JPS6235658B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flash photography device that emits flash light when the shutter is fully open, and in particular, the present invention relates to a flash photography device that emits flash light when the shutter is fully open, and in particular, a device suitable for flash photography that responds to a flash light emission ready signal from a flash discharge lamp control circuit during flash photography. The present invention relates to an exposure time display device for flash photography that displays exposure time.

In response to a flash light emission ready signal from a flash discharge lamp control circuit, the exposure time is automatically switched from the above-described calculated exposure time to a predetermined flash synchronization limit exposure time, and this is displayed on a display device. Various flash photography devices have been proposed in the past. With these devices, the exposure time is automatically selected according to the flashlight's readiness state, so you can set the exposure time suitable for flash photography by simply opening or closing the flashlight's power switch or the flashlight readiness detection circuit. In addition, since the shutter is closed in response to the light emission from the flash discharge lamp, exposure by illumination from the flash discharge lamp can be obtained without wastage and in a reliable manner, which is convenient and rational. However, for example, if the main subject is illuminated with a flash discharge lamp, and the background is not illuminated or is not well-lit, a long exposure may be used to take a well-balanced photo, or the background may be illuminated with a slow shutter. It was not possible to take pictures with special intentions, such as when the subject was washed away and blurred.

JP-A-52-58929 proposes a flash photography device equipped with an exposure time control circuit and a display circuit that performs flash photography for a special purpose only when the exposure time is manually set. ing.
However, flash photography using this control circuit has the disadvantage that it is necessary to read the desired exposure time using the camera's built-in exposure meter or a separate exposure meter, and then manually set it, making the operations during flash photography complicated. , Flash photography for special purposes such as the one described above cannot be used satisfactorily unless a person has advanced photography skills. There was a strong need for a device that would be easy for beginners to perform. In addition, the display format during flash photography by the display circuit is the symbol EF, which indicates the flash photography mode.
The 7-segment type numeric display element displays the numeric value of the manually set or automatically switched exposure time for flash photography in segments.
In this case, the symbol and the numerical value by segment display are
The photographer had to read the two display sections, which was troublesome. Furthermore, the 7-segment type display also has the disadvantage that the displayed values are more difficult to read than the conventional display using a series of exposure time values.

SUMMARY OF THE INVENTION An object of the present invention is to provide an exposure time display device for flash photography in which a display during flash photography can be easily recognized in a flash photography device capable of performing flash photography with a special intention.

Therefore, in the present invention, among a light emitting diode row consisting of a plurality of light emitting diodes provided corresponding to a numerical string of exposure times, a light emitting diode corresponding to a calculated exposure time according to a measured value of subject brightness is selectively selected. In the exposure time display device to be lit, when the calculated exposure time is longer than a predetermined exposure time that can be synchronized with flash, the light emitting diode corresponding to the calculated exposure time blinks, and when it is shorter, the light emitting diode corresponding to the predetermined exposure time blinks. Both the flash photography mode and the controlled exposure time are displayed so that they can be easily recognized by blinking.

The present invention will be explained in more detail with reference to the circuit diagrams shown in FIGS. 1 and 2. FIG. 1 is a circuit diagram showing an example of a flash photography device according to the present invention. 1 is a circuit diagram of a camera equipped with an exposure time control circuit of a Rex camera and an exposure time display circuit according to an embodiment of the present invention. The right side of the figure is a circuit diagram showing an example of a flash discharge lamp control circuit of a flash light emitter connected to this camera. In the figure, 1 is a photometric light receiving element such as a photodiode, for example,
The pentaprism of a single-lens reflex camera is placed on the roof or near the eyepiece, and is designed to receive light from a subject through a photographic lens. 2 logarithmically compresses the photoelectric output of the light-receiving element 1, and electrically performs photographic calculations on it according to the set exposure conditions such as the set aperture value and film sensitivity, so as to compress the photoelectric output appropriately according to the subject brightness and set exposure conditions. This is a photometric calculation circuit that outputs a signal corresponding to exposure time. 4
is a signal corresponding to the exposure time according to the resistance value of the variable resistor 8 which is set by operating an exposure time setting manual operation member (not shown), in other words, it corresponds to the exposure time set by the manual operation member. The manual exposure time signal generating circuit outputs a signal corresponding to the output signal of the photometry calculation circuit, and takes the same level for the same exposure time. _S1 is a manual/automatic selection switch, and automatic exposure contact a or manual exposure contact M is selected by operating a selection operation member (not shown). Note that this selection operation member may be integrated with the exposure time setting manual operation member or may be separate from it.

_S3 is a memory switch that is opened before the reflection mirror of the camera is retracted from the photographing optical path, and when it is opened, the photometry calculation circuit 2 or manual exposure time signal generation circuit 4 selected by the selection switch _S1 is activated. The output of
That is, the potential at point a is stored in the storage capacitor 5. 6 is a logarithmic expansion transistor, and an output current proportional to the inverse logarithm of the storage voltage of the storage capacitor 5 flows through its collector. _S4 is a trigger switch, and _S5 is a short-circuit switch for the integrating capacitor 7. In connection with the shutter opening operation, the switch _S4 closes, and _S5 opens to start charging the integrating capacitor 7 with the output current of the transistor 6. let 8 is an integrating capacitor 7
When the charging voltage reaches a predetermined value, the output goes “high”
This is a switching circuit that inverts the voltage from low to low and cuts off transistor 9. An electromagnet 10 prevents the shutter from closing while it is energized, and allows the shutter to close when it is demagnetized. Transistor 11 is connected to electromagnet 10 in parallel with transistor 9, and is turned on when the output of comparator 53, which will be described later, is "high".

_J11 is connected to the flash discharge lamp control circuit described below, and a signal of a predetermined voltage level is input when the flash is ready to emit, such as when the main capacitor of the flash emitter is fully charged, and when the flash is ready or after the flash is emitted. The inside is an input terminal that becomes "low" level. Comparators 52, 53, constant current source 54, resistors 55, 5
6 and 57 are circuits for determining the level of the signal applied from the flashlight emitter via the input terminal _J11 . The comparator 52 sets its output to a "high" level when the level of the signal exceeds a first level determined by the resistors 55 and 56. The output of this comparator 52 is a transistor 50, which will be described later.
66, 67, and 68 bases, respectively. The comparator 53 sets its output to a "high" level when the level of the signal is below a second level determined by the resistor 56. The output of this comparator 53 is given to the bases of transistors 11, 60, and 61, respectively. transistor 5
0, the series connection body of the resistor 51 is the transistor 6,
Connected in parallel to the series connection body of switch S ₄ , resistor 5
This circuit increases the charging current to the integrating capacitor 7 by an amount corresponding to the resistance value of the switching circuit 8 to hasten the timing at which the switching circuit 8 switches.
The resistance value of the resistor 51 is set to a value such that, for example, when the integrating capacitor 7 is charged only by the resistor 51, the switching circuit 8 is inverted in a time equal to or shorter than the flash tuning limit exposure time. ing.

A constant current source 100, resistors 10 ₁ to 10 _o are circuits for creating n reference potentials V ₁ to V _o , and 20 ₁ to 20 _o are potentials corresponding to the reference potentials V ₁ to V _o and the shutter speed from point a. Comparator for comparing V ₁ , 301
~30n-1 is an adjacent comparator (e.g. 2
This circuit outputs a negative signal of the exclusive OR of the outputs of 0k and 20k+1, and the output of this circuit has an LED.
401 to 40n-1 are connected and this
The LED is such that its illumination is visible, for example, next to the corresponding exposure time scale or number on an exposure time scale or column of exposure time numbers;
Depending on which LED lights up, the manual setting or calculated exposure time will be displayed. Also LED400
When LED40n lights up, it means that the calculated exposure time corresponding to the potential at point a has exceeded the control limit on the high speed side that can be controlled by the camera, and when LED40n lights up, it means that the calculated exposure time has exceeded the control limit on the low speed side. This shows that. For LED40k, the setting or calculated exposure time is the flash synchronization limit speed (e.g. 1/60 seconds)
This indicates that

64 always makes the transistor 65 conductive when the transistor 61 is non-conductive, and makes the transistor 65 conductive while the transistor 61 is conductive;
This is an oscillation circuit that outputs a signal that enables repeating non-conducting states, and can be implemented, for example, by a circuit as shown in FIG. In FIG. 2, an astable multivibrator is configured by transistors 641 and 642, capacitors 643 and 644, and resistors 645 to 648. When transistor 61 is non-conducting, the astable multivibrator becomes inactive and transistor 641 becomes conductive. In this state, the transistor 65 remains conductive. When transistor 61 becomes conductive, the astable multivibrator becomes operational and transistors 641 and 6
42 alternately repeats conducting and non-conducting states, and the transistor 65 becomes able to repeat conducting and non-conducting states. It is also possible to provide this oscillation circuit on the flashlight emitter side and input the oscillating signal as the light emission preparation completion signal. The emitter collector of the transistor 24 may be connected so that when the transistor 24 becomes conductive, the potential at point b becomes +V.

In the flash discharge lamp control circuit shown on the right side of the dash-dotted line in FIG. 1, 31 is a booster circuit that boosts the output of the DC power supply ₃₀ when the power switch S5 is closed. It is completed. 33 is a main capacitor that stores electrical energy at high voltage for flash discharge tube 46 to emit light, and the output current of booster circuit 31 is connected to backflow prevention diode 32.
through which it flows into the main capacitor. 44 is a trigger capacitor, and 45 is a trigger transformer. When the thyristor 43 becomes conductive, a high voltage is applied to the trigger electrode of the flash discharge tube 46 via the secondary coil of the trigger transformer 45 by the discharge current of the trigger capacitor 44. The flash discharge tube 46 is made conductive and emit light.

Zener diode 3 that generates constant voltage between terminals
The neon tube 34 connected in series with 5 is for detecting the voltage of the main capacitor 33, and is used to detect the voltage of the main capacitor 33.
When the main capacitor 33 is charged to a predetermined level or higher with the switch _S7 closed in conjunction with _S6 , the light is turned on, supplying current to the Zener diode 35 and generating a constant voltage between its terminals. 36, 37
1,372 is a voltage dividing resistor that divides the voltage of the Zener diode 35 and applies each divided voltage to contacts F and H of a switch _S9 , which will be described later. These divided voltages are selectively applied to terminals J12, J12 _{and J12} by switch S9.
It is transmitted to the camera side via _J11 .

The transistor 38 is a Zener diode 3
5. When a predetermined base voltage is applied to the resistor 36, it becomes conductive, and this conduction enables the transistor 41 to conduct. The collector of the transistor 41 is connected to the base of the transistor 42, and the emitter of the transistor 41 and the collector of the transistor 42 are connected to the flash discharge lamp side connection terminals J ₂₂ and J ₃₂ and the camera side connection terminals J ₂₁ and J ₃₁ . It is connected to a synchro switch _S8 in the camera, and when the synchro switch _S8 is closed in synchronization with the shutter being fully opened, the emitter of the transistor 41 is grounded. At this time, if the neon tube 34 is lit and a predetermined voltage is generated across the Zener diode 35, the transistors 41 and 42 become conductive and the thyristor 43 becomes conductive.

Next, the operation of the above configuration will be explained.

First, if the flash discharge lamp control circuit is not connected to the exposure time control circuit on the camera side, or even if it is connected, when the camera is operated while the main capacitor 33 is not fully charged, the input terminal _J11 will be " It remains "low". Therefore, the output of the comparator 53 is "low", and the transistor 11 remains non-conductive and does not participate in shutter control. Further, since the output of the comparator 52 is also "low", the transistor 50 is non-conductive, and the capacitor 7 is not charged via the resistor 51. As a result, a signal from the photometry calculation circuit 2 or the manual exposure time signal generation circuit 4 is stored in the capacitor 5, this stored value is converted into an output current logarithmically expanded by the transistor 6, and this output current is converted to the capacitor 7. When this integrated voltage reaches a predetermined value, the output of the switching circuit 8 is inverted, the transistor 9 is rendered non-conductive, the electromagnet 10 is demagnetized, and the shutter starts closing.

The display at this time is that the transistor 67 is non-conductive due to the "low" level of the input terminal _J11 , and the potential at point a is not level-shifted, so the potential at point a is V.
_i and reference potentials V ₁ to V _o are compared, for example, V _k <V _i
When <V _k-1 , comparators 201 to 20k-
The output of 1 becomes "high", the outputs of 20k to 20n become "low", and the exclusive OR 30k-1 inputs the outputs of comparators 20k-1 and 20k.
Only the output of the circuit becomes "low" and all other circuits become "high", the LED 40k-1 lights up continuously, and the exposure time corresponding to the potential at point a is digitally displayed.

Next, connect the camera and flashlight to the connection terminals.
A case in _{which the flash discharge lamp control circuit switch S2 is} connected to _{the F side} and flash photography is performed will be explained _. First, when the power switch _S6 is closed and the main capacitor 33 is charged to a predetermined voltage and the neon tube 34 is lit, a constant voltage is generated across the Zener diode 35, and this constant voltage is applied by the resistors 36, 371, and 372. Partial pressure is applied. At this time, the comparator 52,
Both outputs of 53 become "high". Therefore, transistors 11 and 50 are conductive and switching circuit 8 switches faster than the flash tuning limit speed, but at that time transistor 11 is still conductive and the shutter does not begin to close. When the synchro switch _S8 is closed in response to the shutter being fully opened and the flash discharge tube 46 emits light, the voltage of the main capacitor 33 drops rapidly and the neon tube 34 goes out, causing the input terminal _J11 to become "low". Then, the outputs of the comparators 52 and 53 are inverted to "low", the transistor 11 becomes non-conductive, and the electromagnet 10 is demagnetized to start shutter closing.

The display at this time is that the transistor 67 is turned on due to the "high" level of the comparator 52, and the potential V _i at point a is dropped to the ground potential, and the comparator 201
~20n outputs are all “high”, while
The transistor 68 is made conductive, making it impossible to light up the LED 40n, and the transistors 61 and 66 are made conductive to output an oscillation signal from the oscillation circuit 64, corresponding to the flash tuning limit speed of, for example, 1/60 second.
The LED 40k blinks to indicate that flash photography will be performed at the flash synchronization limit speed.

Next, turn on the switch for the flash discharge lamp control circuit.
The operation when _S9 is connected to the H side will be explained. At this time, the output of the comparator 52 is "low" and the output of the comparator 53 is "high", transistors 11, 60, and 61 are conductive, and transistors 50, 66, 67, and 6 are conductive.
8 becomes non-conductive. When the potential V _i at point a is higher than the potential corresponding to the flash tuning limit speed, the switching circuit 8 inverts the output at a higher speed than 1/60 seconds, but since the transistor 11 is still conductive, the shutter is closed. does not start, and when the flash discharge tube emits light, the light emission ready signal disappears, and comparator 5
3 is reversed to "low" and the shutter starts to close. Further, when the output potential V _i is lower than the potential corresponding to the flash tuning limit speed, the switching circuit 8 changes the voltage according to the potential at point a after the flash discharge tube emits light and the transistor 11 becomes non-conductive. When the exposure time has elapsed, the transistor 9 is turned off, the electromagnet 10 is demagnetized, and the shutter is closed.

Therefore, it is possible to realize flash photography in which the shutter is controlled at a speed lower than the flash synchronization limit speed.

The display in this case is that when the potential V _i at point a is higher than the potential corresponding to the flash tuning limit speed, the output of the comparator 20k is always "low". This signal is inverted to "high" by the inverting circuit 62 to make the transistor 63 conductive, and the LEDs 400 to 40 are turned on.
k-1 is turned off, and at the same time, the LED 40k is blinked using the output signal of the oscillation circuit 64 to indicate that flash photography will be performed at the flash synchronization limit speed.
When the potential V _i at point a is lower than the potential corresponding to the flash tuning limit speed, one of the LEDs 40k to 40n indicating the exposure time corresponding to the potential V _i at point a
One is blinked by a signal from the oscillation circuit 64 to indicate that flash photography will be performed at an exposure time corresponding to the blinking LED.

As detailed above, according to the present invention, when the calculated exposure time according to the measured value of the subject brightness is longer than the predetermined exposure time that can be synchronized with flash, the light emitting diode corresponding to the calculated exposure time blinks, When the exposure time is short, the light emitting diode corresponding to the predetermined exposure time flashes, and the flash photography mode is displayed by the flashing of the light emitting diode, and is controlled by the exposure time number string provided corresponding to this light emitting diode. Since the exposure time display device for flash photography is configured to display the exposure time, the two types of display for flash photography mode and control exposure time can be easily recognized, and the two display parts can be checked as before. There's no need to. Furthermore, if the exposure time control circuit is configured to operate in cooperation with the display device of the present invention, there is no need to read the exposure time from the light meter and manually set it for the above-mentioned special purpose flash photography. Since the exposure time is automatically set to an appropriate value, it is useful for beginners.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of an exposure time display device according to the present invention, and FIG. 2 is a circuit diagram showing an example of a main part 64 thereof. 2... Photometric calculation circuit, 40 ₀ ~ 40 _o ... Light emitting diode, 10 ₀ ~ 10 _o , 20 ₀ ~ 20 _o , 3
0 ₁ ~ 30 _o-1 , 69...display control device, 33 ~
35...discrimination circuit, _S9 ...manual selection means, 52,
64-68...first display control circuit, 53,6
0,62-65...Second display control circuit.

Claims (1)

[Claims] 1. A light emitting diode row consisting of a plurality of light emitting diodes provided corresponding to a number string of exposure time;
A photometric calculation circuit that calculates an exposure time according to a photometric value of subject brightness, and a display control device that selectively lights up a light emitting diode that corresponds to the exposure time calculated from the photometry calculation circuit among the plurality of light emitting diodes. In the exposure time display device, a determination circuit determines whether the flashlight emitter is ready to emit light, a selection means for selectively specifying a first state and a second state by manual operation, and a determination circuit determines whether the flashlight is ready to emit light. is determined and a first state is specified by the selection means, a first display control for blinking a light emitting diode corresponding to a predetermined exposure time that can be synchronized with flash regardless of the exposure time calculated from the photometry calculation circuit; and when the determination circuit determines that light emission is ready and the selection means specifies the second state, if the calculated exposure time is shorter than the predetermined exposure time, the light emission corresponding to the predetermined exposure time is performed. and a second display control circuit that causes a diode to blink and, if the calculated exposure time is longer than the predetermined exposure time, blinks a light emitting diode corresponding to the calculated exposure time. Display device.