JP2009098477A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the chances to perform stroboscopic photography and to reduce the possibility of missing shutter chances. <P>SOLUTION: This imaging apparatus has a deciding means for deciding the light emission quantity of a stroboscopic apparatus; a determining means for determining the heating state of partial constitutive members out of members constituting the stroboscopic apparatus; and a stroboscopic control means for limiting stroboscopic light emission according to the determined result of the determining means (#114, #116). The stroboscopic control means forbids limitation on stroboscopic light emission when the light emission quantity decided by the deciding means before the determination of the determining means is a specified quantity or less even if the determining means determines that the heating of the constitutive members exceeds a reference value (#115). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image pickup apparatus having a strobe control unit that restricts strobe light emission based on information about heat generation.

  A xenon tube or the like is used as the light source of the strobe device. When this type of stroboscopic device emits light continuously, some of the members constituting the stroboscopic device may be irradiated with light emitted from a xenon tube and become high temperature (heat generation). In particular, the Fresnel lens or the like disposed on the front surface of the xenon tube tends to be irradiated with more light than other members because of its role, and therefore tends to be hotter than other members. For this reason, depending on the material constituting the Fresnel lens, there are cases in which the material is damaged due to high temperatures and so on.

For the purpose of suppressing damage to a Fresnel lens or the like, there has been proposed an apparatus that performs continuous shooting and restricts shooting when it is assumed that the temperature is high (for example, a patent) Literature 1, 2, 3). These proposals count an integrated value corresponding to information related to heat generation, and prohibit photography when the count value reaches a predetermined value.
JP-A-2001-66675 JP 2001-305616 A JP 2003-304419 A

  When the light is emitted from the xenon tube, the temperature rises when light is emitted using the full electrical energy stored in the main capacitor in the strobe device. According to the applicant, if the amount of light emitted by a strobe device with a dimming function is very small, it will not necessarily damage the Fresnel lens even if it continues to receive light from the xenon tube. As a result of experiments. Regardless, restricting the flash shooting uniformly will miss the opportunity to shoot with the flash device, and you may not be able to shoot when you actually want to take a stroboscopic shot, and you may miss a photo opportunity. There was sex.

(Object of invention)
An object of the present invention is to provide an imaging apparatus capable of increasing the chances of performing flash photography and reducing the possibility of missing a photo opportunity.

  To achieve the above object, the present invention provides a determining means for determining a light emission amount of a strobe device, a determining means for determining a heat generation state of at least some constituent members of the strobe device, and the determination In an imaging apparatus having a strobe control unit that restricts strobe light emission based on a result of determination by the unit, when the strobe control unit determines that the heat generation of the component exceeds a reference value by the determination unit Even so, when the light emission amount determined by the determination unit before the determination by the determination unit is equal to or less than a predetermined amount, the imaging device prohibits the restriction of the strobe light emission. .

  According to the present invention, it is possible to provide an imaging apparatus capable of increasing the opportunity for performing flash photography and reducing the possibility of missing a photo opportunity.

  The best mode for carrying out the present invention is as shown in the following examples.

  FIG. 1 is a diagram showing an outline of an optical arrangement of a single-lens reflex camera which is an example of an imaging apparatus and a strobe device detachably attached to the camera according to an embodiment of the present invention.

  In FIG. 1, reference numeral 1 denotes a camera body, and an imaging lens 11 is mounted on the front surface thereof. In addition, a detachable strobe device 30 is attached to the camera body 1.

  First, the configuration on the camera body 1 side will be described.

  An optical component, a mechanical component, an electric circuit, and an image sensor such as a film or a CCD are accommodated in the camera body 1 so that a photograph or an image can be taken. Reference numeral 2 denotes a main mirror, which is obliquely installed in the photographing optical path in the finder observation state and retracts out of the photographing optical path in the photographing state. Further, the main mirror 2 is a half mirror, and when it is obliquely arranged in the photographing optical path, approximately half of the light beam from the subject is transmitted to a focus detection optical system described later.

  Reference numeral 3 denotes a focusing plate disposed on the planned imaging surface of the imaging lens 11 constituting a part of the finder optical system, and 4 is a pentaprism for changing the finder optical path. Reference numeral 5 denotes an eyepiece lens, and the photographer can observe the photographing screen by observing the focus plate 3 from a window behind the eyepiece lens 5. Reference numeral 6 denotes an imaging lens, and reference numeral 7 denotes a photometric sensor for measuring subject luminance in the viewfinder observation screen. The imaging lens 6 associates the focusing plate 3 and the photometric sensor 7 in a conjugate manner via the reflected light path in the pentaprism 4.

  Reference numeral 8 denotes a focal plane shutter. Reference numeral 9 denotes a photosensitive member, and an imaging element such as a silver salt film or a CCD is used. Reference numeral 25 denotes a sub-mirror which, like the main mirror 2, is inclined in the photographing optical path in the viewfinder observation state and retracts out of the photographing optical path in the photographing state. The sub-mirror 25 bends the light beam transmitted through the oblique main mirror 2 and guides it toward a focus detection unit 26 described later.

  A focus detection unit 26 includes a secondary imaging mirror 27, a secondary imaging lens 28, a focus detection line sensor 29, and the like. The secondary imaging mirror 27 and the secondary imaging lens 28 constitute a focus detection optical system, and the secondary imaging surface of the imaging lens 11 is formed on the focus detection line sensor 29. The focus detection unit 26 detects the focus adjustment state of the imaging lens 11 by, for example, a so-called phase difference detection method, and the detection result is sent to a camera microcomputer (described later) that controls the focus adjustment mechanism of the imaging lens.

  A lens mount contact group 10 serves as a communication interface between the camera body 1 and the imaging lens 11.

  Next, the configuration on the imaging lens 11 side will be described.

  Reference numerals 12 to 14 denote lenses forming a group, and reference numeral 15 denotes an aperture. The first group lens 12 is a focus lens that adjusts the focus position of the shooting screen by moving back and forth on the optical axis. The second group lens 13 is a zoom lens that changes the focal length of the imaging lens 11 by moving back and forth on the optical axis, and changes the magnification of the shooting screen. The third group lens 14 is a fixed lens.

  Reference numeral 16 denotes a focus drive motor that moves a first lens group (hereinafter referred to as a focus lens) 12 in the optical axis direction, and moves the focus lens 12 back and forth by an automatic focus adjustment operation. Reference numeral 17 denotes an aperture drive motor that drives the aperture 15 so as to change the aperture diameter. A distance encoder 18 detects a signal corresponding to the position of the focus lens 12 by sliding a brush 19 attached to the focus lens 12 on a predetermined pattern of electrodes provided on the distance encoder 18. The second group lens 13 is provided with a position detector (not shown). By obtaining the focal length information obtained from the position of the second group lens 13 and the focus position information obtained from the position of the focus lens 12, the subject distance is determined. Obtainable.

  Next, the configuration of the strobe device 30 will be described. The strobe device 30 can be attached to and detached from the camera body 1 and performs light emission control in accordance with a signal from the camera body 1.

  Reference numeral 31 denotes a xenon tube, which converts current energy into light emission energy. Reference numeral 32 denotes a Fresnel lens, and reference numeral 33 denotes a reflector, each of which plays a role of condensing light emission energy toward a subject efficiently. A glass fiber 37 guides a part of the light emitted from the xenon tube 31 to a light receiving element 38 such as a photodiode in order to monitor the light emission amount of the xenon tube 31. As a result, the amount of preliminary light emission and main light emission of the xenon tube 31 can be monitored.

  A light guide 36 integrated with the reflective shade 33 reflects and guides part of the light from the xenon tube 31 to the fiber 37. Reference numeral 39 denotes a strobe contact group provided on a hot shoe serving as a communication interface between the camera body 1 and the strobe device 30.

  Next, the circuit configuration of the camera body 1 and the imaging lens 11 will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the same part as FIG. 1, and the description is abbreviate | omitted.

  First, the circuit configuration in the camera body 1 will be described.

  Reference numeral 101 denotes a camera microcomputer, which is connected to a focus detection circuit 105, a photometry circuit 106, a shutter control circuit 107, a motor control circuit 108, and a liquid crystal display circuit 111. The camera microcomputer 101 transmits signals to the lens microcomputer 112 disposed in the imaging lens 11 via the lens mount contact group 10. Further, the camera microcomputer 101 performs signal transmission via a strobe contact group 39 with a strobe microcomputer 238, which will be described later with reference to FIG.

  The focus detection circuit 105 performs accumulation control and readout control of the focus detection line sensor 29 according to a signal from the camera microcomputer 101, and outputs each pixel information to the camera microcomputer 101. The camera microcomputer 101 A / D converts this information and detects the focus adjustment state by the phase difference detection method. Needless to say, the focus adjustment state detection method is not limited to the phase difference detection method, and a known method may be used. The camera microcomputer 101 performs focus adjustment control of the imaging lens 11 by exchanging signals with the lens microcomputer 112.

  The photometry circuit 106 outputs a luminance signal in both a steady state in which strobe light is not preliminarily emitted toward the subject and a state in which preliminary light emission is being performed. The camera microcomputer 101 performs A / D conversion on the luminance signal, and calculates the aperture value and shutter speed for adjusting exposure for photographing, and calculates the flash emission amount during exposure. The shutter control circuit 107 performs energization control of 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 101. As a result, the front curtain and the rear curtain travel and an exposure operation is performed. The motor control circuit 108 controls the motor M in accordance with a signal from the camera microcomputer 101, thereby performing up / down of the main mirror 2 and shutter charging.

  SW1 is a switch that is turned on by a first stroke (half-pressing) operation of a release button (not shown) and starts photometry and AF (automatic focus adjustment). SW2 is a switch that is turned on by a second stroke (full press) operation of the release button and starts shutter running, that is, an exposure operation. SWFELK is a switch that performs preliminary light emission independently and then shifts to the FE lock mode. The FE lock mode, which will be described later with reference to FIG. 6, is a mode in which preliminary light emission is performed according to the operation of the switch SWFELK, and the main light emission amount at the time of shooting is determined from the luminance of the subject at this time. Before the switch SW2 is turned on, the user can perform preliminary light emission by operating the switch SWFELK at an arbitrary timing to shift to the FE lock mode.

  The camera microcomputer 101 reads status signals of the switches SW1, SW2, SWFELK, and other switches such as an ISO sensitivity setting switch, an aperture setting switch, and a shutter speed setting switch, which are other operation members (not shown).

  The liquid crystal display circuit 111 controls the in-finder display 24 and the external display 42 in accordance with signals from the camera microcomputer 101.

  Next, a circuit configuration in the imaging lens 11 will be described.

  The camera body 1 and the imaging lens 11 are electrically connected to each other via the lens mount contact group 10 as described above. The lens mount contact group 10 includes a contact L0 which is a power contact for the focus drive motor 16 and the aperture drive motor 17 in the imaging lens 11, a power contact L1 for the lens microcomputer 112, and a clock for serial data communication. Including contact L2. Further, a data transmission contact L3 from the camera body 1 to the imaging lens 11, a data transmission contact L4 from the imaging lens 11 to the camera body 1, a motor ground contact L5 for the motor power supply, and a ground for the lens microcomputer 112 power supply. A contact L6 is included.

  The lens microcomputer 112 is connected to the camera microcomputer 101 via these lens mount contact groups 10, operates the focus drive motor 16 and the aperture motor 17 in accordance with signals from the camera microcomputer 101, and adjusts the focus of the imaging lens 11. Control the aperture. Reference numeral 50 denotes a photodetector, 51 denotes a pulse plate, and the lens microcomputer 112 uses these to count the number of pulses to obtain drive distance information of the focus lens 12. These have higher resolution than the distance encoder 18 and can perform fine focus adjustment of the imaging lens 11. The distance encoder 18 reads the position information of the focus lens 12 that is in focus after being adjusted in focus, inputs it to the lens microcomputer 112, converts it into distance information corresponding to the position of the focus lens 12, and transmits it to the camera microcomputer 101. Is done.

  Next, the circuit configuration of the strobe device 30 will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the same part as FIG. 1, and the description is abbreviate | omitted.

  In FIG. 3, 201 is a power supply battery, 202 is a DC-DC converter, and boosts the battery voltage to several hundred volts. Reference numeral 203 denotes a main capacitor for accumulating light emission energy. Reference numerals 204 and 205 denote resistors, which divide the voltage of the main capacitor 203 into a predetermined ratio. Reference numeral 206 denotes a coil for limiting the light emission current, and reference numeral 207 denotes a diode for absorbing a counter electromotive voltage generated when light emission is stopped. 211 is a trigger generation circuit, and 212 is a light emission control circuit such as an IGBT.

  Reference numeral 232 denotes a comparator for controlling the amount of light emitted during strobe light emission. Reference numeral 236 denotes an integral photometry circuit for logarithmically compressing the photocurrent flowing through the light receiving element 38 and compressing and integrating the light emission amount of the xenon tube 31. A strobe microcomputer 238 controls the operation of the entire strobe device 30.

  Next, each terminal of the flash microcomputer 238 will be described. CNT is a control output terminal for controlling the charging of the DC / DC converter 2, AD1 is an A / D conversion input terminal for reading a charging voltage, and CLK is a synchronous clock input for serial communication with the camera body 1. It is a terminal for. DO is a serial output terminal for transferring serial data from the strobe device 30 to the camera body 1 in synchronization with the synchronization clock. DI is a serial data input terminal for receiving serial data from the camera body 1 to the strobe device 30 in synchronization with the synchronization clock.

  Further, CHG is an output terminal for transmitting whether or not the xenon tube 31 can emit light from the strobe device 30 to the camera body 1, and X is a terminal to which a strobe light emission command from the camera body 1 is input. INT is a terminal for integration control output of the integral photometry circuit 236, AD0 is an A / D conversion input terminal for reading an integral voltage indicating the light emission amount from the integral photometry circuit 236, and DA0 outputs a comparator voltage of the comparator 232 This is a terminal for D / A output. TRIG is a terminal for outputting a light emission trigger signal.

  Next, operations of the microcomputers 101, 112, and 238 in the strobe photographing system configured as described above will be described in detail with reference to the flowcharts of FIGS. Note that the operation of each microcomputer is premised on the operation of multitasking, and some of the plurality of flowcharts described below are performed simultaneously. The flowcharts that proceed simultaneously will be described each time.

  First, the operation when the switch SW1 of the camera body 1 is turned on will be described with reference to the flowchart of FIG.

  When the switch SW1 is turned on, the camera microcomputer 101 forms an image on the focus detection line sensor 29 of the focus detection unit 26 in step # 100. In the next step # 101, focus detection is performed by a known method from the deviation of the subject image formed on the focus detection line sensor 29 of the focus detection unit 26, and the lens driving amount to the in-focus position is calculated. . Then, the calculated lens driving amount is output to the lens microcomputer 112 via the serial communication line.

  In the next step # 102, signals are exchanged between the camera microcomputer 101 and the lens microcomputer 112, and it is determined whether or not the focus lens 12 is within the in-focus width. If it is not within the in-focus range, the process proceeds to step # 103, and the lens microcomputer 112 performs focus drive. That is, the focus drive motor 16 is driven based on the above lens drive amount, and the rotation of the pulse plate 51 directly connected thereto is read by the photodetector 50. When the focus driving motor 16 drives the designated lens driving amount, the focus driving motor 16 is stopped. Thereafter, the process returns to step # 100.

  If it is determined in step # 102 that the focus lens 12 is within the focus width, the camera microcomputer 101 proceeds to step # 104. In this case, a value that is logarithmically compressed by a logarithmic compression amplifier (not shown) of the photometry circuit 106 and converted into a voltage value is read from the A / D input terminal. In the subsequent step # 105, the camera microcomputer 101 determines a shutter speed value (TV value) and an aperture value (AV value) from the photometric result, and displays the TV value and AV value in the finder display 22 and the external display. 42.

  In the next step # 106, the camera microcomputer 101 determines whether or not the switch SW2 is turned on. If it is turned on, the process proceeds to step # 107, and if it is off, the process returns to step # 104 and repeats the above processing. . If the switch SW1 is also turned off, the process is terminated.

  If the switch SW2 is turned on and the process proceeds to step # 107, the camera microcomputer 101 determines whether or not the current flash shooting state is the FE lock mode in which the light emission amount is determined in advance. A detailed description of what operation is performed when the FE lock mode is set will be given with reference to the flowchart of FIG. If it is in the FE lock mode, the process proceeds to step # 114. If it is not in the FE lock mode, the process proceeds to step # 108.

  Hereinafter, although the operation differs depending on whether the FE lock mode is set or not, a case where it is determined that the mode is not the FE lock mode and the process proceeds to step # 108 will be described.

  When the process proceeds to step # 108 because the FE lock mode is not set, the camera microcomputer 101 determines whether or not the heat generation integrated value is an integrated value equal to or greater than a predetermined value. This heat generation integrated value is a value obtained by adding the main light emission amount calculated every time the main light emission is performed and subtracting according to the main light emission execution interval. Stored in internal memory. For example, when the reference value is 100, if the integrated heat generation value is 100 or more, it is assumed that if the light is emitted more than that, the part constituting the strobe device such as the Fresnel lens 32 may be damaged. Proceed to # 116. In other words, in step # 116, the “display due to heat generation” display, that is, the release prohibition display, is performed on the external display unit 42 in FIG. 2, and the process ends. On the other hand, if the heat generation integrated value is 100 or more, it is determined that there is still no damage to the Fresnel lens 32 or the like even if the light is emitted, and the process proceeds to step # 109 to continue the photographing operation.

  When the process proceeds to step # 109 to continue the photographing operation, the camera microcomputer 101 obtains the subject brightness by the steady light from the photometric circuit 106 in the camera body 1 through the imaging lens 11. In the next step # 110, the flash microcomputer 238 is instructed to perform preliminary light emission by serial communication through the terminals S0, S1, and S2. The flash microcomputer 238 receives this preliminary light emission command and performs a preliminary light emission operation with a predetermined light amount.

  Details of the operation of the flash microcomputer 238 will be described with reference to FIG. The strobe microcomputer 238 sets a predetermined voltage (comparative voltage) at the terminal DA0 in accordance with the predetermined light emission level instructed by the camera microcomputer 101. At this time, since the xenon tube 31 has not yet emitted light, the output of the integral photometry circuit 236 input to the inverting input terminal of the comparator 232 does not occur. Since the output of the comparator 232 is Hi (meaning high level), the light emission control circuit 212 becomes conductive.

  Next, when a light emission trigger signal is output from the terminal TRIG, the trigger generation circuit 211 excites the xenon tube 31 that has generated a high voltage, and light emission is started. On the other hand, the flash microcomputer 238 instructs the integration photometry circuit 236 to start integration, and the integration photometry circuit 236 starts integration of the logarithmically compressed photoelectric output of the light receiving element 38.

  At the end of light emission, the flash microcomputer 238 reads the output of the integral photometry circuit 236 integrating the preliminary light emission amount from the A / D input terminal AD0 and performs A / D conversion, and the integrated value, that is, light emission at the time of preliminary light emission. The quantity is read as a digital value.

  Next, in step # 111, the subject reflected light by the preliminary light emission is received by the photometry circuit 106 in the camera body 1 through the imaging lens 11, so the camera microcomputer 101 acquires the subject luminance value by the strobe reflected light. In the next step # 112, the camera microcomputer 101 extracts the luminance value of only the reflected light due to the preliminary light emission by subtracting the subject luminance due to the stationary light from the subject luminance during the preliminary light emission. Then, in the next step # 113, a main light emission amount necessary for obtaining proper exposure is calculated. This is to obtain a ratio between the luminance value of only the reflected light extracted in step # 112 and the ideal luminance value of the reflected light necessary for proper exposure, and multiply the ratio by the amount of light at the time of preliminary light emission. Thus, the main light emission amount is determined.

  Next, the operation when it is determined in step # 107 that the FE lock mode is in effect will be described.

  If it determines with it being in FE lock mode and progresses to step # 114, the camera microcomputer 101 will determine whether the heat_generation | fever integrated value is an integrated value more than predetermined value. If the heat generation integrated value is 100 or more, if further light emission is performed, the process proceeds to step # 115 because there is a possibility that the part constituting the strobe device such as the Fresnel lens may be damaged. If the heat generation integrated value is less than 100, it is assumed that there is still no possibility of damaging the parts constituting the strobe device such as the Fresnel lens even if the light is emitted, and in order to continue the photographing operation, the steps after step # 601 in FIG. Proceed to processing.

  When the process proceeds to step # 115 assuming that there is a possibility that a portion constituting the strobe device such as a Fresnel lens may be damaged, the camera microcomputer 101 determines a light emission amount determined in advance. When the light emission amount is less than 1/16 of the full light emission, the energy is weak, and even if it emits light, there is almost no damage to the parts constituting the strobe device such as the Fresnel lens, so the photographing operation is continued. Then, the process proceeds to step # 601 and subsequent steps in FIG. Further, when the light emission amount is 1/16 or more of the full light emission, the process proceeds to step # 116, where “photographing not possible due to heat generation” is displayed on the external display 42 in FIG. Here, in the FE lock mode (YES in step # 107), it is determined whether or not the light emission amount is 1/16 or more of the full light emission, whereas it is not in the FE lock mode ( The reason why the light emission amount is not determined in step # 107 is described. When not in the FE lock mode, the main light emission amount has not yet been obtained, and in order to obtain the light emission amount, it is necessary to perform preliminary light emission after the switch SW2 is turned on. When not in the FE lock mode, preliminary light emission and main light emission in FIG. 5 to be described later are continuously performed. Therefore, if the user or the subject is not particularly conscious, whether or not only preliminary light emission has been performed, It is difficult to distinguish whether both the main flashes are performed. For this reason, the specification that prohibits the release according to the main light emission amount calculated immediately after the user has turned on SW2 with the intention of taking a picture and performed preliminary light emission from the viewpoint of usability. This is not preferable. Therefore, when the FE lock mode is not set, if the integrated heat generation value is 100 or more when the switch SW2 is turned on, the release is prohibited without performing preliminary light emission. On the other hand, in the FE lock mode, since it is not necessary to perform preliminary light emission after the switch SW2 is turned on, the main light emission amount obtained in advance is small (less than 1/16 of full light emission). However, the main flash is permitted without prohibiting the release.

  Next, a case where the process proceeds to step # 601 in FIG. 5 in order to continue the photographing operation will be described.

  In step # 601 in FIG. 5, the camera microcomputer 101 transmits the flash emission amount to the flash microcomputer 238. In the next step # 602, the heat generation integrated value of strobe light emission is added.

  A specific example of the heat generation integrated value will be described below.

・ When the flash output is full, 8
・ If the flash output is 1/2 of the full flash, 4
・ If the flash output is 1/4 of the full flash, 2
・ If the flash output is 1/8 of full flash, 1
-0 if the flash output is 1/16 or less of the full flash
It is. Here, the heat generation integrated value added to the light emission amount may be determined by an experiment or evaluation of a prototype as a value contributing to the temperature rise.

  In the next step # 603, the camera microcomputer 101 raises the main mirror 2 and the sub mirror 25 and retracts them from the photographing optical path, and at the same time instructs the lens microcomputer 112 to narrow down the diaphragm 15. Then, in the next step # 604, it waits for the main mirror 2 and the sub mirror 25 to be retracted from the photographing optical path. When the main mirror 2 and the sub mirror 25 jump up, the process proceeds to step # 605, where the camera microcomputer 101 energizes the front curtain drive magnet MG-1 and starts the opening operation of the focal plane shutter 8.

  In the next step # 606, the flash microcomputer 238 performs the main light emission control. Specifically, the flash microcomputer 238 first outputs a control voltage to the DA0 terminal. This control voltage is a voltage obtained by adding a control voltage corresponding to the light amount difference between the preliminary light emission and the main light emission to the output voltage of the integral photometry circuit 236 described during the preliminary light emission, that is, the integrated voltage. The amount of main light emission corresponds to the main light emission amount calculated in accordance with the operation of the switch SWFELK or the main light emission amount calculated in step # 113 described above.

  For example, if the integrated voltage when the preliminary light emission is 1/32 of the full light emission amount is V1 and the main light emission amount is the same 1/32, the light emission is stopped when the same integrated voltage is reached. Therefore, V 1 is set as the comparator voltage of the comparator 232. Similarly, when the main light emission amount is 1/16 of the full light emission amount, it is only necessary to stop the light emission when the integrated voltage is increased by one stage with respect to the preliminary light emission. A voltage corresponding to one stage is added and set as a comparator voltage of the comparator 232.

  In a state where the xenon tube 31 has not yet emitted light, almost no photocurrent flows through the light receiving element 38. For this reason, the output of the integral photometry circuit 236 is not generated, and the negative input voltage of the comparator 232 is lower than the positive input terminal. Therefore, the output of the comparator 232 becomes Hi, and the light emission control circuit 212 becomes conductive.

  At the same time, the flash microcomputer 238 outputs Hi from the terminal TRIG for a predetermined time. Thereby, the trigger circuit 211 generates a high trigger voltage. When a high voltage is applied to the trigger electrode of the xenon tube 31, the xenon tube 31 starts to emit light. When the xenon tube 31 starts to emit light, a photocurrent flows through the light receiving element 38, and the output of the integral photometry circuit 236 increases. When a predetermined voltage set at the + input terminal of the comparator 232 is reached, the comparator 232 is inverted and its output becomes Lo (meaning low level), and the light emission control circuit 212 is cut off, so light emission is stopped. The At this point, the xenon tube 31 generates a predetermined amount of light emission and stops light emission, and a desired light amount necessary for flash photography can be obtained.

  When the predetermined shutter opening time has elapsed, in step # 607, the camera microcomputer 101 energizes the rear curtain drive magnet MG-2, closes the rear curtain of the focal plane shutter 8, and ends the exposure. Then, in the next step # 608, the main mirror 2 and the sub mirror 25 are lowered and the photographing is finished.

  FIG. 6 is a flowchart for explaining in detail how the FE lock mode is set. The flowchart of FIG. 6 is processed as one task of multitasking and proceeds simultaneously with other flowcharts.

  In step # 707, the camera microcomputer 101 reads the state of the connected switch SWFELK, and if not, waits in this step until the switch SWFELK is pressed. Thereafter, when the switch SWFELK is pressed, the process proceeds to step # 708 to store the fact that the FE lock mode has been entered. This is left as a flag in the memory inside the camera microcomputer 101 and used in step # 107 of the flowchart of FIG.

  The FE lock mode flag may be cleared after the photographing operation is performed, or may be cleared after a predetermined time has elapsed. If the flag is cleared, the flash photography in the normal mode is executed until the photographer presses the switch SWFELK again.

  In the next step # 709, the camera microcomputer 101 obtains the subject brightness by the steady light from the photometry circuit 106 of the camera body 1 through the imaging lens 11. In the next step # 710, preliminary light emission is commanded to the flash microcomputer 238 by serial communication through the terminals S0, S1, and S2. The flash microcomputer 238 receives this preliminary light emission command and performs a preliminary light emission operation with a predetermined light amount.

  Specifically, the flash microcomputer 238 sets a predetermined voltage (comparative voltage) at the terminal DA0 according to a predetermined light emission level designated by the camera body 1. At this time, since the xenon tube 31 has not yet emitted light, the output of the integral photometry circuit 236 input to the inverting input terminal of the comparator 232 does not occur. Since the output of the comparator 232 is Hi, the light emission control circuit 212 becomes conductive.

  Next, when a light emission trigger signal is output from the terminal TRIG, the trigger generation circuit 211 excites the xenon tube 31 that has generated a high voltage, and light emission is started. On the other hand, the flash microcomputer 238 instructs the integration photometry circuit 236 to start integration, and the integration photometry circuit 236 starts integration of the logarithmically compressed photoelectric output of the light receiving element 38.

  At the end of light emission, the flash microcomputer 238 reads the output of the integral photometry circuit 236 that integrates the preliminary light emission amount from the A / D input terminal AD0 and performs A / D conversion, and calculates the integrated value, that is, the light emission amount during the preliminary light emission. Read as a digital value.

  In the next step # 711, the camera microcomputer 101 receives the subject reflected light by the preliminary light emission through the imaging lens 11 by the photometry circuit 106 in the camera body 1, and acquires the subject luminance value by the strobe reflected light. Then, in the next step # 712, the luminance value of only the reflected light component due to the preliminary light emission is extracted by subtracting the subject luminance due to the stationary light from the subject luminance during the preliminary light emission. Then, in the next step # 713, a main light emission amount necessary for obtaining proper exposure is calculated. This is to obtain the ratio of the luminance value of only the reflected light extracted in step # 712 and the ideal luminance value of the reflected light necessary for proper exposure, and multiply the ratio by the amount of light at the time of preliminary light emission. Thus, the main light emission amount is determined. In the FE lock mode, the main light emission amount is determined at this time.

  FIG. 7 is a flowchart of a task for subtracting the heat generation integrated value with time. The heat generated by the strobe light is cooled with time, but this flowchart is a part for embodying this cooling concept. The flowchart of FIG. 7 is processed as one task of multitasking, and proceeds simultaneously with other flowcharts.

  In step # 801, the camera microcomputer 101 observes the passage of time. When the time of 5 minutes elapses, the process proceeds to step # 802, but waits at step # 801 until the time elapses. If 5 minutes have passed and the process proceeds to step # 802, a certain value is subtracted from the heat generation integrated value. When the heat generation integrated value becomes 0, further subtraction is stopped. Thereafter, the process proceeds to step # 803, the 5-minute timer is restarted, and the process returns to step # 803.

  According to the above-described embodiment, the means for determining the amount of light emitted from the strobe device and detecting the heat generation state of at least some of the constituent members of the strobe device (for example, measuring or measuring the temperature) (Means to substitute). Then, the strobe shooting interval is changed according to the state of the means for detecting the heat generation state, for example, the strobe emission interval is set to a certain time or longer (for example, 5 minutes or longer) (steps # 108, # 114, # 115 in FIG. 4). , See FIG. 7), and the like.

  However, it is assumed that the determined light emission amount is determined to be equal to or less than the predetermined amount (in the example, less than 1/16 of the full light emission of Step # 115 in FIG. 4). In such a case, it is prohibited to restrict the flash emission, and the flash photography is continued.

  As a result, it is possible to solve the problem that causes a great disadvantage for the strobe photographer without restricting the strobe photography uniformly without losing the photographing opportunity using the strobe device. In other words, it is possible to provide a strobe device and an imaging device that can increase the opportunities for performing strobe photography and reduce the chance of missing a shutter opportunity.

  In the above embodiment, the heat generation integrated value is used as a means for measuring or substituting the temperature of at least some of the members constituting the strobe device, but a temperature sensor such as a thermistor may be used.

  The strobe device 30 is detachable from the camera body 1, but may be a strobe device built in the camera body 110.

It is a figure which shows the outline of the optical arrangement | positioning of the imaging device and strobe device concerning one Example of this invention. 1 is a block diagram illustrating a circuit configuration of an imaging apparatus according to an embodiment of the present invention. It is a block diagram which shows the circuit structure of the flash device concerning one Example of this invention. 6 is a flowchart illustrating a part of the operation of the imaging apparatus and the strobe device according to the embodiment of the present invention. 5 is a flowchart showing a continuation of the operation of FIG. It is a flowchart for demonstrating the case where FE lock mode is set in one Example of this invention. It is a flowchart which shows the operation | movement at the time of subtracting the heat_generation | fever integrated value with time in one Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Camera body 11 Imaging lens 12 1 group lens (force lens)
DESCRIPTION OF SYMBOLS 16 Focus drive motor 26 Focus detection unit 30 Strobe device 31 Xenon tube 33 Reflector 32 Fresnel lens 38 Light receiving element 36 Light guide 101 Camera microcomputer 112 Lens microcomputer 238 Strobe microcomputer

Claims (6)

Determining means for determining the amount of light emitted from the flash device;
Determining means for determining a heat generation state of at least some of the constituent members of the strobe device;
In an imaging apparatus having a strobe control unit that limits strobe light emission based on a result of the determination by the determination unit,
The strobe control means is the light emission determined by the determination means before the determination by the determination means, even when the determination means determines that the heat generation of the component exceeds a reference value. An image pickup apparatus, wherein when the amount is equal to or less than a specified amount, restricting the strobe emission is prohibited.   The strobe control unit determines that the heat generation of the component member exceeds a reference value by the determination unit when the light emission is not determined by the determination unit prior to the determination by the determination unit. The imaging apparatus according to claim 1, wherein the strobe device does not emit light.   The imaging apparatus according to claim 1, wherein the determination unit performs preliminary light emission and determines the light emission amount using a subject luminance value obtained when the preliminary light emission is performed.   The strobe control unit determines that the heat generation of the component member exceeds a reference value by the determination unit when the light emission is not determined by the determination unit prior to the determination by the determination unit. The imaging apparatus according to claim 3, wherein the strobe device does not perform preliminary light emission.   5. The image pickup apparatus according to claim 1, wherein when the flash emission is limited, the interval between flash photography is increased.   The imaging apparatus according to claim 5, wherein increasing the interval between strobe shootings sets the interval between strobe emission to a predetermined time or more.

Images