JP3210083B2 - Camera with autofocus device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera having an automatic focusing mechanism.

[0002]

2. Description of the Related Art Conventionally, an automatic focusing mechanism (hereinafter referred to as AF) has been described.
In particular, in the case of a compact camera equipped with a camera, the driving of the taking lens for focusing was performed immediately before the release. That is, when the release is not performed, the lens is made to stand by at the reference start position, and when the release button is pressed, the lens is driven from the start position to the in-focus position, the shutter is opened and closed, an image is taken, and the lens is returned to the start position again. Was common.

[0003]

However, in the above-mentioned conventional example, since the lens is driven immediately before opening and closing the shutter, the time required for this is a release time lag, and the operability is deteriorated. In order to reduce the time lag, the lens is driven by pressing the release button halfway (first stroke). If the release button is pressed down, the sequence proceeds to the release. On the other hand, if the release button is released from the half-pressed state, Some cameras return the lens to the start position, but each time the release button is pressed again, that is, every time the distance measurement or photometry is restarted, the lens reciprocates between the start position and the in-focus position. There is a drawback of high power consumption.

Even if the lens does not return to the start position even when the release button is released, the distance measurement is performed again by half-pressing the release button. As a result, the disadvantage that unpleasant sound is generated by pressing the release button again remains.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is divided into two stages: a half-pressed state (first stroke) of the release button and a deeply pressed state (second stroke). It is an object of the present invention to provide a camera capable of suppressing an unpleasant operation sound and useless power consumption while reducing a release time lag by driving a lens.

[0006]

1 to 3 are flow charts for explaining the operation of an embodiment of the present invention, FIG. 4 is an electric circuit showing the structure, and FIGS. 5 to 7 are examples showing the movement of a lens.

In FIG. 4, reference numeral 1 denotes a switch which is turned on when a release button (not shown) is half-pressed (first stroke) and when the release button is fully pressed (second stroke), and 2 denotes a switch which is pressed when the release button is deeply pressed (second stroke). ON for 2 strokes)
Switch 3, which is turned on when a photographic lens (not shown) is at the start position, 4 is a microcomputer for controlling the camera, 5 is a power supply battery, 6 is a photometric circuit, 7 is a distance measuring circuit, and 8 is a shutter drive. A circuit, 9 is a stepping motor for driving the taking lens, 10 is its coil, 1
Reference numeral 1 denotes a drive circuit for controlling a current flowing through a coil 10 to step-drive a stepping motor (hereinafter referred to as STM) 9; and 12, a film winding circuit.

First, the basic control of the taking lens will be described. The lens position is hexadecimal number of steps 00
It is assumed that the position is controlled to a position of 256 steps from _{H to} 0FF _H. This is shown in FIG. The far side of the object distance has a smaller number of steps, and the near side has a larger number of steps. 00 _H
The step is a start position, which is determined based on whether the switch 3 is ON. This is a reference position for lens control, and also has a purpose of checking whether or not lens control is performed accurately. 20 _H step-focus position relative to the distance ∞, 0F0 _H step is in-focus position with respect to a close distance, thereby providing focusing of the (manufacturing errors, temperature, etc.) the margin of the before and after.

When taking a picture, the lens is used in a state where the lens is driven from a side having a small number of steps to a side having a large number of steps, that is, in a direction of extending from a start position.
This is because the conditions of the mechanical elements such as the backlash of the gear of the lens driving unit are always kept the same.

A description will be given of the release sequence shown in FIG. 1 assuming that the lens is controlled according to the above rules.

In FIG. 1, it is checked in step # 1 whether the release button is half-pressed, that is, whether the release button has been pressed until the first stroke. If it is pressed, switch 1 is turned on, so go to # 2. If it is not pressed, go to # 1.
Return to step 1 and make a loop waiting for switch 1 to turn on. When the release button is half-pressed, the distance measurement circuit 1 shown in FIG.
The microcomputer 4 measures the brightness of the subject by # 4.
Focusing position "a step" of lens based on distance measurement result in 2
Is calculated. Here if the number of steps that a = 88 _H as the in-focus position is to have been determined. # Lower 4bit of a 5 ANDs the numerical value of a and 0F0 _H To a 0 _H This is called a '. If a '= a∧0F0 _H a = 88 _H , then a' = 80 _H. This is the lens position set when the release button is half-pressed.

Here, let x be the number of steps at the current position of the lens. The current position x of the lens at # 6 and # 5
Is compared with a 'calculated in the above. The first is located x = 0 _H lens to the start position. When a '= 80 _H x =
Since it is not a ', go to # 7. In # 7, the subroutine "Lens Set" in # 8 is executed with y = a '. FIG. 2 shows a flowchart of the "lens set" subroutine. The "lens set" subroutine is a program for driving the lens such that when the lens drive destination is set to the number y and executed, the lens positions x and y become equal.

In FIG. 2, it is checked whether or not the destination y is equal to the current position x in # 20. If they are equal, the process proceeds to # 29, and the process ends. If they are not equal, the magnitudes of x and y are compared in # 21. In the case of # 8 in FIG. 1, since y = 80 _H and x = 0 _H , the process proceeds to # 26, where the microcomputer 4 sets the lens driving circuit 11
To advance the lens by one step. X in # 27
In step # 28, it is checked whether x = y. # 2
8. The loop of # 26 to # 28 is performed until x = y at 8.
When x = y, the process proceeds to # 29 and ends.

[0014] x = 80 _H next after completing the # 8 in FIG. 1, the flow proceeds to step # 9. # 9 to # 10 are loops in which the release button is pushed further from the half-pressed state, that is, pressed until the second stroke. If the release button is in the half-pressed state, only switch 1 is ON, so # 9 to # 10 Around the loop. # 1 from # 9 when release button is released
Return to When the release button is depressed deeply, the switch 1 and the switch 2 are turned on, so that the photographing sequence # 11
Go to # 15.

In step # 11, y = a (in-focus position) is set in step # 12.
To execute the "lens set" subroutine. # 12 in the current position x = 80 _H, becomes y = 88 lens 8 step further feeding and because it is _H x = 88 _H proceeds to # 13. In # 13, the shutter is opened and closed based on the photometric information in # 3, and in # 14, the "lens reset" subroutine is executed.

FIG. 3 is a flowchart showing the contents of the "lens reset" subroutine. In FIG. 3, # 3
At 0, it is checked whether the switch 3 is ON.
If it is OFF, the lens is driven by one step at step # 31, that is, the lens is driven to the start position side. # Return the lens in a loop of 30 # 31 to the switch 3 is turned ON to the start position, the switch 3 advances to # 32 from the turned ON # 30, the subroutine in step # 33 as the current position x = 0 _H of the lens finish. 6A, 6B, and 6C show the movement of the lens in the above operation by the lens position.

Returning to FIG. 1, the film is wound up in # 15 and #
It returns to 1 and enters a loop waiting for the release button to be pressed.

Next, the case where the operation of half-pressing and releasing the release button is repeated will be described.

Generally, the current camera measures the distance when the release button is half-pressed. This is an operation called focus lock. If the subject moves afterward and the distance changes or the framing is desired to be changed, release the release button once and then press the release button halfway again to perform distance measurement again. A case where such an operation is performed will be described.

[0020] First, when the release button from the state of the lens position x = 00 _H is half-pressed, the distance measurement is performed as described above, the lens is set in accordance with the focus position. what if,
the movement of the A of a '= 80 _H next to Figure 7 in # 5 and a was a = 88 _H. When the release button is half-pressed, the camera loops around the loop from # 9 to # 10, and when the release button is released, the switch 1 is turned off.
Return to

[0021] in a state in which the lens has been paid out to 80 _H,
Press the release button halfway again. Switch 1 is ON
Then, start over from the distance measurement of # 2. If the first distance measurement result and the second distance measurement result do not change much, that is, if the camera is pointed at the same subject and the release button is half-pressed repeatedly, the focus position a calculated in # 4 is not so much. does not change. # 4 of the calculation result a is 80 _H ～8F when in the range of _H is # 5 calculation result a 'have the same 8 and first results
0 _H. In this case, the process proceeds from # 6 to # 9, and enters a loop in which the lens is not moved by half-pressing the release button and the switch 2 is turned ON. When the release button is depressed deeply and the switch 2 is turned on, the process proceeds to step # 11 to set the lens to the in-focus position. However, since the number of steps to be sent in step # 12 is within 0F _H steps, the shutter drive # 1
The time to 3 is short.

[0022] If the measurement result in the re-pressing of the release button has changed, for example, # 4 of the results will be described the case has changed to 78 _H from 88 _H. A = 88 for the first distance measurement
_H, state lens a '= 80 _H is in the 80 _H (x = 8
_0H ), press the release button again, and the result of # 4 is 7
_Suppose it is 8H. # 5 In a '= 70 _H, and the # 6
Therefore, in step # 7, y = 70 _H (= a ') is set, and the "lens set" subroutine is executed in step # 8.

In the state where y = 70 _H and x = 80 _H , # in FIG.
Execute from 20. Since y = x is not satisfied in # 20, # 21
Is not a proceeds y> x in the flow proceeds to step # 22, the _{y '= (y-10 H} ) ∧0F0 H = (70 H -10 H) ∧0F0 H = 60 H ∧0F0 H = 60 H.

In step # 23, the microcomputer 4 operates the lens driving circuit 11
To move the lens one step to the start position side. In step # 24, x = x−1, and in step # 25, x and y ′ are compared. In the loop from # 23 to # 25, the lens is sent to the start position until x = y '(= _60H ), and x = 6.
When it reaches 0 _H , the process proceeds to # 26. # 26 to # 28 is a loop going feeding of the lens from the start position side, as described above, and ends at the feeding # 29 to _{x = y (= 70 H)} .

This operation is the operation of FIG. 7B. 80 _H
Moreover sent from up to 60 _H to move to 70 _H 70 _H
This is done for the purpose of suppressing the aforementioned backlash and the like.

At the point when the process proceeds from # 8 to # 9 in FIG. 1, x = 7
0 _H. Wait until the release button is deeply pressed in the loop of # 9 to # 10, and when SW2 is turned on, # 11
Proceed to. At step # 11, y = a (= 78 _H ) is set, and at step # 12, a "lens set" subroutine is executed. Since the number of steps to be sent in # 12 is eight, the time required for # 12 is short, and the process proceeds to opening and closing of the shutter in # 13.

[0027]

As described above, the lens drive at the time of release is divided into the half-pressing of the release button and the pressing of the release button deeply, so that the timing at which the release button is actually pressed is pressed. The time from opening to opening and closing of the shutter can be shortened.

Further, since the lens position driven by half-pressing the release button is not moved if the focus position is within a certain range, it is unnecessary even if there is a slight change in the distance when the release button is pressed again. Since the lens is not driven, there is no useless movement and unpleasant operation noise.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an operation flow of a camera according to the present invention.

FIG. 2 is an explanatory diagram showing a lens setting subroutine in the flow of FIG.

FIG. 3 is an explanatory diagram showing a lens reset subroutine in the flow of FIG. 1;

FIG. 4 is a circuit diagram showing one embodiment of a camera according to the present invention.

FIG. 5 is an explanatory diagram illustrating a lens position in the camera of the present invention.

FIG. 6 is an explanatory diagram illustrating a lens control operation in the camera according to the present invention.

FIG. 7 is an explanatory diagram illustrating another example of a lens control operation in the camera according to the present invention.

[Explanation of symbols]

 4 Microcomputer 7 Distance measuring circuit 9 Stepping motor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02B 7/28

Claims (1)

(57) [Claims] 1. A camera having an auto-focusing device comprising a distance measuring means and a lens driving means for driving a lens to a focus position according to a result of the distance measurement by the distance measuring means.
A first operation of the release member drives the lens to a position close to an in-focus position corresponding to the distance measurement result of the distance measurement unit, and holds the lens at the position during the first operation.
Then, without releasing the first operation, the lens is driven to the in-focus position when the second operation of the release member is performed, and the shutter is driven, while the first operation of the release member is performed. After driving the lens to a position close to the focus position and holding the lens at the position, the operation of the release member is released, and then the first operation is performed again. When the focus position according to the obtained distance measurement result and the holding position are within a predetermined range, the lens is kept held at the holding position, and the focus position is set by the second operation of the release member thereafter. A camera having an autofocus device, further comprising control means for driving a lens up to the camera.