JPS6368826A - Exposure controller for single-lens reflex camera - Google Patents

Abstract

PURPOSE:To facilitate strobe photography by performing flashmatic control on the basis of absolute distance data corresponding to the focus adjustment position of a lens and the GNo of an electronic flash. CONSTITUTION:The absolute distance data is utilized to perform flashmatic arithmetic operation using the guide number (GNo) of the internal electronic flash 200 on the basis of an absolute distance signal obtained from the quantity of rotation of a photographic lens 4 from its infinite-distance position. When the obtained shutter speed is slower than an electronic flash synchronizing speed, the electronic flash 300 is permitted to emit light for photography under the flashmatic control and when faster, the electronic flash 300 is inhibited from emitting light for photography in normal program mode. Consequently, exposure is proper and an electronic flash photographic range is widened.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides: - an exposure control device for a flash camera;
Specifically, it relates to an exposure control device for an eye reflex camera that allows flashmatic control using a built-in strobe.

[Prior Art] Conventionally, compact cameras have built-in strobes to perform flashmatic control. As is well known, this flashmatic control has the advantage that the aperture is controlled on the camera side according to the subject distance without changing the light intensity of the strobe, so the correct exposure can be achieved for photographs. Therefore, compared to automatic light control strobes, etc., there is no need for a light control circuit, and the strobe can be made smaller, making it suitable for being built into a camera.

However, to apply this to an eye reflex camera, unlike a lens-shutter compact camera where the lens is fixed and the absolute distance is uniquely determined, an eye reflex camera needs absolute distance data because the lens is replaced. However, flashmatic control using a built-in strobe has not yet been realized.

The method for deriving absolute distance data in an eye reflex camera is described in Japanese Patent Application No. 1986-1 previously filed by the present applicant.
34800 and Japanese Patent Application No. 60=-275251.

[Problems to be Solved by the Invention] Therefore, in the present invention, we focus on the above-mentioned absolute distance data in the eye reflex camera, and skillfully utilize this to calculate the absolute distance obtained by the amount of rotation of the photographic lens from the position. Based on the signal, the guide number of the built-in flash (hereinafter referred to as
(denoted as GNo) performs a flashmatic operation,
When the shutter speed is slower than the obtained shutter speed or the strobe sync speed, the flash is enabled and the camera shoots using Flashmatic control; when it is faster than the strobe sync speed, the strobe is disabled and the camera shoots in normal program mode. An object of the present invention is to provide an exposure control device for a single-lens reflex camera.

[Means and effects for solving the problems] In the present invention, - In order to realize flashmatic control in an ocular reflex camera, a method necessary for determining the relationship between the movement of the lens and the short focal length on the image side is provided. Absolute distance data detection means that derives absolute distance data according to the focus adjustment position of the lens from lens-specific parameters and the amount of relative movement of the lens from the stopper position; Field brightness measurement means; and exposure control that performs predetermined program control. a control means; a strobe light emission ready signal detection means having guide number information; when a detection output of the detection means is obtained, a shutter speed is determined by predetermined program control from field brightness information; A light emission control means that prohibits the strobe from firing if this speed is faster than the synchronization speed of the strobe, and allows it to fire if it is slower; and a light emission control means that prohibits the strobe from firing if this speed is faster than the synchronization speed of the strobe, and allows the strobe to fire if it is slower; The present invention is characterized by comprising an exposure adjustment means for determining the aperture value and performing exposure using the same aperture value and synchronized shutter speed.

[Example] The present invention will be explained below with reference to an illustrated embodiment.

As shown in FIG. 1.2, a single-lens reflex camera to which the present invention is applied has a strobe 200 that pops out during use, and a strobe 200 that pops out during use. A battery that serves as a power source 201 for the electric circuit within the camera body 1 is housed, and a release button 3 is provided on the upper front surface of the grip portion 2. Further, another strobe 300 having an automatic light control function is attached to a well-known hot shoe on the camera body 1.

As shown in FIG. 1, the electric circuit 100 inside the camera body 1 includes a microcomputer (hereinafter referred to as CPU) 1o1 for sequentially performing exposure calculations and a series of exposure controls during shooting, and a built-in strobe 200. An A-D conversion circuit 102 for inputting the output of the voltage determination circuit 204 to the CPUI 01, an aperture control circuit 104 for controlling the aperture of the photographing lens 4 (see FIG. 2), and an aperture control circuit 104 for narrowing down the aperture of the lens 4. A photointerrupter 105 generates a pulse signal by a slit in a light shielding member 106 that rotates following the displacement of a lever, etc., and detects the amount of displacement of the lever or the like from an aperture starting position, and a predetermined pulse output is provided. When obtained from the photointerrupter 105, the photocurrent output of the magnet 108 for operating the aperture lever locking member (not shown) and the light receiving element 110 for measuring the brightness of the field is logarithmically compressed and A-D converted. It controls the photometry processing circuit 109 for controlling the front curtain and the magnets 113 for releasing the front curtain and rear curtain of the focal plane shutter, respectively, and triggers the strobe to emit a flash by closing the front curtain run completion switch 116. A shutter control circuit 111 that receives a signal I5-, and pulses from a pulse generator 122 having a configuration similar to that of the photointerrupter 105 are input manually, and an AP (AP) that operates a lens drive motor 121 for focusing.
It mainly consists of an autofocus) control circuit 120, a film sensitivity setting device 130, and a camera power switch 117.

Further, the electric circuit inside the built-in strobe 200 includes a DC-DC converter 203 for boosting the voltage of the power supply battery 201 to a high voltage that enables the Xe discharge tube 208 to emit light.
Then, it is determined whether or not the voltage boosted by the converter 203 and charged in the main capacitor 210 is capable of emitting light, and when the voltage capable of emitting light is reached, the transistor 206
the voltage determination circuit 204 which turns on and applies an output to the A-D conversion circuit 102; and a light emitting circuit which receives a light emitting signal at the light emitting signal input terminal X and triggers the discharge tube 208 to start discharging. A trigger circuit 207 and a power switch 2 on the strobe side that is turned on when the light emitting section 200a (see Fig. 2) of the built-in strobe 200 is popped up.
It is mainly composed of 02.

Note that a detection resistor 1 is connected between the transistor 206 and the terminal to which the power supply voltage Vcc is applied.
03,205 are connected in series.

On the other hand, the electric circuit of the flash 300, which is attached to the hot shoe of the camera body 1 and has an automatic light control function, includes a power supply battery 304 and a DC-DC that boosts the battery voltage to a high voltage.
A booster circuit 305 consisting of a C converter and a main capacitor 30 charged with the boosted voltage.
6, when the charging voltage of the main capacitor 306 reaches a voltage that allows light emission, the transistor 302 turns on, and the A-D conversion circuit 10
A voltage determination circuit 301 applies an output to the terminal 2, and when a light emission signal is received at the light emission signal input terminal X, a light emission trigger is applied to the Xe discharge tube 308 to start flash light emission, and a stop signal is applied to the stop input terminal T during light emission. It mainly consists of a light emission control circuit 307 that stops emitting light when it receives light, and a flash discharge tube 308 through which a discharge current flows from a main capacitor 306 through a delay element 309 when emitting light.

On the other hand, the interchangeable lens 4, which is detachably attached to the camera body 1, has a built-in storage device 401 that stores data unique to the lens, and the data can be sent to the CPU as needed. 01.

Further, when the release button 3 (see FIG. 2) is pressed halfway, a switch 221 is turned on, and when it is pressed further, a switch 222 is turned on.

The exposure control device of the above embodiment is configured in this way.

Next, the operation of the above embodiment will be explained with reference to the flowchart of FIG.

First, before the release, when the release button 3 is pressed halfway, the switch 221 is turned on, and the CPU 101 instructs the AF control circuit 120 to perform the AF operation according to the necessary procedure by setting the input terminal A to the L (low) level. do. AF
The control circuit 120 detects the state of image formation by the photographing lens 4 using known means, and moves the lens by rotating the lens drive motor 121 in a necessary direction to achieve focusing.

When the motor 121 rotates, pulses are generated from the pulse generator 122 in accordance with the amount of rotation.

This pulse is applied to the patent application filed in 1986-134 mentioned above in the prior art.
As described in the patent application No. 800 or Japanese Patent Application No. Sho BO-275251, the integration is performed by a counter (not shown) that counts the number of pulses from the infinite position of the lens. When focus is detected by the focus detection means, the motor 121 is stopped, and the absolute distance to the subject is calculated based on the pulse count at that time.

In this state, the shutter release is allowed, and the release button 3 is further pressed. Then, the switch 222 is turned on and a release operation is started.

When the release operation is started, first, brightness information Bv (apex notation) of the object field is manually input to the photometry processing circuit 109 by the photocurrent output of the light receiving element 110. Then, after being logarithmically compressed here, it is converted into a digital value and manually input to the CPU 101 as subject brightness information Bv. CPUl
0I determines the necessary exposure film Ev (apex notation) based on the film sensitivity information Sv (apex notation) set in the film sensitivity setting device 130, and provides rain exposure using an algorithm incorporated in the program. Shutter speed Tv (apex notation) and aperture value Av
Calculate the combination of (Apex notation). FIG. 4 shows an example of the combination of the calculated shutter speed Tv and aperture value Av.

That is, if the calculated shutter speed Tv is faster than the strobe's synchronized shutter speed Tvl (shutter fully open seconds), the CPUl0I will not issue a light emission command to the strobe;
IJ does not perform strobe photography, but instructs the aperture control circuit 104 to perform aperture control as usual, and when the necessary number of pulses are generated from the photo incretor 105, the circuit 104 controls the aperture as usual.
Turn off the transistor 107 and turn off the magnet l-108.
to stop the aperture.

Next, when the movable reflective mirror (not shown) completes its upward movement, the shutter control circuit 111 turns off the transistor 114, releases the leading curtain magnet 112, and after a predetermined period of time, turns off the transistor 115, turning off the trailing curtain magnet. Release l-113 to unlock the front curtain and rear curtain, respectively. Therefore, normal photographing is performed.

When the front curtain finishes running, the shutter control circuit 111 does not output a light emission signal to the strobe input terminal X at this time, either by turning on the front curtain run completion switch 116 or by an instruction from the CPU I O1. Therefore, there is no chance that the strobe will fire at a shutter speed that is too high due to the synchronization speed of the strobe and a photograph with uneven exposure due to the end of the curtain will be taken.

On the other hand, the calculated shutter speed Tv is the same as that of the strobe.
If the shutter speed is slower than Tvl, first
01 detects whether or not the strobes 200, 300 are ready to emit light. This is done as follows.

For example, if the resistance value of the detection resistor 103 is R1, then the resistance value of the detection resistor 205 is
The resistance value of the detection resistor 303 is R or RJ, and the resistance value of the detection resistor 303 is R
Then, 7xR1=R3', R=R, 2XR2'-R
, is determined in advance. In addition, the built-in strobe 200
By changing the model, two types of GNo.
In the case of strobe No. 2, the resistance value of the detection resistor 205 is R. Therefore, it is a GNogl strobe.

The voltage at the analog voltage input end of the A-D conversion circuit 102 is 20OA, 200B. When each of the 300 strobes completes charging, the potential reaches a level as shown in FIG. For the old CPU I, the A-reconversion circuit 10
The L terminal voltage is detected by the digital value input from 2, but if this digital value is less than 3/8vcc lJ4, the G
No'g, and 3/8Vcc or more 5/8Vc
If it is less than c, it is detected that each of the fludge control strobes of GNog2 has completed charging (gl and g2 are set to r). And 5/8
If it is less than -1-8/8 Vcc, it is known that the strobe 300, which has an automatic light control function, is ready to emit light.

In this way, it is detected that the strobe is ready to emit light, and when the shutter speed Tv is slower than the synchronized shutter speed T1, and the flashmatic control strobe has completed charging, the AF control circuits 120 to 11
Absolute distance data g and GNog (
or g2) to Avl ==, gOg2g, −00
g2(3,+Sv k(AV2=, eog g
-eog21t1+5v-k), the appropriate aperture value A,, (Av2) is determined, and the aperture control circuit 1
Set to 04.

When the release switch 222 is turned on, the diaphragm is controlled as described above, or the shutter control circuit 111 is supplied with the synchronized shunter speed 'rvl' rather than the value determined from the exposure QEv. It is done.

Then, in synchronization with the end of shutter front curtain travel, the front curtain travel completion switch 1. By closing l[i, the input terminal X of the light emission trigger circuit 2072 and the light emission control circuit 307
A light emission signal is applied to the strobe, and the strobe is ignited to emit light by the outputs of the respective circuits 207 and 307.

Now, assuming that the built-in strobe 20OA (200B) and the dimming strobe 300 have completed their preparations to emit light at the same time, when a light emission signal is output from the shutter control circuit 111, both strobes 20OA (200B) and 300 will emit light at the same time. .

In this case, since the strobe 20OA (200B) does not have an automatic light control function as a standalone strobe, its light emission waveform has a short time and a high peak value, as shown by waveform a in FIG. However, since the strobe 300 has an automatic light control function, it uses a delay element 309 such as a coil to smooth the waveform for the purpose of improving controllability, and the emitted light waveform is as shown by the dotted line. The waveform is as follows.

Since the shutter control circuit 111 has a so-called film reflection metering automatic exposure function, when the integrated voltage reaches the determination level, the shutter control circuit 111
A light emission stop signal is sent from it to the input terminal T, and the light emission is interrupted by a known light emission stop circuit as shown by the dashed line in FIG.

In other words, when the subject is at a distance where Flashmatic photography is possible using only the built-in strobe 20OA (200B),
Built-in strobe 20OA with a sharp emission waveform a
The light of (200B) causes the subject to be properly exposed +IE, and the light is sent to the input terminal T of the dimming strobe 300 at a quick timing +1 = (:'T), so
The strobe 300 hardly emits light.

However, when the subject is far away, the amount of light from the built-in strobe 20OA (200B) may not be enough even if the lens is wide open. Therefore, at this time, by using the dimming strobe 300 at the same time, the amount of light is increased and the range that can be photographed using the strobe increases.

That is, using a lens with an open aperture value FD of -2 to GN.

When using Flashmatic photography with a GL strobe,
The photographing distance Ω that can be obtained with an appropriate rF-optical skewer can be up to. In this case, set the -no j strobe or automatic light control function to 41. In this case, it would be a good idea to control the camera by considering only the GNo of the flashmatic control strobe.

In general, the built-in strobe installed in a camera is not required to be miniaturized and has an intransitive light function, so the flashmatic control in a single-lens reflex camera according to the present invention is very practical and large. You can get some effect.

Next, another embodiment of the present invention shown in FIGS. 7 and 8 will be described. In this embodiment, instead of the strobe 300 having the automatic light adjustment function, a hot shoe strobe 300A having both the functions of "auto light control mode" and "flat light emission mode" known from Japanese Patent Laid-Open No. 60/150037 etc. is used. It was installed on. In addition, in the electric circuit of the exposure control device shown in Fig. 7, the electric circuit of the built-in strobe is omitted.
Also, only the necessary parts of the electrical circuit on the camera body 1 are drawn.

The electric circuit inside the strobe 300A includes a power supply battery 310
, a power switch 311, and a booster circuit 3 consisting of a DC-DC converter that boosts the battery voltage to a high voltage.
12, a main capacitor 313 charged by the voltage of this booster circuit 312, a flash discharge tube 314, its light emission control circuit 315, and a CPU in the camera body 1.
It mainly consists of a detection circuit 316 that performs communication between the main capacitor 313 and the main capacitor 313, and detects the completion of charging of the main capacitor 313. In addition, in the case of this embodiment, the CPU in the camera body 1
01 has a judgment circuit function that detects at least whether the shank speed is faster or slower than the flash light emission synchronization speed of the strobe according to the brightness level of the object field.

The operation of the embodiment of FIG.
To explain with the time chart in the figure, now switch 22
2 (see Figure 1) and a release is performed, CPU 01 activates CEN of the detection circuit 316 next to the strobe and sends a clock signal to the C line in order to communicate with the strobe 300A. The strobe 300 is controlled by serial data sent and received on the D line.
It is detected whether the main capacitor 313 is charged or not, and whether charging of the main capacitor 313 is completed. If charging is completed, then the film sensitivity setting device 13
Film sensitivity information Sv from 0 and photometry processing circuit 10
9, and determine whether the synchronized shutter speed Tvl is greater than or equal to Tvl on the exposure control diagram shown in FIG. If available, strobe 3 can be connected via serial communication.
Instruct 00A to "flat light emission mode", and if below, instruct "automatic light control mode".

When the "flat light emission mode" is instructed, the detection circuit 31
6 decodes the serial data and sets the "flat light emission mode"/"auto dimming mode" switching output terminal S to the H (high) level.

In this state, the CPU 10I operates the aperture and mirror, and then issues a command to the shutter control circuit 111.
The transistor 114 is turned off, the magnet 112 is de-energized, and the shutter photoelectric is started.
The flat light emitting terminal F of is set to H level. As described in -1-, the light emission control circuit 315 is connected to the switching output terminal S which has already been set to H.
level, so within a certain period of time 10, terminal F
When a flat light emission signal arrives at , the flash discharge tube 3 is immediately activated.
14 to perform "flat light emission".

At the same time, the shutter control circuit 111 integrates the limb field light measured by the light receiving element 118 using a known method, and when the appropriate exposure amount level is reached, turns off the shutter rear barrel control transistor 115. Turn off the power to the holding magnet 113. Then, when the operating switch 119 is turned on after the trailing curtain has finished running,
The flat light emitting terminal F becomes L level again, and the light emitting control circuit 315 terminates the energization of the flash discharge tube 314 and stops emitting light (17-).

Also, instead of the switch 1190, the transistor 11
After a certain period of time after 5 is turned off, taking into consideration the curtain running time,
Of course, the flat light emitting terminal F may be set to the L level.

Furthermore, in the above-described operation, even if the front curtain run completion switch 116 is turned on when the front curtain ends running, the light emission control circuit 315
Since the CPU 101 prohibits the sending of a light emission signal from the shutter control circuit 111 to the input terminal The camera will not emit light even if it is set, and even if the shutter curtain or slit is used, the exposure will not be uneven.

On the other hand, when the "auto dimming mode" is instructed, the detection circuit 3
16 sets the switching output terminal S to L level and waits for a light emission signal. In this case, the CPU 01 sends a light emission signal to the input terminal X to the shutter control circuit 111 when the front curtain running completion switch 116 is turned on, in the same way as described in the flashmatic control section, and synchronizes with the turning off of the transistor 115. to set input terminal T to H level. The light emission control circuit 315 switches the flash discharge tube 3 when a light emission signal is applied to the input terminal X when the human power applied to the switching output terminal S is at L level.
14 and the same discharge tube 31 in "auto dimming mode"
4 is made to emit light, and when a light emission stop signal is input to the input terminal T, the light emission is stopped 1-.

In this case, the built-in flash matic control
If 0OA (200B) has completed charging at the same time, a light emission signal is applied to the input terminal
Similar to the multi-flash operation with the automatic light adjustment function of the I-J strobe 300, the exposure is set at an appropriate iF and the flash photography range is expanded.

In this way, in the embodiment described above, a judgment circuit is provided to detect whether the shutter speed is faster or slower than the flash synchronization speed of the strobe, and the light emission mode is switched between "flat light emission mode" and "automatic light control mode". Before the shutter is opened, a light emission mode switching signal is sent to a strobe capable of flash photography according to the output of the judgment circuit, and if there is an output of the judgment circuit, the shutter's front curtain switch is sent. A light emission start signal is sent to the strobe in synchronization with the stop release signal, or, if there is no stop release signal, in synchronization with the front curtain running end signal.

[Effects of the Invention] As described above, according to the present invention, absolute distance data corresponding to the focus adjustment position of the lens can be obtained even if the lens is replaced in a flex camera. Since flashmatic control can be performed with the GNo, not only is strobe photography with a -eye reflex camera extremely easy, but the strobe is also inexpensive and compact. Therefore, since the strobe can be miniaturized, it can be built into the camera, and even when attached, the strobe has a sleek appearance. Furthermore, even when used as a multi-strobe flash, a remarkable effect is exhibited in that the user can take photographs of an appropriate level without any operational considerations.

[Brief explanation of the drawing]

FIG. 1 is an electrical circuit diagram of an exposure control device for a single-lens reflex camera showing an embodiment of the present invention, FIG. 2 is an external view of a single-lens reflex camera to which the present invention is applied, and FIG. , 2. A flowchart showing the operation of the electric circuit in Fig. 1. Fig. 4 is a diagram showing the relationship between aperture value and shutter speed. Fig. 5 is a diagram showing the setting level for flash charging completion. , Fig. 6 is a time chart showing the light emission waveforms of the built-in strobe and the dimming strobe, and Fig. 7 shows the electric circuit of the main part of the exposure control device of a single-lens reflex camera showing another embodiment of the present invention. The route map, Figure 8, is a time chart of the electric circuit shown in Figure 7 above. 1・・・・・・・・・・Eye reflex camera body 200・・Built-in strobe 300・・・Strobe with automatic light control function = 25- 34 Garden 35Δ 3F) 8El

Claims (2)

[Claims] (1) Derive absolute distance data according to the focus adjustment position of the lens from the lens-specific parameters necessary to find the relationship between the amount of lens movement and the image-side focal length and the amount of relative movement of the lens from the stopper position. Absolute distance data detection means; field brightness measurement means; exposure control means for performing predetermined program control; strobe light emission ready signal detection means having guide number information; and a detection output of the detection means. When the shutter speed is obtained, a shutter speed is determined by predetermined program control from the field brightness information, and if this speed is faster than the synchronization speed of the strobe, the flash is prohibited to emit light, and if it is slower than the synchronization speed of the strobe, the flash is allowed to emit light; When the flash is emitted by the light emission control means, an exposure adjustment means is provided for determining an appropriate aperture value from the absolute distance data and guide number information, and performing exposure according to the aperture value and synchronized shutter speed. Exposure control device for single-lens reflex cameras. (2) When a detection output is obtained from the flash-ready detection means of the strobe that has the above guide number information, the aperture is set to the aperture value determined by Flashmatic calculation from the guide number and absolute distance data at the time of release operation. An exposure control device for a single-lens reflex camera according to claim 1, wherein the exposure control device controls: