JP2003233110A - Camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a camera which can give a proper quantity of light not only to the film of high sensitivity but also to conventional film and the coot of which can be reduced. <P>SOLUTION: The sensitivity information of the film is obtained by a film sensitivity recognizing part. A selection signal with which resistances R7 to R9 suitable to the film sensitivity information are selected is outputted to FETs Q8 to Q10 constituting a light quantity integrating part 403 on the basis of the film sensitivity information. A flash light emission period is integrated on the basis of light received by a phototransistor 40c at the light quantity integrating part 403 which has received the selection signal. Since the rising rate of voltage generated at a node C is changed in accordance with a resistance value selected at the light quantity integrating part 403, flash light emission is stopped in timing more quicker than in a conventional practice in the case that an object exists at a short distance. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera having a dimmable flash device.

[0002]

2. Description of the Related Art Many cameras for photographing a subject can be equipped with a flash device so that photographing can be performed day or night. With the recent technical development, many electronic cameras and instant cameras equipped with a flash device are commercially available.

In such a flash device, in order to give an appropriate amount of light to the film when a subject is photographed, the flash device emits a flash of light when the light emitted by the flash device reaches an appropriate amount of light. There is something to stop.

At this time, the appropriate amount of light given to the film is determined in accordance with the marked film sensitivity described on the film. However, when the subject is at a short distance, if an appropriate amount of light obtained from the film sensitivity of the marking is applied to the film as it is, the amount of light applied to the film may be excessive. This is because when the subject is at a short distance, the amount of flash light that hits the subject and returns after the flash light is emitted by the flash device rapidly increases, and thus gives a large amount of light to the film in a short time. This is due to the fact. This is called reciprocity failure.

In this way, when the subject is at a short distance,
There is known a technique for avoiding the influence of reciprocity law failure by giving the film a light amount lower than an appropriate light amount corresponding to the marked film sensitivity described in the film case. That is, in this technique, when it is determined that there is an influence of reciprocity law failure, the film is given a light amount that is lower than the appropriate light amount corresponding to the marked film sensitivity.

However, in the case of the above technique, there are cases in which the influence of reciprocity law failure is well avoided and a photograph of proper exposure can be obtained, and cases in which the influence of reciprocity law failure cannot be avoided are obtained.

[0007]

As described above, the case where the influence of reciprocity law failure is well avoided and a photograph of proper exposure can be obtained, and the case where the photograph where the influence of reciprocity law failure cannot be avoided are obtained are obtained. There is.

In view of the above circumstances, it is an object of the present invention to provide a camera capable of avoiding the influence of reciprocity law failure in any case.

[0009]

A camera of the present invention which achieves the above object comprises a dimming flash device which emits a flash of light toward a subject and stops the flash of light at a timing when a predetermined amount of light is reached, In a camera that guides subject light onto a loaded photographic film to take a photograph on the photographic film, the sensitivity of the photographic film is set, or the sensitivity is detected by detecting the sensitivity of the photographic film. Sensitivity recognition part, and when taking a photo on a photographic film that has a light quantity lower than the appropriate light quantity required for the sensitivity of the photographic film at the time of short-distance shooting and the marked sensitivity is equal to or higher than a predetermined sensitivity. In comparison with the case of taking a photograph on a photographic film with less than the predetermined sensitivity, the flash light emission is stopped at the timing when the light amount reaches a level where the light amount ratio from the appropriate light amount is further reduced. Characterized by comprising a that light quantity control means.

The reciprocity law failure is greatly influenced by a film having higher sensitivity. On the other hand, conventionally, the sensitivity of the photographic film is ignored, and the influence of the reciprocity law failure is corrected to be at the same level regardless of the sensitivity of the photographic film. Therefore, even if the influence of reciprocity law failure was successfully avoided for a photographic film with a certain sensitivity, the effect of reciprocity law failure was left for a photographic film with another sensitivity.

According to the above invention, in the case of a high-sensitivity film, the amount of light further reduced is given to the high-sensitivity film as compared with the appropriate amount of light on the marking, and therefore, it is caused by the sensitivity of the photographic film. Therefore, the influence of reciprocity failure can always be appropriately avoided.

In the camera of the above invention, the light amount control means emits a light toward a subject, receives a flash light reflected by the subject and returned, and is connected in series to the sensor. A condenser that integrates the amount of received light,
A plurality of resistors connected in series to the capacitor and in parallel with each other, and a plurality of resistors connected in series to each of the resistors, and a flow path of a current flowing through each of the resistors are set to a sensitivity of the marking of the photographic film. It is preferable to provide a plurality of switch elements that are connected and disconnected accordingly.

In this way, the exposure time can be adapted to a film having any film sensitivity simply by switching the flow path by the switch element.

Here, it is preferable that the plurality of resistors have different resistance values.

Since the plurality of resistors have different resistance values as described above, various ratios for reducing the light quantity can be set according to the film sensitivity information by combining the resistance values. it can.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

FIG. 1 is an external perspective view of a camera, which is an embodiment of the present invention, as viewed from diagonally above the front surface.

The camera 1 shown in FIG. 1 is a relatively compact instant camera in which a film pack in which film units for instant photography are laminated is loaded and the film unit in the film pack takes a picture.

The film unit used here has its photosensitive surface exposed to the photographing light, and then the film drive mechanism is driven to be developed / discharged outside the camera. Is a mono-sheet type self-developing type photosensitive material in which the developing pod is crushed and the developing solution is uniformly spread between the photosensitive layer and the transfer layer, and a positive image appears immediately after development and transfer processing. is there.

The camera 1 shown in FIG. 1 includes a front cover 1
1 and a rear cover 12, and a front cover 11 and a rear cover 12 thereof, and a battery chamber cover 13 that forms the appearance of the camera 1 together with the front cover 11, the rear cover 12,
A camera body is provided inside the battery compartment cover 13.

At the center of the front surface of the camera 1, there is provided a lens barrel 20 which internally supports a taking lens 21 and whose position is changed with respect to the camera body before and during use of the camera. FIG. 1 shows a state where the lens barrel 20 is extended to a predetermined extension position. The camera 1 can take an image when the lens barrel 20 is extended from a predetermined retracted position provided on the camera body and brought into the state shown in FIG. In this camera 1, the lens barrel 20 is manually extended and retracted, so that a drive mechanism required for the lens barrel 20 extended and retracted is not required, and the cost can be reduced. Furthermore, a finger rest 201 is provided at the tip of the lens barrel 20 so that the user can easily extend the lens barrel 20 from the retracted position. The finger rest 201 in the camera 1 according to the present embodiment projects in the radial direction of the lens barrel 20 over the entire circumference of the lens barrel 20, but is not limited to this and may partially project. It may be recessed in the opposite direction over the entire circumference, may be recessed in conformity with the pad of the finger, or may have increased frictional resistance.

A release button 30 is arranged on the right side (left side in FIG. 1) of the front surface of the camera 1. In the camera 1, when the release button 30 is pressed, the film unit is exposed to the photographing light. In addition, a protector 41 is provided on the front side diagonally above the release button 30.
Is provided with a flash 40. Further, on the left side (the right side in FIG. 1) of the protector 41, a flash light receiving unit for guiding the flash light to a light receiving element (not shown) that receives the light amount of the flash light reflected by the subject and returned when the flash is emitted. A window 50 is provided. The camera 1 also includes a photometric unit 60 for measuring the brightness of the field, and a light receiving window 61 for guiding light to a built-in photometric element (not shown) on the flash light receiving window 50.
Is provided. Further, this camera 1 is equipped with an inverted Galileo finder, a finder objective window 71 is arranged adjacent to the flash 40, and a finder eyepiece window 72 is arranged at the rear of the camera 1. .

The operation of the camera shown in FIG. 1 is controlled by a microcomputer (hereinafter referred to as a microcomputer) provided in the camera. A structural block for performing this control is shown in FIG. 2 and will be described.

FIG. 2 is a functional block diagram showing a control configuration.

As shown in FIG. 2, the microcomputer 100 is provided with a switch group for transmitting to the microcomputer 100 an operation instruction necessary for photographing. Then, in the microcomputer 100, the output signal is output from the motor 10 based on the instruction of the switch group.
1 and each unit. Further, a film sensitivity recognition unit 102 for recognizing the sensitivity of the film when the film is loaded is provided. Based on the sensitivity information recognized by the film sensitivity recognition unit 102, the light amount integration unit 401, which will be described later, is controlled by the microcomputer 100.

First, the operation based on the instruction of the main power switch 110 in the switch group will be described.

When the feeding operation is performed, the contacts come into contact with each other and the main power switch 110 is turned on. This on-state is monitored by the microcomputer 100. The light emitting element 92 for operation display emits light based on the monitored result. At this time, electric power is supplied to each part from a battery (not shown), and all parts are operable.

In addition, the switch group includes a synchro switch 12
0 and a development switch 130, which are activated according to the passage of time during a series of development operations from the loading to the discharging of the film.

Further, a release switch 30 which is activated when a release button 30 for performing a release operation is depressed.
There is also a, which informs the microcomputer 100 that a release operation has been performed. It is understood that when the release button 30 is pressed, the release switch 30a is turned on and the microcomputer 100 is turned on. Then, from the microcomputer 100 to the motor driver 101a
Is instructed to perform a series of expansion operations.

In the motor driver 101a, the microcomputer 10
The rotation of the motor 101 is started based on the instruction from 0. The rotation of the motor 101 is transmitted to a cam mechanism (not shown) that controls the series of unfolding operations to perform the series of unfolding operations.

The synchro switch 12 is operated while a series of unfolding operations are being performed by the cam mechanism (not shown).
0 is turned on. This on-state is monitored by the microcomputer 100. When the synchro switch 120 is turned on, a flash light emission instruction is given to the light emitting unit 40b. In response to this, the light emitting unit 40b gives a flash instruction to the xenon tube (hereinafter, referred to as Xe tube) 40a that constitutes the flash emitting section 40. Then, the Xe tube 40a receives the flash instruction and starts the flash. The light emission amount of this flash is received by the phototransistor 40c as described above.
The stop timing of the flash light is detected within 0b. The light emitting unit 40b is provided with a phototransistor as a light receiving sensor for detecting the amount of light emitted by flashing and hitting the subject and returning, and controlling the amount of light for stopping the flashing of light according to the amount of light received by the light receiving sensor. A light quantity integrating unit forming a part of the means is provided.
Details will be described later.

Further, since a sufficient electric power must be supplied to the Xe tube 40a at the time of flash light emission, the main capacitor C40d which is a main capacitor for supplying the electric power necessary for the flash light to the Xe tube 40a is provided. This main C
A charging unit 40e is provided to charge 40d, and the charging unit 40e is charged based on an instruction from the microcomputer 100.

On the other hand, as described above, the brightness of the field is monitored in the photometric unit 60, and the light emitting element 92 emits light in accordance with the brightness according to the monitored result.

The microcomputer 100 also manages the battery. A battery check unit (hereinafter referred to as BC unit) 103 performs this management, and the management status is transmitted to the microcomputer 100. In the microcomputer peripheral unit 104, cooperation between the microcomputer 100 and each part is achieved, and data is exchanged between the microcomputer 100 and each part through a bus (not shown).

First, the main power switch 115 is turned on to bring the camera into operation. This switch 115
The fact that the main power switch 115 is in the ON state is notified to the microcomputer 100 based on the turning on. Microcomputer 1
At 00, in response to this, power is supplied from a battery (not shown) to each unit in the camera. In order to show this to the user, a light emission instruction is issued from the microcomputer 100, and the light emitting element 92 for operation display emits light. The camera is now in standby for shooting.

When the release button 30 is pressed in this state, photographing starts. Then, as described above, a series of unfolding operations from photographing to discharging operation are started by pressing the release button 30.

The light quantity control means, which is a characteristic part of the present invention, will now be described. FIG. 3 is a circuit diagram including the light quantity control means.

The circuit diagram of FIG. 3 shows the microcomputer 100, the xenon tube 40a, the light emitting unit 40b, the phototransistor 40c, the main capacitor 40d, and the charging unit 40e in the control block diagram of FIG.

As shown in FIG. 3, one end of the xenon tube 40a for flash light emission is connected to the output terminal OUT of the charging IC 401. In addition, the plus (+) of the main capacitor 40d that supplies the energy for flashing light.
It is also connected to the terminal on the side. The minus (-) side of the main capacitor 40d is connected to the minus side (-) of the battery. Here, the main capacitor 40d is charged by the charging IC 401, and the main capacitor 40d is transferred to the xenon tube 40a according to the charging status.
The energy required for the flash emission is supplied from d.

On the other hand, the power supply terminal Vcc of the charging IC 401
Is on the plus (+) side of the battery 402 and the ground GN
The D terminal is connected to the negative side of the battery. The input terminal IN of the charging IC 401 is connected to the output terminal CHARGE of the microcomputer 100, and the charging IC 401 charges the main capacitor 40d based on the charging instruction of the microcomputer 100.

Further, the xenon tube 40a is provided with a trigger electrode Trigger, and the trigger electrode T
When a trigger signal is applied to the rigger, the xenon tube 40a is excited, and a state where flash light can be emitted. One end of the secondary side of the transformer T1 is connected to the trigger electrode Trigger of the xenon tube 40a, and the output terminal OU of the charging IC 401 is connected to the primary side of the transformer T1.
T is connected via a resistor R1. A capacitor C1 is connected to the resistor R1, and the capacitor C1 is connected to the negative (−) side of the battery 402. Further, the primary side and the secondary side of this transformer T1 are commonly connected to the collector of the IGBT Q1,
When Q1 is turned on, the transformer T1 operates to transmit the signal on the primary side to the secondary side, and the trigger signal is applied to the trigger electrode Trigger of the xenon tube 40a.

The emitter of the IGBT Q1 in which one end of the xenon tube 40a is connected to the collector is the battery 4
02 is connected to the minus (−) side, and the gate is connected to the side of the microcomputer 100 that supplies the flash light emission instruction via the resistor R2. From here, it will be explained how the light amount is integrated and the flash light emission is stopped after the flash light emission instruction is given from the microcomputer 100.

A signal notifying the flash emission is output from the output terminal FT of the microcomputer 100.
BT Q1 turns on. At this time, the charging IC 401
The output terminal OUT of is open.

Therefore, the flash emission instruction is the IGBT Q
If it is transmitted to the gate of 1 and the IGBT Q1 operates,
Main capacitor 40d to xenon tube 40a, resistor R
3. The current flows through the flow path formed by the IGBT Q1. At this time, flash light is emitted from the xenon tube 40a.

Here, how an instruction for starting flash light emission is transmitted from the output terminal FT of the microcomputer 100 to the IGBT Q1 will be described.

PNP is provided at the output terminal FT of the microcomputer 100.
The base of the transistor Q2 is connected. Therefore, when a low level L signal is output from the output terminal FT, the base of the PNP transistor Q1 becomes low level and a potential difference is generated between the base and emitter of the PNP transistor Q1 and the subsequent circuits operate. In addition, this P
The emitter of the NP transistor Q1 is connected to the plus (+) side of the battery 402, and the collector is connected to the base of the NPN transistor Q3 of the next stage.

The NPN transistor Q3 operates in response to the operation of the PNP transistor Q2.

The emitter of the NPN transistor Q3 is connected to the minus (-) side of the battery 403, and the collector of this signal is output to the IGBT Q1 when a low level signal is output from the output terminal FT of the microcomputer. It is connected to the base of a PNP transistor Q4 for transmitting the change to the IGBT Q1 side as a start instruction.

The positive side of the capacitor C2 for charging the IGBT is connected to the emitter of the PNP transistor Q4. The connection point A between the resistor R4 and the resistor R5 is connected to the plus (+) side of the capacitor C2,
A voltage is generated at the connection point A due to the current from the main capacitor 40d that has been charged, so that the capacitor C2 is charged with the voltage. The voltage generated when the capacitor is charged becomes the voltage applied to the gate of the IGBT Q1. And by this applied voltage IG
Since the capacitance between the gate and the ground of the BT Q1 increases, when the capacitance reaches a predetermined input capacitance, the IGBT Q1 turns on and flash light emission is performed.

The collector of the PNP transistor Q4 which supplies the voltage stored in the capacitor C2 to the IGBT Q1 is also connected to a latch circuit composed of a PNP transistor Q5 and an NPN transistor Q6. The collector of the PNP transistor Q4 is also connected to the negative (-) side of the battery via the resistor R6.

When one PNP transistor Q5 is turned on with the latch circuit, the NPN transistor Q6 which operates as a pair is turned on and both transistors operate so as to maintain the on state unless a predetermined condition is satisfied. Say. Here, when the PNP transistor Q5 is turned on, the NPN transistor Q5 is also turned on and the current is continuously supplied to the IGBT Q1. Also, NPN
Since the transistor Q6 turns off when the MOSFET Q7 turns on, the off state at that time is also maintained. In this latch circuit, when the flash light emission is started, the flash light emission is maintained, and when the stop timing is detected by the light amount control means 403 including the light amount integrating section 403 described later, the flash light emission is surely stopped.

The light quantity control means 403 will be described here. The light quantity control means 403 includes a phototransistor 40c, a MOSFET Q7, a capacitor C3 and a plurality of resistors R.
7 to R9.

The drain of the MOSFET Q7 is connected to the collector of the NPN transistor Q6 which constitutes the above-mentioned latch circuit, and the stop of flash light emission is stopped by the IGB.
It can be transmitted to TQ1. Connection point B here
Is connected to the gate of the IGBT Q1, the base of the PNP transistor Q5 that forms the latch circuit, the collector of the NPN transistor Q6, and the anode of the diode D1. The diode D1 is provided for supplying a current to the MOSFET Q7 when the MOSFET Q7 operates, and the MOSFET Q7 operates depending on the operating condition of the light quantity integrating unit 402a described later. Here, this MOSFET Q7 operates as a comparison circuit.

The variable resistor VR1 is connected to the source of the MOSFET Q7, and the variable resistor VR1 is connected to the variable resistor VR1.
Both ends of 1 are positive (+) side and negative (-) side of battery
Side and respectively connected to. A voltage divided by the resistor is generated in the tap portion TAP connected to the source of the MOSFET Q7. This divided voltage is MO
It serves as a reference voltage when compared with the voltage generated at the gate of SFET Q7.

On the other hand, the emitter of the phototransistor 40c is connected to the gate of the MOSFET Q7,
The emitter is also connected to the negative (-) side of the battery via the resistor R10. Therefore, when the phototransistor 40c receives light, a current flows into the negative (−) side of the battery through the resistor R10 via the connection point C. At this time, a voltage is generated at the connection point C.
The voltage generated at the connection point C is compared with the reference voltage described above. In the case of the FET, the voltage difference generated between the gate and the source determines whether the FET operates.

The light quantity integrating section 403 for temporally changing the voltage generated at the connection point C is connected to the emitter of the phototransistor PT1. The light quantity integrating unit 403 includes a capacitor C3 and a plurality of resistors R7.
To R9 and a plurality of FETs Q8 to Q10, one end of the capacitor C3 is connected to the connection point C, and the other end of the capacitor C3 has resistors R7 to R each having a different resistance value.
9 is connected to one end of each. These resistors R7
Whether ~ R9 is connected in parallel is determined by the operating states Q8 to Q10 of the three FETs respectively connected to the other ends of the resistors. Since the film sensitivity recognition unit 102 described in FIG. 2 recognizes the film sensitivity information, at least one of the three FETs Q8 to Q10 is connected based on the recognized film sensitivity information, and its resistance is At least one of the resistance values indicated or the resistance values obtained by combining the resistance values indicated by those resistances can be obtained. FETs Q8 to Q based on the film sensitivity information of the film sensitivity recognition unit 102
When 10 is selected and any one of the resistors R7 to R9 is connected, the resistance value changes, so that the voltage generated by the current output from the phototransistor 40c changes. For example, in the case of a low-sensitivity film, it is desirable to select a small resistance because the rise rate is desired to be slow.
On the other hand, in the case of a high-sensitivity film, it is desirable to select a resistor having a high resistance value because it is desired to increase the rate of increase.

Since a control signal is output from the microcomputer 100 to these three FETs Q8 to Q10 based on the film sensitivity information, the resistance value can be obtained by switching these three FETs according to the film sensitivity information. . At that time, at least one resistor corresponding to the film sensitivity is selected from the three resistors R7 to R9. Here, up to 8 types of film sensitivity can be supported. Three FETs Q8-Q
In order to correspond to the respective switching signals supplied to 10, the output terminals of the microcomputer 100 are respectively provided with ISO
The terminal names of 1, ISO2, and ISO3 are attached.

For example, the output terminal ISO of the microcomputer 100
1 becomes high level, and other output terminals ISO2, IS
If O3 remains at the low level, only the FET Q8 is turned on and only the resistor R7 operates. At this time, only the series circuit composed of the resistor R7 and the capacitor C3 operates.

Generally, when a direct current is applied, a current does not flow through the capacitor C3, but when a pulse-like signal or an AC signal is applied, the resistance R is passed through the capacitor C3.
Current flows into 7. Here, the phototransistor 40
When c receives light, only the series circuit including the capacitor C3 and the resistor R7 operates. Therefore,
When the phototransistor 40c receives the return light from the subject and a current starts to flow from the phototransistor 40c, the value of the resistor R10 is large, so that the capacitor C3 mainly passes the current to the resistor R7. At that time, the voltage generated in the resistor R7 and the voltage generated in the capacitor C3 are added, and a voltage that gradually increases with time is generated at the connection point C side. At this time, the rate of increase of the voltage generated at the connection point C changes depending on the values of the resistors R7 to R9 switched by the FETs Q8 to Q10. This light quantity integrating unit 40
3 is the FE value of the resistance of the voltage generation state with the passage of time
It is intended to change by switching by T. Especially, the generation state of the voltage generated at the connection point C is
It is intended to change according to the values of the resistors R7 to R9 switched by 8 to Q10. That is, it is utilized that the voltage generated at the connection point C is small when the resistance value is small, and the voltage generated at the connection point C is large when the resistance value is large. At this time, the voltage generated at the connection point C rises with the passage of time, so the time until the reference voltage is reached changes. In other words, three FET Q8
By turning on at least one of Q10 to Q10, the time to reach the reference voltage set by VR1, that is, the flash emission time is changed.

Here, by properly combining 100Ω, 200Ω, and 400Ω, it is possible to set a large number of times until the reference voltage is reached according to the film sensitivity. For example, a film with an ASA sensitivity of 100 and ASA
The 1600 film has a 16-fold difference in light amount in terms of the marking. Therefore, if the ASA sensitivity is 1600, the ASA
The appropriate light amount is about 1/16 of the light amount when the sensitivity is 100. Conventionally, control was performed based on such a film sensitivity on the marking. In particular, when the subject is at a short distance and the influence of reciprocity law failure is expected to appear, the light amount reduced to a certain ratio from the appropriate light amount on the marking is given to the film.

Therefore, in the present embodiment, this ratio is changed according to the film sensitivity, and in the case of a high-sensitivity film, a light amount much smaller than the appropriate light amount corresponding to the film sensitivity is given to the film as an appropriate light amount. I am devising. In the present embodiment, at least one of the resistors R7 to R9 in the light quantity integrating unit 403 is selected based on the film sensitivity information so that the voltage generated at the connection point C can be adjusted by the resistance value. Has improved. Therefore, by changing the resistance value, the manner in which the voltage generated at the connection point C rises changes, and the time required to reach the reference voltage also changes.

When it is assumed that there is an influence of reciprocity law failure in the above-mentioned manner, even if the appropriate light amount changes depending on the film sensitivity, the light amount which is much smaller than the appropriate light amount on the film is set as the appropriate light amount. Can be given. That is, when the subject is at a short distance, a large amount of light is reflected and returned, so that a large current flows. At this time, if the resistors R7 to R9 are properly selected according to the film sensitivity, the rising time of the voltage generated at the connection point C can be made earlier than in the conventional case.

The procedure for obtaining the film sensitivity information will be described with reference to FIG.

In FIG. 4, when a film is loaded, the sensitivity of the loaded film is recognized by the sensitivity recognition unit 120. Based on the recognized sensitivity information, one of the resistors in the light amount integrating section 403 which constitutes the light amount control means shown in FIG. 3 is selected. FIG. 4 is a flowchart showing the procedure at that time.

First, when the film is loaded, the film sensitivity information is read by the film sensitivity recognition unit 102 from the film. This process is performed in step S401.

In the next step S402, the film sensitivity information is coded and stored in a non-volatile memory (not shown), and the content of the non-volatile memory (not shown) is read and used when necessary. To be done.

Then, in the next step S403, the SV value is calculated. In the camera of this embodiment, the SV value is adopted as the sensitivity calculation factor instead of the ASA value. The correspondence between the SV value and the ASA value, which represent the film sensitivity, is as shown in Table 1.

The SV value indicates the film sensitivity like the ASA value. For example, if the SV value is 3, the ASA value is 2
Corresponds to 5. Further, the SV value corresponds to 9 for a high-sensitivity film having an ASA value of 1600.

[0069]

[Table 1]

First, in step S404, it is determined whether the film is a special film. If it is a special film, the process proceeds to step S405 and the SV value calculated based on the sensitivity information read from the special film is SV +.
Replaced with a value of 1. In the case of a special film, the light amount integrating section 40 can be set at a high sensitivity by adding 1
3 is designed to work.

If the film is not a special film, the process proceeds according to the SV value calculated from the film sensitivity information recognized by the film sensitivity recognition unit 120.

In steps S406 to S412, a high level signal is output from at least one of the output terminals ISO1, ISO2 and ISO3 of the microcomputer 100 according to the SV value calculated in step S403.

For example, when the calculated SV value is a low-sensitivity film of 3, the film is advanced to the No side in step S406 and proceeds to step S413. At this time, all high-level signals are output from the output terminals ISO1 to ISO3 of the microcomputer 100. Then, the resistances R7 (100Ω), R8 (200Ω), and R9 (40) of the light quantity integrating unit 403.
Each resistance of 0Ω) is connected. At this time, the resistors are combined and the resistance value becomes about 57Ω. At this time, the circuit having the smallest resistance value is selected from the circuits forming the light quantity integrating unit. Therefore, in the case of the low-sensitivity film, the rate of increase in the voltage at the connection point C is the slowest.

When the calculated SV value has a high sensitivity of 9 or more, a high level signal is output only from the output terminal ISO3 of the microcomputer and only the resistor R9 (400Ω) is connected. At this time, the circuit having the largest resistance value in the light amount integrating section is selected. At this time, the rate of increase of the voltage at the connection point C becomes the fastest.

In this way, at least one of the three resistors R7 to R9 is selected according to various film sensitivities, and various flash emission times are set by the light quantity integrating section 403.

Here, the value of the resistance connected in parallel is 10
Since they are 0 Ω, 200 Ω, and 400 Ω, if these resistors are properly combined, a resistance value of about 57 Ω to 400 Ω can be selected. Therefore, conventionally, the light amount is reduced at a constant ratio with respect to the film sensitivity to cope with the reciprocity law failure, but in the present invention, the ratio for reducing the light amount is variously set by switching these resistors R7 to R9. can do.

How the flash light emission is controlled after the setting of FIG. 4 is performed will be described with reference to FIG.

FIG. 5 is a flow chart showing the procedure of flash light emission control.

Each reference numeral shown in the flow chart of FIG. 5 is the same as the reference numeral attached to the output terminal of the microcomputer 100 shown in FIG.

When the flash light is emitted from the flash according to the detection result of the photometric unit 60 shown in FIG. 2, first, the program for flash emission from the flash is started.

When it is determined in step S501 in FIG. 5 that flash light emission from the flash is necessary and the process proceeds to the Y side, a low level signal is first output from the output terminal AST_OFF of the microcomputer 100. At this time, the NPN transistor Q6 forming the latch circuit shown in FIG. 3 is turned off, and the latch circuit becomes inoperative.

Then, in the next step S502, a low level signal is output from the output terminal FT. Then, the PNP transistor Q2 operates, and the operation of this transistor also operates the NPN transistor Q3.

The signal output from the output terminal FT of this microcomputer corresponds to the flash light emission instruction.

Then, in the next step S504, time adjustment of 15 μs is performed.

After 15 μs, a low level signal is output from the output terminal AST_ON in the next step S505.
Here, when a low level signal is output from the output terminal AST_ON, the phototransistor 40c is in the operating state. That is, the amount of light reflected back to the subject when the flash light is emitted from the xenon tube 40a is detected by the phototransistor 40c.

At this time, AST_OFF is opened (OPEN)
To be done. At this time, the latch circuit becomes operable. When a low level signal L indicating a flash light emission start instruction is output from the output terminal FT of the microcomputer 100, the change in the signal is transmitted to the IGBT Q1 via the latch circuit.

Up to this point, when the flash emission is started,
This is the processing when the IGBT Q1 is started and flash light emission is started. Since the flash light emission is performed, the light amount of the flash light emitted by the phototransistor 40c is reflected by the subject and returned. At this time, the stop timing of flash light emission is automatically generated in the light amount control means based on the amount of return light received by the phototransistor 40c. In S507, the maximum value of the time required from the start of the flash emission to the stop thereof is shown. Here it is 7 ms.

In step S508, the microcomputer F
A processing time required for flash light emission is counted by a timer, for example, when a low level signal is output from the T terminal as a start time. Then, when the value of the clocked timer reaches 7 ms, the subsequent steps S508-
A reset operation is performed in S510.

Since it is necessary to reset the light quantity control means in preparation for the next flash emission, the light quantity control means is reset in steps S508 to S510.

First, in step S508, the connection of the output terminal FT is opened. When the connection of the output terminal FT is released in this way, the PNP transistor Q2 and the microcomputer 100
And are disconnected.

The same processing is performed at the other output terminals. The output terminal AST_ON is opened, and the phototransistor 40c becomes inoperative.

Further, since the low level signal is output from the output terminal AST_OFF and the NPN transistor Q6 becomes inactive, the latch circuit becomes inactive.

After the above processing is completed, the next flash light emission timing is awaited and the series of processing from steps S501 to S510 is repeated.

As described above, the flash light emission time can be changed according to the film sensitivity information, and when the amount of returning light is large, the phototransistor 40c can be changed according to the amount of light.
It is possible to set the flash emission time according to the film sensitivity by changing the voltage generated by the current output from the.

[0095]

As described above, since the reduction ratio can be changed according to the film sensitivity, it is possible to further reduce the light amount when the film sensitivity is high and to provide the film with a high film sensitivity. Even so, it is possible to provide a camera capable of eliminating the influence of reciprocity law failure.

[Brief description of drawings]

FIG. 1 is an external perspective view of a camera, which is an embodiment of the present invention, as viewed from diagonally above the front surface.

FIG. 2 is a configuration block diagram of a control unit.

FIG. 3 is a circuit diagram showing a light emitting unit and a charging unit controlled by the microcomputer of FIG.

FIG. 4 is a flowchart showing a procedure of film information sensitivity recognition processing performed by the film sensitivity information recognition unit of FIG.

FIG. 5 is a flowchart showing a procedure from flash emission to stop of flash emission and preparation for next flash emission.

[Explanation of symbols]

1 camera 20 lens barrel 201 finger rest 21 Shooting lens 30 Release button 40 Flash emission part 40a xenon tube 40b light emitting unit 40c phototransistor 40d main C 40e charging unit 41 protector 50 flash receiving window 60 Metering unit 61 Light receiving window 71 Finder objective window 72 Finder eyepiece window 80 film unit outlet 91 Aperture setting dial 91a Index 92 Light emitting element 100 microcomputer 102 Film sensitivity recognition section 401 charging circuit IC 402 battery 403 Light intensity integrating unit

Claims (3)

[Claims] 1. A dimmable flash device for emitting flash light toward a subject and stopping the flash light emission at a timing when a predetermined amount of light is reached, and guiding the subject light onto a loaded photographic film to bring the light onto the photographic film. In a camera that takes a picture, the sensitivity of the photographic film on the marking is set, or the sensitivity recognition unit that recognizes the sensitivity by detecting the sensitivity on the marking, and the marking of the photographic film during short-distance shooting. When the amount of light is lower than the appropriate amount of light required from the above sensitivity, and when the photograph is taken on a photographic film having a marked sensitivity of a predetermined sensitivity or higher, when a photograph is taken on a photographic film having a sensitivity lower than the predetermined sensitivity. In comparison with the above, the camera is provided with a light amount control means for stopping the flash light emission at the timing when the light amount is obtained by further reducing the light amount ratio from the appropriate light amount. 2. A light sensor for receiving the flash light emitted from the light amount control means toward a subject, reflected by the subject, and returned, and a light sensor which is connected in series to the sensor and integrates the received light amount of the light sensor. A capacitor, a plurality of resistors connected in series to the capacitor and connected in parallel to each other, and a flow path of a current flowing through each resistor connected in series to each of the plurality of resistors are shown on the photographic film label. The camera according to claim 1, further comprising a plurality of switch elements that are connected and disconnected depending on the sensitivity of the camera. 3. The camera according to claim 2, wherein the plurality of resistors have different resistance values.