JPS5927889B2 - electronic flash device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic flash device which is useful as an artificial light source when taking photographs, and in particular to a notification device which uses sound to notify the charging voltage of a main discharge capacitor and the fact that an automatic light control operation has been performed. The present invention relates to an electronic flash device equipped with an electronic flash device.

Conventionally, as a notification device for the charging voltage of the main discharge capacitor or automatic light control operation in electronic flash devices, devices that utilize the lighting and turning off of light-emitting display elements such as neon tubes have been known. If you want to check the status or dimming operation, you have to take your eyes off the camera's viewfinder and look at the light-emitting display element, which may lead to the inconvenience of missing a shutter release.

To solve this problem, electronic flash devices have recently been developed that have an audible notification device that allows you to check the charging status of the main discharge capacitor and the dimming operation without taking your eyes off the camera's viewfinder. Various proposals have been made.

The present invention also relates to an electronic flash device equipped with a notification device that solves the above-mentioned inconveniences by means of sound, and the sound for notifying the state of charge of the charging voltage of the main discharge capacitor changes in accordance with the charging voltage of the main discharge capacitor. In addition, it is also possible to check the dimming operation, which will be explained below with reference to the drawings.

The figure shows an electric circuit diagram of an embodiment of an electronic flash device equipped with a notification device B according to the present invention.

In the figure, A is a well-known electronic device that causes the flash discharge tube 6 to consume the charging energy of the main discharge capacitor 4, which is charged by the booster circuit 3 that boosts the voltage of the power supply 1, by the operation of the trigger circuit 5, and emit light. It is a flash device. In this circuit configuration, when the power switch 2 is turned on, the booster circuit 3 starts operating and boosts the voltage of the power source 1, and starts charging the main discharge capacitor 4. At the same time, the notification device B The voltage of the power supply 1, which has been rectified by the diode 7 and whose ripples have been absorbed by the capacitor 8, is applied to the voltage.

That is, the DC voltage via the diode 7 and the capacitor 8 becomes the power supply voltage of the notification device B. This power supply voltage constitutes one reference power supply by the resistor 9 and the diodes 10 and 11.
is applied to the husband's inverting input terminal.

The resistor 15 and the variable resistor 16 are connected in parallel with the main discharge capacitor 4 to detect the charging voltage of the main discharge capacitor 4, and the connection point between the resistor 15 and the variable resistor 16 is the non-inverting point of the comparators 17, 18, and connected to the input terminal.

Therefore, a voltage obtained by dividing the charging voltage of the main discharge capacitor 4 by the resistor 15 and the variable resistor 16 is applied to the non-inverting input terminals of the comparators 17, 18, and 19. Note that the output terminals of the comparators 17, 18, and 19 are connected to the bases of transistors 20, 21, and 22 via resistors (23 in the figure is to which the power supply voltage of the notification device B is applied. It is a pulse generation circuit that starts operating at the same time.
For example, if the frequency output from output terminal a is f, the frequency output from output terminal b is 2f, the frequency output from output terminal c is 4f, and the frequency output from output terminal d is 5f. The configuration is such that pulse outputs of different frequencies are output from the respective output terminals.

Transistors 24 and 25 are connected to comparators 17 and 1, respectively.
When the output voltage of the pulse generating circuit 8 reaches a high level, it becomes conductive, and the output terminals a and b of the pulse generating circuit 23 are grounded.

The diodes 26, 27, and 28 prevent mutual signal transfer between the output terminals A, b, and c of the pulse generation circuit 23, and the transistor 29 prevents the transfer of signals from the output terminals A, b, c, and d of the pulse generation circuit 23. The operation is controlled by the output signal of and the states of the transistors 33 and 39, and the sound generating device 30 is operated by being conductive.

In the figure, 31 is a diode, 32 is an oscillation circuit which starts oscillation and generates a rectangular pulse at the same time as the output voltage of the comparator 18 is inverted from a low level to a high level, and 33 is a transistor.

34 is a switching element connected in series with the flash discharge tube 6; 35 is a commutation circuit; 36 is a light-receiving circuit that includes a light-receiving element 37 and outputs an output signal for controlling the operation of the commutation circuit; 38;
is a monostable multivibrator circuit operated by the above output signal of the light receiving circuit 36, 39 is a transistor, 40, 4
1 indicates a backflow blocking diode.

In the configuration as described above, when the power switch 2 is now closed and charging of the main discharge capacitor 4 is started, as is well known, the charging voltage value of the main discharge capacitor 4 gradually increases, and at the same time The voltage applied to each of the non-inverting input terminals of the comparators 17, 18, and 19 increases as the charging voltage value of the main discharge capacitor 4 is divided by the resistor 15 and the variable resistor 16.

Therefore, since the reference voltage applied to the husband's inverting input terminal is set as described later, the comparators 17, 18, and 19 are set to a low level at the same time as the power switch 2 is closed. The respective output voltages of the comparator 19, the comparator 18, and the comparator 17 are inverted to high level in this order.

That is, the reference voltage of the comparators 17, 18, 19 is the voltage generated across the diodes 10, 11, which is connected to the resistor 12.
, 13, 14, and the voltage value is given by dividing the voltage by the main discharge capacitor 4 in the case of the comparator 19.
is set equal to the divided voltage value that appears across the variable resistor 16 when the charging voltage value reaches the lowest voltage value (hereinafter referred to as the first voltage value) that can cause the flash discharge tube 6 to emit light; Further, in the case of the comparator 18, the charging voltage value of the main discharge capacitor 4 is higher than the above-mentioned first voltage value.
In the case of the comparator 17, the third voltage is set to be equal to the divided voltage value generated across the variable resistor 16 when the voltage value of the main discharge capacitor 4 is reached. When the voltage value of
is set equal to the voltage value generated across the terminal.

Therefore, as described above, as the main discharge capacitor 4 is charged, the comparators 19, 18, and 17 sequentially perform the inverting operation. In addition, the pulse generation circuit 2
3 starts operating because the voltage of the power source 1 is supplied through the diode 7 and the capacitor 8 at the same time as the power switch 2 is closed, and the output terminals A, b, c, and d, for example, have the above-mentioned frequency. A pulse output having the following relationship is output.

Therefore, the output voltages of the comparators 17, 18, 19 connected to the bases of the transistors 20, 21, and 22 are set to a low level at the same time as the power switch 2 is closed, so that the transistors 20, 21, and 22 respond to the above-mentioned pulses. Output terminal A of the output,
The conducting state and non-conducting state are controlled by the period of the pulse output output from each of b and c.

Note that the output terminals A, b, c of the pulse generation circuit 23 are also connected to the base of the transistor 29, but as shown in the figure, diodes 26, 27 are connected between the output terminals A, b, c and the base of the transistor 29. , 28, and 40 are connected, and the diode 31 is also connected to the emitter of the transistor 29, so the impedance seen from the output terminals A, b, and c is lower for the transistors 20, 21, and 22. 29 is operated by the pulse output from the output terminals A, b, and c at the same time as the power switch 2 is closed, and no sound is generated from the sound generating device 30.

On the other hand, the pulse output from the output terminal d of the pulse generation circuit 23 is output from the output terminal 381 of the monostable multivibrator circuit 38.
is held at a low level as long as the light receiving circuit 36 does not operate, and therefore, like the pulse output from the other output terminals mentioned above, it is supplied to the transistor 29 at the same time as the power switch 2 is closed, and the sound generating device 30 is operated. Hana(·.

Now, when the charging voltage value of the main discharge capacitor 4 reaches the above-mentioned first voltage value, the output voltage of the comparator 19, which had been at a low level until then, is inverted to a high level. The operation of the transistor 2 whose operation is controlled by the pulse output from the output terminal a of
2 is brought into a completely non-conductive state in which it does not become conductive even when the above-mentioned pulse output is supplied.

When the transistor 22 is made non-conductive, the pulse output from the output terminal a is applied to the base of the transistor 29 via the diode 26, so that the conduction/non-conduction operation of the transistor 29 is controlled. Output terminal a
The sound generating device 30 generates sound only when the transistor 29 is conductive, that is, continuously generates a sound with a pitch determined by the period of the pulse output from the output terminal a. This will be the case.

However, when the charging voltage value of the main discharge capacitor 4 reaches the lowest voltage value that can cause the flash discharge tube 6 to emit light, that is, the first voltage value, and the output voltage of the comparator 19 is reversed from a low level to a high level, In this example,
Since the oscillation circuit 32 starts operating, the transistor 33
The conduction/non-conduction operation control is performed by the rectangular pulse output from the oscillation circuit 32.

Since the collector-emitter of this transistor 33 is connected between the base and ground of the transistor 29, the operation of the transistor 29 can be controlled not only by the pulse output from the output terminal a but also by the conduction or non-conduction of the transistor 33. It will be done. That is, after the comparator 19 performs the inversion operation upon detecting the first voltage described above,
Until the output voltage of the comparator 19 becomes low level again, the transistor 33 repeats the conduction and non-conduction states due to the rectangular pulse output of the oscillation circuit 32, and the transistor 29 operates in two stages together with the pulse output of the output terminal a. Therefore, the operation of the sound generating device 3 is controlled.
The sound of 0 is an intermittent sound with a pitch determined by the period of the pulse output from the output terminal a. Thereafter, the charging of the main discharge capacitor 4 further progresses, and the charging voltage value increases to the second level described above.
When the voltage value reaches , the output voltage of the comparator 18 is inverted from the low level to the high level.

Therefore, the transistor 21, whose operation was previously controlled by the pulse output from the output terminal b of the pulse generating circuit 23, is completely rendered non-conductive, and the transistor 25, which had been non-conductive, is now rendered non-conductive. A conductive state is established.
When the transistor 21 becomes non-conductive, the pulse output from the output terminal b is supplied to the base of the transistor 29 via the diode 27. Furthermore, when the transistor 25 becomes conductive, the output terminal a of the pulse generation circuit 23 is grounded, and the comparator 19
Due to the inversion operation of , the pulse output from the output terminal a that was being supplied to the transistor 29 is no longer supplied to the base of the transistor 29. Therefore, the transistor 29 is
When the charging voltage value of the main discharge capacitor 4 reaches the second voltage value, the operation is controlled by the pulse output from the output terminal b of the pulse generating circuit 23, and the sound generating device 3
Since 0 also operates in accordance with the operation of transistor 29,
The sound generated by the sound generating device 30 is different from the sound when the charging voltage value of the main discharge capacitor 4 reaches the above-described first voltage value.

That is, since the frequency of the pulse output from output terminal a and the frequency of the pulse output from output terminal b are different, the conduction and non-conduction times of the transistor 29 are different, and the sounds generated from the sound generating device 30 are sounds with different pitches. becomes. Furthermore, the oscillation circuit 3
2, the second voltage value is higher than the first voltage value and the output terminal of the comparator 19 is set to a high level regardless of the operation switching as described above, so the operation continues. It goes without saying that sounds of different pitches are also output as intermittent sounds. Next, when the charging voltage value of the main discharge capacitor 4 reaches the aforementioned third voltage value, the comparator 17 performs an inversion operation.

Therefore, the transistor 20 is completely turned off, the transistor 24 is turned on, and among the output terminals A, b, c of the pulse generation circuit, the terminals A and b are connected to the transistor 2.
5, 24 will be grounded.

Therefore, the base of the transistor 29 is supplied with the pulse output from the output terminal c of the pulse generating circuit 23, and the operation of the transistor 29 is also controlled by the frequency of the pulse output from the output terminal c. That is, the sound generated by the sound generating device 30 is determined by the pulse output from the output terminal c and the output from the oscillation circuit 32, and this sound is generated when the charging voltage value of the main discharge capacitor 4 is the first voltage value. Of course, this is an intermittent sound that differs in pitch from the sound when the second voltage value is reached. Through the above-described operation, one embodiment of the electronic flash device according to the present invention notifies the charging voltage of the main discharge capacitor.
Next, a case will be described in which the flash discharge tube 6 emits light and automatic dimming operation is performed by the operation of the light receiving circuit 36 and the commutation circuit 35.

That is, the flash discharge tube 6 emits light, and the light receiving element 37 receives reflected light from the subject. When the amount of received light reaches a predetermined amount, the light receiving circuit 36 outputs a light emission stop signal and the commutation circuit 35
However, in this embodiment, simultaneously with the operation of the commutation circuit 35, the monostable multivibrator circuit 38 starts operating in response to the above-mentioned light emission stop signal.

Therefore, a high level output voltage is outputted to the output terminal 381 of the monostable multivibrator circuit 38 for an arbitrary period of time, making the transistor 39 conductive and releasing the short circuit of the output terminal d of the pulse generation circuit.

When transistor 39 becomes conductive, diode 26
, 27, 28, the supply of the pulse output to transistor 29 is completely cut off, but since the output terminal 38 was at a low level until then, transistor 2
The pulse output from the output terminal d of the pulse generation circuit 23, which had been cut off from supply to the transistor 29, is now supplied to the transistor 29 via the diode 41.
is, while the pulse output from output terminal d is supplied,
The operation is controlled by this pulse output, and the sound generating device 30 generates a sound with a pitch determined by the period of the pulse output from the output terminal d for an arbitrary period determined by the monostable multivibrator 38, Notifies that automatic dimming operation has been performed.

As explained above, the present invention notifies the state of charge of the main discharge capacitor in an electronic flash device by an intermittent sound of a height corresponding to the charging voltage value, and also uses the same sounding device to notify the state of charge of the main discharge capacitor in the dimming operation. It is an object of the present invention to provide an electronic flash device equipped with a notification device in which confirmation can be made using a sound different from the sound for notifying the charging voltage.

[Brief explanation of drawings]

The drawing is an electrical circuit diagram showing an embodiment of an electronic flash device according to the present invention. 4... Main discharge capacitor, 17, 18, 19-
...Comparator, 20, 21, 22, 24, 2
5, 29, 33, 39...transistor, 23
...Pulse generation circuit, 30 ... Sound generating device, 32 ... Single oscillation circuit, 35 ... Commutation circuit, 36 ... Light receiving device , 37... Light receiving element, 38... Monostable multipipelator circuit.

Claims (1)

[Claims] 1. A flash discharge tube that emits light by consuming the charge in the main discharge capacitor; and a light receiving device that receives light reflected from a subject due to the light emitted by the flash discharge tube and operates a commutation circuit that controls the light emission operation of the flash discharge tube. an electronic flash device having a reference power source, a voltage detection unit that detects a charging voltage of the main discharge capacitor, and a plurality of reference voltages obtained by dividing the reference power source by a plurality of resistors; a plurality of comparators to which the output of the voltage detection section is applied to a non-inverting input terminal, and a pulse generation circuit that outputs a plurality of pulse outputs of different frequencies from a plurality of corresponding output terminals; It includes a plurality of switching elements whose operation is controlled by the output signals of the plurality of comparators, selects one of the plurality of output terminals of the pulse generation circuit, and sets the pulse output of the selected terminal as the selected pulse output. a selection circuit including a selection output terminal for output; an oscillation circuit that is supplied with an output signal of one of the plurality of comparators and starts operating when the voltage detection section detects the lowest voltage; A control pole is connected to the output terminal of the oscillation circuit, one end of the main pole is connected to ground, and the other end is connected to the selection output terminal of the selection circuit, and the output of the oscillation circuit is supplied to operate the selection output. A first switching element that intermittently bypasses the selection pulse output output from the terminal, and a connection point between the selection output terminal and the first switching element is connected via a first backflow blocking diode. a second switching element having a control pole and whose operation is controlled by the selection pulse output controlled by the first switching element;
a sounding device that is connected in series with the switching element and generates a sound with a pitch determined by the cycle of the selection pulse output when the second switching element is operated by the selection pulse output; The output terminal of the pulse generation circuit that generates a pulse output different from the selected pulse output is connected in a forward direction to the connection point between the control pole of the second switching element and the first backflow blocking diode. a third switching element whose main poles are connected in parallel with the first switching element; an anode of the second backflow blocking diode and the third switching element; A common output terminal connected to a control pole and kept at ground potential at all times, and a pulse output of a predetermined voltage and arbitrary width is generated at the common output terminal when the output signal of the light receiving circuit is supplied. The second pulse generating circuit notifies the state of charge of the main discharge capacitor with intermittent sounds of different heights, and when the light receiving circuit operates, the second pulse generating circuit generates a signal of the predetermined voltage and arbitrary width. When a pulse output is output, the anode potential of the second backflow blocking diode is increased and the third switching element is made conductive, and another pulse output of the pulse generation circuit is sent to the second switching element. An electronic flash device comprising: a notification device which is supplied regardless of the operating state of the selection circuit/first switching element and which notifies automatic light control operation with a continuous sound having the arbitrary width and having a height different from the intermittent sound.