JPS62198836A - Camera - Google Patents

Abstract

PURPOSE:To change an electronic flash circuit with electricity by utilizing a self-timer period by providing an electronic flash charging control circuit which commands the charging of the electronic flash circuit during self-timer circuit operation. CONSTITUTION:When a self-timer switch 8 is closed, an RS flip-flop 1, a binary counter 13, and an OR gate 14 constitute a self-timer circuit and the binary counter 13, an AND gate 16, and a NOR gate 17 constitute the electronic flash charging control circuit. Consequently, the electronic flash charging operation is performed during the self-timer period, so the circuit is precharged during self-timer operation suitable to an electronic flash automatic lighting system. Further, actual self-timer seconds never become longer than set self-timer seconds and its variance is eliminated, so an invariably constant self-timer wait time is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to an improvement in a camera equipped with a self-timer circuit.

(Background of the invention) In recent years, compact lens-shutter cameras have
Types with a built-in strobe are the mainstream, and the strobe fires automatically when the subject brightness is low.
So-called automatic light-emitting systems are also emerging. In this automatic flash system, it is necessary to charge the strobe in advance, but due to the concept of full auto, the strobe does not pop up and uses a fixed type (to save power), so for example, the lens cover Many methods have been proposed in which the strobe is precharged in conjunction with pre-shooting operations such as opening and closing operations. However, with this method, if the time from opening/closing the lens cover to starting shooting is long, the charge stored in the strobe's main capacitor will be discharged due to leakage current, wasting energy. It had its flaws.

Therefore, a method has been proposed in which the brightness of the subject is determined during the first stroke of the release button and flash charging is started. There is a problem in that the sum of the set self-timer seconds becomes the actual self-timer seconds, that is, the self-timer seconds become longer than the set value. Furthermore, since the strobe charging time varies depending on the residual charge value of the main capacitor of the strobe, the actual self-timer time may vary.

(Object of the Invention) An object of the present invention is to solve the above-mentioned problems, to make the actual self-timer time match the set self-timer time, and to eliminate unnecessary self-time waiting time. The goal is to provide the following.

(Features of the Invention) In order to achieve the above object, the present invention includes a strobe charge control circuit that commands a strobe circuit to charge during self-timer flash photography during self-timer flash photography. It is characterized in that the strobe circuit is charged using the .

(Embodiments of the Invention) The present invention will be described below in detail based on illustrated embodiments.

FIG. 1 is a circuit diagram showing an embodiment of the present invention, where l is a battery as a power source, 2 is a diode for preventing backflow,
3 is a capacitor that backs up power to the logic circuit section, 4 is an oscillation circuit, 5 is a crystal resonator, 6 is a frequency dividing circuit, 7
8 is a release switch that closes with the second stroke of the camera's release button; 8 is a self-starting self-switch; 9. 10 is a pull-up resistor of each switch, 11 is an RS flip-flop, 12 is an inverter, 13 is a binary counter that further divides the output from the frequency dividing circuit 6, 14.15 is a two-man OR gate, and 16 is a two-way OR gate. Man-powered AND gate, 17 is 2-man powered Nantes gate, 18 is RS
Flip-flop 19 is the RS flip-flop 1
NPN transistor connected to the output terminal Q of 8, 20
is a tensioning magnet for starting lens barrel operation.

21 is an NPN switching transistor, 22 is a light emitting diode (LED) for self-indication, and 23.24 is an NPN switching transistor.
A PN switching transistor, 25 a known AF circuit, and 26 a known AE circuit.

27 is a PNP transistor for starting oscillation, 28 and 29
are PNP and NPN transistors for stopping oscillation, 30 is an oscillation transformer, 31 is a diode for rectifying the boosted high voltage, 32 is a Zener diode for detecting the completion of charging,
33 is a resistor, 34 is a trigger thyristor, 35 is a trigger capacitor, 36 is a trigger transformer, 37 is a xenon discharge tube that emits flash light, and 38 is a main capacitor that stores the energy of the xenon discharge tube 37, and is used to start the oscillation. PNP) transistor 27 to the main capacitor 38
This makes up the strobe circuit.

Next, the operation will be explained using FIG. 2. When the self-switch 8 is closed, a high-level signal is input to the set input terminal S, so the RS flip-flop 11 is set, and the output from its output terminal Q becomes low level. Therefore, the output of the OR gate 14 also becomes low level, and the reset of the binary counter 13 is released. When the reset is released, the binary counter 13 starts to further divide the output from the frequency dividing circuit 16, so that the divided output as shown in FIG. 2 is output from the output terminals Q3 to QB. become. As a result, the AND gate 16 outputs a 1/4 duty square wave signal as shown in FIG. 2, and the switching transistor 21 responds to this signal.
turns on and off, and the self-display light emitting diode 22 starts blinking to indicate that it is in self-operation.

Further, during the period in which the output of the AND gate 16 is at a low level, the output of the OR game 14 is at a low level, so the output of the NOR gate 17 is changed to a high level signal, and the switching transistor 23 is turned on. Therefore, the oscillation transformer 30
The base current of the PNP transistor 27 for starting oscillation flows into the switching transistor 23 through the feedback winding and the resistor, and conduction occurs between the emitter and collector of the PNP transistor 27, causing a primary current to flow through the primary winding of the oscillation transformer 30. flows, so that a secondary current flows through the secondary winding of the oscillation transformer 30 due to electromagnetic induction. That is, the oscillation operation of the strobe circuit is started. On the other hand, during the period in which the output of the AND gate 16 is at a high level, the switching transistor 24 is turned on, and the PNP transistor 28 for stopping oscillation is turned on via the resistor.
P) The transistor 27 is turned off and the strobe oscillation operation is stopped. That is, in this embodiment, during the lighting period of the light emitting diode 22 for self-display, the charging operation of the strobe is prohibited to prevent the battery l from decreasing and to prevent the display quality of the light emitting diode 22 from deteriorating. At this time, the charging voltage of the main capacitor 38 and the voltage level of the battery 1 are at the second level.
It fluctuates as shown in the figure. Further, in the strobe circuit of this embodiment, when the charging voltage of the main capacitor 38 reaches a predetermined value, the Zener diode 32 is turned on, and the NPN) transistor 29 is turned on.
The PNP transistor 28 for stopping oscillation is turned on, and the strobe operation is automatically stopped.

Next, when the counting operation of the binary counter 13 progresses and the output of its output terminal Q8 changes to high level, the RS flip-flop 18 is set via the OR gate 15, and its output changes to high level. Therefore, the binary counter 13 is reset via the OR game 14, and the NPN transistor 19 is turned on. As a result, the self-timer operation ends, and the tensioning magnet 20 for starting the operation of the lens barrel is energized, and the lens barrel (not shown) begins to operate. Thereafter, AF operation control and shutter operation control are performed by the functions of the well-known AF circuit 25 and AE circuit 26. Also, during this shutter operation, the
Strobe trigger signal TR from E circuit 26 to strobe circuit
1G is output, which turns on the thyristor 34,
The xenon discharge tube 37 is excited by the action of the trigger capacitor 35 and the trigger coil 36, and a strobe light emission operation is performed.

If the self-timer is not operating, press the second button of the shirt button.
When the release switch 7 is turned on due to a stroke, the output of the inverter 12 changes to high level, and this signal is input to the set input terminal S of the RS flip-flop 18 via the OR gate 15, so the output of the RS flip-flop 18 is immediately turned on. When the level becomes high, the NPN transistor 19 is turned on, power is started to be applied to the clamping magnet 20, and the lens barrel begins to operate as described above.

According to this embodiment, since the strobe charging operation is performed during the self-timer operation, it is possible to perform precharging suitable for an automatic strobe light emission system during the self-timer operation, and
The actual self-timer seconds will not be longer than the set self-timer seconds, and there will be no variation in the self-timer seconds, so the self-waiting time can always be constant.

Furthermore, if the strobe is continuously charged while the self-display light emitting diode 22 is blinking, the display quality of the light emitting diode 22 will deteriorate due to a drop in the power supply battery l.
Since strobe charging is performed only during the period when the light emitting diode 22 is turned off, the above-mentioned disadvantages will not occur.

(Correspondence between the invention and the embodiment) In this embodiment, the RS flip-flop 11, the binary counter 13, and the OR gate 14 are the self-timer circuit of the present invention, and the binary counter 13. The AND gate 16 and the NOR gate 17 correspond to a strobe charge control circuit, respectively.

(Modification) In this embodiment, in order to prevent the display quality of one light emitting diode 22 from deteriorating, strobe charging is performed only during the period when the light emitting diode 22 is turned off, but this is not limiting. For example, the strobe may be charged continuously during the initial period of the self-timer period.Also, although we have described a camera with a built-in strobe circuit, the same applies to cameras that do not have a strobe installed. be able to.

(Effects of the Invention) As explained above, according to the present invention, during self-timer flash photography, a strobe charging control circuit is provided which instructs the strobe circuit to charge while the self-timer circuit is operating, so that the self-timer period Since the strobe circuit is charged using .

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a time chart thereof. 1...Battery, 7...Release switch, 8...Self switch, 11...R
S flip-flop, 13...Binary counter, 14...OR gate, 16...
And gate, 17... Noah gate, 22...
...Light-emitting diode for self-display, 27.28.
... NPN transistor, 30 ... Oscillation transformer, 37 ... Xenon discharge tube, 38 ...
...Main capacitor.

Claims (1)

[Claims] 1. A camera equipped with a self-timer circuit that measures the set timer seconds, and a camera equipped with a strobe charge control circuit that instructs a strobe circuit to charge while the self-timer circuit is operating during self-timer flash photography.