camera microcomputer 100 sets various states by processing the A / D converted values. The camera microcomputer 100 is connected with a focus detection circuit 105, a photometry circuit 106, a shutter control circuit 107, a motor control circuit 108, a film running detection circuit 109, a switch sense circuit 110, and a liquid crystal display (LCD) drive circuit 111. Further, a signal is transmitted to the lens control circuit 112 disposed in the photographing lens via the mount contact 10, and a signal is transmitted to the external flash via the flash contact group 22 to and from the flash microcomputer 200. . The focus detection circuit 105 performs accumulation control and readout control of the CCD line sensor 29, which is a known distance measuring element, in accordance with a signal from the camera microcomputer 100, and outputs respective pixel information to the camera microcomputer 100. The camera microcomputer 100 performs A / D conversion of this information and performs focus detection by a known phase difference detection method. The camera microcomputer 100 adjusts the focus of the lens by exchanging signals with the lens microcomputer 112 based on the focus detection information.

The photometry circuit 106 outputs the output from the photometry sensor 7 to the icon 100 as a luminance signal of the subject. The photometry circuit 106 outputs a luminance signal in both a steady state in which the flash light is not pre-emitted to the subject and a preliminary light emission state in which the pre-emission is performed, and the camera microcomputer 100 converts the luminance signal into an A / D signal. Then, calculation of an aperture value and calculation of a shutter speed for adjustment of exposure for photographing, and calculation of a strobe main light emission amount at the time of exposure are performed.

The shutter control circuit 107 performs the exposure operation by driving the shutter front curtain drive magnet MG-1 and the shutter rear curtain drive magnet MG-2 constituting the focal plane shutter 8 in accordance with a signal from the camera microcomputer 100. The motor control circuit 108 controls the motor in accordance with a signal from the camera microcomputer 100 to move up and down the main mirror 2, charge the shutter, and feed the film. The film running detection circuit 109 detects whether the film has been wound up by one frame at the time of feeding the film, and sends a signal to the camera microcomputer 100.

SW1 is a first stroke switch which is turned on by the first stroke of a release button (not shown) to start photometry and AF. SW2 is a second stroke switch which is turned on by the second stroke of the release button to start an exposure operation. SWLK is a switch for independently performing preliminary light emission, which will be described later. Signals from SW1, SW2, SWLK and other operation members of the camera (not shown) are detected by the switch sense circuit 110 and sent to the camera microcomputer 100. The liquid crystal display circuit 111 controls the display on the LCD 24 in the viewfinder and the monitor LCD 42 (not shown) in accordance with a signal from the camera microcomputer 100.

Next, the configuration of the lens will be described. The camera body and the lens are electrically connected to each other via a lens mount contact 10. The lens mount contact 10 has a power supply contact L0 of the focus drive motor 16 and the aperture drive motor 17 in the lens, a power supply contact L1 of the lens microcomputer 112, and a clock for performing known serial data communication. A contact L2 for transmitting data from the camera to the lens; a contact L4 for transmitting data from the lens to the camera; a ground contact L5 for the motor power supply for the motor; and a ground contact for the power supply for the lens microcomputer 112. L6.

The lens microcomputer 112 is connected to the camera microcomputer 100 via the lens mount contacts 10 and operates the first lens drive motor 16 and the lens aperture motor 17 to control the focus of the lens and the aperture. Reference numerals 35 and 36 denote a photodetector and a pulse plate. The lens microcomputer 112 can obtain position information of the first group lens by counting the number of pulses, and can adjust the focus of the lens. Next, the configuration of the strobe will be described with reference to the electric circuit block diagram shown in FIG.

(4) The flash microcomputer 200 is a circuit that controls a flash in accordance with a signal from the camera microcomputer 100, and controls a light emission amount, a flat light emission intensity and a light emission time, a light emission irradiation angle, and the like. Reference numeral 201 denotes a DC / DC converter, which boosts the battery voltage to several hundred volts according to an instruction from the strobe control circuit 200, and charges the main capacitor C1. R1 / R2 is a voltage dividing resistor provided for the flash microcomputer 200 to monitor the voltage of the main capacitor C1. The strobe microcomputer 200 indirectly monitors the voltage of the main capacitor C1 by A / D converting the divided voltage by an A / D converter built in the strobe microcomputer, and controls the operation of the DC / DC converter 201. By controlling, the voltage of the main capacitor C1 is controlled to a predetermined voltage.

Reference numeral 202 denotes a trigger circuit which outputs a trigger signal via the flash microcomputer 200 according to an instruction of the camera microcomputer 100 when the flash is fired, and discharges the xenon tube 19 by applying a high voltage of several thousand V to the trigger electrode of the xenon tube 19. And the charge energy stored in the main capacitor C1 is emitted as light energy through the xenon tube 19. Reference numeral 203 denotes a light emission control circuit using a switching element such as an IGBT. The light emission control circuit 203 is turned on when a trigger voltage is applied at the time of light emission, the current flows through the xenon tube 19, and is cut off when light emission is stopped. To stop light emission. 204 and 205 are comparators, 204 is used for stopping light emission during flash light emission described later, and the comparator 205 is used for emission intensity control during flat light emission described later. Reference numeral 206 denotes a data selector, which selects an input from the terminals D0 to D2 of the data selector 206 according to the selection signals SEL1 and SEL2 from the flash microcomputer 200, and outputs the input to the terminal Y.

# 207 is a flash light emission control monitor circuit, which logarithmically compresses and amplifies the output of the light receiving element 31. An integration circuit 208 integrates the output of 207. Reference numeral 209 denotes a flat light emission control monitor circuit that amplifies the output of the light receiving element 32. Reference numeral 210 denotes an EEPROM as storage means for storing the flat light emission time and the like. 211 is a known motor drive circuit, 212 is a zoom drive motor, 213 is a pinion gear, 214 is a rack gear, 215 s is a zoom position detection encoder for detecting the position of the reflection shade 20, and 216 is an LED indicating that light emission is possible. Diodes 217 and 218 are junction semiconductors for temperature detection, 219 is a resistor, and 220 is a constant voltage power supply.

Next, each terminal of the flash microcomputer 200 will be described. CK is an input terminal for a synchronous clock for performing serial communication with the camera, D1 is an input terminal for serial communication data, D0 is a data output terminal for serial communication, and CHG is an output terminal for transmitting a strobe light emission enable state to the camera as current. X is an input terminal of a light emission signal from the camera, and ECK is a communication clock for performing serial communication with a writable storage device such as an EEPROM or a flash ROM, which is a storage device connected to the outside of the flash microcomputer 200. EDI is a serial data input terminal from the storage means, ED0 is a serial data output terminal to the storage means, and SELE is an enable terminal for permitting communication with the storage means. , Hi are disabled.

In the present embodiment, the storage means is set outside the flash microcomputer, but it goes without saying that the same is true even if the storage means is built in the flash microcomputer.

POW is an input terminal for inputting the state of the power switch 215p, OFF is an output terminal for turning off the strobe when connected to the power switch 215, and ON is for turning on the strobe when connected to the power switch 215. The POW terminal is connected to the ON terminal in the power ON state, the ON terminal is in the high impedance state, the OFF terminal is in the Lo state, and vice versa in the power OFF state. The LED is a display output terminal that indicates that light emission is possible.

STOP is an input terminal of a light emission stop signal. SEL0 and SEL1 are output terminals for instructing the input selection of the data selector 206. When the combination of SEL0 and SEL1 is (SEL1, SEL0) = (0, 0), the D0 terminal is connected to the Y terminal. Similarly, the terminal D1 is selected at (0, 1), and the terminal D2 is selected at (1, 0).

# DA0 is a D / A output terminal built in the flash microcomputer 200, and outputs a comparator level of the comparators 204 and 205 as an analog voltage. TRIG is a trigger signal output terminal for instructing the trigger circuit 202 to emit light. CNT is an output terminal for controlling the start / stop of oscillation of the DC / DC converter 201. For the sake of explanation, charging is started at Hi and stopped at Lo. INT is a terminal for controlling the start / inhibition of the integration of the integration circuit 208. Hi indicates that the integration is prohibited and Lo indicates that the integration is permitted.

AD0, AD1, and AD2 are A / D input terminals, which convert input voltages into digital data so that they can be processed inside the microcomputer 200. AD0 monitors the voltage of the main capacitor C1. , AD1 monitor the integrated output voltage of the integration circuit 208, and AD2 detects the forward voltage of the diode 217 for temperature detection and reads it as the temperature. Since the temperature coefficient of the forward voltage VF of the diode is approximately -2 mV / deg, the ambient temperature can be measured by driving the diode at a substantially constant current and measuring VF. In this embodiment, the reading accuracy is improved by doubling the temperature coefficient by connecting two diodes in series.

Z0 and Z1 are control output terminals for controlling a motor control circuit 211 for driving the zoom drive motor 212, ZM0, ZM1 and ZM2 are input terminals for inputting signals of a zoom position detection encoder 215s, and COM0 is a zoom position detection encoder 215s Is a common terminal that draws current corresponding to the ground level of

Next, the basic operation of the strobe in the present embodiment will be described with reference to FIG.

FIG. 4 is a flowchart showing a basic operation program built in the flash microcomputer 200.

[Step 101 (# 101)]: When the power switch 215p is turned on, the flash microcomputer 200 wakes up and performs initial setting of each port of the flash microcomputer 200.

[Step 102 (# 102)]: A / D conversion is performed on the divided voltage of the main capacitor C1 input to the AD0 port.

[Step 103 (# 103)]: If the voltage of the main capacitor C1 is equal to or higher than a predetermined voltage at which light emission is possible, the process branches to step 104;

[Step 104 (# 104)]: Since light emission is possible, a predetermined current is drawn from the CHG terminal to notify the camera that light emission is possible. In addition, the LED terminal is set to Hi, and the LED 216 emits light to indicate that light emission is possible.

[Step 105 (# 105)]: Since the light emission is not possible, the CHG terminal is set to non-active, and the current is cut off. Also, the LED terminal is set to Lo, the LED 216 is turned off, and light emission is displayed.

[Step 106 (# 106)]: If the voltage of the main capacitor C1 read in the next step 102 is equal to or higher than the predetermined upper limit voltage, the flow branches to step 107;

[Step 107 (# 107)]: Set the CNT terminal to Lo and stop charging.

[Step 108 (# 108)]: The CNT terminal is set to Hi and charging is started.

[Step 109 (# 109)]: The current zoom position is read from the ZM0 to ZM2 terminals. If the camera is at the predetermined zoom position specified by the camera, the process branches to step 110, and if the camera is not at the zoom position, zoom drive is performed. The process branches to step 111.

[Step 110 (# 110)]: If the camera is at a predetermined zoom position and is currently driving a zoom, a predetermined signal is sent to the motor drive circuit 211 via the Z0 and Z1 terminals to stop the zoom drive motor 212. Output.

[Step 111 (# 111)]: If the zoom position is not at the predetermined zoom position, the current position is compared with the set zoom position, the driving direction is determined, and the motor driving circuit 211 is driven by the motor driving circuit 211 in order to drive the zoom driving motor 212. Is output via the Z0 and Z1 terminals.

[Step 112 (# 112)]: If the POW terminal, which is the power switch detection terminal, is Hi, it is in the power-on state, so it returns to Step 102 and repeats a series of processing. If it is Lo, it branches to Step 113, Perform power-off processing.

[Step 113 (# 113)]: A series of power-off processing such as charging stop, zoom driving stop, and the like are performed, the OFF terminal is set to a high impedance state, the ON terminal is set to a Lo state, and the POW terminal is turned off. The flash microcomputer 200 is set in the STOP state by setting an interruptable state.

[Step 114 (# 114)]: When the power switch is turned on again, the POW terminal becomes Lo. Therefore, the STOP state of the strobe microcomputer 200 is released, initialization of each port is performed, and the ON terminal is turned on. Is set to a high impedance state, the OFF terminal is set to a Lo state, and the process returns to step 102 to repeat a series of processing.

Next, the light emitting operation will be described.
<Pre (preliminary) light emission>
When the strobe is ready to emit light during the above-described basic operation of the strobe, the camera microcomputer 100 detects that the strobe can emit light. When performing pre-flash, the pre-flash is emitted to the strobe via the communication terminal. The intensity and the emission time are communicated, and pre-emission is instructed.

(4) The flash microcomputer 200 sets a predetermined voltage to DA0 according to a predetermined light emission intensity signal instructed by the camera body. Next, Lo and Hi are output to SEL1 and SEL0, and the input D1 is selected. At this time, since the xenon tube 19 has not yet emitted light, the photocurrent of the light receiving element 32 hardly flows, the output of the monitor circuit 209 input to the inverting input terminal of the comparator 205 does not occur, and the output of the comparator 205 is Hi. Therefore, the light emission control circuit 203 is turned on. Next, when a trigger signal is output from the TRIG terminal, the trigger circuit 202 generates a high voltage, excites the xenon tube 19, and starts emitting light.

On the other hand, the strobe microcomputer 200 instructs the integration circuit 208 to start integration after a predetermined time from the generation of the trigger, and the integration circuit 208 outputs the output of the monitor circuit 207, that is, the logarithmically compressed photoelectric output of the light receiving element 31 for light quantity integration. Is started, and at the same time, a timer for counting a predetermined time is started. The reason why the start of integration is delayed from the occurrence of the trigger is to prevent the integration circuit from integrating noise other than the optical signal due to the noise due to the occurrence of the trigger, and at the same time, the substantial light emission is reduced by 10% after the occurrence of the trigger. This is because there is a delay of several μsec.

When the pre-emission starts, the photocurrent of the light-emitting element 32 for controlling the emission intensity of the flat emission increases, the output of the monitor circuit 209 increases, and the predetermined comparator voltage set to the non-inverting input of the comparator 205 When it becomes higher, the output of the comparator 205 is inverted to Lo, the light emission control circuit 203 cuts off the light emission current of the xenon tube 19, and a discharge loop is formed. However, a return loop is formed by the diode D1 and the coil L1, and light emission is performed. The current gradually decreases after the overshoot due to the delay of the circuit stops. Since the light emission intensity decreases as the light emission current decreases, the photocurrent of the light receiving element 32 decreases, the output of the monitor circuit 209 decreases, and when the output drops below a predetermined comparator level, the output of the comparator 205 again becomes Hi. The emission control circuit 203 conducts again to form a discharge loop of the xenon tube 19, and the emission current increases and the emission intensity increases. As described above, the comparator 205 repeatedly increases and decreases the light emission intensity in a short cycle around the predetermined comparator voltage set to DA0, and consequently, the flat light emission in which the light emission is continued at the desired substantially constant light emission intensity Can be controlled.

When the above-mentioned light emission time timer is counted and a predetermined pre-light emission time has elapsed, the flash microcomputer 200 sets the SEL1 and SEL0 terminals to Lo and Lo, and the input of the data selector 206 is D0, that is, the Lo level input is selected. The level is forcibly changed to the Lo level, and the light emission control circuit 203 interrupts the discharge loop of the xenon tube 19 and ends the light emission. At the end of light emission, the flash microcomputer 200 reads the output of the integration circuit 208 that has integrated the pre-emission from the A / D input terminal AD1, performs A / D conversion, and reads the integrated value, that is, the light emission amount at the time of pre-emission as a digital value. Can do things.

Next, the setting of the emission intensity at the time of the pre-emission by the flash will be described with reference to FIG. FIG. 4 is a flowchart showing the light emission operation setting built in the flash microcomputer 200. Since the emission intensity of the pre-emission is basically based on the emission amount of 1 / n of the charge of the main capacitor at the time of the emission of the pre-emission, the charge Qp used for the pre-emission is

　一方コンデンサに蓄えられるエネルギーＵは

On the other hand, the energy U stored in the capacitor is

　従ってプリ発光時のエネルギーは

Therefore, the energy during pre-emission is

　であり、電圧の自乗を係数として補正するとともに、容量Ｃは温度により変動するので、温度に関しても補正する必要がある。

It is necessary to correct the square of the voltage as a coefficient and to correct the temperature because the capacitance C varies depending on the temperature.

Hereinafter, this correction method will be described with reference to FIG.

[Step 201 (# 201)]: A light emission instruction value from the camera is received.

[Step 202 (# 202)]: Read the divided voltage of the main capacitor C1 from the AD0 terminal.

[Step 203 (# 203)]: The correction amount K (V) is obtained from the read main control voltage by the APEX value using the following equation.

　また上記演算は小型のマイクロコンピュータでは負荷が重いので、演算の代わりに、メインコン電圧に応じた補正値をストロボマイコン２００内のＲＯＭテーブルに持つ方法も好ましい。このテーブル化した場合のデータ例を表１にしめす。

In addition, since the above calculation is heavy for a small microcomputer, it is preferable to use a method in which a correction value corresponding to the main controller voltage is stored in a ROM table in the flash microcomputer 200 instead of the calculation. Table 1 shows an example of data in this table.

　［ステップ２０４（＃２０４）］：カメラから受信した発光強度データにステップ２０３で求めた電圧補正値を加算する。

[Step 204 (# 204)]: The voltage correction value obtained in Step 203 is added to the emission intensity data received from the camera.

[Step 205 (# 205)]: To correct the sensitivity of the sensor 32 depending on the zoom position, the current zoom position is read from the ZM0 to ZM2 terminals.

[Step 206 (# 206)]: A sensor sensitivity correction value corresponding to the zoom position is read from a ROM (not shown) in the flash microcomputer 200. This correction value is caused by the fact that the distance between the sensor 32 and the Fresnel lens 21 fluctuates by zooming, so that the light reflected by the Fresnel lens increases on the wide-angle side where the distance from the Fresnel lens is short, and the light is sneak directly from the Fresnel lens other than the light guide 20a. On the telephoto side, which is affected by light and has a long distance from the Fresnel lens, the correction is for correcting the fact that the sensitivity of the light receiving system fluctuates due to the reduced influence of the reflected light. Table 2 shows an example of the correction.

　［ステップ２０７（＃２０７）］：ステップ２０４で求めた発光強度データに対して電圧補正値を加算したデータにステップ２０６で求めたズーム位置感度補正を加算する。

[Step 207 (# 207)]: The zoom position sensitivity correction obtained in Step 206 is added to the data obtained by adding the voltage correction value to the emission intensity data obtained in Step 204.

[Step 208 (# 208)]: The temperature is detected from the VF of the diodes 217 and 218 read from the AD2 terminal. This calculation step is shown in the following 0), 1) and 2). Step 0 is a procedure performed at the time of flash adjustment.

0): When the strobe microcomputer 200 receives a predetermined temperature calibration command and the temperature at the time of adjustment from the serial communication terminal at the time of strobe adjustment, the strobe microcomputer 200 sets the forward voltage of the temperature detection diode at the time of adjustment = VFadj to AD2. The data is read out from the terminal and is written in the writable storage means 210 together with the received temperature = Tadj.

# 1): At the time of execution of step 208, the current forward voltage VFpr of the current temperature detecting diodes 217 and 218 is read.

2): The current temperature Tpr is calculated by the following equation.

　なおΔＶＦは前述ストロボマイコン２００内のＲＯＭに固定記憶されていてもよいし、書き込み可能な記憶手段２１０に記憶してもよい。

Note that ΔVF may be fixedly stored in the ROM in the flash microcomputer 200, or may be stored in the writable storage unit 210.

[Step 209 (# 209)]: A temperature correction value is read from a ROM (not shown) in the flash microcomputer 200 based on the current temperature obtained in Step 208.

Table 3 shows an example of the correction.

　［ステップ２１０（＃２１０）］：ステップ２０７で求めた発光強度データに電圧補正値を加算したデータにズーム位置感度補正を加算したデータにステップ２０８で求めた温度補正データを加算し、プリ発光時の発光強度＝ＦＰＨ＿ＰＲＥとする。なお、このＦＰＨ＿ＰＲＥは後述のフラットメイン発光で用いるので、ストロボマイコン２００内の不図示のＲＡＭに保存しておく。

[Step 210 (# 210)]: The temperature correction data obtained in Step 208 is added to the data obtained by adding the voltage correction value to the emission intensity data obtained in Step 207 and the data obtained by adding the zoom position sensitivity correction. It is assumed that the luminous intensity of FPH_PRE is Since this FPH_PRE is used for flat main light emission described later, it is stored in a RAM (not shown) in the flash microcomputer 200.

[Step 211 (# 211)]: The light emission intensity obtained in the above steps almost accurately indicates 1 / n of the current charging energy of the main capacitor, and the control voltage corresponding to the light emission intensity obtained by this calculation. Is set to the DA0 terminal. Note that the monitor circuit 209, which is a control system of flat light emission, has a linear system configuration (input versus output is a predetermined coefficient corresponding to the gain of the system) in order to increase the response speed of the entire control system. To a control voltage in accordance with

　なお、この変換値はストロボマイコン２００内の不図示のＲＯＭに記憶しておき、発光強度に応じてＤＡ０設定値を読み出してもよい。

The converted value may be stored in a ROM (not shown) in the flash microcomputer 200, and the DA0 set value may be read according to the light emission intensity.

Table 4 shows an example of the conversion.

　以上のステップにより設定された発光強度をもとに前述のプリ発光は行われる。このプリ発光を行っている間、カメラ側では測光素子７の出力を測光回路１０６が読み出し、その出力をＡ／Ｄ変換器１００ｃに取り込み、リアルタイムに測光を行う事により、被写体からの反射光を測光し、後述するストロボ撮影時のストロボ発光量を決定する。
＜メイン（本）発光制御＞
　次にメイン発光制御を説明する。

The pre-emission is performed based on the emission intensity set by the above steps. During this pre-emission, on the camera side, the output of the photometric element 7 is read by the photometric circuit 106, the output is taken into the A / D converter 100c, and photometry is performed in real time, so that the reflected light from the subject can be measured. Photometry is performed to determine the amount of flash emission at the time of flash shooting, which will be described later.
<Main (main) light emission control>
Next, the main light emission control will be described.

タ イ ミ ン グ The timing from the pre-flash to the main flash has two modes.

In the first mode, when the second stroke switch SW2, which is a shutter release switch, is turned on, a pre-emission is performed, and the camera measures the reflected light of the subject due to the pre-emission from the output of the photometry element 7 to obtain a proper flash exposure amount. At the end of the pre-emission, the aperture 15 is driven to set an appropriate aperture, and the mirrors 2 and 25 are flipped up to retract from the optical path, and at the end of the mirror driving, the shutter 8 is opened to perform main flash emission. .

In the second mode, when the pre-emission switch is operated, the above-described pre-emission is performed, and the camera obtains, from the output of the photometry element 7, an appropriate exposure amount of the strobe by measuring the reflected light of the subject by the pre-emission. When the stroke switch SW2 is turned on, the diaphragm 15 is driven to set an appropriate diaphragm, and the mirrors 2 and 25 are flipped up to evacuate from the optical path. Emit light. This second mode is called a FE lock mode, and is known in the art by first placing a subject in the center of a photometry area to perform pre-emission, and then pointing a camera to an area to be photographed and releasing a shutter. As in the case of the AE lock, the proper exposure can be performed by the strobe even when the subject is not at the center of the shooting area during the flash shooting.

Next, the main light emitting operation will be described in order.

In the main light emission sequence after the second stroke switch SW2, which is a shutter release switch, is turned on, the camera microcomputer 100 determines the luminance of reflected light from the photometric sensor 7 during pre-emission, the luminance of external light during natural light, and Determines the shutter speed and aperture from the exposure mode, film sensitivity, and reflected light from the subject at the time of pre-flash, and if the shutter speed is faster than the above-mentioned flash tuning speed, determines the appropriate emission intensity of the main flash in flat flash. Then, the flash microcomputer 200 is instructed of the light emission intensity and the light emission time by serial communication via the communication lines S0 to S2. The light emission time is obtained by adding the shutter opening time corresponding to the shutter speed to the shutter curtain speed, with some allowance for mechanical variations until the shutter curtain actually appears on the screen. It is. If the shutter speed is equal to or lower than the flash tuning speed, the flash unit 200 determines an appropriate amount of main light emission in flash light emission, and instructs the flash microcomputer 200 of the light emission intensity.

発 光 These light emission intensities in the main light emission are defined as relative information with respect to the light emission intensity in the preliminary light emission.

Next, main light emission control during flat light emission will be described.
<Flat main light emission control>
The stroboscopic microcomputer 200 obtains an appropriate light emission intensity of the main light emission amount based on the received light emission intensity corresponding to the received main light emission amount, and sets a predetermined voltage for the appropriate light emission intensity to the DA0 output. The method for setting the appropriate emission intensity will be described later.

Next, Lo and Hi are output to SEL1 and SEL0, and the input D1 is selected. At this time, since the xenon tube 19 has not yet emitted light, the photocurrent of the light receiving element 32 hardly flows, the output of the monitor circuit 209 input to the inverting input terminal of the comparator 205 does not occur, and the output of the comparator 205 is Hi. Therefore, the light emission control circuit 203 is turned on. Next, when a trigger signal is output from the TRIG terminal, the trigger circuit 202 generates a high voltage, excites the xenon tube 19, and starts emitting light. Further, the stroboscopic microcomputer 200 activates a timer for counting a time instructed by the camera when the light emission starts. Note that the emission intensity control of the flat emission is the same as the pre-emission control, and a description thereof will be omitted.

After counting the above-described light emission time timer, and after a predetermined light emission time has elapsed, the flash microcomputer 200 sets the SEL1 and SEL0 terminals to Lo and Lo, and the input of the data selector 206 is D0, that is, the Lo level input is selected. The output is forced to the Lo level, the light emission control circuit 203 interrupts the discharge loop of the xenon tube 19, and the light emission ends.

Next, a method of setting an appropriate light emission intensity during flat main light emission control, which is an important point of the present invention, will be described. The maximum light emission intensity of the flat light emission according to the present embodiment is electrically provided to the non-inverting input terminal of the comparator 205 and is determined by the maximum voltage of the DA0 terminal of the flash microcomputer 200. Then, the gain of the monitor circuit 209 is adjusted so that a predetermined luminance is obtained when a maximum voltage is applied to the non-inverting input terminal of the comparator 205. When the pre-emission is performed, it is desirable to set the light intensity so that the photometry system of the camera can sufficiently measure the reflected light from the strobe, that is, the light emission intensity at which a BV of about 10 is obtained. On the other hand, the longest flat light emission time determined from the curtain speed of the focal plane shutter is 6 msec * 2 + the margin (1 msec) = 13 msec when the curtain speed of the 35 mm vertical running shutter is 6 msec / 24 mm. Become.

In the present embodiment, when the light emission intensity is realized, the light emission intensity is set so that a flat light emission time of approximately 16 msec can be realized if there is no loss in the light emission control circuit 203. However, when a switching element such as an IGBT used in the light emission control circuit 203 is used for flat light emission having a switching speed of several tens of KHz, a response speed of a control circuit system and a drive circuit for driving a gate such as an IGBT are used. Of about 20% due to the power loss in the active region caused by the finite drive time of the gate capacitance due to the drive capability of the IGBT, and the power loss due to the ON resistance of the switching circuit itself such as an IGBT. Is generated, and the above-mentioned flat light emission possible time is about 13 msec. This is a balanced state, but on the other hand you can't afford it at all. That is, the maximum light emission time also varies due to the variation in the capacity of the main capacitor C1, the maximum light emission time also varies due to the variation in the adjustment of the maximum light emission intensity, and further longer time is required for a camera with a slow curtain speed. In some cases, there is a problem that light emission stops at the end of flat light emission due to the necessity of light emission time. As a method for solving these problems, there can be conceived a method of 1) lowering the maximum light emission intensity so as to allow a sufficient time for the light emission, and 2) adjusting the light emission time to obtain a predetermined maximum light emission time. However, in 1), since the preliminary light emission intensity is low, there is a problem that the photometric accuracy of a bright outdoors or a distant subject is reduced. In 2), as described above, since the sensitivity of the sensor 32 for controlling the flat light emission at each zoom position fluctuates, it is difficult to achieve a balance and the adjustment is complicated.

In the present embodiment, in order to solve the above problem with a system having complicated adjustments and to solve the problem in a well-balanced manner, a storage means capable of writing a maximum light emission time capable of flat light emission at the maximum light emission intensity at each zoom position at the time of adjustment is used. The maximum emission time at which uniform flat emission is possible is calculated based on the emission intensity during main emission, the main capacitor voltage at the time of emission, and the stored maximum emission time described above. Only when the light emission time is shorter than the required light emission time, that is, when the flat light emission is expected to stop during the light emission, the correction is made to the maximum light emission intensity obtained from the current light emission energy. As a result, highly efficient flat light emission can be easily realized.

Next, a method of setting the luminous intensity during the above-described flat main light emission will be described in detail with reference to FIG. FIG. 6 is a flowchart showing a method for setting an appropriate light emission intensity at the time of main light emission built in the flash microcomputer 200.

[Step 401 (# 401)]: A light emission instruction value = FPH_MAIN from the camera at the time of main light emission is received.

[Step 402 (# 402)]: The light emission time at the time of main light emission from the camera = FPTIME_MAIN is received.

[Step 403 (# 403)]: Read out the calculated light emission intensity = FPH_PRE at the time of the pre-emission described in step 210 of FIG.

[Step 404 (# 404)]: The difference between the emission intensity at the time of the main emission received at Step 401 and the emission intensity data at the time of the pre-emission read at Step 403 is obtained to obtain the emission intensity at the time of the main emission. .

[Step 405 (# 405)]: The current zoom position is read from the ZM0 to ZM2 terminals in order to obtain the normal light emission possible time.

[Step 406 (# 406)]: The maximum light emission time corresponding to the zoom position stored at the time of adjustment is read out from the writable storage means 210.

Here, the maximum light emission time stored at the time of adjustment will be described.

FIG. 7 shows the maximum light emission time Tfpmax at which the FP light emission at the full charge state and the maximum light emission intensity can be maintained during the adjustment. By measuring this Tfpmax for each zoom position and writing it in a writable storage means, the maximum light emission time during which flat light emission is possible due to individual variations can be easily corrected by calculation as described below. . Note that, as described above, the light receiving element 32 for controlling the flat light emission intensity is affected by the reflected light from the Fresnel lens 21 depending on the zoom position, and the actual sensitivity is stored for each zoom position. Because it fluctuates.

[Step 407 (# 407)]: Read the divided voltage of the main capacitor C1 from the AD0 terminal.

[Step 408 (# 408)]: The longest light emission at the current main capacitor voltage based on the maximum light emission time obtained in Step 406, the light emission intensity obtained in Step 404, and the main capacitor C1 voltage obtained in Step 407. Time is determined by the following steps.

　［ステップ４０９（＃４０９）］：ステップ４０７で求めた現在の設定値での最長発光時間ＭＡＸＴＩＭＥと、カメラより指示された発光時間を比較し、最長発光時間ＭＡＸＴＩＭＥの方が長い場合は発光強度の変更をせずにステップ４１１に分岐し、最長発光時間ＭＡＸＴＩＭＥの方が短い場合はステップ４１０に分岐する。

[Step 409 (# 409)]: The maximum emission time MAXTIME at the current setting value obtained in Step 407 is compared with the emission time specified by the camera, and if the maximum emission time MAXTIME is longer, the emission intensity is reduced. The process branches to step 411 without any change. If the maximum light emission time MAXTIME is shorter, the process branches to step 410.

[Step 410 (# 410)]: In the following steps, the emission intensity is corrected to a level that can maintain flat emission without interruption over the entire emission time range.

　［ステップ４１１（＃４１１）］：前述ステップ２１１と同じ方法で、ＤＡ０設定電圧を設定する。
＜閃光メイン発光制御＞
　次に閃光メイン発光制御に関して説明する。

[Step 411 (# 411)]: The DA0 set voltage is set by the same method as in Step 211 described above.
<Flash main light emission control>
Next, the flash main light emission control will be described.

(4) The flash microcomputer 200 obtains a proper light emission intensity of the main light emission amount based on the received light emission intensity corresponding to the received main light emission amount, and sets a predetermined voltage for the appropriate light emission intensity to the DA0 output. This predetermined voltage is obtained by adding a voltage corresponding to the relative light emission amount to the integrated output read from AD1 at the end of the above-mentioned pre-light emission.

Next, Hi and Lo are output to SEL1 and SEL0, and the input D2 is selected. At this time, since the integration circuit is in the operation prohibited state, the output of the integration circuit 208 input to the inverting input terminal of the comparator 204 does not occur, and the output of the comparator 204 is Hi, so that the light emission control circuit 203 is in the conductive state. Next, when a trigger signal is output from the TRIG terminal, the trigger circuit 202 generates a high voltage, excites the xenon tube 19, and starts emitting light. In addition, the strobe microcomputer 200 sets the integration start terminal INT to the Lo level ten and several seconds after the start of the actual light emission while the trigger noise caused by the trigger application is settled, and the integration circuit 208 outputs the output from the sensor 31 to the monitor circuit 207. Integrate via When the integrated output reaches a predetermined voltage set by DA0, the comparator 204 is inverted, the light emission control circuit 203 is turned off through the data selector 206, and the light emission stops. On the other hand, the flash microcomputer 200 monitors the STOP terminal, and when the STOP terminal is inverted and the light emission stops, the SEL1 and SEL0 terminals are set to Lo and Lo to set the forced light emission prohibition state, and the integration start terminal is inverted to perform integration. This ends the light emission processing.

As described above, according to the first embodiment, the monitoring unit that monitors the emission intensity, the emission intensity is arbitrated based on the output of the monitoring unit, and the emission is controlled by the predetermined emission intensity and the emission time. A flash unit having a flash control unit which performs flash emission under a predetermined flash condition. The storage unit stores data stored in the flash unit, the specified flash intensity and the flash time, and the current status of the flash system. And a determining means for determining whether or not uniform flat light emission is possible, and when the determining means determines that uniform flat light emission intensity cannot be obtained, the light emission intensity is reduced to uniform flat light emission. Equipped with emission intensity correction means that corrects the emission intensity to the maximum possible, enabling high-efficiency, uniform emission intensity and flat emission regardless of temperature fluctuations and charging voltage. It is carried out that flash photography has become possible.

In addition, while the temperature information required for obtaining the light emission intensity for performing stable flat light emission is obtained by the fluctuation of the forward voltage of the diode, the forward voltage of the diode is adjusted by the voltage detection means at the time of adjustment. Measured by a certain A / D converter and stored in a writable storage unit together with information indicating the temperature at the time of adjustment, and at the time of temperature measurement, the forward voltage detected by the same voltage detection unit as that at the time of the adjustment, A simple method of calculating the temperature based on the forward voltage at the time of adjustment, the temperature at the time of adjustment, and the temperature change rate of the temperature detection element set in advance, which is stored in the storage means, is accurate. Temperature can be measured, and strobe photography can be performed stably with respect to temperature fluctuations.

(Second embodiment)
FIG. 8 is an electric circuit block diagram of a flash unit of the camera system according to the second embodiment. Since the configuration of the hardware is the same as that of the first embodiment, the description is omitted. In the second embodiment, writing of the maximum light emission time described in the first embodiment can be performed by a strobe alone. This is to make it possible to easily measure the flat light emission time with an oscilloscope and to easily adjust even a service window which does not have a tool for writing to the EEPROM. This adjustment is started only when a specific service command is received via the communication terminal group 22 of the strobe, so that accurate adjustment can be easily performed without disassembling the strobe.

FIG. 9 is a flowchart showing a program incorporated in the flash microcomputer 200 for writing the maximum light emission time. This program is started by receiving a specific command from the communication terminal with the camera. Hereinafter, description will be given based on the same flow.

[Step 501 (# 501)]: Drive to the first zoom position to be adjusted. This driving method is the same as the step described with reference to FIG.

[Step 502 (# 502)]: AD-convert the divided voltage of the main capacitor C1 input to the AD0 port.

[Step 503 (# 503)]: If the voltage of the main capacitor C1 is in the fully charged state, proceed to Step 504; otherwise, return to Step 502 and wait until the state is fully charged.

[Step 504 (# 504)]: Output the maximum voltage to the DA0 terminal in order to emit flat light at the maximum intensity.

[Step 505 (# 505)]: Output Lo and Hi to the SEL1 and SEL0 terminals and select the comparator 205.

[Step 506 (# 506)]: A trigger generation signal is output from the TRIG terminal to cause the xenon tube 19 to start emitting light.

[Step 507 (# 507)]: At the same time as the start of light emission, a timer in the microcomputer 200 for measuring the light emission time is started.

[Step 508 (# 508)]: The state of the STOP terminal is compared with the measurement state at the time of the previous sampling. If the previous time is Hi and the current time is Lo, flat light emission control has been performed. The flow branches to step 509 to measure and update the time from the start of the light emission. If the STOP terminal is the same as the state at the time of the previous sampling, the flat light emission control is not performed in the current sampling. Branch to

[Step 509 (# 509)]: To update the flat emission maximum time, read and store the above-described emission time count timer, and return to step 508 to continue updating the longest emission time.

[Step 510 (# 510)]: It is determined whether or not the maximum time of the maximum light emission time measurement has elapsed. If the time has elapsed, the process proceeds to Step 511 to end the measurement. If the time has not elapsed yet, the process proceeds to Step 508. Return and continue measuring.

The method of measuring the maximum light emission time will be described with reference to FIGS.

FIG. 10 shows the entire measurement of the maximum light emission time, and FIG. 11 is an enlarged view of the part being measured, that is, the part performed in steps 508 to 510. In FIG. 11, the upper part is the emission waveform, the voltage waveform input to the inverting input terminal of the comparator, and the lower part is the output of the comparator 205, which is also a signal supplied to the emission control circuit 203 through the data selector 206. Referring to the STOP signal in FIG. 11, the state in which the flat light emission control is performed, that is, the last state in which the edge of the STOP signal is switched from Hi to Lo or from Lo to Hi is the maximum light emission time in which the flat light emission control is performed. is there. However, there is no guarantee that predetermined light emission will be performed before the control of the last Hi edge, as shown in FIG. Therefore, in this embodiment, the last Lo edge is determined as the maximum light emission time.

[Step 511 (# 511)]: The maximum light emission time obtained in the above step is written in the EEPROM 210, which is a storage unit capable of writing, in correspondence with the zoom position, and the maximum light emission time measurement processing at the first zoom position is performed. finish.

In the above description, the microcomputer 200 monitors the STOP terminal sequentially. However, the time may be detected by generating an interrupt when the edge of the STOP signal changes.

Steps 501 to 510 are performed corresponding to a certain zoom position, and are driven to another zoom position to perform the same processing, and store the maximum light emission time of all zoom positions at the time of adjustment. .

However, when the sensor 32 is arranged at a position where the sensitivity of the sensor 32 for controlling the light emission intensity does not change due to non-zoom strobe or zooming, it goes without saying that the adjustment of the maximum light emission time only needs to be performed once. Further, when the sensitivity fluctuation of the sensor 32 is measured in advance, the adjustment of the maximum light emission time may be performed only at one zoom position, and the difference may be stored in the storage unit.

の 他 In addition to executing this adjustment command from an external communication means, a service mode for activating flash adjustment communication may be set in the camera body. Thereby, it is possible to easily adjust by combining with the camera.

The adjustment may be started by inputting a specific signal to the test input terminal, instead of being started by receiving the specific serial communication.

As described above, according to the second embodiment, in addition to the feature of being able to perform flash photography by flat emission with high efficiency and uniform emission intensity obtained by the first embodiment, The information of the maximum light emission time used in the strobe is characterized in that the strobe itself can be easily adjusted by incorporating the measuring means in the strobe itself even without a specific tool.

(Third embodiment)
FIG. 12 is an electric circuit block diagram of a camera system showing a third embodiment, and FIG. 13 is an electric circuit block diagram of a strobe. Members corresponding to those in FIGS. 2 and 3 are denoted by the same reference numerals, and description thereof is omitted.

In the third embodiment, a temperature detecting means for correcting the temperature of the strobe light emission is arranged on the camera side, transmitted to the strobe by communication via communication terminals S0 to S2, and based on the received temperature data. Then, the emission intensity is set as described in the first and second embodiments. In FIG. 12, 120 and 121 are temperature detecting diodes, 122 is a resistor, and 123 is a constant voltage power supply.

The merit of providing the temperature detecting means on the camera side is that the camera always needs the temperature detecting means for adjusting and correcting the AF and AE, and the first and second forward voltages VF of the temperature detecting diodes 120 and 121 are adjusted. As in the second embodiment, it is only necessary to read the data with the A / D converter 100c in the camera microcomputer 100 and transmit the obtained temperature data to the strobe by communication. Therefore, it is necessary to provide a temperature detecting means on the strobe side. There is an advantage that the cost of the strobe can be suppressed. Further, when the temperature detecting means is disposed on the strobe side, a large current of several amps flows through the strobe to charge the main capacitor C1, so that accurate temperature cannot be measured unless attention is paid to the location of the temperature detecting means. Although a case may occur, the camera side has a merit that it is easy to accurately measure the temperature since there are relatively few members that generate heat.

As described above, according to the third embodiment, the temperature required for performing flash photography by flat emission with high efficiency and uniform emission intensity obtained by the first and second embodiments is obtained. The information is transmitted to a strobe by communication with temperature detection data by a temperature detection means built in the camera, and is used for correcting the light emission intensity, thereby realizing the strobe without increasing the cost of the strobe.

FIG. 1 is a cross-sectional view illustrating a first embodiment of a camera system in which the present invention is applied to a single-lens reflex camera. FIG. 2 is a block diagram of an electric circuit of the camera system in FIG. 1. FIG. 2 is a block diagram of an electric circuit showing a strobe system in the camera system of FIG. 1. 4 is a flowchart showing a pre-emission operation of the flash system of FIG. 4 is a flowchart showing a pre-emission intensity calculation of the flash system of FIG. 4 is a flowchart illustrating a main light emission intensity calculation of the strobe system in FIG. 3. FIG. 4 is a view showing a maximum light emission time of the flash system of FIG. 3. FIG. 9 is a block diagram of an electric circuit showing a camera system according to a second embodiment. 9 is a flowchart showing calculation of a maximum flash time of a flash system in the camera system of FIG. FIG. 9 is a diagram illustrating measurement of a maximum flash time of a strobe light according to the second embodiment. The figure which shows the measuring method of FIG. FIG. 13 is a block diagram of an electric circuit of a camera system according to a third embodiment. FIG. 12 is a block diagram of an electric circuit of the strobe light system in the camera system of FIG. 11. FIG. 4 is a diagram illustrating a relationship between exposure and flat light emission in a focal plane shutter.

Explanation of reference numerals

19 xenon tubes 31, 32 monitor sensor 100 camera microcomputer 200 strobe microcomputer 203 emission control circuits 204 and 205 comparators 207 integration circuit 210 EEPROM
218, 219: temperature detection element

Claims (9)

A capacitor that stores electrical energy, a light emitting unit that converts the electrical energy of the capacitor into light energy, a monitor that monitors the light emission intensity of the light emitting unit, and arbitrates the light emission intensity based on the output of the monitor unit, A light emission control means for controlling the light emission of the light emitting means based on the light emission intensity and the light emission time, and at least a flat light emission possible time under predetermined light emission conditions is stored in order to calculate a light emission intensity for performing uniform flat light emission. A strobe system having a storage unit, wherein the light emission control unit controls light emission of the light emission unit based on time information of the storage unit,
Measuring means for measuring the flat light emission possible time, time information writing means to the storage means, and measurement start means for performing the measurement, wherein the light emission control means is configured so that the measurement start means starts measurement. When the instruction is given, a flat light emission is performed at a predetermined light emission intensity, and the flat light emission possible time measured by the measurement means is stored in the storage means by the writing means. 2. The flash system according to claim 1, wherein the measurement instruction to the measurement unit is a specific serial communication via a connection terminal with a camera. A capacitor for storing electric energy, a light emitting unit for converting the electric energy of the capacitor into light energy, a monitor for monitoring the light emission intensity of the light emitting unit, and a light emission control for arbitrating the light emission intensity based on an output of the monitor means And a correcting means for correcting the light emission intensity of the light emitting means by the light emission control means based on the temperature information detected by the temperature detecting means. 4. The temperature detecting device according to claim 3, wherein the temperature detecting device detects a forward voltage of the PN junction semiconductor driven at a substantially constant current, and information corresponding to the forward voltage at a predetermined time and surrounding information at a predetermined time. Storage means for storing temperature information; information indicating a forward voltage of the voltage detection means detected by the voltage detection means at the time of temperature detection; and the forward voltage in the predetermined state stored in the storage means. Computing means for computing a temperature at the time of detection based on a difference from the information indicating the temperature, information indicating the ambient temperature, and information indicating a predetermined temperature change of the forward voltage of the temperature detecting element. The strobe system is a feature. 5. The flash system according to claim 4, wherein the PN junction semiconductor is a diode. 6. The flash system according to claim 4, wherein the predetermined time is a point in time of adjustment and a point in time when a specific serial communication is received via a connection terminal with a camera. 5. The strobe system according to claim 4, wherein the voltage detecting means is an A / D converter. 2. The flash system according to claim 1, wherein the predetermined light emission condition of the flat light emission possible time stored in the storage means is a maximum light emission intensity that can be arbitrated by the light emission control means when the capacitor is fully charged. . 5. The flash system according to claim 1, wherein the storage unit is a rewritable storage unit.

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