JPH052897Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a focal plane shutter control circuit.

In a conventional camera equipped with a focal plane shutter, in order to prevent exposure to areas that are fogged when loading the film, the film counter is pressed from S-0 until it reaches "1", which is ready for exposure, after loading the film. I repeatedly open the shutter to wind the film. In this case, if the lens cap is removed and the shutter is blanked, unnecessary exposure will be given to the film, which is a problem.

Additionally, if you open the shutter with the lens cap in place, in the case of a TTL automatic exposure control camera, the shutter time will be significantly longer, which not only causes discomfort to the user but also consumes power. This is a problem because it also becomes noticeable. Moreover, the shutter time for dry cutting can extend to several tens of seconds, and there is a risk that the user may mistakenly operate the machine by mistake.

In order to solve the above-mentioned problems, it has been proposed that the shutter is turned off after a certain shutter time, for example 1/60 seconds, until the film counter reaches "1", or that the magnet is not energized. In the former case, if you remove the lens cap and perform blank cutting, the film will be exposed to unnecessary light, causing a problem, and in the latter case, especially with two-magnet type shutters, due to differences in adjustment and structure of each shutter. If the shutter is turned off without energizing the magnet, there will be variations in exposure and no exposure, which is a problem.

SUMMARY OF THE INVENTION An object of the present invention is to provide a focal plane shutter control circuit which eliminates the above-mentioned drawbacks.

The focal plane shutter blanking control circuit according to the present invention energizes a film counter that is linked to the film winding operation, and a magnet that is switched in the first stage of release operation to hold the leading and trailing shutter curtains, respectively. The magnet energization switch is switched in the second stage of release operation, and deenergizes the shutter front curtain magnet and the shutter rear curtain magnet at predetermined time intervals to operate the front and rear shutter curtains to operate the shutter shutter at a predetermined time interval. In the control circuit for the focal plane shutter, which includes a shutter curtain drive switch that performs exposure, and a film winding completion signal switch that is switched when film winding starts and is switched to the reset state when film winding is completed, a film counter is activated as the film winds. A film counter switch is provided which is switched when the film is wound from the S-0 state to the 1-36 state where the film can be exposed. is characterized in that the control circuit is configured so that the trailing curtain magnet is always deenergized before the leading curtain magnet, and the trailing curtain is operated first to keep the shutter closed.

Because of this structure, according to the present invention, when the focal plane shutter is used for winding the film up to "1" after loading the film, the rear curtain of the shutter always operates first and is in the closed state. Therefore, regardless of whether the lens cap is removed or inserted, the film part during blank cutting is not exposed to light, and the shutter time during blank cutting is determined by the time constant of the delay circuit in the control circuit. By setting these appropriately, winding can be carried out quickly and comfortably.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows a control circuit according to the present invention suitable for use with a known focal plane shutter that operates the shutter by deactivation of the shutter curtain holding magnet, with the film counter in the state S-0 and before the release button is operated. Indicates status and power
Magnetic energization switch SW ₁ connected between the resistor Rm connected to the positive terminal of Vcc and the negative terminal, normally closed, and opened in the first stage of release operation.
and the shutter curtain drive switch _SW2 , which is connected between the negative pole and the resistor Rb, which is similarly connected to the power supply Vcc, and which is normally closed and is opened in the second stage of release operation.
and the winding completion signal switch _SW3 , which is similarly connected between the resistor Rw and the negative pole and is closed during film winding operation and opened when winding is completed;
A film counter switch SW ₄ is connected between Rc and the negative electrode, and the film counter is open during S-0 and closed during 1-36, and one switch is connected to the connection point between resistor Rb and switch SW ₂ . _Exclusive Noah circuit
AND circuit AND _1, in which one input is connected to the output of NOR, and the other input is connected to the connection point between resistor Rw and switch SW ₃ , and a shutter tip, whose one end is connected to the positive terminal of power supply Vcc. Front curtain drive transistor whose collector is connected to the other end of the curtain holding magnet coil 1cMg and whose emitter is connected to the negative electrode.
TR ₃ and the trailing curtain drive transistor TR ₄ , which is also connected between the trailing curtain holding magnet 2cMg and the negative pole.
, a NOR circuit NOR ₁ whose output is connected to the base of transistor TR ₃ via a resistor, and a transistor
It includes a NOR circuit NOR ₂ whose output is connected to the base of TR ₄ via a resistor, and the output of the AND circuit AND ₁ is connected to one input of the AND circuit AND ₂ and the AND circuit
Connected to one input of AND ₃ , AND circuit
The output of AND ₂ is connected to one input of NOR circuit NOR ₁ , and the output of AND circuit AND ₃ is connected to one input of NOR circuit NOR ₂ .

On the other hand, the connection point between resistor Rc and switch SW ₄ is an AND circuit AND ₃ whose other input and output are a NOR circuit.
AND circuit connected to the other input of NOR ₁
Connected to one input of AND circuit AND ₅ , which is connected to one input of AND ₄ , and the other input and output of AND circuit AND ₂ are connected to the other input of NOR circuit NOR ₂ via inverter I ₁ . has been done.

The output of the AND circuit AND ₁ is also connected via an inverter I ₂ and a resistor to the base of the transistor TR ₁ , and likewise via an inverter I ₂ and another resistor to the base of the transistor TR ₂ .

The collector of the transistor TR ₁ is connected to the connection point of the resistor R ₁ and the capacitor C ₁ forming a delay circuit in which the desired time constant can be set, and this connection point is connected to the other input of the AND circuit AND ₄ . ,
The emitter of transistor _TR1 is connected to the negative pole.

Similarly, the collector of transistor TR ₂ is connected to the connection point of delay circuit R ₂ C ₂ , and also connected to the AND circuit
It is connected to the other input of AND ₅ , and the emitter is connected to the negative pole.

Because of this connection, when the film counter is S-0, in the starting state set as shown in Figure 1, switch SW ₁ is closed, switch SW ₂ is closed, switch SW ₃ is open, and switch SW ₄ is closed. The magnet coils 1cMg and 2cMg are both kept in an open state, and the state of each element is as shown in the figure, with both magnet coils 1cMg and 2cMg in a deenergized state.

When the release operation is performed here, in the first stage, switch SW ₁ is opened as shown in Fig. 2, and along with this, exclusive noor circuit X is opened.
A pair of -NOR inputs become L and H, respectively,
Its output is switched to L, and the output of AND circuit AND ₁ becomes L, thereby causing AND circuit AND ₂ ,
AND ₅ is held at L for the time being, but the AND circuit
The outputs of AND ₃ and AND ₄ are an AND circuit that does not go through the delay circuit R ₁ C ₁ by switching the output of the AND circuit AND ₁ to L and thereby switching the transistor TR ₁ to ON via the inverter I ₂ When the other input of AND ₄ is switched to L, the outputs of NOR circuits NOR ₁ and NOR ₂ are both switched to H, resulting in the state shown in Fig. 2, and transistors TR ₃ and TR ₄ are turned on. Immediately, the magnet coils 1cMg and 2cMg are energized to hold the shutter curtain travel prevention member.

Next, when the shutter curtain drive switch SW ₂ is opened in the second stage of the release operation, the output of the exclusive NOR circuit X-NOR is switched to H again, as shown in FIG. 3. The output of the AND circuit AND ₃ becomes H, and the transistors TR ₁ and TR ₂ are switched OFF via the inverter I ₂ . Since one input of the AND circuit AND ₅ is already L, the output is also L, and the NOR circuit is activated. Since the output L is given to NOR ₂ , by switching the output of the AND circuit AND ₃ to H, this output H is given to the input of the NOR circuit NOR ₂ , and the output of the NOR circuit NOR ₂ is switched to L, and the transistor TR ₄ Since the rear curtain magnet coil 2cMg is turned OFF, the trailing curtain magnet coil 2cMg is immediately deenergized, releasing the trailing curtain travel prevention member, and the trailing curtain runs to keep the shutter closed. At this time, after a delay time due to the operation of a delay circuit R ₁ C ₁ having a short delay time time constant to ensure that the leading curtain runs with a slight delay compared to the running of the trailing curtain, the leading curtain magnet coil is activated.
1cMg is deenergized and the leading curtain runs to open the shutter, but since the trailing curtain has already run and closed the shutter, exposure of the shutter is prevented.

In this way, during the empty feed S-0 after the film counter is filled with film, the shutter is always closed and empty cutting is performed.

Next, when the film counter reaches the state 1-36 which enables the film to be exposed, the film counter switch SW ₄ is closed, the initial state of each element is set as shown in FIG. 4, and the output of the inverter I ₁ is is switched to H, and the AND circuit AND ₂ ,
The output of AND ₅ is also switched to H, and the AND circuit
The outputs of AND ₃ and AND ₄ both become L, and the outputs of NOR circuits NOR ₁ and NOR ₂ both become L, turning off transistors TR ₃ and TR ₄ , and making magnet coils 1cMg and 2cMg inactive. Ru.

When the release operation is performed here, in the first stage, the switch SW ₁ is opened as shown in FIG. 5, and the output of the exclusive NOR circuit X-NOR is switched to L, and the AND circuit AND ₁ , Transistors TR ₁ and TR ₂ are turned ON via inverter I ₂ , and the NOR circuit is activated regardless of delay circuits R ₁ C ₁ and R ₂ C ₂ .
The outputs of NOR ₁ and NOR ₂ are set to H, and the magnet coils 1cMg and 2cMg are immediately energized to hold the shutter curtain travel prevention member.

When the switch _SW2 is opened in the second stage of the release operation, the output of the exclusive NOR circuit X-NOR becomes H as shown in FIG. 6, the output of the AND circuit _AND1 is switched to H, and this output is input to the transistors _TR1 and _TR2 via the inverter I2 _.
These transistors TR ₁ and TR ₂ are
OFF, which turns off the delay circuits _{R1C1 and R2
C2} are connected to the AND circuits AND4 _{and AND5} ,
The other input of AND ₅ is switched to H, but another input of AND circuit AND ₄ is already held at L,
Since the output of the AND circuit _AND2 is switched to H, the output of the NOR circuit _NOR1 is switched to L.
to switch transistor _TR3 OFF,
The magnet coil 1cMg is immediately de-energized to release the leading curtain travel blocking member, and the leading curtain travels immediately regardless of the delay time to open the shutter.

On the other hand, the delay circuit R ₂ C ₂ is adjusted to a predetermined time constant by a field brightness detection element or a predetermined time setting device, and is configured by an AND circuit.
The output of AND ₅ is switched to H after a predetermined delay time, and is input to the NOR circuit NOR ₂ along with the output of the AND circuit AND ₃ , which is already held at L, and the output of NOR circuit NOR ₂ is switched to L after a predetermined delay time. Switch the transistor TR ₄ to OFF, deenergize the magnetic coil 2cMg, operate the rear curtain, and close the shutter.

In this way, a predetermined shutter exposure time can be obtained.

As described above, the present invention enables the user to perform dry shuttering comfortably.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the initial state of the control circuit of the present invention when the film counter is S-0. FIG. 2 is a circuit diagram showing the state of the release button of the circuit shown in FIG. 1 during the first stage of operation. FIG. 3 is a circuit diagram showing the state of the release button of the circuit shown in FIG. 1 at the second stage of operation. FIG. 4 is a circuit diagram similar to FIG. 1 when the film counter is 1-36. FIG. 5 is a circuit diagram corresponding to FIG. 2 when the film counter is 1-36. FIG. 6 is a circuit diagram corresponding to FIG. 3 when the film counter is 1-36. Vcc...Power supply, SW ₁ ...Magnetic energization switch, SW ₂ ...Shutter curtain drive switch, SW ₃ ...
Winding completion signal switch, SW ₄ ... Film counter switch, 1cMg... Leading curtain magnetic coil, 2cMg... Trailing curtain magnet coil, X-NOR
…Exclusive Noah circuit, AND ₁ …AND ₅
...AND circuit, NOR ₁ , NOR ₂ ...NOR circuit,
TR ₁ ...TR ₄ ...Transistor, _I1 , _I2 ...Inverter.

Claims (1)

[Claims for Utility Model Registration] A magnet energization switch that is switched in the first stage of release operation to energize the magnets that hold the leading and trailing shutter curtains, respectively, and a magnet energization switch that is switched in the second stage of release operation, a shutter curtain drive switch which deenergizes the magnet for the front shutter curtain and the magnet for the rear shutter curtain at predetermined time intervals to operate the front curtain and the rear curtain to perform a predetermined exposure; , a film winding completion signal switch which is switched to the reset state upon completion of film winding, and a film counter, which is held in the open state in the first state (S-0) of the blank feed winding section after film loading, and Section (S-0)
In the second state (1-36) of the film winding section in which the film can be exposed after the film is exposed, the film counter switch is held in the closed state, the output of the magnetic energization switch and the output of the shutter curtain drive switch are controlled. an exclusive NOR circuit to which the output is input; a first AND circuit to which the output of the film winding completion signal switch and the output of the exclusive NOA circuit are input; the output of the film counter switch and the first AND circuit; The respective outputs of the fourth AND circuit to which the output of the first AND circuit is input are passed through the first NOR circuit through a second AND circuit which receives the output of a leading curtain holding magnet circuit into which the output of the film counter switch and the output of the first AND circuit are input, and a third AND circuit and a second delay circuit into which the output of the film counter switch and the output of the first AND circuit are input. a trailing curtain holding magnet circuit to which the outputs of the fifth AND circuits are inputted via a second NOR circuit, and when the film counter switch is in the first state, When the shutter curtain drive switch is switched to the second stage of release operation, one of the outputs of the first AND circuit passes through the first delay circuit, the fourth AND circuit, and the second stage of release operation. The output of the first curtain holding magnet is input to the NOR circuit, and the leading curtain holding magnet is deactivated with a delay by the first delay circuit, and at the same time, the other output of the first AND circuit is input to the second delay circuit. is inputted to the second NOR circuit via the third AND circuit to deactivate the trailing blade holding magnet regardless of the operation of the leading blade holding magnet. When the film counter switch is in the second state and the shutter curtain drive switch is in the second stage of release operation, one of the outputs of the first AND circuit is delayed. , regardless of the operation of the first delay circuit, the signal is input to the first NOR circuit via the second AND circuit, and the leading holding magnet is deenergized, and the other output of the first AND circuit is is input to the second NOR circuit via the second delay circuit, the fifth AND circuit, and the deactivation of the trailing curtain holding magnet is performed after a delay time by the second delay circuit. , Therefore, a focal plane shutter control circuit is characterized in that it is possible to obtain a predetermined exposure time.