JPS6118497Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a flash camera device equipped with an aperture control means that associates an aperture aperture formed by a plurality of aperture blades with a deflection angle of an ammeter pointer. The present invention relates to a drive means for the aperture aperture control means in this device.

Conventionally, in cameras that have an aperture aperture control means that utilizes the deflection angle of the pointer of a pointer-type ammeter, a silicon-selenium-based photovoltaic element has been used as a drive means for the aperture aperture control means to correspond to the brightness of the subject. A method is known in which the aperture aperture is controlled by supplying a photocurrent to an ammeter to control the diaphragm aperture. The chip area must be increased, which increases costs and requires a large installation space, creating design difficulties. Furthermore, selenium-based photovoltaic elements, which are relatively low in cost, have problems such as poor linearity and easy deterioration due to their characteristics.

Another driving method is to use a combination of a photoconductive element such as cadmium sulfide and a power source to control the aperture aperture by supplying a current corresponding to the brightness of the subject to an ammeter, similar to the driving method described above. be. In the case of this method, a mercury battery with a stable voltage was used as the power source because it was greatly affected by voltage fluctuations in the power source. Therefore, in this case, the driving means becomes expensive, and
Since mercury batteries have a small capacity, they have the problem that if the user forgets to turn off the power switch after using the device, the remaining capacity is easily exhausted and the battery has to be replaced.

For this reason, in the case of the drive means described above, a switch linked to the shutter release button, for example, is placed in the loop between the mercury battery as the power source and the ammeter, and power is supplied to the ammeter only when shooting. Although a configuration has been devised, even with such a configuration, there is a problem that a delay in following the pointer of the ammeter with respect to the subject brightness or an exposure error of the aperture aperture due to damping of the pointer, etc. occurs.

This invention solves these problems and
The purpose of the present invention is to provide a flash camera device that performs aperture control in accordance with fluctuations in the power supply battery when using a strobe device, and matches the amount of light emitted by the strobe device, which will be explained below with reference to the drawings.

The figure shows an electrical circuit diagram of an embodiment of the flash camera device of the present invention.

In the figure, A indicates the DC-DC converter circuit 1 into which the power supply battery 4 is input, the main discharge capacitor 2 that is charged by the output of the DC-DC converter circuit 1, and the flash light that is emitted by consuming the charge of the main discharge capacitor 2. The figure shows a well-known strobe device consisting of a discharge tube 3 and a trigger circuit (not shown), 4 is a power source battery such as a manganese battery, and 5 is an ammeter (not shown) that controls the aperture aperture by the deflection angle of the pointer. be.

In the figure, B indicates the diaphragm aperture driving means according to the present invention. The driving means B according to the present invention is in an interlocking relationship, and has automatic exposure photography (hereinafter referred to as
EE mode) and flash photography (hereinafter referred to as EE mode)
A reference voltage generation circuit consisting of two interlocking changeover switches 6 and 7, a constant voltage element 8 shown by C in the figure, a resistor 9, resistors 10 and 11, and a transistor. The variable resistor 13 and the photoconductive element 14 are selectively connected in series with the ammeter 5 by the operation of the changeover switch 7.

The operation of the drive means B according to the present invention having the above-mentioned configuration will be described below, but before that, the power supply circuit indicated by C in the figure will be explained in detail.

When the power supply circuit C is supplied with a battery 4 as a power source, a current flows through a reference voltage generation circuit consisting of a constant voltage element 8, which is a Zener diode, for example, and a resistor 9. 8
A reference voltage called an arbitrary voltage Vz determined by the characteristics of is generated. This arbitrary voltage Vz is applied between the emitter base of the resistor 10 and the transistor 12 constituting the impedance conversion circuit, and generates a voltage across the resistor 10. This voltage is always kept at a constant value because the above-mentioned arbitrary voltage Vz is not affected by voltage fluctuations within the life of the power source battery 4, and a constant voltage power source is obtained. Therefore, a constant voltage is applied to the ammeter.

Now, in this state, if the changeover switches 6 and 7 are respectively switched to the terminals 6a and 7a as shown in the figure, the EE mode is entered. When the changeover switches 6 and 7 are switched as described above, the series assembly of the ammeter 5 and the photoconductive element 14 is connected to both ends of the resistor 10.

Therefore, the ammeter 5 is supplied with a constant voltage across the resistor 10 and a current determined by the resistance value of the photoconductive element 14 corresponding to the subject brightness, that is, a current corresponding to the subject brightness. Therefore, since the deflection angle of the pointer of the ammeter 5 corresponds to the brightness of the subject, the aperture aperture also naturally corresponds to the brightness of the subject, and proper automatic exposure photography can be performed.

In this state, the power consumed by the constant voltage element 8 and the resistor 9 for generating a constant voltage across the resistor 10 is generated by connecting the arbitrary voltage of the constant voltage element 8 to the resistor through the emitter and base of the transistor 12. Since it is output to both ends of the resistor 10, it will not increase or decrease due to fluctuations in the current flowing through the ammeter 5 and the photoconductive element 14, which are loads connected to both ends of the resistor 10. The lowest value of current that can generate an arbitrary voltage is supplied according to the voltage value at the usage limit of the power supply battery 4, and power consumption in this arbitrary voltage generation loop is not a problem.

Therefore, in the driving means according to the present invention, there is no need to consider wasting power due to forgetting to turn off the power switch, which was a major problem when using a mercury battery as a power source.

Next, switch 6.7 is switched to terminals 6b and 7b to enter FM mode. That is, the power supply battery 4 is the DC-DC converter circuit 1 of the strobe device A.
A series body of a variable resistor 13 and an ammeter 5 is supplied to both ends of the resistor 10.

Now, if we think about the factors that determine exposure in FM mode, we can think of factors such as the light intensity of the flash device, aperture aperture, distance to the subject, shutter speed, etc., but normally the problem in FM mode is , the light amount of the strobe device, the aperture aperture, and the distance to the subject. It is known that the following relationship holds between these factors: the light amount of the strobe device, so-called guide number GN=aperture value F×distance D.

Therefore, in the case of the flash camera device according to the present invention, since the above-mentioned aperture value is set by the deflection angle of the ammeter 5, the above-mentioned variable resistor 13 corresponds to the above-mentioned distance D to the subject. If the configuration is such that the resistance value is set and the resistance value is adjusted, proper exposure can be obtained in FM mode.

Switches 6 and 7 have now been switched to 6b and 7b.
In FM mode, 10 resistors, 1 transistor
Constant voltage element 8 from both ends between the emitter base of 2
is disconnected, and a resistor 15 is connected in its place. In other words, in FM mode,
The resistors 10, 9, 15, and 11 and the transistor 12 form a voltage supply circuit that supplies a voltage according to the power supply voltage.

Therefore, the voltage generated across the resistor 10 is
In the case of FM mode, the aperture aperture that is set changes depending on the voltage value of the power battery 4 because the current supplied to the ammeter 5 depends on the voltage value of the power battery 4. It will change due to fluctuations.

This change in the aperture aperture can only be considered when the voltage fluctuation of the power supply battery 4 decreases, so the voltage generated across the resistor 10 also decreases, the current value supplied to the ammeter 5 also decreases, and naturally the aperture aperture becomes larger. This is a significant change. This kind of operation occurs because if the voltage of the power supply 4 drops, the charging characteristics of the main discharge capacitor 2 will deteriorate, and as a result, the amount of emitted light will decrease when fully charged, so the amount of emitted light will decrease. This is a very effective operation as a correction for the amount of time.

As described above, the present invention enables a flash camera device having an aperture aperture control means including a pointer-type ammeter to share the power source for the strobe device and the power source for driving the ammeter, which is conventionally used. In order to obtain voltage stability similar to that of mercury batteries, a power supply circuit is used, and this power supply circuit is used before or at all times to eliminate exposure errors caused by damping of the ammeter pointer, etc. Even when configured to supply current to an ammeter, the power consumption is extremely low, and the various problems that arise due to the small capacity of mercury batteries are completely solved. The operation of the power supply circuit is controlled by a changeover switch, and the diaphragm aperture control means includes an ammeter of very high practical value, which is also capable of correcting fluctuations in the amount of light emitted due to fluctuations in the voltage of the power supply during flash photography. The present invention provides driving means for the following.

[Brief explanation of the drawing]

The figure is an electrical circuit diagram of an embodiment of the flash camera device of the present invention. A... Strobe device, B... Drive means, C...
Constant voltage circuit, 4...Power battery, 5...Ammeter,
6, 7... Selector switch, 8... Constant voltage element,
9, 10, 11...Resistor, 12...Transistor, 13...Variable resistor, 14...Photoconductive element.

Claims (1)

[Scope of utility model registration request] a strobe device in which a flash discharge tube emits light by consuming the charge of a main discharge capacitor charged by the output of a DC-DC converter circuit into which a power supply battery is input, and one end of which is connected to one end of the power supply battery;
A series body of a first resistor and a constant voltage element that generates a constant voltage, a second resistor having one end connected to the other end of the power supply battery, and an emitter connected to the other end of the second resistor. , a transistor whose base is connected to a connection point between the constant voltage element and the first resistor, and whose collector is connected to one end of the power supply battery;
An ammeter, one end of which is connected to one end of the second resistor, controls the aperture aperture according to the deflection angle of the pointer, a variable resistor for setting a subject distance, a photoconductive element that detects subject brightness, and the power source battery. A series body of the first resistor and a constant voltage element that generates a constant voltage, or a first switch connected to the DC-DC converter circuit.
a switch connected between the other end of the power battery and the base of the transistor via the first switch when the power battery is connected to the DC-DC converter circuit by the first switch; and a second switch that switches and connects the variable resistor or the photoconductive element between the emitter of the transistor and the other end of the ammeter in conjunction with the first switch. , when the first switch switches and connects the power battery to the series body, the second switch switches and connects the photoconductive element between the emitter of the transistor and the other end of the ammeter; When the first switch switches and connects the power supply battery to the DC-DC converter circuit, the second switch switches and connects the variable resistor between the emitter of the transistor and the other end of the ammeter. Flash camera device.