JPH0616148B2 - Strobe control circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shutter control circuit, and more particularly to a strobe control circuit for generating a strobe trigger signal for giving a proper exposure amount during stroboscopic photography.

Conventionally, the flash trigger signal of the shutter is the time at which information such as distance, film sensitivity, guide number, etc. required for flash shooting is input to the shutter control circuit as an analog voltage or current, and the trigger signal is generated by analog calculation. Is making. In the case of such a system, since an analog signal is handled, the performance is likely to change due to temperature characteristics, voltage characteristics, etc. of each element, and therefore a circuit or the like for compensating for them is required.

In recent films, a large number of contacts are provided on the surface of the cartridge, the film sensitivity is coded in the state of these contacts, and a switch group is provided so that the film sensitivity can be automatically read. . In order to perform analog calculation of such a film sensitivity by the conventional method as described above, it is necessary to perform DA conversion once,
This DA conversion accuracy, the contact resistance of the switch, and the like pose problems. Further, in the case of such a system, the time that can be created by analog calculation is a time that changes in an equal difference with respect to the input shooting information (for example, the film sensitivity is 2 times, 4 times, ...
・ When it becomes, it is difficult to make only the time that becomes 1/2, 1/3, ...) and the time that changes proportionally (1/2, 1/4, ...). The opening of the sector needs to correspond to this, and it cannot be applied to a shutter driven by a step motor in which the opening amount of the sector does not have a regular constant relationship with respect to time. That is, when the sector is operated by intermittent power like a step motor, the sector opening changes in a pulsating manner due to backlash and inertial force of each component, and is not regular but irregular depending on each shutter type. This is because it opens and closes in a waveform.

The present invention aims to eliminate the above-mentioned drawbacks.

According to the present invention, the distance required for stroboscopic photography, the film sensitivity, the strobe guide number, the lens open F value, etc. are input to the arithmetic circuit as a digital amount coded by means such as a switch, and the arithmetic values are used in advance. Corresponds to the opening and closing stroke of the sector to be set. Data that determines the flash emission timing is selected from the data storage means, and the selected data is preset in the timer circuit. The timer circuit starts operating in synchronization with the operation of the stepping motor, and generates a strobe trigger signal at the end of the timer operation. The data preset here is a value that corresponds to the way the sector is opened.
The sector gap does not have to have a regular relationship with time.

The present invention will be described below with reference to the embodiments shown in the drawings.

First, the structure of the shutter shown in FIGS. 1A and 1B will be described. 1 is a shutter base plate, and a front plate 2 for holding a lens is attached to the base plate 1 by screws. The base plate 1
And in the center of the front plate 2 an opening 0 for the lens is formed. At the same time, a sector room R for storing a sector 3 described later is formed between the two. A sector ring 4 is rotatably supported by the front plate 2 and is urged clockwise by a spring 7 so as not to slip out by a retaining ring 5.

The sector ring 4 has a deciding portion 4a which regulates a rotation range in relation to a pin 6 fixed to the base plate 1, a sector pin 4c and a tooth portion 4d which will be described later. The sector pin 4c penetrates the front plate 2 and engages with the sector 3 in a shaft-groove relationship. The sector 3 is rotatably supported by a sector pin 8 fixed to the front plate 2. In the figure, two sectors 3 and 3b are used to determine the opening. 9 and 10 are the first gear and the second gear,
The pinion 9a of the first gear is meshed with the tooth portion 4d of the sector ring described above, and the first gear 9 is the pinion 10a of the second gear. Is meshing with. A pinion 13 is attached to a rotor 22 of a motor M, which will be described later, and meshes with the second gear 10. Also, 1
A column 5 is fixed to the front plate 2 and has a female screw portion for mounting the motor.

Next, the structure of the motor M shown in FIGS. 2A and 2B will be described. Reference numeral 16 denotes a motor base plate which has mounting holes 16a for engaging the above-mentioned pillars 15 and guides the positions of the two stators 17 and 18 and the motor upper plate 19 which will be described later and the above-mentioned stators 17 and 18. It has a guide pin 21. Reference numeral 22 denotes a magnet rotor, which has N and S two poles magnetized on the outer periphery and is fixed to the rotor shaft 23. The rotor shaft is rotatably supported at the upper end thereof by the motor upper plate 19 and at the lower end thereof by the motor base plate 16 and penetrates the base plate 16, and the pinion 13 described above is provided at the tip thereof.
Is fixed. The two stators 17 and 18 are arranged at regular intervals from each other and have their respective legs 17a and 18
The first and second coils L1 and L2 are inserted in a. Magnetic poles for driving the rotor 22 are formed in the central portions of both the stators, and the details thereof will be described below.

First, the shape of the first stator 17 will be described.
A hole 17b having a certain clearance is formed at the center of the outer circumference of the rotor 22. And the outer contour of the central part is about 45 degrees with respect to the reference axes X and Y, near the Q1 axis,
Narrow width portions 17c ¹ and 17c ² for narrowing the magnetic flux are formed, and thick portions 17d ¹ and 17d ² are formed near the Q ₂ axis orthogonal to the Q ₁ axis. As a result, in the central portion of the first stator 17, the thick portions 17d ¹ ,
17d ² can act as a magnetic pole. Further, since the second stator 18 placed below has the narrow width portions 18c ¹ and 18c ² formed near the Q1 axis, the magnetic poles 18d1 and 18d ² of the ^second stator are the magnetic poles 1 of the first stator.
It is provided so as to be orthogonal to 7d ¹ and 17d ² . That is, the poles of the rotor 22 have the coils L ₁ , L ₂
If no current flows through the magnetic poles 17 of both stators
It can be stopped by every 90 ° by being pulled by d ¹ , 17d ² or 18d ¹ , 18d ² . In addition, the magnetic poles 17d ¹ , 17d ² or 18 of both the stators 17 and 18 are
d ^1, the foot portion 17a described above is from 18 d ^2, 18a elongation, its tip is short-circuited by the iron core 24, a magnetic circuit is formed. Then, these members are first placed while positioning the second stator 18 in which the coil Lb is inserted into the motor base plate 16 by the guide pin 21, and then the first stator 18.
Place the stator 17 in the same way, further place the iron core 24 on it, insert the rotor 22 in the center, and place the motor upper plate 19 on it and tighten it with screws 25 Configured as. After the pinion 13 is fixed to the tip of the rotor shaft of the motor block thus formed as described above, it is attached to the pillar 15 on the base plate 1 with a screw to form a shutter mechanism.

Next, the circuit diagrams shown in FIGS. 3A to 3K will be described. FIG. 3A is a diagram showing the entire circuit of the embodiment of the present invention.
01 is a microprocessor, 102 is a brightness detection circuit,
Reference numeral 103 is a motor drive circuit, and the microprocessor 101 will be described first. FIG. 3 (B) shows the internal structure of the microprocessor 101, which is a normal single-chip microprocessor function to which a peripheral circuit is added. Reference numeral 104 denotes an oscillator including a ceramic oscillator or a crystal oscillator, and a clock generation circuit, which generates various clock signals required inside the microprocessor 101. Reference numeral 105 is a program counter, which controls a program ROM 106 (hereinafter referred to as P-ROM), and 107 is an instruction decoder, which controls the inside of the CPU according to the instruction output from the P-ROM 106. 108 is an arithmetic / logical operation unit (hereinafter referred to as ALU), 109 is an accumulator, 110 is a register for setting flags such as carry and zero, 111 is a register, 112 is RAM, 11
3 is an output port having a plurality of output terminals, 114 is an input port having a plurality of input terminals, and 115 is an internal bus.

Generally, the circuits 104 to 115 described above are inevitably included in a single-chip computer, and their applications and functions are well known and will not be described in detail here. Reference numeral 116 denotes a ROM (hereinafter, referred to as D-R) in which various data necessary for controlling the shutter are written, as described later.
OM) 117 and 118 are programmable logic arrays (hereinafter referred to as PLA1 and PLA2), and outputs outputs according to the input conditions of the plurality of input terminals IA0 to IA4 and IN0 to IM3 on the bus line 115. Yes (use will be described later). 119 is a counter, 12
0 is a motor control circuit, 121 is a programmable timer (can be used as a timer or counter), 1
Reference numeral 22 is a timer control circuit, the operation and function of which will be described later. Each circuit of 116-122,
Although not specific to any microprocessor, both are connected to bus lines and function as part of the microprocessor. Note that the bus line is 4 bits since it does not require so much information processing for a camera. For convenience of explanation, all input terminals are assumed to have pull-up resistors built-in unless otherwise specified.

Next, a concrete example of the luminance detection circuit 102 shown in FIG. 3 (A) is shown in FIG. 3 (C), and its operation will be described with reference to FIG. 3 (D). (Note that elements with the same number are the same element.) The luminance detection circuit 102 is a circuit that generates a pulse having a pulse width corresponding to the amount of light received by the light receiving element 123 (Cds in this example). A voltage proportional to the logarithm of the amount of light received by the light receiving element 123 is generated at the point. Reference numeral 128 is a logarithmic compression diode. Point b is the constant current source 125
And the connection point of the capacitor 124 are shown and are connected to the comparator 126 as shown. FIG. 3 (D) is a diagram showing the timing of the above circuit. As shown in the figure, the input terminal a changes from the Vss level (hereinafter referred to as L) to V
_When it changes to the _DD level (hereinafter referred to as H), the transistor 127 turns off, the potential at the point b decreases with time as shown in the figure, and when the potential becomes equal to or lower than the potential at the point c,
The output of the comparator 126 is inverted, and the point d has a waveform as shown by d in the figure. Of course, since the potential at the point c changes depending on the brightness, the potential at the point c decreases (indicated by c ') in the case of darkness and the pulse width becomes longer, and conversely becomes shorter in the case of brightness. As described above, since the light quantity is converted into a compressed voltage by the logarithmic compression diode 128, the width of the output pulse is inversely proportional to the logarithm of the light quantity. That is, the brightness is 2.4.8.1.
6 ... When doubled, the pulse width becomes 2, 3, 4, 5, ...
Doubled. However, when the brightness is extremely bright (indicated by c ″) or when it is very dark, the relationship between the light amount and the pulse width is also as described above because the relationship between the voltage and the current of the diode 128 deviates from the logarithmic relationship. There is a region out of the relationship.The range in which the above relationship is exactly established is the region of pulse width t ₁ shown in the figure and the time of t ₀ is the offset time, which is taken into consideration when converting the brightness into a digital amount ( Note that this luminance detection circuit is a known technique, and in the present embodiment, it is used as a light receiving element C
Although ds is used, the same applies to a photodiode.

FIG. 3 (E) is a diagram showing a specific example of the motor drive circuit 103 of FIG. 3 (A), and FIG. 3 (F) is a diagram showing its timing. The signal φ ₀ is a motor switching signal, and as is clear from the figure, when this signal is L, all the transistors that drive the motor coils L ₁ and L ₂ are O.
It is FF. Therefore, φ ₀ is first set to H prior to the operation of the motor. After that, according to the signals of φ ₁ and φ ₂ , the coils L ₁ and L ₂ are excited and the shutter operates as in the example shown in the figure. The details of the shutter operation will be described later.
(Note that the coils L ₁ and L ₂ are assumed to be positively excited in FIG. 3 (F).) FIG. 3 (G) shows the configuration of the counter 119 and the motor control circuit 120 of FIG. 3 (A). 129 is a presettable 10-bit binary down counter, 131 is connected to the bus, and 131 is a data preset circuit for presetting data in the counter 129, which presets fixed data or appropriate data by an instruction. 132 is a right shift or a left shift selectable, a count completion signal that is generated every time the content of the counter 129 is down-counted and becomes 0, and is a 4-bit shift register that shifts right or left. 133 is a shift register 132 shift This is a switch for determining the direction, and the shift direction can be determined by an instruction, and can also be determined by a count completion signal from the counter 129. Reference numeral 130 is a latch circuit which is connected to the bus and whose output can be controlled by an instruction. This output is the motor control signal φ ₀ . Other motor control signals φ ₁ , φ ₂
Is a signal extracted from the shift register 132.

FIGS. 3 (H) to 3 (I) are a main flowchart showing a sequence of the present invention and a flowchart of a subroutine, and the circuit operation of the present invention will be specifically described below with reference to FIGS. 3 (A) to 3 (J). A description will be given together with the flowchart. First, when a release button (not shown) of the camera is pressed, the power switch S ₁ linked with this is turned on, and power is supplied to the microprocessor 101. At the same time, as is clear from FIG. 3 (A), the transistor Tr ₁ is turned off, the charging of the capacitor 135 is started, and after a certain period of time, the potential of the reset terminal R of the microprocessor 101 to which the capacitor 135 is connected becomes H, and the reset occurs. Is released and the program starts operating.
When the program starts to operate, the output of the power hold terminal PH first becomes H, the transistor Tr ₂ turns on, and thereafter, unless the output of the power hold terminal PH becomes L, the power supply becomes stable regardless of the state of the power switch S _1. Supplied. Next, the test terminals T _{1 to} T ₃ are read according to the program, and it is judged whether or not the test mode is set.
(The test mode will be described later, and it is assumed that the test mode is not set here.) If it is not the test mode, the process of opening prevention is executed, but this process is the process when there is an abnormality in the shutter, This will also be described later. If the shutter has no abnormality, this process also immediately passes and the next battery check is made. Generally, it is difficult to judge the degree of battery consumption by only looking at the open circuit voltage of the battery. Therefore, it is necessary to actually flow the load current to judge the battery voltage. In this embodiment, the motor control signal φ ₀
Is set to H, a current is caused to flow through the coils L ₁ and L ₂ of the stepping motor, and the voltage at that time is determined by the battery check circuit 136 in the microprocessor 101. The battery check circuit 136 is a known technique, and although not particularly described, it is configured to be H when the power supply voltage is equal to or higher than the check voltage and L when the power supply voltage is lower than the check voltage. If the output of the battery check circuit 136 is L, that is, the power supply voltage is low, the program jumps to the end, the power hold terminal PH is set to L, and the program is stopped. In this state, the power switch S ₁ Is O
If it is FF, no shooting is done. When the output of the battery check circuit 136 is H, that is, when the voltage is high,
Go to the next process. Although the coil current of the stepping motor was used as the load of the battery, in the case of the coil current, the load does not immediately flow even if the motor control signal φ _{0 is set} to H because it is a load having an inductance. The timing of reading the output of the battery check circuit must be an appropriate time after φ ₀ becomes H. (However, even in the case of a load that does not have an inductance, the battery voltage may drop with time, so this time must be taken into consideration.) If the battery voltage passes the battery check and the subject brightness is checked, ,
Start metering. Microprocessor 1 starts photometry
This is performed by setting the output terminal a'of the timer control circuit 122 of No. 01 to H according to the instruction. Since the output terminal a'is connected to the terminal a in FIG. 3 (C), the brightness detection circuit 102 operates as described above and outputs a pulse having a pulse width corresponding to the brightness to the output terminal e. Output.
The output terminal e is connected to the input terminal e'of the timer control circuit 122 of the microprocessor 101 shown in FIG. 3 (B). Since e'is a signal for forming the gate signal of the timer 121, a numerical value of 100 is set in advance in the timer 121, for example.
Then, the difference 30 becomes a numerical value corresponding to the brightness. However, as described above, in order to compensate the non-linearity with respect to the light amount of each element of the luminance detection circuit 102, the pulse width is offset, and therefore it is necessary to subtract this amount from the photometric value. If this amount is 10, 30-10 = 20 is a numerical value indicating brightness. The above-described work of converting the brightness into the number of pulses takes time, as is apparent from the circuit diagram, and is usually designed to have a number of several hundred μsec to several msec depending on the brightness. During this period, the microprocessor 101 has the ability to process a considerable amount of work, so as shown in the flow chart, only the signal for photometric start is issued, and immediately after that, the next "ISO"
Move on to the process. The work done here is to read the film sensitivity, and as a method of reading the film sensitivity, there is a method (automatic) to read the state (code) of the contacts provided on the cartridge with the new film as described above. , The input terminals IA _{0 to} IA ₄ shown in FIG.
A switch using contacts formed in the cartridge is connected, and a manual switch is connected to the input terminals IM _{0 to} IM ₃ . The most preferable method for determining which of the film sensitivities to be read from these two series is to be read automatically by the microprocessor 101, and the specific method is shown below.

The currently announced film speed code is
It consists of five contacts that represent film information and a common contact. Even if a film with any film sensitivity up to ISO25 ・ 32 ・ 40 ・ 50 ・ ・ ・ 5000 is selected, at least one contact always has the same potential as the common contact. It is configured to be. Therefore, if it is connected to the common contact V _SS , at least one contact becomes L, and if the common contact is V _DD , at least one contact becomes H. Considering the example were to V _SS a common contact to temporary, if the conventional film having no code contacts are used, IA ₀ ~ of FIG. 3 (A)
Since it is connected to IA ₄ and all switches are turned off, 5
The input terminals of all the bits become H. In this embodiment (the input terminal has a built-in pull-up resistor), the microprocessor 101 is a 4-bit microcomputer.
Read the 4 bits of A _{0 to} IA ₃ , add 1 to it, and if the carry flag is set, it can be judged that the film does not have a code contact, so it is sufficient to read the film information input with the manual switch, and then read it. Fig. 3 (I-
It is shown in the flowchart of 1). If the common contact is set to V _DD , in the case of a film having no code contact, all the switches connected to the input terminals IA _{0 to} IA ₄ are O.
Since it becomes FF, the 5-bit input terminal becomes L. (In this case, it is assumed that the input terminal has a built-in pull-down resistor.) Therefore, when 4 bits of IA _{0 to} IA ₃ are read and 1 is subtracted from them, a hollow occurs and the carry flag is set, It can be judged as a film without contacts. Further, as a feature of this film code, at least one of the two specific terminals has the same potential as the common contact regardless of the film sensitivity. Therefore, this feature can be used to determine which of the film speed information to read in a different manner than described above. As a method, if the common contact is at the _VSS level, the film sensitivity information manually set may be read only when both of the two specific terminals are “H”. By such a method, it is determined which series of information should be read from the film speed information set automatically or manually. In addition, the code indicating the film speed information is not necessarily entered as a code that is easy to do in the internal calculation as described later, and rather, if it is not considered as a series code completely different from the internal calculation code, it is a manual code. There is a restriction on the configuration of the switch, which is disadvantageous. Therefore, it is necessary to perform code conversion, and the code conversion is performed by the programmable logic arrays PLA1, 117 and PL shown in FIG. 3 (B).
A2 and 118. Even if the film speed information input from the two series of switch groups is another code series, for example, if both are ISO100, PLA1 and PLA2 are configured so that the same code can be read by an instruction. The ISO code read in this way is R
It is stored in the AM 112. (In this embodiment, the code conversion is performed using the programmable logic array, but if the code conversion is easy, it may be converted by a program. In this case, the PLA is unnecessary.)
Then, the microprocessor 101 has its input terminal
Read the T / W status. In the case of middle-class cameras, lenses cannot be exchanged in general, and I had to shoot with a lens with the same focal length for both portrait photography and landscape photography, but this does not always lead to sufficient photography. Instead, recently, there has been proposed a method of changing the focal length by moving a lens in and out of a photographing optical path as needed. In this case, since the open F value of the lens system changes, it is necessary to take that information into consideration when performing the exposure calculation. The role of the input terminal T / W is for this purpose.It indicates whether the lens system is on the telephoto side or the wide side. Generally, the wide side is bright, so when this is used as a reference, how dark becomes when switching to the telephoto side. In advance microprocessor 101
It is written inside the PROM and used for various calculations. It is assumed that the wide lens is selected when the switch S ₃ connected to the T / W terminal is ON, and the telephoto lens is selected when the switch S ₃ is OFF, and the telephoto lens is selected here. That is, S /
It is assumed that the T terminal is H. Further, it is assumed that the F value of the lens at wide angle is F2.8 and the F value of the lens at telephoto is F5.6. That is, the difference in F value is two steps, and since the lens on the telephoto side is selected now, the numerical value “16” corresponding to two steps in the code system described later is stored in the RAM. (If it is on the wide side, "0" is stored.)
The processing up to this point is completed immediately because the processing speed of the microprocessor 101 is fast (usually several μS to several tens of μS per step). The process shown in FIG.
As shown in the flowchart of (-2), when the photometry is completed, the output e of the luminance detection circuit 102 becomes eH. ) When the photometry is completed, the measured value is calculated by the method as described above. If the metering has not ended, check whether the metering value has exceeded the maximum value, and if not, wait for the metering to end, and this loop until the metering end or the metering value overflow is bypassed. repeat. Normally, the maximum photometric value is selected at the limit where the relationship between the light intensity and the pulse becomes non-linear as described above.Therefore, if the maximum value is exceeded, exposure may not be performed correctly. Also, the exposure time becomes too long and exceeds the practical range. Therefore, when the photometric value exceeds the maximum value, the photometric value is stopped at that point, and the maximum value of the photometric value is set to the predetermined maximum value.

In the case of the program shutter, the information required in the case of automatic photographing by natural light is sufficient if the brightness of the subject and the film sensitivity are known, but it is also necessary when the open F value of the lens changes as in the present invention. . Since these pieces of information have been clarified by the processing up to this point, the conditions for automatic photographing can be obtained, and the processing is performed in the next "EE calculation" processing.

Explaining the arithmetic processing method of the present invention, first, since the relationship between the brightness and the photometric value is logarithmically compressed, if other elements such as film sensitivity and F value are treated in the same manner, they can all be processed by the apex operation. It will be possible. In the case of using a microprocessor, in principle, multiplication and division are possible, but in reality the calculation becomes extremely complicated and it takes a long processing time. Therefore, it is convenient to be able to perform apex calculation and add / subtract processing. Therefore, in the present invention, the film sensitivity and the F value are once converted into a code capable of performing an apex operation for calculation. Specifically, if the film sensitivity to be used is, for example, the highest ISO1600 and the lowest ISO25, the ISO1600 is set to 0. And 8 is added every time the sensitivity is further lowered. That is, ISO160
0 for 0, 800 for 8, 400 for 16, 50 for 4
0 and 25 were set to a relationship of 48, and the difference in F value was also added by 8 for each step. As described above, if F2, 8 and F5, 6 are two steps, the difference is set to 16. In the case of film speed, there may be 1/3 and 2/3 stages of film between one stage, so in this case 1/3 stage is 3 and 2/3 stage is 5, and approximate values are It was realized. Therefore, the code becomes 35 in the case of ISO80 and 38 in the case of 64. As for the brightness as well, in the case of the highest brightness that can be measured, the brightness detection circuit 102 and the brightness detection circuit 102 are set so that the photometry value is 0 and the photometry value is incremented by 8 each time the brightness becomes half. The constants of the timer 121 and the clock frequency are set in advance. Then, for example, if the photometric value becomes 24 at a certain brightness and the film sensitivity is ISO100 at that time, the photometric value code L, the film sensitivity code S,
The code A and the sum Ex of the difference between the open F values are Ex = L + S + A
= 24 + 32 + 16 = 72 (when switched to the telephoto side). This sum Ex represents the exposure amount Ev because it is a program shutter, and if Ex = 72 and Ev13, the film sensitivity is ISO2.
If 00, Ex = 16 + 32 + 16 = 64,
Ev is also changed to Ev14. If the lens is on the wide side, A = 0. Therefore, Ex = L + S + A = 24.
At + 32 + 0 = 56, Ev = 15. Therefore,
The Ev value also changes by one step each time the operation code changes by 8, and an appropriate operation is performed. In the process of this “EE operation”, the above “L + S + A” is performed to obtain E, and the obtained Ex is R
Stored in AM112.

When the EE calculation is completed, the "shake" is checked to see if the shutter speed is slow and shakes. This is the same as checking whether the “Ex” value already obtained is greater than a certain value.
If the Ex value is larger than the shake limit value, the strobe is used, so the SC terminal is checked to see if the strobe has been charged. If the strobe has not been charged, the L1 terminal is set to H and the light emitting diode LED1 is turned on to give a warning. Under such a condition, even if the photograph is forcibly taken, camera shake occurs, and an appropriate photograph cannot be taken. Therefore, the program jumps to the step indicated by and the photograph cannot be taken as in the case described above. If the strobe has been charged, a process for obtaining distance information necessary for strobe photography is executed. The distance information is obtained from an autofocus circuit (not shown), and is input as parallel data encoded in the input terminals AF _{0 to} AF ₃ of the microprocessor 101. However, the code entered here has a distance It is necessary to have a series that increases by 8 each time, but the range is generally 0.8m to 4.5m, so if 0.8m is code 0, 4.53m will be coded. It must be 40, but if the code exceeds 15, it cannot be handled with 4 bits, and it is not easy to perform such code conversion by the autofocus circuit. For example, if the distance measurement series of the autofocus circuit is 0.
8, 0.9, 1.0, 1.1, 1.2, 1.5, 0.
If the lengths are 7, 2.0, 2.5, 3.0, 4.0, and 4.5 m, if codes of 0.1, ... Can be selected, and there is no particular problem even if the distance exceeds 4.5 m and becomes 6 m or 8 m, and it is easier to make such a sequential code for the autofocus circuit. However, in the case of a code representing such an order, since it cannot be used as it is as an operation code, it is necessary to convert the code, and the code after conversion has a distance as described above. It must be a series that is incremented +8 each time.

This code conversion is performed using the D-ROM 116. A specific method thereof will be described later, and the description will be continued here assuming that the code conversion has been performed. The code-converted data is used in the processing of the next “FM calculation”. The “FM calculation” means the film sensitivity, the distance to the subject at the time of flash photography, and the flash guide number from the flash guide number.
This is an operation for obtaining a value. However, in the case of the present invention, since it is an electric shutter, there is no mechanism for mechanically stopping the sector so that the F value obtained from the calculation is obtained, and the F value obtained in the process of opening the sector. When the position becomes
An appropriate F value can be obtained by issuing a trigger signal for causing the strobe to emit light, and the sector is configured to open until fully open and then close. Therefore, the exposure amount (exposure time) is set to a specific value irrespective of the value “Ex” obtained by the EE calculation described above. Between the guide number GNO, the distance D, and the aperture F, F = G
The relationship of NO / D is established, and if the camera has a built-in flash like a recent camera, the guide number is constant, so if the distance is determined, the aperture is also automatically determined. Since it is difficult for the microprocessor to perform division, if you make a correspondence table for distance and aperture instead, you can easily obtain aperture. However, since it is necessary to consider the film sensitivity, the "FM calculation" is performed by the following equation. If the desired aperture code A _FM is used, the film sensitivity code S, the distance code D, and the difference A of the open F value are the codes A.
The relationship of A _FM = S + D + A is established between and. Here, with respect to the code A _FM of the diaphragm, the area of the diaphragm increases as the value of the code increases, and the area of the diaphragm decreases with the decrease of the code value. Further, the aperture increases by one step each time the value of AFM is added (for example, F
16 → F11) Necessary. Therefore, for example, ISO
Aperture required at 100 and distance of 1.4m is F16
When the distance is 2m, the aperture becomes F11,
If the ISO is 200 and the distance is 1.4 m, it becomes F16. However, in the above formula, the code value of the aperture is obtained, and the aperture itself is not obtained. The diaphragm is obtained by a correspondence table in the D-ROM 116 described later. If the aperture of the AFM is equal to or larger than the open F value of the lens, the AFM is set to AFM if the open F value is 49.
= 49. As described above, when the aperture required by the calculation is brighter than the open aperture value of the lens, even if the aperture is fully opened, the amount of light will be insufficient, and a warning is issued.
(This is shown as a "outside linkage warning" in the flowchart.) Next, in the case where the brightness is such that the camera shake does not result in the "camera shake" determination, the process proceeds to the determination as to whether or not there is backlight. The information that the backlight is
When the subject is on the back of the sun, the photographer inputs with SW or the like. If there is no backlight, the exposure time is determined based on the calculated value Ex described above. Of course, no strobe is needed.

Next, regarding the processing in the case of backlight, the exposure time is determined by the calculated value Ex, as in the case of not using a normal strobe, and the strobe which is auxiliary light is controlled according to the distance to the subject. . Therefore, the maximum opening of the sector may have various sizes depending on the brightness of the entire screen at that time. However, in order for the flash light to be appropriate, it is necessary to emit light with the aperture value obtained by the above-mentioned method, but the sector may not be opened to that extent. For example, when the maximum aperture of the sector is F5.6 and the aperture value at which the strobe light is appropriate is F4, that is, the maximum aperture aperture obtained by EE shooting is larger than the aperture aperture required for the flash. If it is small, the flash is emitted when the sector is most opened under the EE shooting conditions (mountain emission). In the opposite case, for example, when the aperture size required for the strobe is F8 and the maximum aperture size obtained by EE photography is F5.6, the strobe emits light at a timing such that it becomes F8 (hillside emission). What has been described above is shown in the flow, and "Tsync ← TsyncFM" means that the above-mentioned mountainside emission is set, and "Tsync ← TsyncEE" means that the above-mentioned peak emission is set. When emitting light from the mountaintop, it may be possible to issue a signal that causes the strobe to emit light when a signal that causes the stepping motor to rotate in reverse is issued, but in that case, there is a delay between the electrical inversion signal and the stepping motor (sector) inversion. Therefore, there is a difference in the time from the output of the reverse rotation signal until the stop aperture reaches the peak, and the difference varies depending on the backlash and inertial force of each component and is not uniformly determined. Therefore, the TsyncEE data has a value corresponding to the opening of the sector obtained by the pre-sampled shutter and the delay is taken into consideration. Furthermore, since TsyncEE can be freely determined, it can be designed so that there is no error even with a small diameter and a large diameter.

The operation up to this point is automatically and continuously performed after the power switch is turned on. It should be noted that although various warnings and displays have not been particularly described, they may be processed as necessary.

A determination that the flow chart of the next step "S ₂ ON" is, in the step of the release switch S ₂ to see whether the ON, After the release switch S ₂ is ON, the process moves to the next shooting mode. However, since the release switch S ₂ is connected to an input circuit having a chattering prevention function and a latch function, the power switch S ₁ and the release switch S ₂ are turned on for a short time (several tens of ms) and then turned off immediately. You can also shoot with the so-called "Jung push" or "fast push". Also, based on this judgment, the release switch S ₂
Is not turned on yet, the power hold is released after that, so the power switch S ₁ is turned off.
Then, the whole circuit is turned off, and it ends with only photometry. When the release switch S ₂ is turned on, the power hold signal is output again, and a series of operations is performed until the end of the predetermined operation regardless of the state of the power switch S ₁ . After the power hold signal is output, if the self-timer switch Ss shown in FIG. 3 (A) is ON, the self-timer mode is in effect and the self-timer operates. If the self-timer switch Ss is OFF, the next Go to processing. The process called "self-timer" measures the time of about 10 seconds, displays the fact that it is in the self-timer state, etc., and then starts the next process, as in the case of a normal self-timer. The next process called “release MgON” is a process of turning on the electromagnet (release magnet) for releasing the taking lens, and the release magnet is O
When N, the lens is stopped by the signal from the autofocus circuit when the taking lens moves to the required focus position.
Here, the microprocessor is tasked with only issuing a signal to initiate the movement of the taking lens.
Then, when the movement of the lens is completed, the autofocus circuit generates a completion signal. When the movement of the lens is completed, the next "date lamp" process is performed. This process
Depending on the film sensitivity read before, the ON time of the imprinting lamp when imprinting the shooting date etc. on the film is shortened for high sensitivity, long for low sensitivity and given an appropriate exposure amount. is there.

In the next process "exposure", the sector is actually operated by the step motor to perform exposure. A detailed flowchart is shown in FIG. 3 (I-3).

First, "select", that is, the counter 129
Select the clock frequency input to. The selection criterion is to select a slow clock frequency if the exposure time is long and a fast clock frequency if the exposure time is short, depending on the calculated exposure amount at that time. Subsequently, the signal φ ₀ of the step motor becomes “H”, which excites the step motor,
This state is maintained for 10 mS. The purpose is to operate the step motor stably. The static position of the rotor immediately before excitation is determined by the static pulling torque of the rotor magnet and the stator, so it is easily affected by friction and load,
The position is not always fixed. If the start position of the step motor is not constant, the exposure amount naturally varies. Since a large force works when excited, the stop position becomes a constant position, but it takes some time until the stop position stabilizes immediately after moving from the stationary position to the stop position by excitation.
If the next pulse is generated before it stabilizes, the exposure amount is large. That is, there is no problem in the case of low Ev, but the exposure amount is small, that is, the exposure amount varies in the case of high Ev. Therefore, in order to obtain a stable exposure amount, it is necessary to take sufficient time for the rotor to stabilize. Next, it is checked whether or not the strobe is used, and when it is used, the time data for firing the strobe is set in the timer 121,
The timer 121 is started. Here, the timing of the start of the timer becomes a problem, but this may be performed at the same time as the start of the stepping motor, or may be shifted by a fixed time. If it is shifted, it is necessary to correct the time data accordingly. In addition, the data set in the timer is based on the calculation result described above, and the D-ROM
It is accessed from 116, including other data,
Here, the configuration and usage of the D-ROM will be described.

FIG. 3 (J) shows an example of the configuration of the D-ROM 116. D
-ROM 116 consists of 16 bits x 256 words, and the whole is divided into 4 blocks as shown in a to d of the figure. In the block a, information regarding the exposure amount, that is, control information of the stepping motor is written, and the information includes the number of steps Ns indicating how many steps the stepping motor is rotated and the width T of the driving pulse at the time of changing the direction.
It consists of d and. This information is selected (accessed) by Ex obtained from the EE operation described above, that is, E
When the value of x is small, the number of steps Ns is small because the exposure amount is high Ev, and when the value of Ex is large, the number of steps Ns is large because the exposure amount is low Ev. Normal,
The range of the exposure amount that must be controllable is approximately Ev19 to 3, and if 1Ev is divided into eight, the type of exposure amount becomes 16 × 8 = 128 types. An appropriate exposure amount is selected (accessed) from the 128 types of exposure amounts according to the value of “Ex”. Therefore, Ex = 0 to 12
7 In this embodiment, the number of steps Ns is 4 bits and the pulse width Td is 10 bits.

The block b will be described below. Here, the time information Tsync (F) for creating the timing for triggering the strobe in the shooting mode in which the sector is fully opened and closed is described.
M) is written.

This information Tsync (FM) indicates the timing at which the blade reaches a certain aperture value F during the process of opening the exposure blade,
A type equivalent to F2.8 to F22 required for stroboscopic photography is necessary, and if one stop is divided into eight, a total of 6 (steps) x
8 + 4 = 49 kinds of data, which are written as data corresponding to the way of opening the sector having the previously obtained relationship as described above, and this data is the calculated value A described above.
It is selected (accessed) by a value AFM ×, which is obtained by adding a constant value C ₀ to FM. In addition, other information necessary for backlight photography is also written in this block, and this information is used when comparing the maximum aperture diameter obtained by EE photography with the aperture diameter required for the flash. To compare the aperture size,
You have to know the maximum aperture size that can be obtained by EE shooting, but you cannot know it with the "Ex" that is obtained from the EE calculation. Therefore, when you obtain the aperture size required for the strobe from AFMx, it will be the same address. A value E ₀ corresponding to the calculated value “Ex” of the EE calculation that becomes the same as the aperture diameter is written. Therefore, if EE ≦ E ₀ , the aperture diameter required for the strobe is larger, and thus the above-described peak light emission occurs, and if Ex> E ₀ , the hillside light emission occurs. In the case of hillside emission, since the aperture is used in the process of opening the sector, Tsync (FM) is used as the timing to trigger the strobe, and the timing to emit light from the mountaintop is shown in block c. (EE). When emitting light at the summit, a value E obtained by adding a constant value C ₁ to E ₀
Data Tsync (EE) with address ₁ is obtained. Note that T
sync (FM) and Tsync (EE) are 9-bit data, and E ₀ is 7-bit data.

The block d is for converting the order code of the distance obtained from the autofocus circuit into the operation code as described above, and the data whose address is the value obtained by adding the constant value C ₂ to the order code DAF is the order. It is an operation code corresponding to the distance indicated by the code DAF. It should be noted that the operation code is considered to be sufficient if it has about 7 bits, although it depends on the range of distance. Also, the size of the D-ROM is 16 bits x 25
Although it is set to 6 words, since 16 bits in 1 word are not all used as described above, the number of bits per word may be reduced to increase the number of words, and there is flexibility in the configuration. , The most rational way. As described above, the reason why the D-ROM is used to control the exposure time, the strobe light emission timing time, and the like is that the way the sectors are opened is not constant with time. That is, if the shutter opening area is opened in a constant relationship with the driving pulse number of the stepping motor, D-
It is not necessary to control the closing using the data of ROM,
The closing timing can be determined only by the time generation means and the exposure information. However, if the relationship between the stepping motor and the sector is designed so that the shutter opening has a constant relationship with respect to time, a simple train wheel is not sufficient for the transmission mechanism between them, and the transmission mechanism becomes complicated. The same applies to the flash emission timing, and since the relationship between time and aperture is not constant, a D-ROM is required. Returning to the "exposure" flow again, when the operation of the counter 119 is started, this is directly connected to the motor control circuit 120 as described above, and the step motor control is performed via the motor drive circuit 103. The sector begins to operate at the stage.
To explain according to the flow, “forward rotation pulse output” is to output a pulse having a constant pulse width (for example, 2 mS) as described above, and the number of output pulses is
The number of steps N written in the above-mentioned D-ROM 116
s. After outputting the pulse for a predetermined time for Ns steps, the width Tv of the drive pulse at the time of changing the direction of the D-ROM 116 is set in the counter 119, and the down counting is started. The counter 129 is down-counted, and when the counting is finished, a count completion signal is generated, and this signal causes the shift register 133 to reverse the shift direction and shift the content by one bit. The subsequent "reverse rotation pulse output" is the same as the "normal rotation pulse output", and outputs a pulse for a fixed time by the number of steps Ns.
The relationship between the pulse and the aperture diameter at this time is shown in FIG. 3 (K).
(The motor drive signals φ ₁ and φ ₂ in the figure are written in the same timing as in FIG. 3 (F), so the excited states of the coils L ₁ and L ₂ can be seen in (F).) The number of output pulses is positive.・ Because the direction was changed by reversing, the timing should originally match the diagram showing the relationship between the diameter and time, but the mechanical system has a delay in response, so a deviation occurs as shown in the figure. ing. That is, "forward rotation pulse output" is a signal for opening the shutter, and "reverse rotation pulse output" is a signal for closing the shutter. After outputting a predetermined reverse rotation pulse, the state is continued for 10 mS. This is when the rotor is stopped from rotating and the coil is not excited.
A strong position regulation force does not work, it stops while damping with a relatively large amplitude and a long cycle, the sector moves in conjunction with the movement, and the phenomenon that the shutter closes once and then opens again (re-exposure) is likely to occur. However, if the coil is excited, a strong position regulating force works, so that the above-mentioned problem does not occur. With the above, the exposure routine is completed, and then "opening prevention"
Enter the process. "Opening prevention" is a process when the shutter is not closed for some reason, and is processed by observing the state of the home switch SWH that is turned on only when the sector is closed. As described above, the "opening prevention" process is the same in both cases, although it is also at the beginning of the flowchart.

FIG. 3 (I-4) shows a flow chart for prevention of opening.
If the home switch SWH is ON, this routine is skipped as it is. If the home switch SWH is OFF, the step motor is rotated in the reverse direction by one step, and then, in this routine, whether or not the reverse rotation pulse is output up to the specified number MAX. If it is equal to or less than NMAx, it is checked again whether the home switch SWH is ON or OFF. If the home switch SWH is ON, the process returns to the main routine, OF
If F, the output of the reverse pulse is repeated again. The reason for setting the limit NMAx to the number of times of repetition is that if the step motor fails and does not move at all, the home switch SWH does not turn on no matter how many pulses are output, and the program does not continue from this part. This is to prevent
In this case, it jumps to the step from the failure.

When the opening prevention routine is passed, the excitation signal φ ₀ of the step motor is set to “L”, and then the power hold terminal P
When the H output becomes L, the transistor Tr ₂ is turned off, and the power switch S ₁ is turned off, immediately when it is not turned off, when it is turned off by returning the release, the entire circuit is turned off, and the whole operation is completed. .

The test mode, which has not been described so far, will be briefly described. The purpose of this test is to measure the performance of the shutter and the like. A specific exposure (for example, Ev16) is realized depending on the condition of the test terminal. Or, it has a function of outputting a strobe signal of a specific aperture in FM mode, and is used for measurement and adjustment.

As described above, the code value necessary for flash photography such as distance information is calculated, and the data accessed from the D-ROM is preset in the timer circuit as a result, and the flash emission timing is selected when the timer operation is completed. Therefore, unlike the case of calculating with an analog amount, it is not affected by temperature, voltage characteristics, etc., so that a compensating circuit is not required, sufficient calculation accuracy can be obtained, and reliability is high. Further, since the light emission timing can be freely set by the data stored in the data ROM, even if the shutter mechanism is not regularly operated, the timer is corrected by the data corrected corresponding to the opening and closing strokes of the sector. It is preset and controlled in the circuit, and can be finely controlled regardless of the drive pulse of the step motor, and its effect is great.

[Brief description of drawings]

FIG. 1 shows a shutter mechanism portion of an embodiment of the present invention, FIG. 2 is a structural diagram of a stepping motor used in FIG. 1, FIG. 3 is a circuit diagram for controlling a sequence and a shutter mechanism, and FIG. The figure shows a conventional exposure diagram. In the figure, 3 ... Sector, 4 ... Sector ring M ... Stepping motor 17, 18 ... Stator 22 ... Rotor 104 ... Oscillator 102 ... Luminance detection circuit 116 ... Data ROM 119, 129 ... Counter 121 ... Programmable timer 132 ... Shift register 133 ... Switching device.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Yamazaki 934-13 Shikato, Yotsukaido, Chiba Seiko Koki Co., Ltd. (56) References JP-A-55-144221 (JP, A) JP-A-57 -66429 (JP, A) JP 57-207230 (JP, A) JP 50-137536 (JP, A)

Claims (2)

[Claims] 1. A strobe device, distance input means for inputting a distance to an object, a plurality of sectors forming a lens aperture, and a stepping motor capable of controlling forward and reverse rotations, the stepping motor and the stepping motor. In a shutter that directly or indirectly connects with a sector to control the opening and closing strokes of the sector, a timer that operates a timer in synchronization with the reference oscillator and the oscillator, and generates a signal that triggers the strobe device when the timer operation is completed. A circuit, means for generating a code value corresponding to the distance input to the distance input means, an arithmetic circuit for calculating the code value and a code value corresponding to the guide number of the strobe device, and a calculation circuit for calculating the code value. The flash strobe timing data corresponding to the opening and closing strokes of the sector is stored in the The data storage means and means for presetting the data from the data storage means accessed according to the calculated value in the timer circuit are provided, and in synchronization with the stepping motor that drives the sector when a strobe is used, A strobe control circuit characterized by the timer circuit starting operation. 2. The apparatus according to claim 1, further comprising film sensitivity input means for inputting a code value corresponding to film sensitivity, the code value and the code value corresponding to the distance. And the data in the data storage means is accessed using the calculated value as an address value.