JP4717263B2 - Lens barrel and camera - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lens barrel and a camera having a mechanism for transmitting a driving force of an actuator to a lens and moving the lens in an optical axis direction.
[0002]
[Prior art]
For focus adjustment in a camera or the like, for example, a light receiving sensor detects a focus state by receiving a photographic light beam, and based on the detection result, the driving force of the actuator is transmitted to the focus lens to drive the focus lens to the in-focus position. It is done by doing. Many products equipped with such an autofocus (AF) mechanism have been put on the market, and nowadays they occupy the mainstream.
[0003]
In such an AF mechanism, a transmission system such as a plurality of transmission gears, a focus lens driving helicoid or a cam is provided between the actuator and the focus lens, and the focus lens calculated based on the distance measurement result is provided. Configuration to control the energization of the actuator by comparing the amount of movement with the amount of movement of the focus lens estimated from the output of the encoder that detects the operating state of either the actuator, part of the transmission system or the focus lens Has been.
[0004]
Here, in order to stop the focus lens at a predetermined in-focus position, there is a type in which energization control is performed on the actuator so that the moving speed of the focus lens follows a predetermined speed pattern.
[0005]
[Problems to be solved by the invention]
However, in the AF mechanism described above, when the actuator and the focus lens are displaced due to backlash of the transmission system, deformation of the member, backlash, etc., the energization control to the actuator is changed so as to change the operating state of the focus lens. In practice, the focus lens cannot actually follow the movement. Therefore, the focus lens cannot be accurately moved to the predetermined focus position and must be driven again to the predetermined focus position, which may cause the photographer to feel uncomfortable. Further, in order to perform an operation according to a predetermined speed pattern, it is necessary to repeatedly correct the energization control, and it takes a long time to move the focus lens.
[0006]
An object of the present invention is to provide a camera capable of moving a focus lens to a predetermined in-focus position with high accuracy in consideration of backlash of a transmission system, deformation of a member, backlash, etc. in order to solve the above-described problems. It is to provide a lens barrel.
[0007]
[Means for Solving the Problems]
A lens barrel according to one aspect of the present invention controls a drive source, a lens movable in an optical axis direction, a transmission mechanism that transmits power of the drive source to the lens, and energization to the drive source. And a second detecting unit for detecting an operating state of the lens in a lens barrel having a control unit for moving the lens to a predetermined position. And the control means includes:
By comparing the outputs of the first detection means and the second detection means, it is determined whether or not the operation of the lens is performed following the operation of the drive source via the transmission mechanism. permits the energization control to the driving source, such as the operating state of the lens is changed when the operation of the lens to follow the operation of the driving source is determined to have been made, the drive source The energization control to the drive source is not permitted such that the operation state of the lens changes when it is determined that the lens operation is not performed following the operation .
[0008]
In this way, by allowing energization control to the drive source such that the lens operation state changes only when the lens operation according to the operation of the drive source is performed, the play that has occurred in the transmission mechanism, The lens is not driven again without stopping at the predetermined position due to the displacement of the driving source and the lens due to deformation of the member, etc., and the lens is accurately moved to the predetermined in-focus position by one driving. It can be moved well, and the photographer does not feel uncomfortable by preventing the lens from being driven again. Further, it is not necessary to repeatedly correct the energization control even when an operation along a predetermined pattern is performed, and the moving time of the focus lens can be shortened.
[0009]
In addition, when only the output of the first detection means is changing, the energization to the drive source may be controlled so that the drive source operates in a predetermined operation based on the output of the first detection means. it can.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a simple block diagram of a camera according to an embodiment of the present invention. In FIG. 1, 1 is a camera body, and 2 is a lens body.
[0011]
First, the configuration of the lens body 2 will be described.
[0012]
A motor 7 is a power source for moving the focus lens 3. Reference numeral 5 denotes a focus unit (transmission mechanism described in claims of the present application), which has a mechanical mechanism for moving the focus lens 3 to a predetermined in-focus position during focus adjustment.
[0013]
Reference numeral 6 denotes a speed reducer (transmission mechanism described in claims), which is mechanically interlocked with the motor 7 and the focus unit 5, and increases the torque of the motor 7 by decelerating the rotational speed of the motor 7, thereby focusing. Transmit to unit 5.
[0014]
Reference numeral 10 denotes a lens microcomputer (determining means and control means described in the claims of the present application) that controls all operations related to the lens body 2. Reference numeral 11 denotes an electrically erasable storage element (EEPROM) that stores various histories and data relating to the lens housed in the lens body 2 through communication with the lens microcomputer 10.
[0015]
A driver circuit 8 supplies driving power to the motor 7 according to a command from the lens microcomputer 10. Reference numeral 4 denotes an encoder unit A (first detection means described in claims of the present application), which detects the drive amount of the motor 7 driven by the power supplied via the driver circuit 8. Reference numeral 9 denotes an encoder unit B (second detection means described in claims of the present application), which detects the drive amount of the focus lens 17 driven by the motor 7 via the speed reducer 6 and the focus unit 5.
[0016]
Reference numeral 12 denotes a lens contact unit having a contact for the lens microcomputer 10 to communicate with the camera microcomputer 15 disposed in the camera body 1.
[0017]
Next, the configuration of the camera body 1 will be described.
[0018]
Reference numeral 15 denotes a camera microcomputer that controls all operations related to the camera body 1. Reference numeral 13 denotes a distance measuring unit that measures the distance to the subject in response to a command from the camera microcomputer 15 and sends the measurement result to the camera microcomputer 15.
[0019]
Reference numeral 16 denotes a camera contact unit, which has a contact for the camera microcomputer 15 to communicate with the lens body 2. When the lens body 2 is attached to the camera body 1, the lens contact unit 12 and the camera contact unit 16 are in electrical contact with each other.
[0020]
In FIG. 1, a dotted line represents mechanical contact or connection, and a solid line represents electrical connection. In the present embodiment, the motor 7, the speed reducer 6, the lens microcomputer 10, and the like are disposed in the lens body 2, but may be disposed on the camera body 1 side.
[0021]
2 and 3 are flowcharts of the camera operation in the present embodiment, and the focusing operation of the lens will be described with reference to FIG.
[0022]
In step 101, when the camera microcomputer 15 receives an AF operation start command from an operation of an operation unit (not shown) provided outside the camera body 1, the camera microcomputer 15 sends the command to the distance measurement unit 13 to perform the distance measurement operation. . This distance measurement result is sent to the camera microcomputer 15. When the distance measuring operation is completed, the camera microcomputer 15 requests the lens microcomputer 10 to transmit optical data related to the lens body 2, and the lens microcomputer 10 transmits this optical data to the camera microcomputer 15.
[0023]
The camera microcomputer 15 calculates a moving amount D of the focus lens 3 for focusing on the subject based on the output (ranging result) of the ranging unit 13 and the optical data. Here, the movement amount D of the focus lens 3 is a value corresponding to the output (number of pulses) of the encoder unit B accompanying the movement of the focus lens 3. The driving direction of the focus lens 3 is given by the positive or negative of the movement amount D. For example, the lens feeding direction is positive and the lens feeding direction is negative.
[0024]
In step 102, the camera microcomputer 15 transmits the previously calculated movement amount D (including positive and negative of the driving direction) to the lens microcomputer 10, and in step 103, the lens microcomputer 10 drives the focus lens 3 from the received movement amount D. Determine the direction.
[0025]
In step 104, the lens microcomputer 10 supplies the voltage V to the motor 7 via the driver circuit 8 based on the determined driving direction and the moving amount | D |, thereby starting the focus driving operation of the focus lens 3. The Here, | D | indicates the absolute value of the moving amount of the focus lens 3.
[0026]
In step 105, the lens microcomputer 10 monitors the change in the output of the encoder unit A4. If the output change is confirmed, the process proceeds to step 106, and if not confirmed, the process proceeds to step 107.
[0027]
In step 106, the lens microcomputer 10 monitors the change in the output of the encoder unit B9. If the output change is confirmed, the process proceeds to step 108. If the change is not confirmed, the process proceeds to step 109.
[0028]
In step 108, the lens microcomputer 10 subtracts 1 from the moving amount | D | of the focus lens 3 to obtain this value | D |. In step 110, the lens microcomputer 10 determines whether or not the moving amount | D | If it is determined that the movement amount | D | is 0, the process proceeds to step 111. If it is determined that the movement amount | D | is not 0, the process proceeds to step 112.
[0029]
In step 111, the lens microcomputer 10 sends a command to the driver circuit 8 to stop energization of the motor 7 and stop driving the focus lens 3. In step 113, the lens microcomputer 10 transmits the end of movement of the focus lens 3 to the camera microcomputer 15, whereby the AF operation ends.
[0030]
On the other hand, when the output change of the encoder unit A4 cannot be confirmed in step 105 and the process proceeds to step 107, in step 107, the lens microcomputer 10 adds ΔV to the current motor supply voltage V and then returns to step 104. The added voltage V is supplied to the motor 7 via the driver circuit 8.
[0031]
If the output of the encoder unit B9 cannot be confirmed in step 106 and the process proceeds to step 109, the lens microcomputer 10 calculates the rotational speed of the motor 7 based on the output of the encoder unit A4 confirmed in step 105. To do.
[0032]
In step 114, it is determined whether or not the rotation speed of the motor 7 calculated in step 109 has reached a predetermined rotation speed set in advance. Here, the predetermined rotation speed set in advance is a predetermined rotation speed of the motor 7 set in advance so that the focus lens 3 can move smoothly even when a load due to backlash or the like is generated in the speed reducer 6. Indicates the rotation speed.
[0033]
If the rotational speed of the motor 7 has not reached the predetermined rotational speed in step 114, the process proceeds to step 115, and if it has reached, the process returns to step 105. In step 115, the lens microcomputer 10 increases the rotation speed of the motor 7 by increasing the supply voltage V to the motor 7 via the driver circuit 8, and then returns to step 105.
[0034]
If it is determined in step 110 that the amount of movement | D | is not 0 and the routine proceeds to step 112, in step 112, the lens microcomputer 10 monitors the output change of the encoder unit B9. Return to. If there is a change in the output of the encoder unit B9 in step 112, a program interruption process (step 121) is entered in the lens microcomputer 10, and the process proceeds to step 122.
[0035]
In step 122, the lens microcomputer 10 calculates the moving speed of the focus lens 3 based on the output of the encoder unit B9 confirmed in step 112. In step 123, the lens microcomputer 10 calculates the moving speed of the focus lens 3 calculated in step 122 and a preset moving speed (the predetermined speed pattern described in the claims of the present application. The focus lens 3 is moved to a predetermined in-focus position. And the acceleration / deceleration control speed based on the remaining drive amount at the time of movement to the upper limit (including the allowable maximum speed, etc.), and the comparison result is stored in the EEPROM 11 in step 124.
[0036]
In step 125, the lens microcomputer 10 monitors the output change of the encoder unit A4, and proceeds to step 126 after confirming the output change. In step 126, the lens microcomputer 10 calculates the rotational speed of the motor 7 based on the output of the encoder unit A4 confirmed in step 125.
[0037]
In step 127, the lens microcomputer 10 multiplies the rotational speed of the motor 7 calculated in step 126 by the speed reduction ratio of the speed reducer 6 and the focus unit 5 (the moving speed of the focus lens 3 predicted from the rotational speed of the motor 7). ) And the moving speed of the focus lens 3 calculated in step 122 are determined. If they match, the process proceeds to step 128, and if they do not match, the process proceeds to step 131. Exit.
[0038]
In step 128, the lens microcomputer 10 reads the comparison result stored in the EEPROM 11 in step 124. If the actual moving speed of the focus lens 3 is slower than the preset moving speed, the process proceeds to step 129. If the actual moving speed of the focus lens 3 is higher than the preset moving speed, the process proceeds to step 130.
[0039]
In step 129, the lens microcomputer 10 increases the supply voltage V to the motor 7 via the driver circuit 8 to increase the rotational speed of the motor 7, and then the process proceeds to step 131 to end the program interruption process. In step 130, the lens microcomputer 10 lowers the supply voltage V to the motor 7 via the driver circuit 8, thereby lowering the rotational speed of the motor 7, and then proceeds to step 131 to end the interrupt operation of the program.
[0040]
According to the present embodiment, the energization control of the motor 7 from the start of lens driving until the focus lens 3 actually starts moving (a state in which no load is applied due to transmission play or deformation of the speed reducer 6 and the focus unit 5) is provided. The focus lens 3 can be started in a short time because the rotation can be appropriately performed according to the rotation speed of the motor 7 itself, and the necessary generated torque of the motor 7 can be reduced by keeping the rotation speed of the motor 7 below a preset rotation speed. By ensuring, the movement of the focus lens 3 can be smoothly started even with a sudden load applied when the transmission backlash of the speed reducer 6 and the focus unit 5 is clogged.
[0041]
Even after the focus lens 3 actually starts moving, it is always monitored whether or not the movement of the focus lens 3 can correctly follow the rotation of the motor 7, and only when the focus lens 3 is able to follow, the preset focus lens 3 is set. By changing the rotational speed of the motor 7 according to the movement speed (acceleration / deceleration control speed based on the remaining drive amount when the focus lens 3 is moved to a predetermined in-focus position, allowable maximum speed, etc.), It reacts sensitively to phenomena such as follow-up delay of the focus lens 3 caused by deformation or twisting of the speed reducer 6 (focus unit 5) due to load fluctuations during acceleration / deceleration driving of the lens and overshoot of the focus lens 3 due to inertia during deceleration. Thus, unnecessary acceleration / deceleration control of the motor 7 can be prevented, and the focus lens 3 can be driven at a predetermined focus position once. Until it can be moved in a short time with high accuracy.
[0042]
In the present embodiment, the encoder unit A4 is disposed at a position where the rotation amount of the motor 7 can be detected, and the encoder unit B9 is disposed at a position where the movement amount of the focus lens 3 can be detected. However, if the states of the motor 7 and the focus lens 3 can be detected substantially, the encoder unit can be disposed on the speed reducer 6 or a part of the focus unit 7.
[0043]
In the present embodiment, the focusing operation has been described. However, the present invention is not limited to this, and the same can be applied to a zooming operation of a zoom lens (not shown) housed in the lens body 2.
[0044]
【The invention's effect】
According to the present invention, only when the operation of the lens according to the operation of the drive source is performed, the energization control to the drive source so that the operation state of the lens changes is permitted, thereby causing the transmission mechanism. The lens does not stop driving at the predetermined position and the lens is not driven again due to a shift in the operation of the driving source and the lens due to backlash, deformation of the member, and the like. Can move well.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram of a camera according to an embodiment of the present invention.
FIG. 2 is a flowchart showing camera operation during AF operation.
FIG. 3 is a flowchart showing camera operation during AF operation.
[Explanation of symbols]
1 Camera body 2 Lens body 3 Focus lens 4 Encoder unit A
5 Focus unit 6 Reducer 7 Motor 8 Driver circuit 9 Encoder unit B
10 Lens microcomputer 11 EEPROM
12 Lens contact unit 13 Distance measuring unit 15 Camera microcomputer 16 Camera contact unit

Claims (7)

A drive source, a lens movable in the optical axis direction, a transmission mechanism for transmitting the power of the drive source to the lens, and a control for moving the lens to a predetermined position by controlling energization to the drive source A lens barrel having means,
First detection means for detecting an operating state of the drive source;
Second detecting means for detecting an operating state of the lens,
The control means includes
By comparing the outputs of the first detection means and the second detection means, it is determined whether or not the operation of the lens is performed following the operation of the drive source via the transmission mechanism. permits the energization control to the driving source, such as the operating state of the lens is changed when the operation of the lens to follow the operation of the driving source is determined to have been made, the drive source A lens barrel characterized by not permitting energization control to the drive source such that the operation state of the lens changes when it is determined that the lens operation is not performed following the operation .   The lens barrel according to claim 1, wherein the control unit performs energization control to the drive source so as to move the lens along a predetermined speed pattern.   When the difference between the moving speed of the lens calculated from the output of the first detecting means and the moving speed of the lens calculated from the output of the second detecting means is zero, The energization control to the drive source is performed based on a comparison result between the moving speed of the lens calculated from the output of the second detection means and a predetermined speed pattern. Lens barrel.   The control means calculates from the output of the second detection means for the predetermined speed pattern by comparing the moving speed of the lens calculated from the output of the second detection means with the predetermined speed pattern. The lens barrel according to claim 3, wherein the voltage supplied to the drive source is increased when the moving speed of the lens is low.   The control means calculates from the output of the second detection means for the predetermined speed pattern by comparing the moving speed of the lens calculated from the output of the second detection means with the predetermined speed pattern. 5. The lens barrel according to claim 3, wherein the voltage supplied to the drive source is lowered when the moving speed of the lens is high.   The control means energizes the drive source so that the drive source performs a predetermined operation based on the output of the first detection means when only the output of the first detection means is changing. The lens barrel according to claim 1, wherein the lens barrel is controlled.   A camera comprising the lens barrel according to claim 1.