JP2001109039A - Stroboscope device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stroboscope device which is to be optimized when a charging switch and a light emission selecting switch are made to be a switch part having three contacts. SOLUTION: A 3-contact switch part 17 opens and closes the interval between a trigger capacitor 35 and a synchronous switch 38 and the interval between the fourth terminal 30d of an oscillation transformer 30 and the base terminal of an oscillation transistor 29. When the switch part 17 is in an ON state, the transistor 29 oscillates with a bias current from a battery 19 and a secondary- side current of the secondary coil 32 and a main capacitor 16 and the trigger capacitor are charged with the secondary-side current and also stroboscopic light emissions are performed with the ON of the synchronous switch 18. Since a primary-side current does not flow through the switch part 17, a charging time does not become long. When the switching part 17 is made to be in an OFF state, since the supplying of the bias current and the secondary-side current are interrupted, the oscillation of the transistor 29 is stopped and the stroboscopic light emissions are inhibited. A diode for protection 52 protects the transistor 29 from voltages to be generated by contact resistances of the part 17 when the capacitor 35 is discharged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flash device.

[0002]

2. Description of the Related Art When photographing a subject or the like having an insufficient exposure amount, a good printed photograph can be obtained by emitting a strobe light. Some cameras and film units with lenses have a built-in strobe device. When performing flash photography, it is necessary to charge the main capacitor to a specified charging voltage in advance, so that the charge switch is normally turned on prior to flash photography.

In this strobe device, the main capacitor is charged only while the charging switch is being turned on, and the charging is stopped in response to the turning off of the charging switch. There is an automatic charging stop type having an auto cut function for automatically stopping charging when the battery is charged to a specified charging voltage.

In an automatic charging stop type strobe device,
For example, Japanese Patent Application Laid-Open No. 10-153 filed by the present applicant
As known from Japanese Patent Publication No. 814, for example, a push-type charging switch is used, and once this charging switch is turned on, charging is continued until the main capacitor reaches a specified charging voltage even when the charging switch is turned off and turned off. When charging is stopped by reaching the specified charging voltage,
Using a one-push system in which charging is continuously stopped until the charging switch is turned on again, or using a sliding charging switch, for example, charging is stopped when the main capacitor reaches a specified charging voltage, and while the charging switch is turned on. Then, there is an additional charging system in which when the charging voltage of the main capacitor is reduced due to spontaneous discharge or the like after the charging is stopped, the charging is automatically performed up to a specified charging voltage, and the additional charging is performed intermittently.

There is also known a strobe device having a light emission selecting function which enables selection of necessity of strobe light emission in conjunction with on / off operation of a charging switch (for example, Japanese Utility Model Registration No. 2535884). , JP-A-8-
No. 304888). Further, there is also known a strobe device in which charging completion is indicated by lighting a light emitting diode instead of a neon tube (for example, Japanese Patent Application Laid-Open No. 8-115796). The above-mentioned JP-A-10-
Japanese Patent Application Publication No. 153814 discloses a strobe device having an auto-cut function and a light emission selection function, and displaying a charge completion display using a light emitting diode.

FIG. 6 shows a circuit of a strobe device having a light emission inhibiting function described in Utility Model Registration No. 2535884. In this strobe device, a known blocking oscillation circuit that converts a low voltage of the battery 62 into a high voltage is configured by the oscillation transistor 60 and the oscillation transformer 61. The oscillation transistor 60 includes a tertiary coil 63
Is supplied to the base terminal from the battery 62, a primary current (= collector current) flows through the primary coil 64 of the oscillation transformer 61, and flows with an electromotive force induced in the secondary coil 65. When the secondary current is fed back to the base terminal, it oscillates and amplifies the primary current. Then, during this oscillation, the main capacitor 66 for strobe light emission is charged with the secondary current flowing by the high voltage electromotive force generated in the secondary coil 65.

The charge switch 67 is connected to the oscillation transistor 6
0 is connected to the emitter terminal of
2 to control whether or not to flow the bias current, the primary current and the secondary current, and determine whether to charge by oscillating the oscillation transistor 60 or to stop charging by stopping the oscillation transistor 60. I try to switch. A light emission selection switch 68 that is turned on and off in conjunction with the charge switch 67 is provided between the emitter terminal and the trigger capacitor 69. The light emission selection switch 68 is turned off when the charge switch 67 is turned off. .

When the light emission selection switch 68 is turned on in conjunction with the charge switch 67, the trigger capacitor 69 is charged with the secondary current flowing through the light emission selection switch 68, and the synchronization switch 70 is turned on. When this happens, the charged trigger capacitor 69 allows a discharge current to flow to the primary side of the trigger transformer 71 to allow the trigger capacitor 69 to discharge, so that strobe light emission is performed. When the light emission selection switch 68 is off, the synchronization switch 7
Even if 0 is turned on, strobe light emission is prohibited by keeping the trigger capacitor 70 not connected to the primary side of the trigger transformer 71. By arranging the charging switch 67 and the light emission selection switch 68 in this way, one contact of each of the switches 67 and 68 can be shared with each other. The switch 68 can be constituted by one switch unit having three contacts.

FIG. 7 shows a circuit of an additional charging type strobe device which has an auto-cut function and a light-emitting selection function described in Japanese Patent Application Laid-Open No. H10-153814, and displays the completion of charging with a light-emitting diode. It is. In FIG. 5, the configuration of the blocking oscillation circuit that generates a high-voltage electromotive force in the secondary coil and causes the secondary current to flow is the same. And a detailed description thereof will be omitted.

In the case of this strobe device, a charge switch 67 is provided between the battery 62 and the tertiary coil 63, and one contact of the charge switch 67 is a light emission selection switch 68.
And the charge switch 67 and the light emission selection switch 68 can be constituted by one switch unit having three contacts.

Reference numeral 72 in the figure denotes an oscillation stop circuit which operates as an auto cut function.
The operation of the blocking oscillation circuit is stopped when 6 is equal to or higher than the specified charging voltage. Even if the blocking oscillation circuit is stopped by the oscillation stop circuit 72, if the charging switch 67 is on, the main capacitor 6
When the charging voltage of No. 6 falls below the specified charging voltage due to spontaneous discharge or the like, the blocking oscillation circuit operates again, and the main capacitor 66 is charged to the specified charging voltage.

Reference numeral 73 denotes a light-emitting diode that starts to turn on when the main capacitor 66 is charged to near the specified charging voltage during the operation of the blocking oscillation circuit, and notifies the completion of charging. The light emitting diode 73 is connected between the terminals of the tertiary coil 63 of the oscillation transformer 61,
While the blocking oscillation circuit is operating, the main capacitor 16
Of the tertiary coil 63 is changed based on the change of the charging voltage of the tertiary coil 63. When the main capacitor 16 is charged to the predetermined display charging voltage, the main capacitor 16 is charged. Lighting starts, and when the battery is charged to the specified charging voltage, the lamp lights up brightly.

In the strobe device shown in FIG.
Although the charge completion display is performed by the neon tube indicated by reference numeral 75, the charge completion display can be performed by using a light emitting diode instead of the neon tube 75. In this case as well, a light emitting diode is connected between the terminals of the tertiary coil 63, similarly to the strobe device shown in FIG. Alternatively, the cathode of the light emitting diode may be connected to the negative electrode of the battery 62, and the anode may be connected to the collector terminal of the oscillation transistor 60 or the terminal of the tertiary coil 63 on the positive electrode side of the battery 62.

[0014]

In the case where a light emission selection switch is provided, it is better to provide one switch unit having three contacts as described above than to provide a charge switch and a light emission selection switch separately. It is possible to suppress an increase in the number of manufacturing steps due to an increase in the number of parts, an increase in manufacturing cost, and a probability of occurrence of a contact failure or the like when turning on and off. However, for example, when a charging switch is provided as in the strobe device shown in FIG. 6, the problem that the charging time becomes longer occurs for the following reasons.

A primary circuit of a blocking oscillation circuit, which is connected in order from the positive electrode of the battery to the negative coil of the battery via the primary coil of the oscillating transformer and the oscillating transistor (between the collector and emitter), is connected to the primary circuit during charging of the main capacitor. Although a large (for example, a maximum of about 5 A) primary-side current (= collector current) flows, the primary-side current flows through the charge switch, so that the primary-side current decreases due to the contact resistance of the charge switch. That is, electric energy is lost due to the contact resistance of the charging switch, and the electric energy supplied to the main capacitor by the secondary current per unit time decreases accordingly. For this reason, the time until the predetermined electric energy is stored in the main capacitor,
That is, there is a problem that the charging time required to reach the specified charging voltage becomes longer.

Such a problem occurs not only when the charging switch is connected to the emitter terminal of the oscillation transistor but also when the charging switch is arranged on the primary circuit of the blocking oscillation circuit. For example, in the strobe device shown in FIG. 8, the charge switch 67 is disposed between the positive electrode of the battery 62 and the primary coil 64 and the tertiary coil 63. In this case as well, the primary current is supplied to the charge switch 67. This causes a loss of electric energy due to the contact resistance of the charging switch 67, so that the charging time becomes longer. In the flash device of FIG. 8, substantially the same components as those of FIG. 7 are denoted by the same reference numerals, and detailed description thereof will be omitted.

If the auto-cut function, that is, the oscillation stop circuit is removed from the strobe device shown in FIG. 7, the charge switch and the light emission selection switch are combined into one switch unit having three contacts, so that the strobe light is combined. The manufacturing cost of the device can be reduced. However, regardless of the presence or absence of the oscillation stop circuit, this strobe device does not immediately stop charging when the charge switch and the light emission selection switch are turned off. In this case, even though the light emission selection switch is turned off, the light emitting diode is turned on for a while when the charging voltage of the main capacitor reaches a predetermined voltage, so that the strobe device has failed or The photographer may be erroneously recognized as being in a state of strobe light emission.

The reason that the charging does not stop immediately is that when the charge switch is turned off, the supply of the bias current from the battery to the oscillation transistor is stopped, but the connection between the primary coil and the battery is not released, and the oscillation does not occur. Since the secondary current from the secondary coil of the transformer can flow into the base of the oscillation transistor, the charging voltage of the main capacitor increases, and the back electromotive force generated in the secondary coil decreases. This is because the oscillation transistor self-oscillates until it weakens.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. A charge switch and a light emission selection switch are selected by using a single switch unit having three contacts to select charging and strobe light emission. It is an object of the present invention to provide a strobe device optimized for:

[0020]

To achieve the above object, according to the present invention, a first switch for opening and closing a circuit for supplying at least a bias current from a battery to a base terminal of an oscillation transistor, and a trigger. A second switch that opens and closes a circuit that supplies a discharge current from the capacitor to the primary side of the trigger transformer via a synchro switch, and includes one of the contacts of the first switch and one of the contacts of the second switch; A switch unit for turning on and off the three contacts at the same time, and a line connecting the contact connected to the base terminal side of the oscillation transistor and the base terminal of the oscillation transistor among the three contacts of the switch unit. Connected to the emitter terminal of the oscillation transistor, the synchro switch is turned on, and the trigger Capacitor in which is provided a protective diode for reducing the magnitude of the reverse bias to become the voltage between the base and emitter of the oscillation transistor caused by the contact resistance of the switch unit upon discharge.

According to the second aspect of the invention, the charging of the main capacitor is continuously performed while the switch is on, and the charging of the main capacitor and the trigger capacitor is stopped in response to the turning off of the switch. It is made to be done. In the invention according to claim 3, the tertiary coil inductively coupled to the primary coil and the secondary coil, one end is connected to one end of the tertiary coil, and the other end is connected to a connection point between the tertiary coil and the secondary coil, respectively. A light emitting diode that lights up in response to the main capacitor reaching a predetermined charging voltage, and the light emitting diode performs a charge completion display.

According to the fourth aspect of the present invention, the first switch opens and closes a circuit for supplying a bias current to the base terminal of the oscillation transistor and opens and closes a circuit for supplying a secondary current to the base terminal of the oscillation transistor. It is something to do. According to a fifth aspect of the present invention, the first switch opens and closes a circuit for supplying a bias current to the base terminal of the oscillation transistor and simultaneously opens and closes the connection between the tertiary coil and the light emitting diode.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows a film unit with a lens incorporating a strobe device of the present invention. In the film unit with a lens, a photographic film is built in a unit body 2 having a simple photographing mechanism, and an exterior paper 3 is wound around the unit body 2. On the front surface of the unit main body 2, there are provided a photographing lens 4, an object side window 5a of a finder 5,
An electronic flash unit 6 and an operation lever 7 are provided. Further, on the upper surface of the unit main body 2, there are provided a shutter button 8, a counter window 9 for displaying the number of remaining photographable frames, and an opening 10a from which a display light guide 10 for displaying completion of flash charging is projected. Further, on the back side of the unit main body 2, a hoisting knob 11 that is rotated and operated every time one frame is shot is exposed.

The exterior paper 3 is provided with an opening for exposing the photographing lens 4, the finder 5, the counter window 9, and the like, and is wound around the strobe light emitting portion 6, the shutter button 8, the operation lever 7, the winding knob 11, and the like. Therefore, the photographing operation can be performed while the exterior paper 3 is wound around the unit main body 2.

The operation lever 7 is for turning on and off the switch 17 (see FIG. 1) of the strobe device. The operation lever 7 is slidable between an ON position slid upward in the film unit with the lens and an OFF position slid downward. When the operation lever 7 is set to the ON position, the switch unit 17
Is turned on, charging is performed, and strobe light emission is allowed. When the operation lever 7 is set to the OFF position, the switch unit 17 is turned OFF, charging is stopped, and strobe light emission is prohibited. Operation lever 7
Are not shifted from the set position by vibration or the like. The display light guide 10 protrudes from the upper surface of the unit body 2 in conjunction with the operation lever 7 being slid to the ON position.

FIG. 3 shows the appearance of a flash device built in the above-mentioned film unit with lens. This strobe device displays charging completion with a light emitting diode,
The charge switch and the light emission selection switch are configured as a single three-contact switch unit, thereby reducing manufacturing costs. The charging of the main capacitor is continuously performed while the switch unit 17 is on, and the charging is stopped in response to the off of the switch unit 17. That is, the manufacturing cost is further reduced by omitting the auto cut function.

The strobe device is constructed by assembling a strobe light emitting unit 6, a main capacitor 16, a switch unit 17, a synchro switch 18, a battery 19 (see FIG. 1) as a power source of the strobe device, electronic parts, and the like on a strobe circuit board 15. It is a thing.

The switch section 17 comprises a single conductive movable piece 20 and first to third contacts (lands) 21 a to 21 c provided on the surface of the strobe circuit board 15.
The switch unit 17 is a three-contact switch having both functions of a charge switch for switching whether or not to perform charging and a light emission selection switch for switching between allowing and prohibiting strobe light emission. The movable piece 20 is formed by processing an elastic metal plate, and has one end divided into two parts (hereinafter, for convenience of explanation, each part of the one end will be referred to as a first end 20a, a second end). This will be described as an end 20b). The other end 20c of the movable piece 20 is the third contact 21c.
Is fixed on the flash circuit board 15 by soldering. The switch unit 17 connects the first end 20a and the second end 20b to a first contact 21a and a second contact 21b, respectively.
And the third contact 21c is separated from the first and second contacts 21
a, 21b, the first end 20a and the second end 20b are brought into contact with the first contact 21a and the second contact 21b, respectively. Is electrically connected to and turned on.

When the operation lever 7 is set to the OFF position, the switch unit 17 is turned off. When the operating lever 7 is slid to the ON position, the pressing portion 7a formed at the rear end of the operating lever 7 is slid upward, and one end of the movable piece 20 is pressed by the pressing portion 7a. Strobe circuit board 15
, The first end 20a is pressed against the first contact 21a, and the second end 20b is pressed against the second contact 21b, so that the switch unit 17 is maintained in the ON state.

In this example, one end of the movable piece 20 is divided into two for making one end contact with the first contact 21a and the second contact 21b for reliable electrical connection.
The first to third contacts 21a to 21c are electrically connected to the movable piece 20.
Therefore, one end of the movable piece 20 need not be divided into two parts. Further, the contact for fixing the movable piece 20 may be any one of the first to third contacts 21a to 21c. Further, the movable piece 20 may be separated from all the contacts in the OFF state, and may be in contact with all the contacts in the ON state.
If it is fixed to the individual contacts, the possibility of contact failure can be reduced.

The synchro switch 18 is composed of a pair of contact pieces 18a and 18b arranged vertically, and a pressing piece (not shown) formed integrally with the shutter blades when the shutter mechanism is operated. It is turned ON when the piece 18a is pressed and comes into contact with the lower contact piece 18b. This ON of the synchro switch 18 is used for timing control of strobe light emission.

FIG. 1 shows a circuit of the above strobe device. As described above, the switch unit 17 includes the movable piece 20 and the first to third
The movable piece 20 is composed of contacts 21a to 21c.
Is connected to the third contact 21c, and is separated from the ON state in which the first end 20a and the second end 20b are in contact with the corresponding first contact 21a and second contact 21b by operating the operation lever 7, respectively. It is shifted in the OFF state.

Oscillation transistor 29 and oscillation transformer 30
"" Constitutes a known blocking oscillation circuit for converting the low voltage of the battery 19 to a high voltage in order to charge the main capacitor 16 with a high voltage. The oscillation transformer 30
Each is composed of a primary coil 31, a secondary coil 32, and a tertiary coil 33 which are inductively coupled. In the following description, each terminal of the primary coil 31 is a first terminal 30a, a second terminal 30b, one terminal of the secondary coil 32 is a fifth terminal 30e, and the other terminal is a common terminal with one terminal of the tertiary coil 33. , The other terminal of the tertiary coil 33 is referred to as a third terminal 30c.

The oscillation transformer 30 has a first terminal 30a
Are connected to the collector terminal of the NPN-type oscillation transistor 29, and the second terminal 30 b is connected to the positive electrode of the battery 19. The third terminal 30c is connected to the positive electrode of the battery 19 via the resistor 34a, and the fourth terminal 30d is connected to the oscillation transistor 2 via the switch 17 and the resistor 34b.
9 base terminals. The fourth terminal 30 d is connected to the trigger capacitor 3 via the switch unit 17.
5 is connected to one end. The fifth terminal 30e is connected to the cathode of the rectifying diode 36. One end (minus side) of the main capacitor 16 is connected to the anode of the rectifier diode 36, and is connected to the other end of the trigger capacitor 35 via the resistor 34c.
The emitter terminal of the oscillating transistor 29 is connected to the negative electrode of the battery 19 and grounded. The positive terminal of the main capacitor 16 is connected to this emitter terminal.

The trigger coil 37 is composed of a primary coil 37a and a secondary coil 37b which are inductively coupled. One end of each of the primary coil 37a and the secondary coil 37b is a common terminal. The other end of the primary coil 37a is connected to the other end of the trigger capacitor 35, and the secondary coil 37b
The other end is connected to a trigger electrode 39 provided close to a strobe discharge tube 38 built in the strobe light emitting section 6. The common terminal of each of the coils 37a and 37b is connected to the switch section 17 via the sync switch 18. Each terminal of the strobe discharge tube 38 is connected to both ends of the main capacitor 16.

The strobe device connected as described above
From the positive electrode of the battery 19 to the resistor 34a and the tertiary coil 3
3, switch section 17, resistor 34b, oscillation transistor 2
The circuit connected in order to the negative electrode of the battery 19 via the base and the emitter of No. 9 is a bias circuit for flowing a bias current for operating the oscillation transistor 29.

The switch section 17, the base-emitter of the oscillation transistor 29, the main capacitor 16, the rectifying diode 3
6, a circuit sequentially connected to the fifth terminal 30e of the secondary coil 32 is a main secondary circuit that charges the main capacitor 16 and flows a secondary current that causes the oscillation transistor 29 to oscillate. The fourth terminal 30d of the secondary coil 32
, Switch unit 17, trigger capacitor 35, resistor 34
The circuit connected in order to c, the rectifying diode 36, and the fifth terminal 30e of the secondary coil 32 is a sub-secondary circuit that flows a secondary current for charging the trigger capacitor 35.

Further, a circuit connected in order from one end of the trigger capacitor 35 to the switch section 17, the synchro switch 18, the primary coil 37a of the trigger transformer 37, and the other end of the trigger capacitor 35 is connected when the synchro switch 18 is turned on. A trigger discharge circuit for flowing a discharge current from the trigger capacitor 35 to the primary coil 37a.

When the switch unit 17 is turned on, the bias current and the secondary current are supplied to the oscillation transistor 29, and the secondary current is supplied to the trigger capacitor 35. When the trigger discharge circuit is turned on, the trigger discharge circuit is closed. When the trigger discharge circuit is turned off, the supply of the bias current and the secondary current to the oscillation transistor 29 is cut off.
The connection is made such that the trigger discharge circuit is kept open even if 8 is turned on. Therefore, the switch unit 17 forms a first switch that opens and closes a circuit that supplies a bias current and a secondary current to the oscillation transistor 29, and a second switch that opens and closes a trigger discharge circuit. Are arranged in the circuit such that each one contact is shared.

In this example, the first contact 21a is connected to the fourth terminal 30d of the oscillation transformer 30 and the synchro switch 18, the second contact 21b is connected to one end of a trigger capacitor 35, and the third contact 21c is connected to the oscillation transistor via a resistor 34b. 29 base terminals are connected to each other. The first contact 21a and the third contact 21c are the contacts of a first switch (charging switch) that opens and closes a circuit that supplies a bias current and a secondary current to the oscillation transistor 29. The two contacts 21b are the respective contacts of a second switch (light emission selection switch) for opening and closing the trigger discharge circuit,
The first contact 21a is a contact shared by the first and second switches.

The above connection is an example. For example, one end of the trigger capacitor 35 and the base terminal of the oscillation transistor 29 are connected to one contact, and the other two contacts are connected to the fourth terminal of the oscillation transformer 30. The terminal 30d and the synchro switch 18 may be connected. Further, the base terminal of the oscillation transistor 29 and the synchro switch 18 are connected to 1
Connected to the third contact, and the fourth terminal 30 is connected to the remaining two contacts.
d, one end of the trigger capacitor 35 may be connected. Further, the synchro switch 18 is designated by reference numeral 2 in the figure.
4 may be arranged.

When the switch section 17 is turned on, the bias circuit, the main secondary circuit, and the sub secondary circuit are closed.
When the bias circuit is closed, the oscillation transistor 29
Receives power from the battery 19 to the base terminal, that is, a base current (bias current) flows and starts operating.
A primary-side current (collector current) flows through the primary coil 31.
Then, the oscillating transistor 29 oscillates by increasing the collector current by increasing the base current as the positive feedback action of the oscillating transformer 30, that is, the secondary current flowing through the main secondary circuit flows as the base current.

The secondary coil 32 includes an oscillation transistor 2
During the oscillation of No. 9, an electromotive force of a high voltage, for example, about 300 V is generated according to the winding ratio between the primary coil 31 and the secondary coil 32. The rectifier diode 36 allows only the secondary current in the direction from the fifth terminal 30e to the fourth terminal 30d to flow to the closed main secondary circuit and sub secondary circuit by this electromotive force. Thereby, the main capacitor 16 and the trigger capacitor 3
5 are charged respectively.

When the synchronizing switch 18 is turned on while the switch section 17 is turned on, the trigger discharge circuit is closed. As a result, the trigger capacitor 35 can be discharged by the trigger discharge circuit.
Flows through the primary coil 37a of the trigger transformer 37. When a discharge current flows through the primary coil 37a, a trigger voltage (for example, 4 KV) is generated on the secondary coil 37b,
This trigger voltage is applied to the strobe discharge tube 38 via the trigger electrode 39. When the trigger voltage is applied in a state where the charging of the main capacitor 16 is completed, the electric charge of the main capacitor 16 is discharged in the strobe discharge tube 38, and strobe light is emitted from the strobe discharge tube 38.

When the switch section 17 is turned off, the switch section 17 opens the bias circuit, the main secondary circuit, and the sub secondary circuit. When the bias circuit and the main secondary circuit are opened, the bias current and the secondary current as the base current do not flow through the oscillation transistor 29, so that the oscillation transistor 29 stops without self-excited oscillation, and the main capacitor 16 and the Trigger capacitor 35
Is stopped. Further, even if the sync switch 18 is turned on while the switch unit 17 is in the OFF state, the trigger discharge circuit is opened by the switch unit 17.
The trigger capacitor 35 does not discharge, and no strobe light emission is performed.

The light emitting diode 48 is provided for notifying the photographer that charging has been completed. The light emitting diode 48 is connected between the terminals of the tertiary coil 33, that is, the anode is connected to the fourth terminal 30d of the oscillation transformer 30 and the cathode is connected to the third terminal 30c via the resistor 48a. The light emitting diode 48 is illuminated by utilizing the change in the voltage between the fourth terminal 30d and the third terminal according to the change in the charging voltage of the main capacitor 16 during the operation of the blocking oscillation circuit. When the charging voltage of the main capacitor 16 is charged to a predetermined display charging voltage (for example, 265 V), the lighting is started, and when the charging is substantially completed to the specified charging voltage, the lighting is bright. The operation of the light emitting diode 48 is described in detail in
-115796.

The light emitting diode 48 is arranged at a position facing the lower end of the display light guide 10 in a state of protruding above the film unit with a lens. The photographer can check the lighting of the light emitting diode 48 through the display light guide 10 and know that the charging is completed.
It is to be noted that the charging completion display can be performed by using a neon tube as in the related art, but the light emitting diode is less expensive than the neon tube, and thus the use of the light emitting diode can reduce the manufacturing cost.

The line 50 connecting the base contact of the oscillation transistor 29 and the third contact 21c connected to the base terminal side of the oscillation transistor 29 among the three contacts of the switch section 17, and the emitter terminal of the oscillation transistor 29, that is, the ground. A protection diode 52 is connected to the line 51. The protection diode 52 is connected so that the emitter terminal side of the oscillation transistor 29 becomes an anode. As the protection diode 52,
A general silicon diode is used, and a voltage (drop voltage) generated at both ends when a forward current flows is 0.7 V.

The protection diode 52 is provided to protect the oscillation transistor 29 from a voltage generated by the contact resistance of the switch unit 17 when the synchro switch 18 is turned on and the trigger capacitor 35 is discharged. More specifically, while the synchro switch 18 is ON, the trigger discharge circuit is attenuated, but an electric vibration is generated. At this time, between the first contact 21a and the third contact 21c, A large voltage is generated that reversely biases the base and the emitter of the oscillation transistor 29.
When this voltage is generated, the protection diode 52
The voltage applied between the base and the emitter of the oscillation transistor 29 is reduced to prevent the oscillation transistor 29 from being deteriorated or destroyed.

Next, the operation of the above configuration will be described.
The photographer uses the winding knob 1 of the film unit with lens.
1 is rotated to wind up the photographic film and to charge the shutter to prepare for photographing. Further, when it is necessary to fire the strobe and take a picture, the operation lever 7 is slid upward to set it to the ON position. By setting the operation lever 7 to the ON position, the display light guide 10 protrudes from the opening 10a. Further, the movable piece 20 is elastically deformed by the pressing portion 7a of the operation lever 7, and its first end 20a and second end 20b
Contact the corresponding first contact 21a and second contact 21b, the first to third contacts 21a to 21c are connected to each other by the movable piece 20, and the switch unit 17 is turned on.

When the switch section 17 is turned on, the bias circuit is closed, so that the resistor 34a, the tertiary coil 3
3. A bias current from the battery 19 flows to the oscillation transistor 29 as a base current via the first contact 21a, the movable piece 20, the third contact 21c, and the resistor 34b of the switch unit 17. As a result, the oscillation transistor 29 causes a collector current to flow according to the base current. This collector current is generated by using the battery 19 as a power source, and as a primary current from the second terminal 30b to the first terminal 30a.
Flow to 1.

When the primary current starts to flow (increases), a high voltage electromotive force is generated in the secondary coil 32. Since the main secondary circuit is closed by turning on the switch section 17, the fourth terminal is connected to the fifth terminal 30e by the electromotive force generated in the secondary coil 32.
A secondary current flows in the direction of the terminal 30d. The secondary current flows as the base current of the oscillation transistor 29 via the switch unit 17, so that the base current increases and the collector current (primary current) from the primary coil 31 further increases.

As described above, the oscillation transistor 29
The base current is increased by the positive feedback action of the oscillating transformer 30 to increase the collector current, that is, the primary current. However, as the oscillating transistor 29 approaches a saturation state, the change in the collector current decreases. As a result, the change in the primary current becomes small, and each coil 31
33 generates back electromotive force. Because of the back electromotive force, the oscillation transistor 29 sharply decreases the collector current because the base current from the secondary coil 32 sharply decreases.

However, since the bias current is supplied from the battery 19 to the oscillation transistor 29, after the back electromotive force of the oscillation transformer 30 has disappeared, the collector current is increased again to increase the primary current. Thus, the oscillation transistor 29 oscillates while the switch unit 17 is in the ON state, and the oscillation operation of the blocking oscillation circuit is continuously performed.

The secondary current in the direction from the fifth terminal 30e to the fourth terminal 30d due to the electromotive force generated in the secondary coil 16 during the oscillation operation flows through the main secondary circuit, that is, the fourth terminal 3
0d to the first contact 21a of the switch unit 17, the movable piece 2
0, third contact 21c, base of oscillation transistor 29
It flows into the main capacitor 16 via the emitter,
The main capacitor 16 is charged. Further, since the sub-secondary side circuit is also closed, a part of the secondary side current flowing out of the fourth terminal 30d is reduced by the first contact 21a of the switch unit 17,
It flows into the trigger capacitor 35 via the movable piece 20 and the second contact 21b, and the trigger capacitor 35 is charged.

When the charging proceeds in this manner, with reference to the potential of the negative electrode of the battery 19, the main capacitor 16 is configured such that the potential on the negative side drops while the potential on the positive side remains 0 V. The voltage between the terminals of the main capacitor 16 (= charging voltage) increases. Then, when the main capacitor 16 reaches the display charging voltage, the light emitting diode 48 starts lighting. When the charging is further advanced and the charging voltage of the main capacitor 16 reaches almost the specified charging voltage, the light emitting diode 48 lights up brightly.

As described above, the main capacitor 16
Is charged, but since the switch is not provided on the circuit through which the large primary current flows, the primary current does not decrease due to the contact resistance of the switch. Therefore,
The charging time of the main capacitor 16 is short.
In addition, there is also a contact resistance between the switch portion 17 where the secondary current for charging the main capacitor 16 flows, that is, between the second contact 21b and the third contact 21c. It gets smaller. Therefore, the electric energy loss is extremely small, and the delay of the charging time due to the contact resistance is negligibly small.
For example, the voltage at which the primary current flows, that is, the voltage of the battery 19 is 1.5 V, and the voltage of the electromotive force of the secondary coil 32 is 300.
V, and assuming that the contact resistance is the same when the charging switch is provided on the primary side and when the charging switch is provided on the secondary side, the electric energy loss on the secondary side It can be suppressed to 1/40000 (= (300 / 1.5) ² ). Further, although the bias current supplied from the battery 19 also passes through the switch section 17, there is no problem because the bias current is small.

After confirming that the light emitting diode 48 is brightly lit, the photographer presses the shutter button 8. At the moment when the shutter blades are fully opened in response to the pressing operation of the shutter button 8, the trigger switch 18 is turned on. In the switch section 17, the first contact 21 a and the second contact 21 b disposed in the trigger discharge circuit are connected by the movable piece 20. Therefore, when the synchro switch 18 is turned on, the trigger discharge circuit is closed. As a result, the charged trigger capacitor 35 is discharged, and the discharge current flows to the trigger discharge circuit. That is, the discharge current is equal to the primary coil 37a of the trigger transformer 37.
The trigger voltage generated in the secondary coil 37b is applied to the strobe discharge tube 38, and the electric charge of the main capacitor 16 is discharged in the strobe discharge tube 38, so that strobe light emission is performed.

On the other hand, when photographing is performed without flash emission, the operation lever 7 is set to the OFF position. This operation may be performed during the charging of the main capacitor 16 or after the charging is completed. For example, when the operation lever 7 is turned to the OFF position while the main capacitor 16 is being charged, the switch unit 17
The state changes to the FF state, and the bias circuit, the main secondary circuit, and the sub secondary circuit are opened. When the bias circuit is opened, the bias current from the battery 19 stops flowing as the base current of the oscillation transistor 29. Also,
When the main secondary circuit is opened, the oscillation transformer 3
The secondary current from the secondary coil 32 of 0 does not flow as a feedback current to the oscillation transistor 29. This allows
The oscillation transistor 29 is completely stopped without self-excited oscillation in response to the switching unit 17 being turned off, and the charging of the main capacitor 16 is stopped.

After the charging is completed, the O
Even in the FF state, charging of the main capacitor 16 is similarly stopped. In this case, the light emitting diode 48 that has been turned on is turned off when the blocking oscillation circuit is stopped.

When the shutter button 8 is pressed and photographed after the operation lever 7 is turned to the OFF position, the synchro switch 18 is turned on at the moment when the shutter blades are fully opened, but the switch section 17 is turned off. Therefore, since a part of the trigger discharge circuit, that is, between the first contact 21a and the second contact 21b, is open, the trigger capacitor 35 does not discharge. Therefore, even if the charging voltage of the main capacitor 16 is charged up to the specified charging voltage, the trigger voltage is not applied to the strobe discharge tube 38, so that no strobe light is emitted.

FIG. 4 schematically shows the contact resistance between the respective contacts 21a to 21c when the switch section 17 is in the ON state, and illustrates some of the circuits without illustration. When the switch unit 17 is in the ON state, the first contact 21a, the second contact 21b, and the second contact 21b
And the third contact 21c, and contact resistances 54a to 54b between the third contact 21c and the first contact 21a.

[0063] When the trigger capacitor 35 synchro switch 18 is turned ON to discharge, current I ₁ flows. The electric current I ₁ flows from the trigger capacitor 35 in the direction and path returning to the trigger capacitor 35 via the switch unit 17 and the primary coil 37 a of the trigger coil 37, and as described above, the trigger is applied to the primary coil 37 b of the trigger coil 37. Generate voltage.

Since the trigger discharge circuit is a circuit in which the trigger capacitor 35 and the primary coil 37a are connected, the current I ₁ continues to flow even after the charging voltage of the trigger capacitor 35 becomes 0 V as is well known, and the current I _{1 By 1 the} trigger capacitor 35 is charged with a polarity opposite to that of the previous charge. Thereafter, this way to trigger capacitor 35 is discharged again charged, electric current I ₂ in a direction opposite to the direction of the code I _1, after the charging voltage becomes 0V, the current of the opposite direction I ₂ Will be charged. Trigger capacitor 35 is charged by the current I ₂ passes a current I ₁ and discharged again. In this way, electric vibration is generated in the trigger discharge circuit.
Of course, the magnitudes of the currents I ₁ and I ₂ are attenuated, and finally the electric oscillation disappears. The currents I ₁ and I ₂ are switched
7, the contact resistances 54a to 54
b generates a potential difference, that is, a voltage, between the contacts 21a to 21c.

The first contact 21a to which the emitter terminal of the oscillation transistor 29 is connected via the tertiary coil 33 and the light emitting diode 48 of the oscillation transformer 30 and the battery 19 is connected to the base terminal of the oscillation transistor 29 via the resistor 34b. and between the third contact 21c, the voltage potential of the second contact 21b side becomes higher occurs when the current I ₁ flows. This voltage poses no particular problem since the potential at the base terminal of the oscillation transistor 29 is made higher than the potential at the emitter terminal and the base-emitter of the oscillation transistor 29 is forward-biased.

On the other hand, when the current I ₂ flows, a voltage at which the potential of the third contact 21c becomes higher is generated between the second contact 21b and the third contact 21c. That is, the voltage at this time is set so that the potential of the base terminal of the oscillation transistor 29 is lower than the potential of the emitter terminal, and the oscillation transistor 2
9 is reverse biased between the base and the emitter. Then, in the early development of the electric oscillation, the current I ₂ is relatively large, large voltage reverse biasing in the case no protective diode 52, for example, if the reference potential of the emitter terminal, base terminal of the oscillation transistor 29 Is -2
It becomes about 0V, destroys the oscillation transistor 29,
Even if the oscillation transistor 29 is not destroyed, the performance of the oscillation transistor 29 may be deteriorated.

However, in the strobe device of the present invention, the protection diode 52 is connected between the base and the emitter of the oscillation transistor 29 as described above. For this reason, the second contact 21 generated when the current I ₂ is flowing
A current due to the voltage between the second contact 21b and the third contact 21c flows from the second contact 21b through the tertiary coil 33, the light emitting diode 48, and the battery 19 to the protection diode 51, and flows from the protection diode 51 to the third contact 21c. When a current flows through the protection diode 51, the voltage generated between both ends of the protection diode 51 is maintained at 0.7V. As a result, the magnitude (absolute value) of the voltage reversely biased between the base and the emitter of the oscillation transistor 29 is reduced to 0.7 V or less, and destruction of the oscillation transistor 29 and performance deterioration are prevented.

FIG. 5 shows a circuit of another strobe device embodying the present invention. Except for the details described below, this embodiment is the same as the above-described embodiment, and substantially the same components are denoted by the same reference numerals, and description thereof will be omitted.

The oscillation transformer 30 has the first terminal 30a of N
The second terminal 30 b is connected to the positive electrode of the battery 19, and is connected to the collector terminal of the PN-type oscillation transistor 29. The third terminal 30c is connected to the switch unit 17, the resistor 34,
The fourth terminal 30d is connected to the positive electrode of the battery 19 via a, and the base terminal of the oscillation transistor 29 via the resistor 34b. The emitter terminal of the oscillation transistor 29 is connected to the negative electrode of the battery 19 and is grounded.

Thus, the resistance 34a, the switch 17, the tertiary coil 33, and the resistance 34
b, a circuit sequentially connected to the negative electrode of the battery 19 through the base and the emitter of the oscillation transistor 29 is a bias circuit for flowing the bias current of the oscillation transistor 29. Also, the fourth terminal 30d of the secondary coil 32
From the base to the emitter of the oscillating transistor 29, the main capacitor 16, the rectifying diode 36, and the fifth terminal 30e of the secondary coil 32 in that order are the main secondary circuit. The fourth terminal 30
d, between the base and the emitter of the oscillation transistor 29,
A circuit sequentially connected to the battery 19, the resistor 34a, the switch unit 17, the trigger capacitor 35, the resistor 34c, the rectifying diode 36, and the fifth terminal 30e of the secondary coil 32 is a secondary battery for charging the trigger capacitor 35. It is a side circuit.

Further, similarly to the above-described embodiment, a circuit sequentially connected from one end of the trigger capacitor 35 to the switch unit 17, the synchro switch 18, the primary coil 37a of the trigger transformer 37, and the other end of the trigger capacitor 35 is triggered. It is a circuit.

In this example, a resistor 34a is connected to the first contact 21a.
The positive electrode of the battery 19 is connected through the second contact 2
1b, one end of the trigger capacitor 35 is connected to the third contact 21c.
The third terminal 30c of the tertiary coil 33 is connected to the synchro switch 18 and the resistor 34b. And
The first contact 21a and the third contact 21c are the respective contacts of a first switch (charging switch) that opens and closes a circuit that supplies a bias current to the oscillation transistor 29.
a, the second contact 21b for opening and closing the trigger discharge circuit
Each contact of the switch (light emission selection switch)
The first contact 21a is a contact shared by the first and second switches.

The protection diode 52 is connected to the base terminal of the oscillating transistor 29 and the oscillating transistor 29 of the three contacts of the switch unit 17 in the same manner as in the above embodiment.
Is connected between the connection point of the fourth terminal 30d and the resistor 34b on the line connecting the third contact 21c connected to the base terminal side of the first transistor and the ground, that is, the emitter terminal of the oscillation transistor 29.

In this example, the switch 17 does not open and close the main secondary circuit, but only opens and closes the bias circuit. Therefore, when the switch 17 is turned off, there is a delay in response to this. The charging operation stops. That is, when the switch unit 17 is turned off, the supply of the bias current from the battery 19 to the oscillation transistor 29 is stopped, but the connection between the primary coil 31 and the battery 19 is not released, and the connection from the secondary coil 32 is not released. Since the secondary side current is in a state where it can flow into the base of the oscillation transistor, the charging voltage of the main capacitor increases,
The oscillation transistor continues self-oscillation until the back electromotive force generated in the secondary coil weakens, after which self-oscillation of the oscillation transistor 29 stops and charging stops.

As described above, the charging operation is stopped after the switching of the switch unit 17 to the OFF state.
Is turned off, the light emitting diode 48
And the connection with the tertiary coil 33 is disconnected. Therefore, even if the charging operation is continued for a while after the switch section 17 is turned off and the main capacitor 16 reaches the display charging voltage, the light emitting diode 48 does not light up. As a result, the photographer does not give the photographer an erroneous recognition that the strobe device has failed or the strobe light has been emitted.

Similarly to the above embodiment, when the synchro switch 18 is turned on, a reverse bias is applied between the base and the emitter of the oscillation transistor 29 due to the contact resistance of the switch section 17, but a voltage is generated. Since the diode 52 is connected, the performance of the oscillation transistor 29 is not degraded because the oscillation transistor 29 is broken. Further, since the switch section 17 is not on the circuit through which the primary current flows, the charging time does not become long.

In the above embodiment, an example in which the flash device is built in the film unit with a lens has been described. However, the present invention can be applied to a flash device built in or connected to a single-lens reflex camera or a compact camera. It can also be used for strobe devices used alone.

[0078]

As described above, according to the strobe device of the present invention, the first switch for opening and closing at least the circuit for supplying the bias current from the battery to the base terminal of the oscillation transistor, and the discharge from the trigger capacitor. A second switch for opening and closing a circuit for supplying a current to the primary side of the trigger transformer via a synchro switch, and sharing either one of the first switch and the second switch with three contacts And a protection diode is connected between the line connecting the base terminal of the oscillation transistor and the contact of the switch unit connected to the base terminal side of the oscillation transistor, and the emitter terminal of the oscillation transistor. Since the primary current does not decrease due to the contact resistance of the switch, the charging time of the main capacitor Kill is possible to shorten. Also, when the synchro switch is turned on and the trigger capacitor is discharged, the magnitude of the voltage which is generated by the contact resistance of the switch portion and becomes a reverse bias between the base and the emitter of the oscillation transistor is reduced by the protection diode. Deterioration and destruction of the oscillation transistor can be prevented.

Further, charging of the main capacitor is continued while the switch section is on, and charging is performed in response to turning off of the switch section, so that the auto cut function is omitted. By performing the charging completion display by the light emitting diode connected to the coil, the cost of the strobe device can be further reduced.

Further, by opening and closing the circuit for supplying the secondary current together with the bias current to the oscillation transistor by the first switch, the charging can be stopped immediately in response to the turning off of the switch section. In addition, if the circuit for supplying the bias current to the oscillation transistor is opened and closed by the first switch, and simultaneously the connection between the third coil and the light emitting diode is opened and closed, the charging operation is stopped with a delay in response to the turning off of the switch unit. Even in such a case, since the light emitting diode is not turned on by turning off the switch unit, the photographer does not give the photographer an erroneous recognition that the strobe device has failed or is in a strobe light emission state.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a strobe device embodying the present invention.

FIG. 2 is an external view of a lens-fitted film unit incorporating a strobe device.

FIG. 3 is a perspective view illustrating an appearance of a strobe device.

FIG. 4 is a circuit diagram schematically showing contact resistance of a switch unit.

FIG. 5 is a circuit diagram of another strobe device embodying the present invention.

FIG. 6 is a circuit diagram of a conventional flash device using a three-contact switch unit.

FIG. 7 is a circuit diagram of a strobe device having an auto-cut function and displaying the completion of charging with a light emitting diode.

FIG. 8 is a circuit diagram of a strobe device in which a charging switch is provided between a battery, a primary coil, and a tertiary coil, and a three-contact switch unit is formed together with a light emission selection switch.

[Explanation of symbols]

 7 Operation lever 16 Main capacitor 17 Switch section 19 Battery 20 Movable piece 21a-21c Contact 29 Oscillation transistor 30 Oscillation transformer 35 Trigger capacitor 38 Strobe discharge tube 37 Trigger transformer 52 Protective diode

Claims (5)

[Claims] 1. A bias current from a battery is supplied to a base terminal, so that a primary current flows through a primary coil of an oscillation transformer, and a secondary current flowing through a secondary coil of the oscillation transformer is supplied to a base terminal. An oscillation transistor that oscillates to amplify the primary current, a main capacitor and a trigger capacitor for strobe light emission charged by the secondary current, and a trigger transformer that turns on at the time of strobe light emission and discharges a current from the trigger capacitor. Sink
A synchro switch for causing a strobe discharge tube to emit light by a trigger voltage generated on the secondary side thereof, comprising: a first switch for opening and closing a circuit for supplying at least a bias current from a battery to a base terminal of the oscillation transistor; And a second switch for opening and closing a circuit for supplying a discharge current from the trigger capacitor to the primary side of the trigger transformer via a synchro switch, wherein one of the contacts of the first switch and one of the second switches And a switch unit for turning on and off the three contacts simultaneously, a contact connected to the base terminal side of the oscillation transistor and a base terminal of the oscillation transistor among the three contacts of the switch unit. Connected between the connecting line and the emitter terminal of the oscillation transistor, A protection diode for reducing the magnitude of a voltage which is generated by the contact resistance of the switch section and becomes a reverse bias between the base and the emitter of the oscillation transistor when the trigger capacitor is discharged when the synchro switch is turned on. An electronic flash device. 2. The charging of the main capacitor continues while the switch is on, and the charging of the main capacitor and the trigger capacitor is stopped in response to the turning off of the switch. The strobe device according to claim 1, wherein: 3. A tertiary coil inductively coupled to the primary coil and the secondary coil, one end connected to one end of the tertiary coil, and the other end connected to a connection point between the tertiary coil and the secondary coil, respectively, A light emitting diode that lights up in response to reaching a predetermined charging voltage,
2. The flash device according to claim 1, wherein a charge completion display is performed by the light emitting diode. 4. The first switch opens and closes a circuit that supplies the bias current to the base terminal of the oscillation transistor and opens and closes a circuit that supplies the secondary current to the base terminal of the oscillation transistor. The strobe device according to any one of claims 1 to 3, wherein: 5. The circuit according to claim 1, wherein the first switch opens and closes a circuit for supplying the bias current to a base terminal of the oscillation transistor, and simultaneously opens and closes a connection between the tertiary coil and a light emitting diode. The strobe device according to any one of claims 1 to 3.