JPS58214134A - Flash device - Google Patents

Abstract

PURPOSE:To prevent erroneous emission of light, by turning off a display of charging detection when the power switch of a DC power supply is turned off with disabled triggering and then enabling the triggering only when the charging is over if the power switch is turned on. CONSTITUTION:A DC power supply E is supplied to a DC/DC converter 1 when a power switch 2 is turned on, and the charging of a main capacitor 3 is started. If a neon tube 5 glows when the charging of the capacitor 3 is over, a capacitor 8 is charged. Then a thyristor 10 for operation of a trigger circuit 11 conducts. Thus a flash discharge tube 13 can emit light only when the tube 5 glows. When the switch 2 is turned off, the electric charge of the capacitor 8 is discharged. At the same time, the tube 5 is turned off. Under such conditions, the circuit 11 has no operation if an X contact 9 is closed. Thus no light is emitted.

Description

DETAILED DESCRIPTION OF THE INVENTION In a flash device, when the power switch is on the side that supplies DC power (ON side), the flash discharge tube is triggered after detecting that charging of the main capacitor is completed. , and the power switch is D
This invention relates to a device for turning off the main capacitor charge detection display and disabling the triggering of the flash discharge tube when the C power supply is disabled (OFF side).

Conventionally, in flash devices, there was no relationship between the charge detection display of the main capacitor and the trigger circuit of the flash discharge tube, and if the X contact was turned on before the charge detection display was displayed, the trigger circuit would be activated and the amount of light emitted would be insufficient. There was a risk that this would occur. In other words, it is possible to supply power to trigger the trigger circuit before the main capacitor charge completion detection display is displayed, and the power supply voltage level is set to a level at which the trigger circuit can operate by the time the charge completion display is displayed.
This was not possible in individual circuits due to variations in element constants.

In addition, when you do not want to emit a flash, simply opening the power switch and stopping the operation of the DC-DC converter will still cause the charge in the main capacitor and the power source for the trigger circuit to remain, so if you turn on the X contact as it is, There was a risk that the flash would emit light and cause unintended operation.

The present invention is a device for improving the above-mentioned two drawbacks, and also works reliably and without error in a device that operates a camera control circuit by using charge detection of a flash's main capacitor. .

Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.

FIG. 1 shows an embodiment of the present invention, and FIG. 2 shows the voltage at each point in FIG. 1 and the movement of the power switch.

In Figure 1, the DCC power supply is DC-DC converter 1
A high voltage is applied to the main capacitor 3 through the main capacitor 3, and a flash discharge tube 13 is connected in parallel with the main capacitor 3. Further, ten poles of the main capacitor 3 are connected to ten poles of the neon tube 5 via a resistor 4. One pole of the neon tube 5 is connected to ground potential through an impedance element 7 and a capacitor 8 connected in parallel. The ten poles and negative poles of this neon tube 5 are connected to the cathode and anode of a diode 6, respectively.

Further, the connection point between one pole of the neon tube 5 and the impedance element 7 is connected to the gate of the thyristor 10 via the X contact switch 9, and when the thyristor lo is conductive, the trigger circuit 11
is connected to work.

1-The output of the trigger circuit 11 is connected to the trigger terminal 12 of the flash discharge tube 13. Further, a connection point between one pole of the neon tube 5 and the impedance element 7 is connected to another circuit block 14 such as a camera control circuit. The power switch 2 forms a switching arrangement.

The earth potential is the common terminal, the terminal ON is connected to the DCC power supply, and the terminal OFF is connected to the ten poles of the neon tube 5.
This is used to switch between the two terminals.

Figure 2 shows the state (a) of the power switch 2 in Figure 1.
(b) showing the charging voltage V3 of the main capacitor 3 and (c) showing the voltage 2.7 generated in the impedance element 7 change over time t.

The operations will be explained in sequence below. In the following description, it is assumed that the X contact switch 9 is open in a steady state.

When the power switch 2 is switched to the ON side, the 1]C power source E is supplied to the DC-DC converter 1, and the main capacitor 3 starts to be charged. This is the time tl in FIG.

When the charging voltage of the main capacitor 3 reaches a certain value, the neon tube 5 is opened, current flows through the current limiting resistor 4 and lights up, and further current flows through the impedance element 7 to generate a voltage. Charge capacitor 8. Here, the capacitor 8 only needs to store enough energy to trigger the thyristor 1o, and a relatively small capacitance is sufficient. Therefore, the rise time of v7 in FIG. 2 can also be shortened. The energy generated by converting the voltage generated in the impedance element 7 into stored energy closes the X contact switch 9, thereby opening the gate 1- of the thyristor]O.
1 to trigger, close the thyristor IO, and trigger circuit 11
can be activated to cause the flash discharge tube 13 to emit light. This is t2 in FIG.

What is important here is that the flash discharge tube can be triggered only after the neon tube 5, which detects the charging of the main capacitor 3, is turned on.

Next, we will discuss a case where you do not want the flash device to emit light. When the power switch 3 is switched to the OFF side, the stored energy for triggering the gate of the thyristor 10 to 1 is immediately discharged via the diode 6. Furthermore, the neon tube 5 is also turned off.

(c) in FIG. 2 shows the stored energy in terms of voltage. At this point, even if the X contact switch 9 is closed, the trigger circuit 11 is not activated and the flash device does not emit light. Also, impedance element 7
Voltage 7 generated at
7 can be detected by another circuit block 14 such as a camera control circuit, it is possible to create a system that is linked to the completion of charging of the main capacitor 3 of a flash (not shown). For example, when the camera control circuit detects the voltage 7, the shutter speed is set to the synchronized shutter speed of the flash, or the main capacitor 3 of the flash is charged within the viewfinder of the camera. It is possible to light up a display element such as an LED to display the information. Furthermore, by switching the power switch 2 to the OFF side, the voltage V7 is no longer generated, and the linkage with other circuit blocks 14 such as the camera control circuit can be cut off. 14 can be made independent of flash. Note that in one or more operations, the voltage generated in the forward direction of the diode 6 can be ignored.

As described above, according to the present invention, the desired operation can be achieved reliably by simply switching the power switch according to the breath, the operation is simple and reliable, and erroneous light emission can be prevented. Furthermore, the interlocking of other circuit blocks, such as the flash device and camera control circuit, can be selected by operating only the power switch, which has a wide range of applications.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of the present invention, Figure 2 is fJ
State of the power switch at s + li l (a)
shows the charging voltage v3 of the menin capacitor 3 (
b) and the voltage v7 of the impedance element 7 (c
) is a diagram illustrating changes in time (1). lΣ,: DC power supply 1: DC-DC converter 2:
Power switch 3: Main capacitor 4: Resistor
5: Neon tube 6: Diode 7: Impedance element 8: Capacitor 9: X contact switch lO: Thyristor 11: Trigger circuit 12: Trigger terminal 13:
Flash discharge tube 14: Other circuit blocks such as camera control circuit ■3: Charging voltage of main capacitor 3 v7: Voltage generated in impedance element 7 Patent applicant
, Asahi Optical Industry Co., Ltd. ＼Representative: Retired Matsumoto

Claims (1)

[Claims] I DC power source and D generating high voltage from the DC power source
A C-DC converter, a flash discharge tube, a trigger circuit for causing the flash discharge tube to emit light, a main capacitor that stores energy for causing the flash discharge tube to emit light, and detecting the charging voltage of the main capacitor. When the power switch is on the side that supplies DC power, it enables the triggering of the flash discharge tube after detecting the completion of charging of the main capacitor; 2. A flash device characterized in that, when the main capacitor charge detection display is turned off and the triggering of the flash discharge tube is disabled when the supply of the flash discharge tube is disabled. 2 DC power supply and D that generates high voltage from the DC power supply
A C-DC converter, a flash discharge tube, a trigger circuit for causing the flash discharge tube to emit light, a main capacitor that stores energy for causing the flash discharge tube to emit light, and detecting the charging voltage of the main capacitor. When the power switch is on the side that supplies DC power in a flash device with a neon tube for flash discharge, it enables the triggering of the flash discharge tube and activates the camera control circuit after detecting the completion of charging of the main capacitor. Further, when the power switch is on the side that disables the supply of DC power, the main capacitor charge detection display is turned off, the trigger of the flash discharge tube is disabled, and the linkage with the camera control circuit is cut off. A flash device featuring: