JPH0749455Y2 - Camera with automatic focus adjustment device - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention detects the deviation from the in-focus position of the taking lens with respect to the subject, and based on this deviation, the taking lens can be moved to perform automatic focus adjustment. The present invention relates to a camera with an automatic focusing device.

[Conventional technology]

In the above-described camera with the automatic focus adjustment device, it is required that the taking lens which is not in the in-focus position is moved to the in-focus position as quickly as possible and stopped at the in-focus position as smoothly as possible. If the moving speed of the taking lens is increased, the in-focus position is reached quickly, but inertia may cause the in-focus position to be passed.

Therefore, the driving speed for the photographing lens is switched between high and low so that the photographing lens is moved at a high speed when the photographing lens is away from the in-focus position, and is moved at a low speed when it is near the in-focus position. There has been proposed a device configured to appropriately satisfy two contradictory requirements (see, for example, JP-A-57-46216 or JP-A-58-18611).

Furthermore, the residual deviation obtained by subtracting the amount of actual movement from the detected deviation from the in-focus position of the photographing lens is obtained, and as the residual deviation decreases, the duty ratio of the pulse for driving the photographing lens becomes smaller. (For example, JP-A-58-223108 or JP-A-58-223108)
-129406), a state in which the photographing lens is continuously driven as the photographing lens approaches the in-focus position, and a duty ratio for driving the photographing lens is provided. In which the photographing lens is driven by a large pulse driving unit, the state in which the photographing lens is driven by a pulse driving unit having a small duty ratio, and the driving motor is reversely rotated (for example, Japanese Patent Laid-Open No. 58-214130). (See Japanese Patent Publication) and the like are proposed.

[Problems to be solved by the invention]

By the way, in particular, an automatic focusing device in a single-lens reflex camera is required to take advantage of this camera that various photographing lenses can be exchanged. There are various types of taking lenses, and there are various types of moving ranges and moving load torques of the taking lenses that move during the automatic focus adjustment operation.

Further, in the period immediately before the lens reaches the focal position, the lens speed has a great influence on the movement amount of the lens after the motor braking, so it is necessary to control the lens speed to a low speed.

However, according to the conventional device, the lens is controlled by a predetermined energization amount regardless of the actual moving speed of the lens, so if the mounted lens is a lens with a small load and easy to accelerate, it will be accelerated too much. There was a problem.

It is an object of the present invention to solve the above problems and to provide an automatic focusing device capable of accurately controlling the moving speed of a lens according to a mounted lens and accurately stopping the lens at a predetermined focal position. It is what

[Means for Solving the Problems] In order to achieve the above object, the camera with an automatic focusing device of the present invention provides a motor for moving a taking lens, and a pulse for each predetermined amount of movement of the taking lens by the motor. The pulse output means for outputting, the movement amount output means for converting the required movement amount required to move the photographing lens to the planned focus position into the number of pulses and outputting the pulse number, and counting the pulses output from the pulse output means A remaining movement amount detecting means for detecting a remaining movement amount based on the counting result, a movement amount control means for controlling the motor so as to stop the photographing lens at a position where the remaining movement amount becomes zero, It operates just before the remaining movement amount becomes zero and controls the movement speed of the taking lens by repeating the energized state and the non-energized state to the motor. And a speed control means, wherein the speed control means starts energization to the motor when the pulse output time interval becomes longer than a first predetermined time interval, and after the energization starts, Regardless of the pulse output from the pulse output means, the energization to the motor is always continued for the second predetermined time, and the energization is stopped in response to the elapse of the second predetermined time. Means, second energization stopping means for stopping energization of the motor in response to a pulse output from the pulse output means after starting the energization, and switching between the first energization stopping means and the second energization stopping means. And a switching means.

[Operation] That is, when the output time interval of the pulse output for each predetermined movement amount of the lens becomes longer than the first predetermined time interval, energization of the motor is started. Thereafter, the energization of the motor is continued and stopped for the second predetermined time regardless of the output of the pulse, or stopped in response to the output of the pulse.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a circuit configuration of a control device of a camera with an automatic focusing device according to the present invention.

In the figure, (1) is a microcomputer (hereinafter referred to as AFC) that controls the automatic focus adjustment function, and (2) is a brightness distribution of light from a subject that has passed through different regions of the exit pupil of the taking lens (not shown). It is a light-receiving element for measuring autofocus and is a solid-state image element such as CCD.

(3) is an interface circuit (hereinafter abbreviated as IF) between the AFC (1) and the CCD (2), which is a drive circuit for the CCD (2) and AD conversion for digitally converting the analog output from the CCD (2). And a circuit for transferring the digitally converted data to the AFC (1).

(4) is a microcomputer (hereinafter abbreviated as AEC) that controls the entire camera and controls exposure calculation.

(5) is a lens ROM in the taking lens, which is connected to the AFC (1) via a signal pin provided between the lens and the camera body. In the lens ROM (5), data necessary for the autofocus operation, that is, information such as the configuration and optical characteristics of the taking lens, and information such as the reduction ratio of the lens drive system are written.

(6) is a motor drive control circuit that is an example of lens drive control means, and controls the rotation speed of the motor (M) that is lens drive means according to a command from the AFC (1). (7)
Is an encoder circuit which is an example of a pulse generating means including a combination of a disk having several cuts on the outer circumference and a photo interrupter, and generates a pulse according to the rotation of the motor (M) to generate a pulse. The rotation speed and rotation amount of are transmitted to the motor drive control circuit (6) and AFC (1).

(8) is a buzzer control circuit, to which a sounding body (BZ) such as a piezoelectric buzzer is connected.
Upon receiving the "L" level pulse signal from the AFC (1), the sounding body (BZ) is made to ring for a certain period of time.

(9) is a flash device, which is a light emitting unit for photographing, and an auxiliary light source including a near infrared light emitting element (IRED) for performing an autofocus operation at low contrast and low light as described later. Is equipped with. (L1)
Is an LED for focus display which is turned on when the taking lens is at the focus position.

(S _o ) is a start switch that is closed by the contact operation with the release button (RB). When the activation switch (S _o ) is closed, the camera control device is activated and the focus determination operation by the focus deviation detection means (1a) and the focus determination means (1b) of the AFC (1). Is configured to be launched. That is, the activation switch (S _o ) serves as a switching unit that activates the focus determination operation.

(S ₁ ) is a changeover switch that is closed by pressing the release button (RB) beyond the first stroke. Then, as described later, this switch (S ₁ )
A state in which the lens driving by the motor (M) is allowed even after the focus determination means (1b) of C (1) determines that the taking lens is in the focus position, and a motor is determined once the focus is determined to be the motor. It is a switching means for switching to a state in which the lens driving by (M) is prohibited.

(S ₂ ) is a release switch that is closed by pressing the release button (RB) beyond the second stroke. Then, by closing the release switch (S ₂ ), the mirror is raised and the shutter is released.

Release button (RB) and switches (S ₀ ), (S ₁ ),
The relationship with (S ₂ ) will be described with reference to FIG.

On the upper surface of the release button (RB), a pair of electrodes (x),
(Y) is located in close proximity. Usually both electrodes (x),
The resistance value between (y) is infinite, but by touching the upper surface of this release button (RB) with a finger, both electrodes (x),
The resistance value between (y) is low (several hundred Ω to several tens Ω). When the sensor (S ₀ ′) detects the change in the resistance value, the start switch (S _o ) is closed.

In addition, the release button (RB) is provided with a first protrusion (RBa) facing the changeover switch (S ₁ ) and a second protrusion (RBb) facing the release switch (S ₂ ). . When the release button (RB) is pressed beyond its first stroke, the changeover switch (S ₁ )
Further, when the release button (RB) is pressed beyond its second stroke, the changeover switch (S ₁ ) and the release button (S ₂ ) are closed by the contact with the protrusion (RBa or RBb), respectively. It is configured to be.

Next, according to the flowchart shown in FIG. 2, AFC (1)
The operation of will be described.

By closing the power switch (not shown), the AFC
(1) and AEC (4) start operation by power-on reset. The AFC (1) first initializes the output ports (P4) to (P8) in steps # 1 and # 2. In other words, by outputting the "H" level signal to the output port (P4), the focusing buzzer (BZ) is turned "OFF",
The motor (M) is stopped by outputting an "H" level signal to the output ports (P6) to (P8). The focus indicator LED (L1) is turned off by outputting an “L” level signal to the output port (P5).

Next, the procedure proceeds to step # 3 to enable the low contrast search. This low contrast search is performed when it is determined that the low contrast is obtained as a result of distance measurement, that is, when the contrast of the subject is low and sufficient accuracy cannot be obtained.
Alternatively, when the defocus amount exceeds the distance measurement cover range and distance measurement becomes impossible, distance measurement is performed while forcibly moving the taking lens to search for a position where low contrast is lost.

Then, in step # 4, the state of the start switch (S _o ) is determined by the state of the input port (P1). When the start switch (S _o ) is closed and the input port (P1) goes to “L” level, the process proceeds to the next step # 5, but the start switch (S _o ) is open and the input port (P1) If it is at "H" level, step # 4 is repeated without proceeding to the next step. Further, the AEC (4) starts photometry and exposure calculation by closing the start switch (S _o ).

AFC (1) goes to step # 5 and data bus (DB2)
Read data from the lens ROM (5) through and store. The lens ROM data also includes a conversion coefficient for converting a defocus amount, which is a deviation from the in-focus position of the photographing lens described later, into an encoder pulse count.

When the process proceeds from step # 5 to step # 6, the distance measuring operation is performed. First, a command is issued to the IF (3) through the data bus (DB1) to cause the CCD (2) to start integration. When the integration progresses and the charge accumulation level reaches a predetermined level, the integration operation ends, and the data transfer from the CCD (2) to the IF (3) is performed. The IF (3) sequentially digital-converts the analog signals sequentially input from the CCD (2) and transfers them to the AFC (1).

The focus deviation detecting means (1a) of the AFC (1) performs a predetermined calculation based on the transferred subject brightness distribution data, and in step # 6, the defocus which is the deviation from the in-focus position of the taking lens. The amount is calculated and converted into the number of pulses in step # 9 as described later. The low contrast is also determined during this calculation.

Next, the process proceeds to step # 7. If the result of the calculation indicates that the contrast is low, the process proceeds to step # 19. If the result is that the contrast is not low, the process proceeds to step # 8 and subsequent steps.

First, the operation when it is determined that the contrast is not low will be described.

In step # 8, the low contrast search is prohibited. Therefore, even if the low contrast state is set thereafter, the low contrast search is not performed.

Subsequently, the process proceeds to step # 9, and the defocus amount is set to the motor (M) by using the conversion coefficient read in step # 5.
The pulse count of the encoder is converted to the defocus pulse count according to the rotation amount of the. That is,
From the obtained defocus amount, the amount of rotation of the motor (M) required to move the lens to the in-focus position is obtained as the number of pulses.

Next, in step # 10, the focus determination means (1b) of the AFC (1) checks whether this defocus pulse count is within the allowable focus range. If the defocus pulse count is within the in-focus range, the process proceeds to step # 14 and subsequent steps.

If the defocus count is within the in-focus range, by outputting a "H" level signal to the output port (P5) of AFC (1) in step # 14, the signal is output to the transistor (Tra) through the resistor (Rb). Supply base current and transistor (Tra)
To activate the focus indicator LED (L1). Then, to determine the state of the input port (P2) in steps of # 15, if this port (P2) is "H" level, i.e., if the changeover switch (S ₁₎ is in an open state, # 5 Then, the process returns to step and the distance measuring operation is started again.

On the other hand, if it is determined in step # 15 that the input port (P2) is at the “L” level, that is, if the changeover switch (S ₁ ) is in the closed state, the process proceeds to step # 16 and the output port (P4) ) Output "L" level pulse signal. In response to this, the buzzer control circuit (8) sounds the buzzer (BZ) for a fixed time. Then, in step # 17, input port (P
Waiting until 2) becomes "H" level.

If Kaware the input port (P2) is "H" level, i.e., if it is the changeover switch (S ₁₎ is opened, the process proceeds to step # 18, further to determine the state of the input port (P1). If this port (P1) is at the "L" level, that is, if the activation switch (S _o ) is closed, the process returns to step # 5 to perform the distance measuring operation again. If the start switch (S _o ) is open, the autofocus routine is exited and the initial state (step # 1) is returned to.

In other words, in this camera control device, there is a continuous mode in which a distance measurement operation can be continuously performed to follow a fast-moving subject, and if a focus state occurs once during distance measurement, One-shot mode, which keeps the state and does not follow up even if the distance measurement object changes, can be easily switched by operating the release button (RB). That is, the changeover switch (S ₁ ) interlocking with the operation of the release button (RB) switches between these two modes, and the start switch (S _o ) starts the distance measuring operation.

As described above, when the release button (RB) is touched with a finger, the start switch (S _o ) is closed and the distance measuring operation is started, but at this time, it is always in the continuous mode.
When the release button (RB) is pushed in from this state until it exceeds the first stroke, the changeover switch (S ₁ ) is closed and the mode is switched to the one-shot mode. That is, steps # 5 to # 15 are repeated in the continuous mode, and # 5 to # 15 in the one-shot mode.
The steps up to 18 are repeated.

Therefore, in the continuous mode, the "L" level pulse signal is not output to the buzzer control circuit (8) in step # 16, and the buzzer (BZ) continues even if the focus state continues. Does not continue to ring. Also,
When the buzzer (BZ) sounds in the focused state, it is always in the one-shot mode, and the photographer can easily recognize that it is in the focus lock state in which the shutter can be released as it is.

Next, the operation when the defocus pulse count is determined to be out of the focusing range in step # 10 and the process proceeds to step # 11 will be described.

In the step of # 11, the focus display LED (L1) is turned off by outputting the "L" level signal to the output port (P5).
Then, in step # 12, a subroutine << lens drive control >>
Is called to move and control the taking lens, as will be described later. In this step, the taking lens is moved by the defocus pulse count. After driving the taking lens, the process proceeds to step # 13 to determine the state of the changeover switch (S ₁ ) based on the state of the input port (P2).

If the selector switch (S ₁ ) is closed and the input port (P2) is at the “L” level, that is, in the one-shot mode, it returns to step # 5 for re-ranging and the selector switch (S 1 _{If 1} ) is open and the input port (P2) is at "H" level, that is, in the continuous mode, the focus is determined and the process proceeds to step # 14 and thereafter.

Here, the reason why the route is changed to a different route as described above depending on the state of the changeover switch (S ₁ ) is that in continuous mode, the ability to follow a moving subject is taken into consideration.
Even if there is still some error at the end of driving the taking lens based on the result of the focus determination, it is possible to move to the next distance measuring operation assuming that the taking lens is in the in-focus position. In shot mode, focusing accuracy is emphasized, and after re-ranging, the focusing lens (1b) determines that it is in focus again in step # 10, and the shooting lens is in focus position for the first time. Buzzer (BZ) ringing and LE
The output for lighting D (L1) and so on is performed.

Next, in step # 7, it is determined that the contrast is low,
The operation when the process proceeds to step # 19 will be described.

In step # 19, the state of the changeover switch (S ₁ ) is determined by the state of the input port (P2). Changeover switch (S ₁ )
If is open, that is, if it is in continuous mode, proceed to step # 25, and switch (S ₁ )
Is closed, that is, in the one-shot mode, the process proceeds to step # 20.

First, the latter case will be described. In step # 20, it is further determined whether or not it is low light. If it is low light, the process proceeds to step # 23, and if it is not low light, the process proceeds to step # 21. Here, low light is when the subject brightness is low and the charge level of the CCD (2) within a predetermined time is insufficient.

When it is determined that it is a low light and the process proceeds to step # 23, it is checked whether or not the auxiliary light source is in standby. The state of the auxiliary light source is determined by the state of the output signal (ALOK) from the flash device (9) connected to the input port (P15). This signal (ALOK) is changed from "H" level to "L" level by mounting the flash device (9) on the camera and closing the start switch (not shown) of the camera, for example. .

If it is determined in step # 23 that the auxiliary light source is in the standby state, the process proceeds to step # 24 to emit auxiliary light having a wavelength in the near infrared region. The auxiliary light is emitted by outputting an "L" level signal to the output port (P14) to cause the auxiliary light source including the near infrared light emitting element (IRED) equipped in the flash device (9) to emit light. . After the auxiliary light is emitted, #
In step 5, the distance measuring operation is performed as described above.

The emission of the auxiliary light is designed to continue until the integration of CCD (2) is completed. In addition, a filter with multiple slits is provided in front of the auxiliary light source, and even in the case of low contrast, irradiating the auxiliary light causes a certain amount of contrast on the subject, and the distance measuring operation is performed. It's made possible.

If it is determined in step # 20 that the light is not low light, and if it is determined in step # 23 that the auxiliary light is not in standby, the process proceeds to step # 21 and the low contrast search is prohibited. Check if there is. If the low contrast search is prohibited, the process proceeds to step # 5 for re-ranging. If the low contrast search is permitted, the process proceeds to step # 22 to perform the low contrast search.

This low-contrast search changes when the normal start switch (S _o ) is closed and the low-contrast is determined to be low contrast in the first distance measurement operation, and when the selector switch (S ₁ ) is changed from the closed state to the open state. , Only when the start switch (S _o ) is closed and the first distance measurement determines that the contrast is low.

In other words, during shooting operation, if the target object is separated from the focus area due to camera shake or movement of the object, and it is determined that the contrast is low, the low contrast search is unexpectedly performed to adjust the focus position. It is prohibited to move the photographic lens in the vicinity.

In the low contrast search of step # 22, the distance measuring operation is performed while moving the taking lens, the lens is stopped when it is determined that the contrast is not low, the low contrast search is prohibited, and then the normal distance measuring operation is performed. Return to step # 5 to do. Perform a contrast search while moving the photographic lens to each of the closest and infinity ends once, and if the low contrast state is still not resolved, then the distance measurement operation is performed with the photographic lens stopped. , And low contrast search is prohibited.

If it is determined in step # 19 that the input port (P2) is at the "H" level, that is, in the continuous mode, the process proceeds to step # 25 to determine whether low contrast search is prohibited. If it is not prohibited, the process proceeds to step # 22, and the low contrast search operation is performed as in the previous case.

If the low contrast search is prohibited, it is determined in the next step # 26 whether or not the distance measuring operation is performed immediately after the changeover switch (S ₁ ) is switched from closed to open. If this switch (S ₁ ) is immediately after switching from closed to open, that is, immediately after switching from one-shot mode to continuous mode, proceed to the next step # 27, immediately before. Check to see if the auxiliary light operation was started.

When the auxiliary light operation is not started and the mode is switched to the continuous mode by opening the selector switch (S ₁ ), the low contrast search is performed in step # 22 as described above. If the auxiliary light operation has been started immediately before, go to the next step # 28 to check whether or not the light is low light.

If it is not determined immediately after switching from the one-shot mode to the continuous mode in the determination in step # 26,
Proceed to step # 29 to check whether the auxiliary light operation has been entered in the one-shot mode. If the auxiliary light operation has not been entered, the procedure returns to step # 5 to continue the distance measuring operation. When the auxiliary light operation is started, #
Go to step 28 and check if it is low light. If it is determined that the low light is detected, the process returns to step # 5 to continue the distance measuring operation and wait until the low contrast is lost or the low light is lost. If it is determined in step # 28 that it is not low light, the process proceeds to step # 22 to perform low contrast search.

In other words, even if the one-shot mode is switched to continuous mode in the low-contrast state, if the auxiliary light operation is active in the one-shot mode, the low-contrast search is not performed immediately and the low-light mode is canceled It is designed to perform a low contrast search.

Next, the operation when the release button (RB) is further pressed to exceed the second stroke and the release switch (S ₂ ) is closed will be described with reference to FIG.

When the start switch (S _o ) and the changeover switch (S ₁ ) are both closed, the AEC (4) is performing photometry and exposure calculation, and the closing operation of the release switch (S ₂ ) When it is detected by the fall of (Pc) from "H" level to "L" level, the release operation is performed based on the exposure calculation result.

On the other hand, the release switch (S ₂ ) is connected to the input port (P3) of the AFC (1). This input port (P3)
Is an interrupt terminal, and the release switch (S ₂ )
Is closed and the input port (P3) changes from "H" level to "L" level, an interrupt occurs and the process proceeds to step # 30 in FIG.

In step # 30, the output port is initialized to stop the motor (M), and the focus buzzer (BZ) and focus display LED (L1) are turned “OFF”, as in steps # 1 and # 2.
Put in a state. Next, the process proceeds to step # 31 and waits until the release operation is completed. When the release operation is completed, the interrupt routine is exited and the operation returns to step # 4 to start the normal operation again.

Next, drive control of the photographing lens will be described.

The graphs of FIGS. 3A and 3B show the control state of the rotation speed of the motor (M) during lens movement.

The graph of FIG. 3A shows the case where the amount of movement of the photographing lens is large. In the graph of FIG. 3A, each curve represents the relationship between the speed of the motor (M) and the defocus pulse count corresponding to the moving amount of the lens, using the moving load torque of the photographing lens as a parameter. There is. The broken line [I] indicates the case where the moving load torque of the taking lens is small, which is indicated by the alternate long and short dash line [II]
[I] shows the case where the moving load torque of the taking lens is large, and the solid line [II] shows the case where the moving load torque of the taking lens is about the middle of them.

The magnitude of the moving load torque of the photographic lens varies depending on the weight of the lens group forming the photographic lens, the viscosity of grease involved in the lens movement, and the like. Then, the respective characteristics are exhibited by controlling the rotation speed of the motor (M) by the AFC (1). Various information relating to the magnitude of the moving load torque of the photographing lens described above is written in the lens ROM (5), and the AFC (1) changes the drive control of the motor (M) according to the various information. You may make it do it.

First, in a region where the remaining amount (C) of the defocus pulse count corresponding to the required movement amount of the photographing lens is larger than the set value (Ct ₁ ), the motor (M) is continuously energized and rotated at full power, Move the shooting lens as fast as possible.

The remaining amount (C) of the defocus pulse count is the set value (Ct
_{When 1} ) is reached, deceleration is started to stop the shooting lens smoothly and accurately. Until the remaining defocus pulse count (C) reaches the set value (Ct ₂ ),
The rotation speed (v) of the motor (M) is controlled to be the set speed (v ₁ ).

As shown by the curve [I] in the graph of FIG. 3, when the moving load torque of the taking lens is relatively small, the remaining amount (C) of the defocus pulse count reaches the set value (Ct ₂ ). Since the rotation speed (v) of the motor (M) does not fall sufficiently to the set speed (v ₁ ), the remaining amount (C) of the defocus pulse count is the set value (Ct ₂ ).
Even if it becomes the following, the deceleration is continued as it is.

On the other hand, in the graph of FIG. 3 (a), [II] and [III]
As shown by the curve of, in the case of a photographic lens with a large moving load torque, the motor (M) is required before the remaining amount (C) of the defocus pulse count reaches the set value (Ct ₂ ).
Speed of rotation (v) is reduced to the set speed (v _1), from that point to maintain the rate this setting (v _1).

The remaining amount (C) of the defocus pulse count is the set value (Ct
_{When 2} ) is reached, this time the rotation speed (v) of the motor (M)
Control to the set speed (v ₂ ). Even with a photographic lens with a small moving load torque, the rotation speed (v) of the motor (M) reaches the set speed (v ₂ ) by the time the remaining defocus pulse count (C) reaches the set value (Ct ₃ ). The set speed (v ₂ ) and the set value (Ct ₃ ) are set so as to decrease.

If the rotation speed (v) of the motor (M) becomes lower than the set speed (v ₂ ), the starting force of the motor (M) will be large and the variation in speed will be extremely large even if an attempt is made to control the speed to a constant value. The stopping accuracy of (M) becomes poor. Therefore, in this area, the short-time energization method is switched to.

There are two types of this short-time energization method. A method of always energizing the motor (M) for a set period of time (hereinafter referred to as <short-time energizing method 1>), and an encoder circuit (7) corresponding to the rotation of the motor (M) during energization. When a rising edge of the output pulse from (1) occurs, the motor (M) is de-energized (hereinafter referred to as <short-time energization method 2>).

The latter method can sufficiently improve the stopping accuracy of the motor (M), but since the moving speed of the photographing lens is slowed by that much, it is adopted only for a few pulses immediately before the stopping of the motor (M). . The former method is a drive control method at the joint between the constant speed control and the latter method, and it suffices if a stopping accuracy of several pulses for performing the latter method can be obtained.
The moving speed of the taking lens can be increased to some extent.

In both types, after turning off the power to the motor (M),
The rotation speed (v) of the motor (M) is configured to re-energize when it reaches the set sufficiently slow speed, so that the speed of the motor (M) does not increase too much.

The graph of FIG. 3B shows the control state of the rotation speed of the motor (M) when the moving amount of the photographing lens is small.

When starting the lens movement in the control range (Ct _{1 to} Ct ₂ ) at the set speed (v ₁ ), as shown by the curve [IV], the control range (Ct ₂ at the set speed (v ₂ ) ~ Ct ₃ ) When starting the lens movement, as shown by the curve [V],
Further, when the lens movement is started in the short-time energization control range (Ct ₃ to), the respective movements are controlled as shown by the curve [VI]. That is, even if the amount of movement of the photographing lens is small, the rotational speed (v) of the motor (M) is increased to some extent and then decelerated, and the accuracy is adjusted in the final stage, so that the lens can be swiftly and highly accurate. I am able to move.

Then, the remaining amount (C) of the defocus pulse count is
The deviation area determining means (1c) of the AFC (1) determines which of the above-mentioned control areas, that is, which deviation area includes the deviation from the in-focus position of the photographing lens. Based on the discrimination result by the deviation area discrimination means (1c), the moving speed of the photographing lens by the motor (M) which is the lens driving means is set to be slower when the photographing lens is in the deviation area closer to the in-focus position. It is the motor drive control circuit (6) which is the lens drive control means already described that changes the speed in the following five stages.

Next, the operation of AFC (1) during the drive control of the taking lens is
Description will be given according to the flowcharts shown in FIGS. 4 and 5.

First, in step # 51 in FIG. 4, the AFC (1) loads the calculated defocus pulse count into the built-in down counter. This down counter is configured to decrement the count by "1" every time the input signal to the input port (P13) of AFC (1) rises from "L" level to "H" level. As shown in Fig. 1, AFC
A signal (ENCP) from the encoder circuit (7) is input to the input port (P13) of (1), and the built-in down counter counts the number of output pulses from the encoder circuit (7). Has become.

Next, the routine proceeds to step # 52, where it is determined by the deviation area determination means (1c) whether the defocus pulse count is larger than the set value (Ct ₁ ). If the defocus pulse count is larger than the set value (Ct ₁ ), the process proceeds to step # 62. In step # 62, the output ports (P9), (P11), so that the motor (M) is driven by continuous energization,
The "H" level signal is output to (P12) and the output port (P
The “L” level signal is output to each of 10). Output signals from the output ports (P9) to (P12) are input to the motor drive control circuit (6), and the motor drive control circuit (6) receives these signals and continuously energizes the motor (M). Set to drive. Next, the process proceeds to step # 63, where the subroutine << MSTART >> is called.

The subroutine << MSTART >> starts from step # 74 shown in FIG. In step # 74, first, the motor (M)
It is determined whether or not is driving. If the motor (M) is being driven, nothing is done and the process returns. If the motor (M) is stopped, the process proceeds to step # 75 to determine the moving direction of the taking lens.

When it is necessary to drive the motor (M) in the direction that the shooting lens is extended, output an "H" level signal to the output port (P7 (▲ ▼)) and output port (P6
"L" level signals are output to (▲ ▼)) and (P8 (▲ ▼)) respectively, and as described later, the motor drive control circuit (6) is activated to start moving the taking lens in the feeding direction. .

If it is necessary to drive the motor (M) in the direction in which the taking lens is retracted, the output port (P6 (▲
Outputs "H" level signal to (▼)) and outputs "L" to output ports (P7 (▲ ▼)) and (P8 (▲ ▼)) respectively.
A level signal is output to start moving the taking lens in the retracted direction. After performing the above operation, the process returns to the main routine.

After returning to the main routine, the program proceeds to step # 64 in FIG. 4 and the remaining amount of defocus pulse count (C)
Continue to energize the motor (M) until reaches the set value (Ct ₁ ). When the deviation area determining means (1c) determines that the remaining amount (C) of the defocus pulse count has reached the set value (Ct ₁ ), the process proceeds to step # 65.

On the other hand, if the defocus pulse count (C) is smaller than the set value (Ct ₁ ) in step # 52, the process proceeds to step # 53. In step # 53, the deviation area determination means (1c) determines whether or not the defocus pulse count (C) is larger than a set value (Ct ₂ (Ct ₂ <Ct ₁ )), and this count (C ) Is larger than the set value (Ct ₂ ), the process proceeds to step # 65.

In step # 65, in order to control the rotation speed (v) of the motor (M) to the set speed (v ₁ ), the output port (P9),
An "L" level signal is output to (P10), and an "H" level signal is output to the output ports (P11) and (P12). Upon receiving these signals, the motor drive control circuit (6)
Is set to drive the motor (M) at the set speed (v ₁ ). Then proceed to step # 66 to call the subroutine << MSTART >>. The processing with Saburchin << MSTART >> is as described above.

After returning to the main routine, the routine proceeds to step # 67, where the rotation speed (v) of the motor (M) is increased until the remaining defocus pulse count (C) reaches the set value (Ct ₂ ).
The drive control is continued so that the speed becomes the set speed (v ₁ ), and when the remaining amount (C) reaches the set value (Ct ₂ ), the process proceeds to step # 68.

On the other hand, if the defocus pulse count (C) is less than or equal to the set value (Ct ₂ ) in step # 53, the process proceeds to step # 54. In step # 54, the defocus pulse count (C) is set to the set value (Ct by the deviation area determination means (1c).
_It is checked whether it is larger than ₃ (Ct ₃ <Ct ₂ ), and if the count (C) is larger than the set value (Ct ₃ ), the process proceeds to step # 68.

In ♯68 step, the motor (M) set speed the rotational speed (v) of _{(v 2 (v 1> v} 2)) output to control the port (P9), the (P10), (P11) is It outputs an "L" level signal and an "H" level signal to the output port (P12). Receiving these signals, the motor drive control circuit (6) is set to drive the motor (M) at the set speed (v ₂ ). Then, the process proceeds to step # 69, the subroutine << MSTART >> is executed, and after returning, the process proceeds to step # 70. In step # 70, the motor (M) is controlled so that the rotation speed (v) of the motor (M) becomes the set speed (v ₂ ) until the remaining amount (C) of the defocus pulse count reaches the set value (Ct ₃ ). ) Drive control is continued and this remaining amount (C)
Reaches the set value (Ct ₃ ), the process proceeds to step # 71.

On the other hand, if the defocus pulse count (C) is less than or equal to the set value (Ct ₃ ) in step # 54, the process proceeds to step # 55. In step # 55, the defocus pulse count (C) is set to the set value (Ct by the deviation area determination means (1c).
₄ (Ct ₄ <Ct ₃ )) is determined. If the count (C) is greater than the set value (Ct ₄ ), then # 71
I will proceed to the step.

In the step of # 71, in order to drive the motor (M) by the <short-time energization method 1>, “L” level signals are output to the output ports (P9) and (P12), respectively, and the output port (P10). A signal of "H" level is output to the motor drive control circuit (6), and the motor drive control circuit (6) is set to receive these signals and drive the motor (M) by the <short-time energization method 1>. Then, the process proceeds to step # 72, the process in the subroutine << MSTART >> is performed as before, and after returning, the process proceeds to step # 73. In step # 73, until the remaining amount (C) of the defocus pulse count reaches the set value (Ct ₄ ),
The drive control of the motor (M) is continued by <Short-time energization method 1>, and when the remaining amount (C) reaches the set value (Ct ₄ ), the process proceeds to step # 56.

On the other hand, if the defocus pulse count (C) is less than or equal to the set value (Ct ₄ ) in step # 55, the process proceeds to step # 56.

In the step of # 56, in order to drive the motor (M) by <short-time energization method 2>, an “L” level signal is output to the output port (P9), and output ports (P10) and (P12) are also connected. Each output a "H" level signal. Upon receiving this signal, the motor drive control circuit (6) is set to drive the motor (M) by <short-time energization method 2>. Then #
Proceed to step 57 to perform the processing of the subroutine << MSTART >>, and after returning, proceed to step # 58. In step # 58, the remaining defocus pulse count (C)
The drive control of the motor (M) is continued by <Short-time energization method 2> until is "0" and the counting is completed.

When the counting is completed, the process proceeds to step # 59, where an "H" level signal is output to the output ports (P6 (▲ ▼)) and (P7 (▲ ▼)) to stop the energization of the motor (M).
At this time, the output port (P8 (▲ ▼)) remains at the “L” level, and the motor (M) is braked. Then, in step # 60, after waiting until the motor (M) completely stops, the process proceeds to step # 61.
An "H" level signal is output to the output port (P8 (▲ ▼)) to release the braking state for the motor (M).

This is the end of the movement of the taking lens.

Next, the configuration and operation of the motor drive control circuit (6) which is an example of the lens drive control means will be described.

FIG. 6 is a circuit diagram showing the configuration of the motor drive controller (6a).

In the figure, (AN1) to (AN5) are AND circuits, and (OR1) to (OR
7) is an OR circuit, (NA1) to (NA3) are NAND circuits, and (IV1) and (IV2) are inverter circuits. Also,
(DLY1) to (DLY4) are delay circuits, and (OSP1) to (OSP1)
P8) is a one-shot pulse circuit, which outputs a short pulse signal of "H" level when the input signal rises from "L" level to "H" level. (D-FF1) and (D-FF
2) is a D-flip-flop circuit. (PG) is a reference pulse generation circuit whose output signal is a counter (CNT)
It is connected to the clock input terminal (CP) of. (SL) is a signal selection circuit for selecting inputs (Sl ₁ ), (Sl ₂ ), (Sl ₃ ).
Depending on the state of, the counter (CNT) output terminal (Q ₁ )
Input terminals (I ₁ ) to (I ₄ ) to which the signal from (Q ₄ ) is input
Select one of them and output the input signal to that terminal to the output terminal (O ₁ ).

FIG. 7 shows the configuration of the motor drive section (6b).

When the output (m) of the NAND circuit (NA2), the output (n) of the NAND circuit (NA3), and the output (o) of the OR circuit (OR7) are all "H" level, (m) is "H". Since it is at the level, the transistor (Tr ₅ ) is in the “OFF” state, and thus the transistor (Tr ₃ ) is also in the “OFF” state. Further, since (n) is at the "H" level, the transistor (Tr ₆ ) is in the "OFF" state, and thus the transistor (Tr ₄ ) is also in the "OFF" state. Further, since the output of the OR circuit (OR7) (o) is at "H" level, the transistor (Tr ₇₎ is "OFF" state, the transistor (Tr ₈₎ is also turned "OFF" state. Further, since the transistor (Tr ₃ ) and the transistor (Tr ₄ ) are also in the “OFF” state, the base current is not supplied to the transistors (Tr ₁ ) and (Tr ₂ ) and both are in the “OFF” state. Therefore, no current flows through the motor (M) and the motor (M) remains stopped.

When only the output (m) of the NAND circuit (NA2) becomes the “L” level, the transistor (Tr ₅ ) becomes the “ON” state, and thus the transistor (Tr ₃ ) also becomes the “ON” state. By turning on the transistor (Tr ₃ ), the resistance (R 3
Base current is supplied to the transistor (Tr ₂ ) through ₁₃ ), and the transistor (Tr ₂ ) is turned on. Therefore, the electric current is supplied to the motor (M) to start the rotation of the motor (M). Then, the rotation of the motor (M) is transmitted to a photographing lens drive mechanism (not shown) via a transmission mechanism (not shown), and the photographing lens is configured to move in the retracting direction.

Moreover, when only the output (n) of the NAND circuit (NA3) becomes the "L" level, the transistor (Tr ₆ ) becomes the "ON" state, and thereby the transistor (Tr ₄ ) also becomes the "ON" state. . When the transistor (Tr ₄ ) is in the “ON” state, the base current is supplied to the transistor (Tr ₁ ) through the resistor (R ₁₄ ) and the transistor (Tr ₁ ) is in the “ON” state. Therefore, the motor (M) is supplied with a current in the opposite direction to the above case, and the motor (M) starts rotating in the opposite direction to the above case. The rotation of the motor (M) is transmitted to the photographing lens drive mechanism via the transmission mechanism, and the photographing lens is configured to move in the feeding direction.

Furthermore, when only the output (o) of the OR circuit (OR7) goes to the "L" level, the transistor (Tr ₇ ) goes into the "ON" state, which turns the transistor (Tr ₈ ) into the "ON" state. . By turning on the transistor (Tr ₈ ), the transistor (T 3) passes through the diode (D 3) and the resistor (R ₁₅ ).
The base current is supplied to r ₂ ) and to the transistor (Tr ₁ ) through the diode (D4) and the resistor (R ₁₆ ) respectively, and both the transistor (Tr ₁ ) and the transistor (Tr ₂ ) are in the “ON” state. become. In this state, the transistor (T
r ₁ ) and diode (D2) or transistor (T
Both terminals of the motor (M) are short-circuited to the power source (Vcc) side through r ₂ ) and the diode (D1), and the braking operation for the motor (M) is performed.

Next, the motor drive control circuit (6) shown in FIG. 6 and FIG.
The operation of will be described.

When driving the motor (M) with continuous energization, AFC (1)
Since the output signal (GSO) from the output port (P9) of is at "H" level, the output (1) of the OR circuit (OR6) is at "H" level. This output (l) is a NAND circuit (NA2),
(NA3) and one of the input terminals of the OR circuit (OR7). The output (o) of the OR circuit (OR7) is "H"
Since the level is reached, the braking operation for the motor (M) is not performed.

Output signal from the output port (P7) of AFC (1) (▲
▼) and the output signal from the output port (P6) (▲
▼) sets the output signal (▲ ▼) to the “L” level when the motor (M) is driven in the direction in which the photographing lens is extended depending on the driving direction of the motor (M), and the motor ( When driving M, output signal (▲
▼) is set to "L" level.

The output (m) of the NAND circuit (NA2), when either signal (▲ ▼ or ▲ ▼) becomes “L” level,
Alternatively, only one of the outputs (n) of the NAND circuit (NA3) becomes "L" level, and the motor (M) is continuously energized.

Next, the operation of the constant speed control of the motor (M) will be described together with the time chart shown in FIG. The eighth
In the time chart shown in the figure, the motor (M) is
The figure shows the case where an "L" level signal is output to the output ports (P6) and (P8) in order to drive and rotate the taking lens in the feeding direction, and the following description will also be made based on that.

In case of constant speed control, each output signal from AFC (1) is “L” level, output signal (GS0) from output port (P9) and output signal (GS1) from output port (P10) respectively. , The output signal (SS) from the output port (P12) is "L" level,
And the output signal (GS2) from the output port (P11) is
When controlling to the set speed (v ₁ ) on the high speed side, it is at “H” level. Since the output signal (GS1) is at “L” level, the output (i) of the AND circuit (AN4) and the AND circuit (AN3)
The output (g) of each becomes "L" level. Since the output signal (SS) is at "H" level, the output of the NAND circuit (NA1) is at "H" level.

The signal selection circuit (SL) uses the signal (Sl
₁ (GS1)) is "L" level and signal (Sl ₂ (GS2))
Is configured to select the input terminal (I ₁ ) when is at “H” level. The input terminal (I ₁ ) has a counter (CN
T) output terminal (Q ₁ ) is connected, and the output of this terminal (Q ₁ ) is the output terminal (O ₁ ) of the signal selection circuit (SL).
Is output to.

The counter (CNT) counts the output pulses from the reference pulse generator (PG), and when a predetermined number is counted from the start of counting, the output terminals (Q ₁ ) to (Q ₄ ) respectively count It is configured to become "H" level according to. The time from the start of counting the output terminal (Q ₁ ) to the “H” level is the pulse signal (ENCP) from the encoder circuit (7) at the set speed (v ₁ ) (hereinafter referred to as the encoder pulse). It is set to the same as the cycle.

First, the operation when the motor (M) is controlled to the set speed (v ₁ ) on the high speed side will be described.

In the above-mentioned state, when the signal (▲ ▼) for driving the motor (M) in the direction to extend the taking lens, which is output from the output terminal (P6) of the AFC (1), becomes “L” level (T ₀ ). The output (a) of the AND circuit (AN1) becomes "L" level, and the output (b) of the OR circuit (OR1) also becomes "L" level. Therefore, the output (c) of the OR circuit (OR2) also becomes "L" level, the clear state of the counter (CNT) is released, and counting is started.

Further, the output (b) of the OR circuit (OR1) becomes "L" level, so that the output (j) of the OR circuit (OR4) also becomes "L".
The level becomes high, and the clear state of the flip-flop (D-FF1) is released. Similarly, when the output (b) of the OR circuit (OR1) becomes "L" level, the OR circuit (OR1)
The output (k) of 5) also becomes "L" level, and the clear state of the flip-flop (D-FF2) is released.

When the output (a) of the AND circuit (AN1) becomes "L" level, the output of the inverter circuit (IV1) changes from "L" level to "H" level, and the one-shot pulse generation circuit (OS
From P3), a short “H” level pulse signal is output.
As a result, the output (d) of the OR circuit (OR3) becomes "H" level in a pulse shape, and this output (d) is input to the preset input terminal (PR) of the flip-flop (D-FF1). The output terminal (Q) of the preset flip-flop (D-FF1) becomes "H" level, so the OR circuit (OR
The output (l) of 6) goes to "H" level.

On the other hand, the signal (▲ ▼) from the output terminal (P6) is at "L" level, and the inverted signal (MF) of this signal (▲ ▼) is at "H" level. Therefore, the output (n) of the NAND circuit (NA3) shown in FIG. 7 becomes the “L” level, the motor (M) is energized, and the motor (M) starts rotating in the lens extending direction. .

While the motor (M) starts rotating and the speed does not increase yet, it is faster that the output terminal (Q ₁ ) of the counter (CNT) becomes “H” level than the cycle of the encoder pulse (ENCP). As shown in FIG. 8, when the timing (T ₁₎ at the output terminal of the counter (CNT) (Q ₁₎ becomes "H" level, the output of the signal selection circuit (SL) (e) to "H" level Become. As a result, the output (f) of the AND circuit (AN2) becomes "H" level and the output (d) of the OR circuit (OR3) becomes "H" level. Therefore, the flip-flop (D-FF1) remains in the preset state, and the output terminal (Q) maintains the "H" level,
The output (l) of the OR circuit (OR6) also remains at the "H" level, and the motor (M) continues to be energized.

The output (e) of the signal selection circuit (SL) is the delay circuit (DLY1).
Is input to the one-shot pulse generation circuit (OSP6) via this, and a short "H" level pulse signal is output from this circuit (OSP6) in synchronization with the rising edge of the output (e).
This pulse signal is input to the clear input terminal (CL) of the counter (CNT) via the OR circuit (OR2), and the counter (CNT) restarts counting.

Next, as shown in FIG. 8, when the encoder pulse (ENCP) rises at the timing (T ₂ ), the flip-flop (D
-FF2) is input to its input terminal (D) in synchronization with the rising edge of this encoder pulse (ENCP), that is,
The output from the output terminal (Q) of the flip-flop (D-FF1) is latched and output to the output terminal (Q) of the flip-flop (D-FF2). Therefore, the flip-flop (D
Since the output from the output terminal (Q) of -FF1) is at "H" level, the output terminal (Q) of the flip-flop (D-FF2) also becomes "H" level and the output of the OR circuit (OR6) ( In l), the "H" level is maintained and the motor (M) continues to be energized.

The output terminal (Q) of the flip-flop (D-FF2) is "H".
When the level becomes high, an "H" level signal is input to the one-shot pulse generation circuit (OSP7) via the delay circuit (DLY3), and this circuit (OSP7) outputs a short "H" level pulse signal. . This pulse signal is the OR circuit (OR4)
Is input to the clear input terminal (CL) of the flip-flop (D-FF1) via the, and the flip-flop (D-FF1) is cleared, and its output terminal (Q) becomes "L" level.

At the rising edge of the encoder pulse (ENCP), the “H” level signal is input to the one-shot pulse generation circuit (OSP4) via the delay circuit (DLY2), and this circuit (OS
A short “H” level pulse signal is output from P4). On the other hand, the output signal (SS) from the output port (P12) is at "H" level, and the output of the NAND circuit (NA1) to which the inverted signal (▲ ▼) of this signal (SS) is input is "H". Since it is the level, the output (h) of the AND circuit (AN5) becomes the “H” level in a pulse form. This output (h) passes through the OR circuit (OR2) and the clear input terminal (C) of the counter (CNT).
L) and each output terminal (Q ₁ ) of the counter (CNT)
(Q ₄ ) all go to “L” level and restart counting from “O”.

If the output terminal (Q ₁ ) of the counter (CNT) goes to “H” level earlier than the next rising of the encoder pulse (ENCP) (T ₂ ′), the rotation speed (v) of the motor (M) is It is still slower than the set speed (v ₁ ).

At this time, as described above, the output (e) of the signal selection circuit (SL) becomes "H" level, and the output (f) of the AND circuit (AN2) becomes "H" level. The output (d) of the OR circuit (OR3) also becomes "H" level, and the flip-flop (D
-FF1) is preset and its output terminal (Q) is "H"
Become a level. The output (1) of the OR circuit (OR6) maintains the "H" level and the motor (M) continues to be energized.

Also, the output terminal (Q) of the flip-flop (D-FF1)
At the rising edge of the output from the one-shot pulse generation circuit (OSP8), a short "H" level pulse signal is output. This pulse signal is passed through the OR circuit (OR5) to the clear input terminal (C of the flip-flop (D-FF2)).
L), the flip-flop (D-FF2) is cleared, and its output terminal (Q) becomes "L" level.

When the output (e) of the signal selection circuit (SL) goes to "H" level, the "H" level signal is input to the one-shot pulse generation circuit (OSP6) through the delay circuit (DLY1). (OSP6) outputs a short “H” level pulse signal. This pulse signal is input to the clear input terminal of the counter (CNT) via the OR circuit (OR2) (CL), a counter the output terminals of the _{(CNT) (Q 1) ~} (Q 4) All "L"
The level is reached and counting is restarted from "O". Since the output terminals (Q ₁ ) to (Q ₄ ) of the counter (CNT) are all at "L" level, the output (e) of the signal selection circuit (SL) is also at "L" level. The output (f) of (AN2) becomes "L" level, and the output (d) of the OR circuit (OR3) also becomes "L" level.

When the next rising edge of the encoder pulse (ENCP) occurs (T ₃ ), the operation is the same as that at the rising timing (T ₂ ) of this pulse (ENCP) described above.

Next, when the rising edge of the encoder pulse (ENCP) occurs (T ₄ ) faster than the output terminal (Q ₁ ) of the counter (CNT) goes to “H” level, the rotation speed (v) of the motor (M) ) Is faster than the set speed (v ₁ ).

By the rising edge of this encoder pulse (ENCP), the flip-flop (D-FF2) latches the output of the output terminal (Q) of the flip-flop (D-FF1) which is at the "L" level, and the output terminal Output from (Q). As a result, the output (l) of the OR circuit (OR6) becomes the "L" level, and the output (n) of the NAND circuit (NA3) that has been maintaining the "L" level up to the "H" level,
Power supply to the motor (M) is stopped. At the same time, since the output signal (▲ ▼) from the output terminal (P8) is at “L” level, the output (o) of the OR circuit (OR7) goes to “L” level, and the braking operation for the motor (M) Done.

At the rising edge of the encoder pulse (ENCP), the “H” level signal is input to the one-shot pulse generation circuit (OSP4) via the delay circuit (DLY2), and this circuit (OS
A short “H” level pulse signal is output from P4). As before, the output of the NAND circuit (NA1) is at "H" level, so the "H" level is applied to the input terminal (CL) of the counter (CNT) via the AND circuit (AN5) and OR circuit (OR2). A level pulse signal is input, and each output terminal (Q ₁ ) to (Q ₄ ) of the counter (CNT) is cleared.

After that, the above-described operation is repeated so that the rotation speed (v) of the motor (M) is controlled to the set speed (v ₁ ).
The operation at the rising edge of the encoder pulse (ENCP) at the timings (T ₅ ) and (T ₆ ) in FIG. 8 is the same as the operation at the timing (T ₄ ). The operation at the rising edge of the output terminal (Q ₁ ) of the counter (CNT) at the timing (T ₇ ) is the same as the operation at the timing (T ₁ ). In addition, encoder pulse (ENCP) at timing (T ₈ )
The operation at the rising edge of is the same as the operation at the timing (T ₂ ).

Next, the operation for controlling the motor (M) to the set speed (v ₂ ) on the low speed side will be described.

AFC at timing (T ₉ ) to change control speed
When the output signal (GS2) from the output port (P11) of (1) is set to "L" level, the inverted signal of this signal (GS2) (▲
Since ▼) is input to the one-shot pulse generation circuit (OSP2), a short “H” level pulse signal is output from this circuit (OSP2).

As a result, the output (b) of the OR circuit (OR1) becomes the “H” level in a pulse shape, and this output (b) becomes the OR circuit (OR
It is input to the clear input terminal (CL) of the flip-flop (D-FF1) via 4). Flip-flop (D-FF
1) is cleared and its output terminal (Q) becomes "L" level. Further, this output (b) is passed through the OR circuit (OR5) to the clear input terminal (C) of the flip-flop (D-FF2).
L).

As a result, the flip-flop (D-FF2) is cleared, and its output terminal (Q) also becomes "L" level. Therefore,
The output (l) of the OR circuit (OR6) becomes "L" level, and the output (m) of the NAND circuit (NA2) and the NAND circuit (NA
Both outputs (n) of 3) become "H" level, and the power supply to the motor (M) is stopped. This is to reduce the rotation speed of the motor (M) from the set speed (v ₁ ) to the set speed (v ₂ ).

When the output (b) of the OR circuit (OR1) goes to "H" level in a pulse form, an "H" level pulse signal is sent to the clear input terminal (CL) of the counter (CNT) via the OR circuit (OR2). Is input and the counter (CNT) is also cleared.

When the output signal (GS2) from the output port (P11) changes from the “H” level to the “L” level, the signal selection circuit (SL) causes the input signal to the input terminal (I ₂ ), that is, the counter ( Select the output from the output terminal (Q ₂ ) of CNT) and output to the output terminal (O ₁ ). Counter (CNT) output terminal (Q
₂ ) is the same as the period of the encoder pulse (ENCP) when the rotation speed (v) of the motor (M) is the set speed (v ₂ ) from the start of counting to the “H” level. It is set. Other than the change of the selection input source of the signal selection circuit (SL), other operations are exactly the same as the case of controlling the rotation speed (v) of the motor (M) to the set speed (v ₁ ).

Next, regarding the operation of the motor drive control circuit (6) in the short-time energization method, circuit diagrams shown in FIGS.
Also, description will be given using a time chart shown in FIG.
As in the previous case, in the time chart shown in FIG. 9 as well, in order to drive and rotate the motor (M) in the feeding direction of the taking lens, the output ports (P6) and (P8) are set to the “L” level. The case where a signal is output is shown, and the following description will be made based on it.

In this system, each output signal from AFC (1) is
The output signal (GS0) from the output port (P9) is "L" level, the output signal (GS1) from the output port (P10) is "H" level, the output signal (SS) from the output port (P12) is
In the case of <short-time energization method 1>, the level is “L”, and in the case of <short-time energization method 2>, the level is “H”.

In the signal selection circuit (SL), the selection input (Sl ₁ (GS1)) is "H".
Level and the selection input (Sl ₃ (l)) is “H” level, the input terminal (I ₃ ) is selected and the selection input (Sl ₁ (GS
1)) is at "H" level and the selection input (Sl ₃ (l)) is at "L"
In the case of the level, the input terminals (I ₄ ) are selected respectively. Input terminal (I ₃ ) of the signal selection circuit (SL)
Is connected to the output terminal (Q ₃ ) of the counter (CNT), and the input terminal (I ₄ ) of the signal selection circuit (SL) is connected to the output terminal (Q ₄ ) of the counter (CNT). (Sl ₂ ),
Depending on the combination of the states of (Sl ₃ ), the output of either terminal (Q ₃ ) or (Q ₄ ) is output to the output terminal (O ₁ ) of this circuit (SL).

After the counter (CNT) starts counting, output terminal (Q
The time until ₃ ) changes to "H" level is set to be the same as the energization time to the motor (M) in the short-time energization method. In addition, the time from the start of counting (Q ₄ ) of the output terminal (Q ₄ ) of the counter (CNT) to the change to “H” level is the cycle of the limit encoder pulse (ENCP) for reenergization in the short-time energization method. Set to the same.

First, the operation in the case of controlling the drive of the motor (M) by the <short-time energization method 1> will be described.

In this method, since the output signal (SS) from the output port (P12) is at "L" level, the AND circuit (AN4)
The output (i) of is at "L" level. On the other hand, since the output signal (GS1) from the output port (P10) is at "H" level, the output (f) of the AND circuit (AN2) is at "L" level. The output (k) of the OR circuit (OR5) is at "H" level, and this output (k) is a flip-flop (D-FF).
Since it is input to the clear input terminal (CL) of 2), the flip-flop (D-FF2) is cleared and its output terminal (Q) is at "L" level.

In this state, when the signal (▲ ▼) for driving and rotating the motor (M) in the direction to extend the taking lens, which is output from the output terminal (P6) of the AFC (1), becomes “L” level (T ₁₀ ), The output (a) of the AND circuit (AN1) becomes "L" level, and the output (b) of the OR circuit (OR1) also becomes "L" level. When this output (b) goes to "L" level, the clear input terminal (C) of the counter (CNT) is passed through the OR circuit (OR2).
The "L" level signal is input to the L) and to the clear input terminal (CL) of the flip-flop (D-FF1) via the OR circuit (OR4). Therefore, the clear state of both the counter (CNT) and the flip-flop (D-FF1) is released.

Furthermore, when the output (a) of the AND circuit (AN1) becomes "L" level, the output of the inverter circuit (IV1) changes from "L" level to "H" level, and the one-shot pulse generation circuit (OSP3) changes to "L" level. A pulse signal with a short H "level is output. This pulse signal causes the flip-flop (D-FF1) to be preset through the OR circuit (OR3), and the output of the output terminal (Q) of the flip-flop (D-FF1) becomes "H" level. Therefore, the output (1) of the OR circuit (OR6) becomes "H" level, the output (n) of the NAND circuit (NA3) becomes "L" level, and the motor (M) is energized.

The output (l) of the OR circuit (OR6) is at "H" level, and
The inverted signal (▲ ▼) of the output signal (SS) from the output port (P12) is also at “H” level, so the output of the NAND circuit (NA1) goes to “L” level and the AND circuit (AN5).
The gate of is closed and its output (h) is at "L" level. Therefore, the timing (T ₁₁ ) in FIG.
Even if the encoder pulse (ENCP) changes from "L" level to "H" level at (T ₁₂ ), the operation of the motor drive control circuit (6) is not affected and the motor (M) continues to be energized. .

Timing output terminal of the counter (CNT) by (T ₁₃₎ (Q ₃₎
Becomes the output "H" level, the signal selection circuit (SL) so selects the input terminal (I _3), the output (e) also becomes "H" level. As a result, the output (g) of the AND circuit (AN3) also changes from "L" level to "H" level, and the flip-flop (D-FF1) goes to its input terminal (D) in synchronization with this rising edge. Input, that is, the output from its own output terminal () is latched.

Therefore, the output terminal (Q) becomes "L" level and the output terminal () becomes "H" level. When the output of the output terminal (Q) of the flip-flop (D-FF1) becomes "L" level, the output (l) of the OR circuit (OR6) also becomes "L" level and the output (n) of the NAND circuit (NA3) (n). ) Becomes "H" level, and the power supply to the motor (M) is stopped.

At the same time, since the output signal (▲ ▼) from the output port (P8) of AFC (1) is at “L” level, the OR circuit (OR
The output (o) of 7) becomes "L" level and the motor (M)
The braking operation for is performed. Furthermore, the signal selection circuit (SL) selects the input terminal (I ₄ ) by changing the combination of the states of the selection inputs (Sl ₁ (GS1)) and (Sl ₃ (l)), and the counter (CNT) The output from the output terminal (Q ₄ ) of is output to the output terminal (O ₁ ). Also, the output of the NAND circuit (NA1) goes to "H" level, and the AND circuit (AN5).
Opens the gate.

In this state, before the timing at which the output terminal of the counter (CNT) by (T ₁₄₎ (Q ₄₎ becomes "H" level, if the encoder pulse (ENCP) rises to "H" level from the "L" level In the case, the rotation speed (v) of the motor (M) does not decrease to the speed at which the power is re-energized.

At this time, the "H" level signal is input to the one-shot pulse generation circuit (OSP4) via the delay circuit (DLY2) by the rising edge of the encoder pulse (ENCP), and this circuit (OSP4) outputs the "H" level signal. A short pulse signal is output, and this pulse signal is input to the clear input terminal (CL) of the counter (CNT) via the AND circuit (AN5) and OR circuit (OR2), and the counter (CNT) is cleared. .

As a result of the rotation speed (v) of the motor (M) decreasing, the counter (CNT) counts the set time before the encoder pulse (ENCP) changes from "L" level to "H" level, and the output terminal When (Q ₄ ) becomes “H” level (T ₁₅ ),
The output (e) of the signal selection circuit (SL) becomes "H" level.
As a result, the output (g) of the AND circuit (AN3) changes from "L" level to "H" level, and the flip-flop (D-
FF1) latches the input to its input terminal (D), that is, the output from its own output terminal (), in synchronization with this rising, and the output from its output terminal (Q) is "H".
Change to a level.

Therefore, the output (l) of the OR circuit (OR6) becomes "H" level, the output of the OR circuit (OR7) also becomes "H" level,
The braking state for the motor (M) is released. On the other hand, since the output (n) of the NAND circuit (NA3) becomes the "L" level, the motor (M) is energized again. The output (l) of the OR circuit (OR6) becomes "H" level, the output of the NAND circuit (NA1) becomes "L" level, the gate of the AND circuit (AN5) is closed, and its output (h ) Becomes “L” level.

When the output (e) of the signal selection circuit (SL) changes from the "L" level to the "H" level, the one-shot pulse generation circuit (OSP6) receives the "H" level signal via the delay circuit (DLY1). Is input, and a short “H” level pulse signal is output from this circuit (OSP6). This pulse signal passes through the OR circuit (OR2) and the clear input terminal (C) of the counter (CNT).
It is input to L) and the counter (CNT) is cleared. Further, since the combination of the states of the selection inputs (Sl ₁ (GS1)) and (Sl ₁ (l)) changes, the signal selection circuit (SL) selects the input terminal (I ₃ ) again.

Next, the operation of controlling the drive of the motor (M) by the <short-time energization method 2> will be described.

In this method, AFC (1) output port (P9) ~
The level of the output signal from (P11) is the same as in <Short-time energization method 1>, and only the output signal (SS) from the output port (P12) becomes the “H” level.

When the output signal (SS) changes to "H" level at the timing (T ₁₆ ) in FIG. 9, the output of the NAND circuit (NA1) becomes "H" level and the gate of the AND circuit (AN5) is opened. In addition, the output signal from the output ports (P10) and (P12) (GS
Since 1) and (SS) are both at "H" level, the gate of the AND circuit (AN4) is also opened. Explaining according to FIG. 9, when the output signal (SS) is switched from the “L” level to the “H” level, the output (1) of the OR circuit (OR6) is at the “L” level. That is, the motor (M) is not energized.

At timing (T ₁₇ ), the encoder pulse (ENCP) changes from “L” level to “H” before the output from the counter (CNT) output terminal (Q ₄ ) changes from “L” level to “H” level. When rising to the level, the "H" level signal is input to the one-shot pulse generation circuit (OSP4) through the delay circuit (DLY2), and this circuit (OSP4) outputs a short "H" level pulse signal. It This pulse signal is input to the clear input terminal (CL) of the counter (CNT) via the AND circuit (AN5) and the OR circuit (OR2), and the counter (CNT) is cleared.

In addition, “H” from the one-shot pulse generation circuit (OSP5)
A pulse signal with a short level is output. This pulse signal passes through an AND circuit (AN4) and an OR circuit (OR4),
Clear input terminal (CL) of flip-flop (D-FF1)
To the flip-flop (D-FF1) to be cleared. Therefore, the output from the output terminal (Q) of the flip-flop (D-FF1) remains at "L" level, and the motor (M) is not energized.

From this state, at the timing (T ₁₈ ), the counter (CNT) counts the set time before the encoder pulse (ENCP) changes from “L” level to “H” level, and the output of its output terminal (Q ₄ ) When the "L" level rises to the "H" level, that is, when the rotation speed (v) of the motor (M) falls below the set lower limit speed, the output (e) of the signal selection circuit (SL) outputs Since (I ₄ ) is selected, it goes to “H” level.

As a result, the output (g) of the AND circuit (AN3) also becomes "H" level, and the flip-flop (D-FF1) receives the input to its input terminal (D), that is, the flip-flop (D-FF1) in synchronization with this rising. Latch the output from the output terminal () of. Therefore, the output terminal (Q) becomes "H" level and the output terminal () becomes "L" level. Flip-flop (D
When the output of the output terminal (Q) of -FF1) becomes "H" level, the output (l) of the OR circuit (OR6) becomes "H" level and the output (n) of the NAND circuit (NA3) becomes "L". "At the level, the motor (M) is energized. Further, the output (o) of the OR circuit (OR7) becomes "H" level.

Further, when the output (e) of the signal selection circuit (SL) becomes "H" level, the "H" level signal is input to the one-shot pulse generation circuit (OSP6) through the delay circuit (DLY1), and this circuit (OSP6) outputs a short “H” level pulse signal. This pulse signal is input to the clear input terminal (CL) of the counter (CNT) via the OR circuit (OR2),
Counter (CNT) is cleared. On the other hand, the signal selection circuit (SL) selects the input terminal (I ₃ ) because the combination of the states of the selection inputs (Sl ₁ (GS1)) and (Sl ₁ (l)) changes.

In this state, if the encoder pulse (ENCP) changes from "L" level to "H" level at the timing (T ₁₉ ) in Fig. 9, the one-shot pulse generation circuit (OSP5) outputs a short "H" level pulse. The signal is output. This pulse signal is input to the clear input terminal (CL) of the flip-flop (D-FF1) via the OR circuit (OR4), and the flip-flop (D-FF1) is cleared.

As a result, the output from the output terminal (Q) of the flip-flop (D-FF1) becomes "L" level and the OR circuit (OR
The output (l) of 6) also goes to "L" level, and the NAND circuit (NA)
Output (n) of 3) changes to "H" level and motor (M)
Is turned off. At the same time, since the output signal (▲ ▼) from the output port (P8) is at “L” level, the output (o) of the OR circuit (OR7) goes to “L” level and the braking operation for the motor (M) Done.

When the encoder pulse (ENCP) rises from the "L" level to the "H" level, the "H" level signal is input to the one-shot pulse generation circuit (OSP4) via the delay circuit (DLY2), and this circuit (OSP4 ) Outputs a short “H” level pulse signal. This pulse signal is an AND circuit (AN
5) And counter (CNT) via OR circuit (OR2)
Input to the clear input terminal (CL) of, counter (CNT)
Is cleared. On the other hand, the signal selection circuit (SL) selects the input terminal (I ₄ ) because the combination of the states of the selection inputs (Sl ₁ (GS1)) and (Sl ₁ (l)) changes. After that, this operation is repeated.

As described above, a plurality of output terminals (Q ₁ ) of the counter (CNT) that counts the output pulses from the reference pulse generation circuit (PG) and becomes “H” level at different timings depending on the number of counts The structure that compares the output from (Q ₄ ) with the rising timing of the pulse signal (ENCP) from the encoder circuit (7) is set to the output time interval of the pulse that is output each time the photographing lens moves by a predetermined amount. It is an actual speed detecting means for detecting the moving speed of the photographing lens based on the actual speed detecting means. By controlling the operation of (M), it is possible to always perform reliable and highly accurate lens movement control regardless of the movement load torque of the photographing lens and the difference in the power supply voltage. In the motor drive control circuit (6), the four output terminals (Q ₁ ) of the counter (CNT)
The configuration in which the drive speed of the motor (M) is made different by using the output from (Q ₄ ) constitutes a drive unit that is selectively operated to drive the photographing lens at different drive speeds.

Table 1 on the next page shows the levels of the output ports (P6) to (P12) of the AFC (1), that is, the levels of the control signals in each drive system. The (*) mark in the table indicates that the operation is irrelevant at any level.

Output ports (P10) to (P1
The level of 2) may be "H" or "L",
In consideration of the shift to the next constant speed control method, the settings are made as shown in the table. Further, a control signal (▲ ▼) for driving and rotating the motor (M) in the retracting direction of the photographing lens, which is output from the output port (P6), and the output port (P7)
The control signal (▲ ▼) for driving and rotating the motor (M) in the feeding direction of the photographing lens, which is output from the above, is prohibited from becoming "L" level together.

On the other hand, Table 2 shows the input selected by the combination of the selected inputs (Sl ₁ (GS1)), (Sl ₂ (GS2)), and (Sl ₃ (l)) in the signal selection circuit (SL). Signal source (I
₁ (Q ₁ )) to (I ₄ (Q ₄ )) are shown together. The (*) mark in the table indicates that there is no relation whether the level is "H" or "L".

By setting the time from when the counter (CNT) starts counting until either the output terminal (Q ₃ ) or the output terminal (Q ₄ ) becomes “H” level, The rotation speed (v) and the stop accuracy change, respectively. Regarding the relationship between the rotation speed (v) of the motor (M) and the stop accuracy, the stop accuracy becomes worse as the rotation speed (v) increases. Therefore, an appropriate value may be selected depending on the case. In addition, including constant speed control and short-time energization control,
The number of steps for changing the moving speed of the taking lens may be increased.

In the above-described embodiment, a so-called phase difference detection type passive system in which light from a subject is taken in from different exit pupils and arithmetic processing is performed in the microcomputer (1) has been described. The focus determination may be performed by an active method that detects reflection of ultrasonic waves, and the principle of the focus determination can be changed as appropriate.
The AFC (1) portion for detecting the deviation from the in-focus position of the subject from the information obtained from the subject is the focus deviation detecting means (1a), and the photographing lens based on the detection result by the focus deviation detecting means (1a). The portion of the AFC (1) that determines whether or not is at the focus position is referred to as focus determination means (1b).

In the previous embodiment, the release button (RB) is provided with a pair of protrusions (RBa), (RBb), and when the release button (RB) is pressed beyond its first stroke, the changeover switch (S ₁ ) Further, when the release button (RB) is pressed beyond its second stroke, the changeover switch (S ₁ ) and the release switch (S ₂ ) respectively have protrusions (RBa or RB).
It was configured to be closed by contact with b), but instead of that, for example, changes in capacitance and magnetic field due to changes in the stroke of the release button (RB) are detected. The switches (S ₀ ), (S ₁ ), and (S ₂ ) may be electrically opened and closed based on the detection result.

[Effects of the Invention] As described above, in the camera with an automatic focusing apparatus of the present invention, when the output time interval of the pulse output for each predetermined movement amount of the lens becomes longer than the first predetermined time interval, the motor is controlled. In those having an energization starting means for energizing,
A first energization stop means for stopping energization to the motor after continuing for a second predetermined time regardless of the output of the pulse, and a second energization stop means for stopping in response to the output of the pulse. It is also characterized in that they are combined and are appropriately switched.

In the case of the first energization stopping means, energization is continued for a predetermined time regardless of the pulse output indicating the amount of movement of the lens, so that the moving speed of the taking lens can be increased. On the other hand, in the case of the second energization stopping means, the energization is stopped in response to the pulse output indicating the movement amount of the lens, so that the stopping accuracy can be sufficiently improved. By appropriately switching these to control the moving speed of the lens, the moving speed of the lens can always be made appropriate, and the lens can be accurately stopped at the planned focal position.

[Brief description of drawings]

The drawings show an embodiment of a camera with an automatic focusing device according to the present invention. FIG. 1 is a schematic configuration diagram of the automatic focusing device, FIG. 2 is a flow chart of a focusing operation, and FIGS. 3 (a) and 3 (b). ) Are graphs showing the speed control states of the motors for respectively driving the lenses, FIG. 4 is a flow chart of the lens drive control, FIG. 5 is a flow chart of the start of the motor, FIG. FIG. 7 is a circuit diagram of the motor drive unit, FIGS. 8 and 9 are time charts of motor speed control, and FIG. 10 is a schematic view of the release button portion. (1a) ... Focus deviation detection means, (6) ... Lens drive control means, (7) ... Pulse generation means, (M) ... Lens drive means.

 ─────────────────────────────────────────────────── --Continued from the front page Judgment body for referee Judge Katsunori Ishii Judge Judge Watanuki Akira Hiroshi Ohara (56) References JP 59-26709 (JP, A) JP 50-158327 (JP, A) ) JP-A-54-119232 (JP, A) JP-A-52-76590 (JP, A) JP-A-57-46216 (JP, A) JP-A-58-18611 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A motor for moving a taking lens, a pulse output means for outputting a pulse each time the taking lens moves a predetermined amount by the motor, and a required moving amount required for moving the taking lens to a planned focus position. Moving amount output means for converting and outputting the number of pulses, remaining pulse detecting means for counting the pulses output from the pulse output means, and detecting the remaining moving amount based on the counting result, and the remaining movement A movement amount control means for controlling the motor so as to stop the photographing lens at a position where the amount becomes zero, and an operation state immediately before the remaining movement amount becomes zero, and a state in which the motor is energized or de-energized. And a speed control means for controlling the moving speed of the photographing lens by repeating the above-mentioned procedure, wherein the speed control means has a first predetermined output time interval of the pulse. Energization to the motor is always performed during the second predetermined time regardless of the energization starting means for starting energization of the motor when the time is longer than the time interval and the pulse output from the pulse output means after the energization is started. And first energization stopping means for stopping the energization in response to the passage of a second predetermined time, and energizing the motor in response to the pulse output from the pulse output means after the energization is started. A camera with an automatic focus adjustment device, comprising: a second energization stopping means for stopping; and a switching means for switching between the first energization stopping means and the second energization stopping means.