JPH06100706B2 - Camera shooting lens drive circuit - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photographic lens driving circuit of a camera that drives a photographic lens with a motor for focus adjustment.

(Prior Art) As for the weight and the photographing lens driving circuit of the camera, for example,
By driving the motor in one direction, the shooting lens is extended from the predetermined reset position, and the distance measurement circuit performs the distance measurement operation when this extension is performed, and when the focus position is detected, the extension of the shooting lens is stopped and shooting is performed. After the end, the motor is driven in the other direction according to the sequence of the camera to return the shooting lens to the reset position to prepare for the next distance measurement operation, and to start the operation to return the shooting lens to the reset position. Is configured to be performed by some sort of reset signal.

(Problems to be Solved by the Invention) However, in such a photographing lens drive circuit of a conventional camera, when the photographing lens is in the process of moving to the reset position, the battery is exhausted, or the external If the motor that drives the shooting lens has stopped due to some abnormality from the, the motor can be operated again by recharging the battery or removing the abnormality from the outside. , The sequence for outputting the reset signal for starting the operation of returning the taking lens to the reset position has already been passed, and therefore the motor is not driven and the taking lens remains stopped during the movement to the reset position. However, there is a problem that the operation after that is not restarted.

The present invention has been made in view of such a conventional problem, and when the photographing lens is in the process of moving to the reset position, the battery is exhausted or some abnormality from the outside. Even if the motor that drives the shooting lens stops due to this, the reset position of the shooting lens will be reset when the motor is made operable again by recharging the battery or removing an abnormality from the outside. It is an object of the present invention to provide a photographing lens drive circuit for a camera in which the movement to is always restarted prior to other operations, and does not hinder subsequent operations.

(Means for Solving the Problems) The gist of the present invention for achieving such an object is to provide a photographing lens drive circuit of a camera that drives a photographing lens by a motor 18 to perform focus adjustment. A motor drive circuit that drives the motor in one direction to extend it, and drives the motor in the other direction to return the shooting lens to the reset position.
Then, the half-press detection means (half-press switch 1) that becomes the first state (ON state) by half-pressing the release button and the second state (OFF-state) by releasing the half-press, and the taking lens are set to the reset position. A lens position detection means (switch 9) that is in a first state (on state) at a certain time, and is in a second state (off state) before starting the movement to the reset position and during the movement to the reset position; When the lens position detecting means and the half-press detecting means are in the second state, respectively, the motor driving circuit includes holding means (RS latch circuits 12 and 13) for holding the state in which the motor can be driven in the other direction. The present invention resides in a photographing lens driving circuit of a camera.

(Operation) In the photographing lens drive circuit of the camera, the half-press detection means (half-press switch 1) is in the second state (OFF state), and the lens position detection means (switch 9) is also in the second state. When it is in the (OFF state), the holding means (RS latch circuits 12, 13) holds the state in which the motor drive circuit 17 can drive the motor 18 in the other direction,
As a result, when the shooting lens is in the process of moving to the reset position, even if the motor is stopped due to the battery being pulled out or some abnormality from the outside, the battery is re-loaded again. Alternatively, by removing an abnormality from the outside, the movement of the photographing lens to the reset position is always restarted before the other operation when the motor is made operable.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a photographing lens drive circuit of a camera according to an embodiment of the present invention.

This photographic lens drive circuit drives the photographic lens by a motor to adjust the focus.

As shown in FIG. 1, the release button (not shown) is half-pressed (first stroke) to turn on (first state).
And the half-push is released to turn off (second state)
A half-push switch 1 as a half-push detection means is connected to the pull-up resistor 2.

The NOR gate 4 is connected to the input terminal of the one-pulse generation circuit 3. The half-press switch 1 and the switch 9 are connected to the input terminal of the NOR gate 4.

The switch 9 is in an ON state (first state) when the taking lens is in the reset position, and is in other positions, that is, before the movement to the reset position is started and during the movement to the reset position. It constitutes a lens position detecting means which is in an off state (second state).

The one-pulse generation circuit 3 outputs an L pulse when the output of the NOR gate 4 rises from L to H, that is, when the taking lens is in the reset position and the half-push switch 1 is in the ON state. The output of the one-pulse generating circuit 3 is connected to the set terminal of the RS latch circuit composed of the NAND gates 5 and 6. The outputs of the RS latch circuits 5 and 6 are connected to the motor drive circuit 17.

This motor drive circuit 17 drives the motor 18 in the forward direction (one direction) to extend the taking lens from the reset position, and moves the motor 18 in the reverse direction (other direction) to return the taking lens to the reset position. When the outputs of the RS latch circuits 5 and 6 are H, the motor 18 is energized in the positive direction and the photographing lens (not shown) is extended.

The focus detection signal generation circuit 7 is connected to the reset terminals of the RS latch circuits 5 and 6. Focus detection signal generation circuit 7
Outputs an L pulse when the distance measuring circuit (not shown) detects the in-focus position, and resets the RS latch circuits 5 and 6.

The taking lens drive circuit of the camera according to the present embodiment sets the lens reset position to the position where the taking lens is most retracted, performs distance measurement with the distance measuring circuit while extending the taking lens, and when the focus is detected, the motor 18 The automatic focus adjustment shall be performed by stopping the energization in the positive direction and stopping the taking lens.

Further, the photographic lens drive circuit is configured such that the photographic lens is extended when the motor 18 is energized in the forward direction and is retracted when the motor 18 is energized in the reverse direction.

Half-push switches 1 and 9 are connected to the input terminal of the NAND gate 11. The output of the NAND gate 11 becomes L when the half-push switch 1 is off, the photographing lens is not in the reset position, and the switch 9 is off. This output L is latched by an RS latch circuit composed of NAND gates 12 and 13.

The switch 9 is connected to the reset terminals of the RS latch circuits 12 and 13. RS latch circuit when switch 9 is turned on
12,13 are reset. The outputs of the RS latch circuits 12 and 13 are
It is connected to AND gate 14.

The switch 19 connected to the pull-up resistor 10 is a release switch that is turned on by the second stroke of the release button. The release switch 19 is connected to the input terminal of the AND gate 21 via the inverter 20. And gate
The output terminal of the NAND gate 23 is connected to the other input terminal of 21. The output terminal of the AND gate 21 is connected to the shutter control circuit 15.

The shutter control circuit 15 starts its operation when the output of the AND gate 21 rises, and opens and closes a shutter (not shown). Further, the shutter control circuit 15 outputs a signal holding H during operation. The output terminal of the shutter control circuit 15 has an AND gate via a one-pulse generation circuit 22 and an inverter 16.
14 and connected respectively.

The one-pulse generating circuit 22 outputs an L pulse when the input signal rises. The output terminal of the one-pulse generation circuit 22 is
It is connected to the reset terminal of the RS latch circuit composed of AND gates 23 and 24. The output terminals of the focus detection signal generation circuit 7 are connected to the set terminals of the RS latch circuits 23 and 24.

The output terminal of the AND gate 14 is the motor drive circuit 17
It is connected to the. Motor drive circuit 17 is AND gate
When the output of 14 is H, the motor 18 is energized in the reverse direction,
It is designed to drive the taking lens toward the reset position.

It should be noted that the RS latch circuits 12 and 13 allow the motor drive circuit 17 to operate the motor when the lens position detecting means (switch 9) and the half-press detecting means (half-press switch 1) are off (second state), respectively. A holding means for holding the state in which 18 can be driven in the other direction is configured.

Next, the operation will be described.

Since the photographing lens is stopped at the reset position, the switch 9 is in the ON state, the RS latch circuits 12 and 13 are in the reset state, the output thereof is L, and the output of the AND gate 14 is L.
Therefore, the motor drive circuit 17 does not energize the motor 18 in the reverse direction. Since the half-push switch 1 is also in the off state, the output of the one-pulse generation circuit 3 holds H,
The outputs of the RS latch circuits 5 and 6 remain L, and the motor 18
Is not energized in the positive direction either. Furthermore, since the release switch 19 is off, the shutter control circuit 15 is not operating. Therefore, the photographic lens remains stopped at the reset position as it is.

Half-press switch 1 with the first stroke of the release button
When is turned on, since the switch 9 is in the on state, the NOR gate 4 becomes H, the one-pulse generating circuit 3 outputs an L pulse, and this is latched by the RS latch circuits 5 and 6. RS
The latch circuits 5 and 6 hold the output at H. When the outputs of the RS latch circuits 5 and 6 become H, the motor drive circuit 17 energizes the motor 18 in the forward direction. As a result, the taking lens is driven by the motor 18.

Simultaneously with the start of the feeding, the distance measuring circuit starts the distance measuring operation. Since the taking lens is moved out of the reset position by being extended, the switch 9 is turned off, but at this time, the input signal to the motor drive circuit 17 does not change.

When the photographing lens is extended and the distance measuring circuit detects the in-focus position, the in-focus detection signal generation circuit 7 outputs an L pulse, resets the RS latch circuits 5 and 6 and sets the RS latch circuits 23 and 24. To do.

When the RS latch circuits 5 and 6 are reset, the motor drive circuit 17 stops energizing the motor 18 in the positive direction,
The taking lens stops at the in-focus position. This completes the focus adjustment operation.

When the release button is pushed down to the second stroke after the focus adjustment operation is completed, the release switch 19 is turned on. This signal is input to the AND gate 21 via the inverter 20. Since the other input of the AND gate 21 is H, the output of the AND gate 21 is H and the shutter control circuit 15 starts its operation. The output signal of the shutter control circuit 15 becomes H.

When the shutter control circuit 15 finishes the opening / closing operation of the shutter, the one-pulse generating circuit 22 outputs an L pulse and resets the RS latch circuits 23 and 24.

The operation performed after the user turns off the release switch 19 is to turn off the half-push switch 1.
There are two possible timings for this operation.

In the first case, the half-press switch 1 is turned off while the shutter control circuit 15 is operating. Since the shutter control circuit 15 is in operation, the output of the AND gate 14 remains L through the inverter 16. Switch 9 at this time
Is in the off state, and when the half-push switch 1 is in the off state, the output of the NAND gate 11 becomes L, and the RS latch circuits 12 and 13 hold the output at H. Eventually, the shutter control circuit 15 completes its operation, but at the same time as the operation is completed, the output of the inverter 16 becomes H and the output of the AND gate 14 becomes H. As a result, the motor drive circuit 17 energizes the motor 18 in the reverse direction, and the photographing lens starts driving toward the reset position.

In the second case, the half-press switch 1 is turned off after the shutter control circuit 15 completes its operation. When the shutter control circuit 15 completes its operation, the output of the inverter 16 becomes H. At this time, the upper input of the AND gate 14 is still L, and the taking lens is not driven.

Here, when the half-push switch 1 is turned off, the output of the NAND gate 11 becomes L, and the RS latch circuits 12 and 13 hold the output H. As a result, the output of the AND gate 14 becomes H
Then, similarly to the first case, the taking lens starts driving toward the reset position.

While the photographing lens is being driven toward the reset position, the switch 9 remains in the off state even when the halfway press switch 1 is in the on state, so that the output of the NOR gate 4 remains at L. Therefore, the output of the one-pulse generation circuit 3 remains H. Therefore, the outputs of the RS latch circuits 5 and 6 remain L. The output of the NAND gate 11 becomes H when the half-press switch 1 is turned on, but the outputs of the RS latch circuits 12 and 13 do not change.

When the taking lens returns to the reset position, the switch 9 is turned on. As a result, the RS latch circuits 12 and 13 are reset, the output becomes L, the motor drive circuit 17 stops the energization of the motor 18 in the reverse direction, and the drive of the taking lens to the reset position is completed. Further, since the switch 9 is turned on, one input of the NOR gate 4 becomes L,
After that, when the half-push switch 1 is turned on, the operation of extending the photographing lens and the distance measuring operation are started again.

As described above, once the photographing lens starts driving toward the reset position, the photographing lens drives the photographing lens to the reset position regardless of the state of the half-press switch 1 thereafter.

Next, consider a case where the taking lens that is being driven is stopped at a halfway position due to a battery drain or the like.

When the battery is turned on again, the switch 9 is in the off state,
The half-push switch 1 is also in the off state. Therefore, the output of the NAND gate 11 becomes L, and the RS latch circuits 12 and 13 hold the output at H. At this time, the shutter control circuit 15
Is not in operation, the output of the AND gate 14 becomes H, and the motor drive circuit 17 energizes the motor 18 in the reverse direction to drive the taking lens in the reset direction.

When the taking lens is driven to the reset position, the switch 9 is turned on, so that the RS latch circuits 12 and 13 are reset and the motor 18 is deenergized in the reverse direction.

Further, it is possible to turn on the release switch 19 when the photographing lens has stopped due to some abnormality, but the shutter must not be opened or closed at this time.

There are two possible timings at which the taking lens is abnormally stopped, that is, when the taking lens is being extended toward the in-focus position and when the taking lens is being retracted toward the reset position.

If the shooting lens stops abnormally during extension,
Since the RS latch circuits 23 and 24 are not set and the output of the NAND gate 23 is L, the shutter control circuit 15 does not operate even if the release switch 19 is turned on.

Also, if the shooting lens abnormally stops during retraction to the reset position, it means that the shutter has already been opened and closed at the in-focus position, RS latch circuits 23 and 24 have been reset, and the NAND gate 23 Since the output is L, the shutter control circuit 15 also does not operate. Therefore, when the photographing lens is stopped at a position other than the in-focus position, the release is prohibited even if the release switch 19 is turned on.

As described above, when both the half-push switch 1 and the switch 9 are in the off state, the RS latch circuits 12 and 13 as holding circuits hold their outputs at H, which causes the motor drive circuit 17 to drive the motor 18 in the reverse direction. Since it is held in a state where it can be driven to, the shooting lens will not It is always driven again to the reset position side.

Furthermore, since the signal when the release switch 19 is turned on can be input to the shutter control circuit 15 only when the taking lens is stopped at the in-focus position, the taking lens is stopped at some other position for some reason. Sometimes, even if the release switch 19 is turned on, the shutter control circuit 15
Does not operate, and therefore the opening and closing of the shutter is prohibited, which prevents erroneous or double exposure of the film.

In the above embodiment, the half-push switch 1 and the switch 9 are each set to the first state as the on state, but may be configured to have the off state as the first state and the on state as the second state. Good.

(Advantages of the Invention) According to the photographing lens drive circuit of the camera of the present invention, when the half-push detection means is in the second state and the lens position detection means is also in the second state, the holding means is provided. In order to return the shooting lens to the reset position, the motor drive circuit keeps the motor capable of driving the motor in the other direction, so when the shooting lens is in the process of moving to the reset position, the battery is removed. Even if the motor is once stopped due to a failure or some abnormality from the outside, when the motor is made operable again by recharging the battery or removing the abnormality from the outside, The movement of the photographing lens to the reset position is resumed prior to the above operation, and the subsequent operations are not hindered.

[Brief description of drawings]

FIG. 1 is a block diagram showing a photographing lens drive circuit of a camera according to an embodiment of the present invention. 1 ... Half push switch (half push detection means) 9 ... Switch (lens position detection means) 12, 13 ... RS latch circuit (holding means) 17 ... Motor drive circuit, 18 ... Motor

Claims (1)

[Claims] 1. A photographic lens drive circuit of a camera, wherein a photographic lens is driven by a motor for focus adjustment, in order to extend the photographic lens from a reset position, the motor is driven in one direction to return the photographic lens to the reset position. For this purpose, the motor drive circuit for driving the motor in the other direction, the half-press detection means that is in the first state when the release button is half-pressed and is in the second state when the half-press is released, and the photographing lens are in the reset position The lens position detecting means, which sometimes becomes the first state, becomes the second state before starting the movement to the reset position and during the movement to the reset position, and the lens position detecting means and the half-press detecting means, respectively. In the state of 2, the motor drive circuit comprises a holding circuit for holding the state in which the motor can be driven in the other direction. The shooting lens drive circuit of the camera.