JPH0933788A - Lens driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the time required up to the reaching to a target position of a lens by detecting the level of drive resistance at the time of driving the lens and making the range of a speed-limit region where a lens decelerating means is actuated smaller as the drive resistance is higher. SOLUTION: The lens which starts to drive from a standby position QS is accelerated in a full energizing region 66, in such a manner that a power supply voltage is continuously applied to a motor, to reach a full speed. When the lens passes through a first boundary position Q1 , entering into the speed-limit region 60 is attained. The speed-limit region 60 is constituted of first and second regions 62 and 64 in which different control speeds 56a and 56b are set respectively. At this time, the lengths W1 and W2 of the first and second speed-limit regions 62 and 64 are changed in accordance with the driven state of the lens, to shorten a lens drive time. For instance, the lengths W1 and W2 are generated by a battery voltage detected as the driven state of the lens and an ambient temp., according to a table, to set first and second decelerating positions. The lengths W1 and W2 are set to be larger, as the battery voltage and the ambient temperature higher.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, in a lens driving device such as an autofocus camera, a control method of decelerating a lens driving speed before a target position is adopted in order to accurately stop the lens at a target position, for example, a focus position. There is. That is, in the speed limit area before the target position, that is, in the deceleration area,
The lens drive speed is controlled to be low so that the lens is sufficiently decelerated to reach the target position so that overrun does not occur. Then, the range of the speed limiting area, that is, the distance is generally set to a large fixed value so that the lens can be accurately stopped at the target position when the lens driving speed is the highest. This is because the faster the lens drive speed when entering the speed limit area, the longer the distance required for deceleration, so if the distance in the speed limit area is short, it will not be possible to sufficiently decelerate before the target position. Is past the target position.

However, when the ambient temperature is low or when the lens driving power supply voltage is low, the lens driving speed when entering the speed limiting region is originally low. Alternatively, the lens driving speed may slow down due to variations in the mechanical load of the lens driving system. In such a case, if the distance in the speed limit area remains set to a large fixed value, the distance in the speed limit area is longer than necessary, so the time for driving the lens at low speed becomes long, and the target position from the start of lens drive It takes longer to reach. As a result, the release time lag from pressing the release button to opening the shutter is increased, which is one of the reasons for missing a shutter opportunity.

[0004]

Therefore, the technical problem to be solved by the present invention is to make the size of the speed limiting region variable so as to shorten the time required for the lens to reach the target position.

[0005]

In order to solve the above technical problems, the present invention provides a lens driving device having the following structure.

That is, the lens driving device basically comprises a lens decelerating means for decelerating the lens driving speed when the lens enters the speed limiting area before the target position, that is, the decelerating area. The lens driving device includes a driving resistance detecting unit that detects the magnitude of the driving resistance when driving the lens, and the speed limiting region in which the lens deceleration unit operates as the driving resistance detected by the driving resistance detecting unit increases. And a lens deceleration control means for reducing the range.

In the above structure, the drive resistance detecting means is
The magnitude of the drive resistance when driving the lens is detected. When the lens is driven and enters the speed limiting area, the lens speed reducing means reduces the lens driving speed. The lens deceleration control means reduces the range of the speed limiting region as the drive resistance increases, based on the drive resistance during the lens drive detected by the drive resistance detection means. That is, the deceleration start position in the speed limit area approaches the target position, and the deceleration start of the lens drive speed becomes slow. If the driving resistance when driving the lens is large, the lens is decelerated quickly by the driving resistance.
When the driving resistance is large, the lens is sufficiently decelerated by the time the target position is reached, even if the range of the speed limit region in which the lens deceleration means operates becomes small. As the range of the speed limit area becomes smaller, the non-speed limit area in which the lens is driven at high speed without deceleration becomes wider accordingly, while the speed limit area in which the lens is driven at low speed and slowed down becomes smaller accordingly.

Therefore, it is possible to shorten the time required for the lens to reach the target position by changing the size of the speed limiting area.

In the above structure, there are a plurality of speed limiting regions, and the lens may be decelerated in stages. Further, the drive resistance detecting means may detect the drive resistance each time the lens is driven, at a constant cycle, or at any time. It is also possible to detect when the lens driving speed is reduced. Furthermore, the drive resistance may be detected by monitoring the load during lens driving, for example, by monitoring the current supplied to the drive motor.

Preferably, the drive resistance detecting means is an acceleration detecting means for detecting an acceleration when the lens driving speed is accelerated before the lens reaches the speed limiting area. The lens deceleration control means reduces the range of the speed limiting area in which the lens deceleration means operates as the acceleration detected by the acceleration detection means decreases.

In the above structure, when the lens driving is started, the lens is accelerated. The acceleration detecting means detects the acceleration of the lens driving speed. In other words, the driving resistance when driving the lens is detected by the acceleration during lens acceleration,
The larger the driving resistance when driving the lens, the smaller the acceleration or acceleration of the lens driving speed, and the smaller the acceleration. Then, when the lens enters the speed limiting region, the lens driving speed is reduced by the lens deceleration means.
The range of the lens deceleration region is set by the lens deceleration control unit to be smaller as the acceleration is smaller, that is, as the driving resistance when driving the lens is larger.

In the above structure, the lens driving resistance that varies intricately due to various factors such as environmental temperature and variations in mechanical characteristics of individual lens driving systems is detected only from the lens acceleration. Therefore, it is not necessary to allow a margin in setting the range of the speed limit area, and thus the time required for the lens to reach the target position can be efficiently shortened.

Also, preferably, the drive resistance detecting means is a temperature detecting means for detecting an environmental temperature. The lens deceleration control means reduces the range of the speed limiting region in which the lens deceleration means operates as the environmental temperature detected by the temperature detection means decreases.

In the above structure, the environmental temperature, which is a major factor for the fluctuation of the lens driving resistance, is detected, and the range of the speed limit area is set in the same manner. That is, generally, the lower the environmental temperature is, the larger the driving resistance at the time of driving the lens becomes. Therefore, the lens deceleration control unit sets the range of the speed limit region to be smaller as the environmental temperature is lower. In the above configuration,
The range of the speed limit area can be set with a relatively simple structure.

Preferably, the lens deceleration control means further comprises voltage detection means for detecting a drive voltage applied to the motor for driving the lens in the non-speed limited area until the lens enters the speed limited area. Further, the lower the drive voltage detected by the voltage detecting means, the smaller the range of the speed limiting area in which the lens decelerating means operates.

In the above structure, the range of the speed limit region is set according to the environmental temperature and the drive power supply voltage applied to the motor. That is, the lower the drive power supply voltage, the slower the lens drive speed when starting to enter the speed limit region. Therefore, since the lens is decelerated quickly, it is possible to set the range of the speed limit region to be small. Therefore, by setting the range of the speed limit area according to the speed at which the lens enters the speed limit area, the time required for the lens to reach the target position can be further shortened.

Preferably, when the drive resistance is obtained from the above-mentioned acceleration to set the range of the speed limiting region, the following configuration is adopted.

That is, a constant voltage is applied to the motor for driving the lens in the non-speed limiting area before entering the speed limiting area. The acceleration detecting means is a time measuring means for detecting a moving time required for the lens accelerated in the non-speed limited area to move a predetermined moving amount from the start of driving, and the moving time detected by the time measuring means and the predetermined moving time. Acceleration calculating means for calculating the acceleration based on the quantity.

In the above structure, since a constant voltage is applied to the motor, the acceleration a is considered to be constant.
A predetermined amount of movement L, and the moving time required to move a predetermined amount of movement and t, since it is L = at ^2/2, the acceleration a
Can be obtained as a = 2L / t ² .

Therefore, with a simple structure, the acceleration can be obtained in an extremely short time immediately after the lens driving is started.

As another configuration, a constant voltage is applied to the motor for driving the lens in the non-speed limiting area before entering the speed limiting area. The acceleration detecting means includes a moving amount detecting means for detecting a moving amount of the lens accelerated in the non-speed limited area and moving within a predetermined moving time from the start of driving, the moving amount detected by the moving amount detecting means, and the moving amount detecting means. An acceleration calculating means for calculating the acceleration from the predetermined moving time is provided.

Also in the above structure, similarly, with a simple structure, the acceleration can be obtained from the predetermined moving time and the moving amount in an extremely short time immediately after the lens is driven.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a lens driving device according to an embodiment of the present invention will be described in detail with reference to FIGS.

First, the configuration of the control system of the lens driving device will be described with reference to the block diagram of the camera control shown in FIG.

That is, the camera control system includes a CPU
10, an operation unit 12, a distance measuring unit 14, and a shutter 16
The lens drive unit 18, the flash 20, the film feeding unit 22, the temperature detection unit 24, the power supply unit 26, and the display unit 28 are connected to each other.

The CPU 10 controls the operation of the camera.
The operation unit 12 has a shutter button, a mode set button, and the like operated by the user. The photometry / distance measuring unit 14 measures a distance to a subject, brightness, and the like. Shutter 16 opens and closes to provide exposure to the film. Lens drive unit 1
Reference numeral 8 extends and retracts the lens. The lens drive unit 18 performs focus adjustment, that is, focus drive in the case of an autofocus camera, and also performs zooming in the case of using an electric zoom lens. The flash 20 provides auxiliary lighting. The film feeding unit 22 winds and rewinds the film loaded in the camera. The temperature detector 24 detects the environmental temperature. The power supply unit 26 supplies power to each device and detects the power supply voltage. The display unit 28 displays information such as the number of films, shooting conditions, and warnings.

Next, the structure of the lens driving section 18 will be described with reference to FIGS.
This will be described with reference to FIG.

That is, as shown in FIG. 2, the lens drive section 18 includes a motor 1, a reduction gear 2, a motor side drive shaft 3, a worm gear 4, a spur gear 5, a lens side drive shaft 6, and A lens frame 7, a lens position detector 8, and a lens drive detector 9 are provided.

The motor 1 gives a lens driving force, and can rotate in the normal direction or the reverse direction depending on the polarity of the applied voltage. The reduction gear 2 is a reduction gear pair for reducing the shaft speed of the motor 1. In the example shown in FIG. 2, a pair of gears 2a, 2b
However, the number of deceleration stages may be any number. The motor-side drive shaft 3 is a shaft to which the final stage gear 2b of the reduction gear 2 is fixed. A worm gear 4 is fixed to the lens side end of the motor side drive shaft 3. On the other hand, the photo interrupter blade 9a of the lens drive detection unit 9 is fixed to the other end side. A male screw 3a is formed on the outer peripheral surface of the drive shaft 3. This male screw 3a has
A cylindrical holder 8a having a penetrating female screw is screwed into it.
The rotation of the holder 8a is restricted, and the holder 8a is moved in the axial direction by the rotation of the drive shaft 3. A lens side drive shaft 6 is arranged orthogonal to the motor side drive shaft 3. The motor-side drive shaft 3 is attached to one end of the lens-side drive shaft 6.
The worm gear 4 is provided with a spur gear 5, which is adapted to transmit rotation from the motor-side drive shaft 3. A male screw 6a is formed on the outer peripheral surface of the lens side drive shaft 6. The male frame 6a has a lens frame 7 for supporting the lens.
Are screwed together. That is, the lens frame 7 has a projecting piece 7a, and the penetrating female screw formed on the projecting piece 7a is screwed into the male screw 6a of the lens side drive shaft 6. The rotation of the lens frame 7 is restricted, and the lens frame 7 is moved in the axial direction by the rotation of the lens side drive shaft 6.

The lens position detector 8 comprises a holder 8a screwed onto the motor-side drive shaft 3 and a pattern 8c extending along the motor-side drive shaft 3. The holder 8a has a contact piece 8b that contacts the pattern 8c. Pattern 8c
Includes a ground side pattern 8f and a CPU side pattern 8e which extend along the motor side drive shaft 3 and are electrically separated from each other. The ground side pattern 8f is grounded and C
The PU side pattern 8e is connected to the input terminal of the CPU 10 via the contact A, as shown in FIGS. The CPU side pattern 8e is formed so as to surround both ends and one side of the ground side pattern 8f in a U-shape. The contact piece 8b of the holder 8a has two legs 8s and 8t, and each leg 8s and 8t contacts the ground side pattern 8f and the CPU side pattern 8e, respectively.

When the lens driving unit 18 starts driving the lens, the lens is moved to the camera body 4 as shown in the sectional view of FIG.
The lens frame 7 is moved forward from the initial state in which the lens frame 7 is housed in 0, ie, the retracted position, to the state in which the lens barrier 34 is opened to allow photographing as shown in the sectional view of FIG. 5, ie, the standby position. By extending the lens,
Since the holder 8a of the lens position detector 8 moves, the contact piece 8b moves from the retracted position 42 to the standby position 46, as shown in FIG. Then, when the release switch is pressed, the lens is driven to focus, the lens is further extended to the front of the camera, and the contact piece 8b moves in the direction opposite to the retracted position 42.

As shown in FIG. 6, the lens position detector 8 detects the lens position of "Hi" or "Lo" corresponding to the position where the legs 8s and 8t of the contact piece 8b slide on the pattern 8a. The signal 8x is generated and output to the CPU 10. That is, at the collapsible side end portion 43 and the lens extension side end portion 47 of the pattern 8c, the legs 8s and 8t of the contact piece 8b are both CPUs.
In contact with the side pattern 8e, the lens position detection signals 8p and 8q of "Hi" are generated. On the other hand, in the intermediate portion 45 of the pattern 8c, the legs 8s and 8t of the contact piece 8b are connected to the CPU side pattern 8e.
Since the CPU side pattern 8e and the ground side pattern 8f are brought into contact with each other and the ground side pattern 8f, the lens position detection signal 8r of "Lo" is generated. "Hi" and "Lo" of the lens position detection signal 8x change at the pattern boundary portions 44 and 48 near both ends of the ground side pattern 8f. The standby position 46 of the lens is a position slightly retracted from the lens boundary pattern 48. As will be described later, in the lens drive control during focusing, the level change of "Hi" and "Lo" of the lens position detection signal 8x at the lens extension side pattern boundary portion 48 is used as a control reference. Because.

As shown in FIG. 2, the lens drive detector 9 includes a photo interrupter blade 9a fixed to the motor-side drive shaft 3 and a photo interrupter 9b provided so as to face the photo interrupter blade 9a. The photo interrupter blade 9a is configured by arranging radially extending light transmitting portions 9c and light shielding portions alternately in the circumferential direction. The photo interrupter 9b has a light emitter and a light receiver, and the photo interrupter blade 9a crosses between them. When the photo interrupter blade 9a is rotated, the light transmitting portion 9c of the photo interrupter blade 9a is intermittently changed to the photo interrupter 9b.
The light passing through between the light emitting device and the light receiving device is guided and shielded by the detection light of the photo interrupter 9b. As a result, Fig. 7 (a)
As shown in, a photo interrupter output signal 9x is generated. The photo interrupter output signal 9x is output from the photo interrupter circuit 32 shown by the equivalent circuit in FIG. 3, and is input to the CPU 10 via the waveform shaping circuit 30. The shaping circuit 30 shapes the photo interrupter output signal 9x into a rectangular signal 9y as shown in FIG. 7B. The CPU 10 has an edge counting function, and detects the lens driving amount by counting the number of edges of the rectangular signal after molding. In the present specification, the counted number of edges will be expressed in a unit of "PI" for convenience. Although various devices are connected to the CPU 10 as described above, only the temperature detection unit 24 is shown in FIG.

To drive the lens, the motor 1 is controlled by the control circuit shown in FIG. This control circuit is a bridge circuit composed of four transistors 52 and the motor 1. At the base of each transistor element 52, control ports MP1, MP2, MN of the CPU 10 are provided.
1 and MN2 are connected respectively. Control port is M
When P1 and MP2 are "Lo", when MN1 and MN2 are "H"
At the time of i ", the bias current causes a current to flow between the collector and the emitter. Therefore, depending on the combination of" Hi "and" Lo "of each control port shown in FIG. 9, each control of forward rotation, reverse rotation, braking, and stop is performed. D _{1 to} D ₄ are diodes for preventing back electromotive force.

That is, during normal rotation, the control port MP1
Is "Lo" and MN2 is "Hi", and arrows 53a, 53b, 5
As shown at 3c, current flows from Vp through the transistor element 52 connected to MP1 and the motor 1 to the transistor element 52 connected to MN2. That is,
In FIG. 8, a current flows in the motor 1 in the leftward direction 53b. On the other hand, when reversing, MP2 is "Lo" and MN1 is "H".
i ", and the current flows through the transistor element 52 connected to MP2 and the motor 1 to the transistor element 52 connected to MN1, and the motor 1 has a dotted arrow 53b '.
Current flows in the opposite direction as shown by. Further, during braking, MP1 and MP2 become "Lo", the transistor element 52 connected to MP1, the transistor element 52 connected to MP2, and the counter electromotive force prevention diode D ₁ ,
D ₂ and the motor 1 form a closed circuit, and the induced current due to the rotation of the motor 1 is consumed by the resistance (not shown) of the closed circuit, and the motor 1 is braked. When stopped, the control ports MP1 and MP2 become "Hi" and the MN1 and MN2 become "Lo", so that no current flows through the motor 1.

The moving speed of the lens changes as shown in FIG. 10 during focusing, that is, when the lens is driven for focusing. In FIG. 10, the vertical axis represents the moving speed PI /
It is shown in msec unit, and the horizontal axis is the position of the lens in the optical axis direction.
It is expressed in units. The solid line 54 indicates the actual moving speed of the lens, that is, the actual speed, and the dotted line 56 is the target value of the control command in the lens drive control, that is, the control speed. The lens extended from the standby position Q _S reaches the final braking region 68 via the full energization (non-speed limit) region 66 and the speed limit region 60, and stops at or near the target position Q _T.

The lens, which has been driven from the standby position Q _T, is not speed-controlled in the fully energized area 66. That is, the motor 1 is in a fully energized state in which the power supply voltage is continuously applied. This accelerates the lens to reach maximum speed. Along the way, the lens
The lens position detection signal 8x passes through the reference position Q ₀ corresponding to the lens extension side pattern boundary portion 48 where the level changes from “Lo” to “Hi”.

Next, when the lens passes the first boundary position Q ₁ before the target position P _T , the lens enters the speed limiting region 60. In the speed limit region 60, when the actual speed 54 is higher than the control speed 56, the motor 1 is braked and controlled so as to be a constant speed. The speed limit area 60 is composed of a speed limit 1 area 62 starting from the first boundary position Q ₁ and a speed limit 2 area 64 starting from the second boundary position Q ₂ respectively. , 56
b is set. That is, the control speed 56b in the speed limit 2 area 64 is set smaller than the control speed 56a in the speed limit 1 area 62, and the lens is decelerated in stages.

Then, the lens moves to the third position immediately before the target position P _T.
When the vehicle passes through the boundary position Q ₃ and enters the final braking area 68, the motor 1 is braked until the motor 1 stops, that is, the lens stops. Since the lens moving speed is sufficiently decelerated in the speed limiting area 60 and is a constant low speed when the third boundary position Q ₃ is reached, the distance required to stop by the braking in the final braking area 68 varies. Is small. Therefore,
The lens accurately stops at or near the target position P _T.

Next, the operation of the lens driving device will be further described with reference to the flow charts of FIGS.

First, the schematic flow of the main routine of the lens driving device will be described with reference to FIG.

That is, when the battery is loaded in the camera, various initializations such as CPU operation environment setting, port setting, and RAM clearing are executed in step # 001. Then, in step # 002, it waits for the main switch to be turned on. When the main switch is turned on, in step # 003 the retracted lens is extended to the standby position. Then, when the camera is in the standby state, in step # 004,
Waiting for input of various switches. If there is a switch input, in step # 005, the operation corresponding to the switch turned on is executed. For example, if the main switch is turned off, the lens is returned to the retracted position. When the rewind switch is turned on, the film feeding unit 22 is operated to rewind the film. When the release button is half pressed and the shooting preparation switch (referred to as S1) is turned on, the lens drive unit 18 is operated, the lens is driven to focus, and the focus is adjusted. When the release button is further pressed from the half-pressed state, the shutter release switch (S2) is turned on, the shutter 16 is operated to expose the film, and then the film feeding unit 22 is operated to operate the film for one frame. Roll up.

Next, the detailed flow of the control for moving the lens to the standby position in step # 003 in FIG. 11 will be described.

That is, as shown in FIG. 12, in step # 101, the CPU 10 rotates the motor 1 forward,
Start to extend the lens. Then, step # 10
2 to 104, it is determined whether or not the contact piece 18b has reached the lens feed-out side signal change position 48 according to the level change of "Hi" and "Lo" of the lens position detection signal 8x from the lens position detection unit 8. When it is determined that the contact piece 18b has reached the lens extension side pattern boundary portion 48, the motor 1 is braked in step # 105, and then,
In step # 106, the motor 1 is rotated in the reverse direction. The contact piece 8b returns to the standby position 46 from a position slightly extended from the lens extension side pattern boundary portion 48. Therefore, in steps # 107 to 110, after it is detected that the contact piece 8b has passed the lens extension side pattern boundary portion 48 due to the signal change from "Hi" to "Lo", 1
After applying the motor brake for 00 msec, stop the motor. This causes the lens to stop in the standby position.

In the standby state, that is, in FIG.
When the user presses the release button halfway down to turn on the S1 switch in the state waiting for the switch input in step # 004 of FIG.
Follow the flow shown in. This flow is a detailed flow of step # 005 in FIG.

That is, first, steps # 201 to # 2.
In 03, the CPU 10 operates the power supply unit 26 and the photometry / distance measurement unit 14 to execute battery check (BC), photometry, and distance measurement. Although not shown, if the battery voltage Vp is lower than the specified value by the battery check, a warning display is displayed on the display unit 28 to warn the user that photographing is not possible. At this time, the camera including the lens driving device does not operate. Then, in step # 204, the distance data output from the photometry / distance measuring unit 14 is used to calculate the lens extension amount in order to obtain the lens drive amount necessary for focusing. The calculation result is calculated in units of "PI" corresponding to the edge count number by the photo interrupter output signal 9x. Then, in step # 205, the motor 1 is normally rotated for focusing and the lens is extended. Details of this step will be described later. When the focusing operation is completed, in steps # 206 to # 208, the release button is further pressed from the half-pressed state and the shutter release switch S2 is turned on. When S2 is turned on in the S2 receivable state, shutter release is performed in step # 208, and the lens is retracted to the standby position again in step # 209. On the other hand, when the photographing preparation switch S1 is turned off by the user stopping the release button or the like, the lens is retracted to the standby position in step # 209 without releasing.
If the film is loaded in steps # 210 to # 212, the film feeding unit 22 and the display unit 28
Are operated to wind up one frame of the film and count up the number of films displayed, and then the standby state is entered. If the film is not loaded, the standby state is maintained.

Next, the lens drive control during focusing in step # 205 of FIG. 13 will be described with reference to the detailed flowchart of FIG.

That is, in step # 301, C
The PU 10 operates the temperature detection unit 24 to detect the environmental temperature necessary for setting the deceleration start position. The battery voltage required to set the deceleration start position is determined in step # 20 in FIG.
The reading is executed by the battery check when S1 is on in No. 1. Then, in step # 302,
The motor 1 is normally rotated to extend the lens. Then, in step # 303, the deceleration start position is set. Details of step # 303 will be described later. Here, the deceleration start position corresponds to the lens drive amount by "P
It is output in units of I ″. That is, after the lens extension side pattern boundary portion 48 is detected, that is, the reference position Q
_The number of “PI” from ₀ to the first deceleration start position, that is, the first boundary position Q ₁ is P ₁ . Also, the "PI" number from the reference position Q ₀ to the second deceleration start position, that is, the second boundary position Q ₂ is P ₂ . Then, in step # 304,
The detection of the level change of the lens position detection signal 8x from "Lo" to "Hi", that is, the passage of the reference position Q ₀ is waited for on the lens extension side pattern boundary portion 48. Since the lens moves from the standby position 46 on the retracting side with respect to the lens boundary pattern boundary 48, the lens should pass through the lens boundary pattern boundary 48 by lens extension. When the lens extension side pattern boundary portion 48 is detected, counting of the lens movement amount "PI" is started in step # 305. That is, the lens extension side pattern boundary portion 48 is used as a reference position of the lens extension amount.

Then, in step # 306, the fully energized area 66 until the lens reaches the speed limiting area 60.
In, the speed control is not performed, the motor 1 is normally rotated, that is, full energization is performed, and the count of “PI” of the lens movement amount from the reference position Q ₀ is read. When the lens reaches the first deceleration start position Q ₁ , a predetermined speed control 1 is executed within the speed limit 1 region 62 until the lens reaches the second deceleration start position Q ₂ . After reaching the second deceleration start position Q ₂ and entering the speed limit 2 region, the speed limit 2 is executed. Details of the speed control will be described later. Here, two speed limiting areas 62 and 64 are provided, but the number may be one, or three or more. Then, in step # 307, the number PI of the target positions P _T is in front.
When it is detected that the final braking area 68 (here, 3 PI before) is reached, the motor 1 is braked and the lens driving is stopped in steps # 308 to # 310. The reason why the motor 1 is braked a few PI before the target position Q _T is that the lens being driven does not stop immediately no matter how much the speed is reduced. In step # 309, a predetermined waiting time obtained by adding a margin value to the time required for completely stopping the rotation of the motor 1 after braking the motor 1 in step # 308 is waited for, and in step # 310, Stop the motor 1. Instead of setting the waiting time, the lens drive or PI
If the change in No. is no longer detected, it may be determined that the rotation of the motor 1 has stopped.

Next, the detailed flow of the deceleration start position setting in step # 303 of FIG. 14 will be described with reference to FIGS.
With reference to FIG. 3, three embodiments will be described.

That is, in the conventional deceleration start position setting, as shown in FIG. 18, a value obtained by subtracting a constant value from the target value P _{T is} set as the first deceleration start position P ₁ and the second deceleration start position P _2. I was there. That is, the range of the speed limit 1 area 62 and the speed limit 2 area 64 was always fixed. On the other hand, in the present invention, the speed limit 1 and 2 regions 62,
The lengths W ₁ and W ₂ of 64 are changed in accordance with the lens driving state to shorten the lens driving time.

First, the first embodiment, that is, the case where the deceleration start position is set by detecting the battery voltage Vp and the environmental temperature in the lens driving state will be described with reference to the detailed flow chart of FIG.

That is, in step # 401, step # 201 in FIG. 13 and step # 30 in FIG.
Based on the battery voltage Vp detected in 1 and the environmental temperature, W ₁ and W ₂ representing the lengths of the speed limit 1 region and the speed limit 2 region by the PI number are generated according to the table. Then, in step # 402, from the target position P _T ,
The value obtained by subtracting W ₁ and W ₂ is used as the first deceleration start position P ₁ and the second deceleration start position P ₁ .
Deceleration start position P ₂ . At this time, if the target position Q _T is close and one or both of P ₁ and P ₂ becomes a negative number, the negative number is reset to 0.

W ₁ and W ₂ are set to be larger as the battery voltage Vp is higher and the environmental temperature is higher. As can be seen from FIG. 21, for example, generally, the lower the battery voltage Vp and the lower the environmental temperature, the smaller the lens overrun amount. This is because the distance required for can be shortened.

That is, FIG. 21A is a graph showing how the amount of overrun changes depending on the ambient temperature when the battery voltage is set to the standard state. Here, speed control is not provided in order to easily grasp the characteristics. The vertical axis indicates the amount of overrun when the motor 1 is braked for the first time after reaching the target position, by the PI number, and the horizontal axis indicates the environmental temperature. It can be seen that the amount of overrun increases as the environmental temperature increases. It is considered that when the environmental temperature rises, the mechanical load is lightened due to the softening of oils and fats, and the amount of overrun increases.

Further, FIG. 21 (b) is a graph showing how the amount of overrun changes with the battery voltage in the same manner as in FIG. 21 (a) at a constant environmental temperature of about 25 ° C. Is. Similarly, the vertical axis represents the amount of overrun by the PI number, and the horizontal axis represents the battery voltage. When the battery voltage increases, the voltage applied to the motor 1 also increases, so that the motor torque and rotation speed increase. Therefore, it is considered that the higher the battery voltage, the faster the lens moving speed at the start of braking, and thus the amount of overrun increases.

Next, the second and third embodiments,
That is, two embodiments will be described in which the lens driving state is detected from the acceleration during driving of the lens and the deceleration start position is set.

In the second embodiment, as shown in FIG. 16, in steps # 501 to 504, it is detected within a specified time t after the lens drive in the fully energized area 66 in which the speed control is not performed is started. This is due to the method of counting the PI number of the lens movement amount. This count value is
It is proportional to the lens moving distance L from 0 to t within the specified time. The lens movement distance L has a value proportional to the acceleration a of the lens movement. That is, since it is considered that the acceleration a of the lens movement is constant in the fully energized state, L = at ²
/ 2. That is, the count value of the PI number of the lens movement amount is proportional to the acceleration of the lens movement. Therefore, based on this count value that is proportional to the acceleration, step # 505
In, the W ₁ and W ₂ are determined according to the table, and the first deceleration start position P ₁ and the second deceleration start position P ₂ are similarly calculated in step # 506.

In the third embodiment, as shown in FIG. 17, in steps # 501 'to 503', the time from the lens driving start position to passing a certain position is measured. Here, the standby position Q
_The time t required to move the distance L from _S to the reference position Q ₀ is measured. As described above, since it is L = at ^2/2, the ^{t = (2L / a) 1/2} . That is, the measured time t
Is inversely proportional to the square root of acceleration a. So step #
In step 504 ', W ₁ and W ₂ are determined according to the table according to the measured time, and in step # 505',
Similarly, the first deceleration start position P ₁ and the second deceleration start position P ₂ are calculated.

In each of the embodiments described here, W
_{Although 1} and W ₂ are generated based on the table, W ₁ and W ₂ may be determined by some calculation.

Next, speed control in the speed limit area 60 will be described with reference to FIGS.

FIG. 19 shows the speed control 1 in the speed limit 1 area 62, and FIG. 20 shows the speed control 2 in the speed limit 2 area 64. In both cases, the amount of lens movement within a certain period of time, that is, the lens movement speed, is monitored, and when it exceeds a certain threshold PI number, the motor 1 is braked. It is controlled so that the speed becomes constant by repeating the above.

First, the control in the speed limit 1 region shown in FIG. 19 will be described. That is, step # 60
At 1, a timer for a predetermined monitoring loop time, here 1 msec, is started. Then, in step # 602, the lens movement amount, that is, PI is read out, and in step # 603, the difference, that is, the change amount Δ, between this read PI and the PI read when this routine was passed last time is calculated, and step # 604, At 605, if the amount of change Δ is 3 PI or more, the motor 1 is braked,
Otherwise, the motor 1 is normally rotated. That is, FIG.
The first control speed 56a shown at 0 is set to 3 PI / msec. Then, step # 606
Now wait for the remaining elapsed time of the monitoring loop time. By doing so, the lens moving speed can be known while keeping the monitoring loop time constant.

On the other hand, the same applies to the speed control 2 in the speed limit 2 region shown in FIG. However, the second control speed 56b is smaller than the first control speed 56a, and in order to ensure accuracy, the time of the monitoring loop in step # 701 is usually shorter than the time of the monitoring loop in step # 601. Here, step # 601
It's half of. Also, in step # 704,
If the change Δ is 1 PI or more, the motor 1 is braked. That is, the second control speed 56b shown in FIG. 10 is set to 2 PI / msec.

As described above, in the lens driving device of the above embodiment, the sizes W ₁ and W ₂ of the speed limiting area 60 can be made variable to shorten the time required for the lens to reach the target position. .

The present invention is not limited to the above embodiment, but can be implemented in various other modes. For example, the lens drive control can be performed in the same manner not only during focusing but also during zooming.

[Brief description of drawings]

FIG. 1 is a block diagram of camera control.

FIG. 2 is a conceptual perspective view showing a configuration of a lens driving unit.

FIG. 3 is a circuit diagram of FIG.

FIG. 4 is a sectional view of a camera. The lens is in the retracted position.

FIG. 5 is a sectional view similar to FIG. 4; The lens is extended and in the standby position.

FIG. 6 is an explanatory diagram of a lens position detector. (a) is a main part configuration diagram, and (b) is a graph diagram of an output voltage.

FIG. 7 is an explanatory diagram of a movement amount detection unit. (a) is a waveform diagram of a photo interrupter output signal, and (b) is a waveform diagram after waveform shaping.

FIG. 8 is an electric circuit diagram of a motor control circuit.

9 is a control pattern diagram of the circuit of FIG.

FIG. 10 is a graph showing a lens moving speed.

FIG. 11 is a flowchart in a schematic flow of a main routine of lens drive control.

FIG. 12 is a detailed flowchart of drive control when the lens is extended to the standby position.

FIG. 13 is a detailed flowchart of step # 005 in FIG.

FIG. 14 is a flowchart of drive control during focusing.

FIG. 15 is a detailed flow chart of deceleration start position setting according to the first embodiment. The acceleration is calculated from the battery voltage and the detected temperature.

FIG. 16 is a detailed flow chart of deceleration start position setting according to the second embodiment. The acceleration is calculated from the lens moving distance.

FIG. 17 is a detailed flow chart of deceleration start position setting according to the third embodiment. The acceleration is calculated from the lens movement.

FIG. 18 is a detailed flowchart for setting a deceleration start position in a conventional example.

FIG. 19 is a detailed flowchart of lens drive control in the speed control 1 area.

FIG. 20 is a detailed flowchart of the lens drive control in the speed control 2 area.

FIG. 21 is a graph showing the overrun amount when speed control is not performed. (a) is when the temperature is changed, (b)
Indicates when the battery voltage is changed.

[Explanation of symbols]

1 motor 2 reduction gear 2a motor side gear 2b drive shaft side gear 3 motor side drive shaft 3a male screw 4 worm gear 5 spur gear 6 lens side drive shaft 6a male screw 7 lens frame 7a projecting piece 8 lens position detector 8a holder 8b contact piece 8c Pattern 8e CPU side pattern 8f Ground side pattern 8t, 8s Legs 8p, 8q "Hi" level signal 8r "Lo" level signal 8x Lens position detection signal 9 Lens movement amount detection section 9a Photo interrupter blade 9b Photo interrupter 9c Light transmission section 9x Photo interrupter output signal 9y Rectangular signal 10 CPU 12 Operation unit 14 Photometry / distance measuring unit 16 Shutter 18 Lens drive unit 20 Flash 22 Film feeding unit 24 Temperature detection unit 26 Power supply unit 28 Display unit 30 Waveform shaping circuit 32 Photo interrupter circuit 34 Lens barrier 40 Camera 42 Collapsed position 3 Collapse side end 44 Collapsible side pattern boundary 45 Intermediate part 46 Standby position 47 Lens extension side end 48 Standby side pattern boundary 52 Transistor 54 Actual speed 56 Control speed 60 Speed limit area 62 Speed limit 1 area 64 Speed limit 2 Area 66 Fully energized area 68 Final braking area Q ₀ Reference position Q ₁ First boundary position Q ₂ Second boundary position Q ₃ Third boundary position Q _S Standby position Q _T Target position

Claims (6)

[Claims] 1. A speed limit region before a target position (Q _T ).
In a lens driving device equipped with a lens deceleration means (10, 18) for decelerating a lens driving speed when a lens enters the inside of (60), a driving resistance detecting means (8, 9, 10, 24) and the driving resistance detection means (8, 9, 10, 24) that has a larger drive resistance, the lens deceleration means (10, 18)
And a lens deceleration control means (10) for reducing the range (W ₁ , W ₂ ) of the speed limiting area (60) in which the lens driving device operates. 2. The drive resistance detecting means (8, 9, 10, 2)
4) is an acceleration detecting means (8, 9, 10) for detecting an acceleration when the lens driving speed is accelerated until the lens reaches the speed limiting area (60), and the lens deceleration controlling means (10) ) Is the acceleration detection means
The smaller the acceleration detected by (8, 9, 10), the faster the speed limiting region in which the lens deceleration means (10, 18) operates.
_2. The lens driving device according to claim ₁ , wherein the range (W1, W2) of (60) is reduced. 3. The drive resistance detecting means (8, 9, 10, 2)
4) is a temperature detecting means (24) for detecting the ambient temperature, and the lens deceleration controlling means (10) is the temperature detecting means.
The lower the ambient temperature detected by (24), the lower the speed limit region (60) in which the lens deceleration means (10, 18) operate.
_2. The lens driving device according to claim ₁ , wherein the range (W ₁ , W ₂ ) is reduced. 4. A voltage detecting means for detecting a driving voltage (Vp) applied to a motor (1) for driving a lens in a non-speed limiting area (66) until the lens enters the speed limiting area (60). The lens deceleration control means (10) further includes (26), and the lens deceleration means (10, 18) operates as the drive voltage (Vp) detected by the voltage detection means (26) decreases. 4. The lens driving device according to claim 3, wherein the range (W ₁ , W ₂ ) of the speed limiting region (60) is reduced. 5. A motor for driving a lens in a non-speed range (66) until the speed limit range (60) is entered.
(1) To apply a constant voltage, the acceleration detecting means (8, 9, 10) a predetermined amount of movement from the accelerated lens driving started in the non-rate limiting region (66) (Q _S to Q ₀ ) above on the basis of the timing means for detecting a moving time required to move (8, 10), the moving time and the predetermined amount of movement of the regimen during means (8, 10) detects the (Q _S to Q ₀₎ The lens driving device according to claim 2, further comprising an acceleration calculating means (10) for calculating an acceleration. 6. A constant voltage is applied to the motor (1) for driving the lens in the non-speed limiting area (66) until the speed limiting area (60) is entered, and the acceleration detecting means (8, 9) is applied. , 10) is a movement amount detecting means for detecting the movement amount of the lens accelerated in the non-speed limited area (66) within a predetermined movement time from the start of driving.
(9, 10), and an acceleration calculation means (10) for calculating the acceleration from the movement amount detected by the movement amount detection means (9, 10) and the predetermined movement time. Item 2. The lens driving device according to item 2.