JP2810251B2 - Zoom lens 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 zoom lens device.
More specifically, move the movable barrel from the collapsed position to the tele end position.
The zoom lens from the retracted position by moving
The present invention relates to a zoom lens device that moves to a telephoto end position .

[0002]

2. Description of the Related Art In recent years, most products are equipped with microcomputers, and automation and miniaturization of various mechanisms have been achieved. Such a microcomputer is usually developed for each model, and a dedicated input terminal is assigned to perform each control. For example, in the case of a low-cost type zoom camera, an input terminal for obtaining the amount of movement of the variable power lens and an input terminal for subject distance data are prepared for autofocus control, and data from these input terminals are used. A terminal for outputting the determined focus position data of the focus lens to the focus lens drive motor is also provided. Since analog signals such as the amount of movement of the variable power lens and subject distance data cannot be directly input to the input terminal of the microcomputer developed in this manner, these analog signals are transmitted through an A / D converter. To input digital signals. This A / D converter is used in accordance with a predetermined processing capability of a microcomputer, and a microcomputer that is used most frequently at present is one that processes eight bits collectively. ing.

However, in the case of a camera using an 8-bit microcomputer and an A / D converter as described above, digital data that can be input and output at one time is 25 bits.
Only six digital quantities can be obtained. Therefore, for example, in a compact camera having a built-in zoom lens, when trying to read the movement amount of the variable power lens with high accuracy in order to increase the accuracy of focusing by auto focus, 256 digital amounts are insufficient in accuracy. Was. Further, when an A / D converter of 8 bits or more is used to cope with this inconvenience, a new microcomputer has to be developed, which leads to an increase in cost. To eliminate such disadvantages,
A plurality of analog signals determined in advance according to the signal level
, And amplify each one of the
A / D converter for selecting A / D conversion by selecting
No. 202031 and Japanese Utility Model Application No. Sho 60-22035
It is known as Kurofilm. In addition, the amplification means is simplified
To convert analog signals according to their signal levels.
Set the range and set the analog signal based on this conversion range.
A / D converter for amplifying the signal is also disclosed in JP-A-1-250127.
It has been proposed in gazettes and the like. Using such A / D converter
If there is, the area included in the signal level of the analog signal
Amplification can be performed with the amplification width set accordingly.
256 types using A / D converters
Of the movable cylinder can be detected.

[Problems to be solved by the invention] A / D conversion like this
To read the amount of movement of the zoom lens with high accuracy
In this case, the moving range of the zoom lens,
Analog output corresponding to the movement range between the end position
Of the fixed change in the signal level of the
I do. However, among zoom lens devices, wide
Zoom lens device that moves between end position and tele end position
In the case of, the A / D converter described in the above-mentioned publication is used as it is.
Move between the retracted position and the tele end position.
In the case of a zoom lens device that moves,
Is the moving area up to the end position used for shooting? This
Specially amplifies the area to precisely move the zoom lens
It is not necessary to specify
It is wasteful to use the / D converter, which increases cost and time.
There is a drawback that leads to loss between them.

The present invention solves the above problems.
It is possible to detect the zoom position with high accuracy.
To improve the focusing accuracy during focusing,
It is an object to provide a zoom lens device which can be achieved at low cost .

[0005]

SUMMARY OF THE INVENTION The present invention provides the above
2. A zoom lens device according to claim 1, wherein the zoom lens device includes:
For moving the movable cylinder from the collapsed position to the telephoto end position,
On the other hand, when the signal level changes monotonically within a certain
And signal output means for outputting the analog signal; signal output means
Analog signal is input from the
Is set for each area obtained by dividing into a number of areas
Amplifying under different reference voltages
Of the stages that include the signal level of the analog signal
Select the amplifying means with the reference voltage set according to the frequency range
And an amplifier selection means for amplified by the amplifier means selected; its
The output signal from the amplification selection means of the
These analog signals are input and each signal is
A that converts into a digital signal according to the signal level and outputs it
/ D converter ;; zoom lens retracted position and wide end position
A / D conversion in the range of movement of the movable cylinder
Signal output means of a plurality of digital signals from the
Select the one corresponding to the analog signal from
Lens can be moved between the wide end position and the tele end position.
In the moving range of the moving cylinder, the output signal from the amplification selecting means
A signal selecting means for selecting one corresponding; this signal selection
Movable based on digital signal selected by selection means
Position specifying means for specifying the moving position of the cylinder .

In the zoom lens device according to the second aspect,
Each area obtained by dividing the fixed change width into multiple areas
Amplification under different reference voltages set for each
Analog signals from the signal output means to a plurality of amplifying means.
Input each, and each signal to its signal level
A / D converter converts the signal into a corresponding digital signal and outputs it
You. Then, the signal selecting means moves the zoom lens to the collapsed position.
Between the moving cylinder and the wide end position
Of the plurality of digital signals from the A / D converter
Select one that corresponds to the analog signal from the signal output means.
The zoom lens between the wide end position and the tele end position.
In the movement range of the movable cylinder to be moved by
Set according to the area containing the signal level of the analog signal.
Supports output signal from amplifying means with fixed reference voltage
This is to select the one that has been done.

In the zoom lens device according to the third aspect,
The quasi-voltage selecting means divides a fixed change width into a plurality of regions.
The different composites set for each area
Signal level of analog signal among reference voltages
Select the reference voltage corresponding to the area to be
Amplify analog signal with one amplifying means under pressure
It is something that has been done .

[0008]

2 and 3 show a zoom camera according to an embodiment of the present invention.
When the N operation is performed, the lens barrel is extended from the retracted position, and the focal length of the photographing lens is changed between the wide side and the tele side by operating the zooming operation member 12. This is a 35 mm lens shutter zoom camera. As is well known, when the shutter button 15 is half-pressed, distance measurement and photometry are started. When the shutter button 15 is fully pressed, the camera automatically focuses on the subject and shoots with an appropriate exposure. Note that reference numerals 14a and 14
Reference numeral b denotes a distance measurement window incorporating an IR filter that cuts visible light and transmits only infrared light, and includes a well-known infrared light emitting diode (IRED) and a position detection diode (PSD) behind these windows. The distance measuring device 14 is built in.

The focus system of the photographing lens of this camera is a rear focus system in which a rear lens group 21 which is a compensator lens having a focusing function with respect to a front lens group 20 which is a variator lens advances and retreats in the optical axis P direction. The lens barrel is composed of a fixed cylinder 23 integrally formed with the camera body, an intermediate cylinder 24 helicoidally coupled inside the fixed cylinder 23, and a movable cylinder 25 helicoidally coupled inside the intermediate cylinder 24. It is configured.
The front group lens 20 is fixed to the movable barrel 25 by a well-known bayonet connection or the like, and the rear group lens 21 is
0, the rear lens frame 28 fixed to the movable barrel 25
Are incorporated in the rear lens group frame 29 via the.

When the zoom operation member 12 is operated, the zoom motor 34 is driven in accordance with the operation. This drive is transmitted to the two-stage gear 50, the gear 54, and the gear portion 24c of the intermediate cylinder 24. Accordingly, the intermediate cylinder 24 rotates, and advances and retreats in the optical axis P direction with respect to the fixed cylinder 23 according to the helicoid lead. The movable barrel 25 advances and retreats in the direction of the optical axis P according to the rectilinear guide member 35 by the rotation of the intermediate barrel 24. The gear 54 is rotatably provided on the bush 52. The bush 52 is fixed to an end of the straight guide member 35 and moves forward and backward according to the lead of the lead screw 51. Lead screw 51
Are formed so as to correspond to the advance and retreat of the movable cylinder 25. A slider 35 is provided at the rear end of the bush 52, and is always in contact with the resistor 33. Therefore, the moving amount of the movable cylinder 25 is the same as that of the slider 35.
Can be detected by the analog signal 37 transmitted from the.

As shown in FIG. 1, an analog signal 37 corresponding to the amount of movement of the movable cylinder 25 is an offset voltage (ibr ₁ ).
Is applied to the amplifier 38, and the analog signal 37a in the range of the voltage of 0 to Vcc is taken into the A / D converter. The A / D converter includes a differential amplifier circuit 3
9, a multiplexer circuit 41 and an A / D converter 43. The differential amplifier circuit 39 amplifies the range of the analog signal 37a for each of three sections and outputs three amplified signals 47a, 47b, and 47c to the multiplexer circuit 41. The multiplexer circuit 41 is a data selector, and selects one of the analog signal 37a and the amplified signals 47a, 47b, and 47c according to a selection signal 36a output from the CPU 36. Output to the / D converter 43.
The A / D converter 43 converts the output selection signal 44 into an 8-bit digital signal and outputs it to the CPU 36.

When the operation of the variable power operation member 12 is completed, the CPU 36 sends a selection signal 36a for inputting the analog signal 37a to the multiplexer circuit 41, and converts a digital signal corresponding to the analog signal 37a into an A / D signal.
Read from converter 43. Further, if the digital signal corresponds to a range requiring high-precision reading out of the range, the CPU 36 sends one of the amplified signals 47 to the A / D converter 43 accordingly. The selection signal 36a to be input is sent to the multiplexer circuit 41, and a digital signal corresponding to the amplified signal 47 is read.

When the CPU 36 reads the digital signal corresponding to the amplified signal 47, the CPU 36 responds to the read digital signal.
The position data of the movable cylinder 25 is determined with reference to a table in which the position data of the movable cylinder 25 is stored in the ROM 51 in advance. In addition, CPU
36 is a range in which the digital signal corresponding to the analog signal 37a does not require high-precision reading out of the range;
For example, in the case of the range of the digital signal obtained when the movable barrel 25 moves between the retracted position and the wide position,
The digital signal corresponding to the analog signal is directly used as the position data of the movable barrel 25.

The CPU 36 temporarily stores the obtained position data of the movable barrel 25 and the subject distance data obtained from the distance measuring device 14, reads out the stored data as necessary, and reads out the stored data of the rear lens group 21. The focus position is determined, and a drive control signal 50a corresponding to the focus position is transmitted to the lens drive circuit 50 to control the focus motor 26a. Focusing motor 26a
Is driven by gears 26b, 26c, 26 as shown in FIG.
The power is transmitted to the gear portion 29d via the gears d and 26e. Thereby, the rear group lens 21 advances and retreats in the optical axis P direction with respect to the front group lens 20, and the focusing is completed. Note that a stepping motor is used as the focusing motor 26a.
Reference numeral 6f denotes a detector such as a rotary encoder that detects step-out of the stepping motor.

Next, the operation of the above configuration will be briefly described. In FIG. 2 showing a state where the lens barrel of the camera is in the collapsed position, when the main switch 11 is turned on, the lens barrel is extended to the wide position. Thereafter, when the variable power operation member 12 is operated,
In response, the movable barrel 25 moves forward and backward. Variable magnification operation member 12
Is completed, the CPU 36 reads the moving amount of the movable barrel 25 via the A / D converter.

Here, the A / D converter will be briefly described. The analog signal 37a sent from the slider 35 via the amplifier 38 is taken into the A / D converter at a voltage in the range of 0 to Vcc. Differential amplifier circuit 39
Sets the range of the analog signal 37a to, for example, "0.35V
To 0.57 V, 0.57 V to 0.78 V, and 0.78 V to VccV.
VccV ". That is,
The reference voltages V ₁ and V _{2 of} the differential amplifiers 39a to 39c shown in FIG.
V ₂ and V ₃ are set to “V ₁ = 0.35 V” and “V ₂ =
Predetermined to 0.57V "and" V ₃ = 0.78 V ", respectively the amplification degree of the differential amplifier 39a~39c" 4.5 "
The values of the resistors r ₂ and r ₃ are determined in advance so that

The CPU 36 first transmits a selection signal 36a and outputs a digital signal corresponding to the analog signal 37a to the A / A
Read via D conversion 43. The read digital signal is compared with a range requiring high-precision reading. The range requiring high-precision reading corresponds to the range in which the differential amplifier 39 amplifies the analog signal 37a. That is, “0.35 V to 0.57
When a digital signal corresponding to the analog signal 37a in the range of "V" is read, this digital signal is processed as data in the "first level range", and the amplified signal 47a is read.
Is input to the multiplexer circuit 41.
To send to.

As a result, the output selection signal 44 output from the multiplexer circuit 41 is read by the CPU 36 via the A / D converter 43 as a digital signal in the "first level range" corresponding to the amplified signal 47a. Therefore, the digital signal in the “first level range” is “0.
Analog signal 37 in the range of “35 V to 0.57 V”
Since this is a digital signal corresponding to the amplified signal 47a obtained by amplifying “a” to “0 to VccV”, there are 256 kinds of digital amounts. The moving amount of the movable barrel 25 corresponding to the 256 digital amounts is stored in advance in a first table of the ROM 51, and the position data of the movable barrel 25 is determined with reference to this table.

Next, the CPU 36 sets "0.57V to 0.
When a digital signal corresponding to the analog signal 37a in the range of “78 V” is read, this digital signal is processed as data in the “second level range”, and the amplified signal 4
The selection signal 36a for inputting the signal 7b is sent to the multiplexer circuit 41. Thereby, the multiplexer circuit 41
The output selection signal 44 output from the A / D converter 43
"Second level range" corresponding to the amplified signal 47b via
Is read by the CPU 36 as a digital signal. Therefore, the digital signal in the "second level range"
An amplified signal 47b obtained by amplifying the analog signal 37a in the range of “0.57V to 0.78V” to “0 to VccV”
Since the digital signal corresponds to the above, there are 256 kinds of digital amounts. The moving amount of the movable barrel 25 corresponding to the 256 digital amounts is stored in advance in the second table of the ROM 51, and the movable barrel 25 is referred to by referring to this table.
5 is determined.

Next, the CPU 36 sets "0.78 to Vcc
When the digital signal corresponding to the analog signal 37a in the range of “V” is read, this digital signal is processed as data in the “third level range”, and the amplified signal 47c is read.
Is input to the multiplexer circuit 41.
To send to. As a result, the output selection signal 44 output from the multiplexer circuit 41 is read by the CPU 36 via the A / D converter 43 as a digital signal in the “third level range” corresponding to the amplified signal 47c. Therefore, the digital signal in the “third level range” is “0.
Since the digital signal is a digital signal corresponding to the amplified signal 47c obtained by amplifying the analog signal 37a in the range of “78 to VccV” to “0 to VccV”, there are 256 kinds of digital amounts. The moving amount of the movable barrel 25 corresponding to the 256 digital amounts is stored in the third table of the ROM 51 in advance, and the position data of the movable barrel 25 is determined with reference to this table.

When the CPU 36 reads a digital signal corresponding to the analog signal 37a in a range that does not require high-precision reading, for example, in the range of "0 to 0.35 V", Analog signal 37
The digital signal corresponding to a is determined as the position data of the movable barrel 25 as it is.

In this embodiment, the analog signal 37a
Are, for example, "0.35 V to 0.57 V", "0.
57V to 0.78V "and three ranges of" 0.78V to VccV ". However, the present invention is not limited to this. For example, the range of the analog signal 37a is reduced to four ranges or five ranges. A fixed example may be used. Further, in order to enable good reading even at the boundary of the range of the analog signal 37a, a range overlapping at each boundary, for example, "0.35 V to 0.6 V", "0.5
An example in which the amplification degree of the amplifier 39 is set to a small value in advance so as to be in the range of “7 V to 0.82 V” and “0.78 V to VccV” may be used. Further, if the amplification degree to be amplified is different for each range of the analog signal 37a, the detection accuracy can be changed for each range.

Further, in this embodiment, the differential amplifier 39
Has a configuration of three differential amplifiers 39a, 39b, 39c, but as shown in FIG.
The reference voltages V ₁ , V ₂ , and V ₃ may be switched by a control signal 60 output from the CPU 36. According to this, the predetermined analog signal 37
The circuit itself can be reduced in cost without amplifying each of the plurality of ranges a. In addition, each reference voltage is V
Three differential amplifiers of ₁ , V ₂ and V ₃ may be provided, and the analog signal may be input only to the optimum one according to the level of the analog signal 37a.

[0024]

As described above, the zoom lens of the present invention is
In the telescopic device, the movable cylinder is moved between the wide end position and the tele end position.
In the movement area where the signal is moved between
Positioning means can be moved using digital signals corresponding to signals
Since the movement position of the cylinder is specified, the A / D conversion corresponding to 8 bits is performed.
The variable magnification of more than 256 kinds of movable cylinders
Position can be detected, and focus accuracy at the time of focus can be improved.
Can be improved. Also, move the movable cylinder to the collapsed position and
A / D conversion is performed in the movement area to move between
Out of multiple digital signals from the
The signal selection means selects the signal corresponding to the analog signal of
To quickly detect sections that do not require high accuracy.
Can be Also, it is necessary to divide this section into multiple
Therefore, it is possible to omit amplification means and the like.
Thus, the cost of the circuit itself can be reduced. Ma
In the zoom lens device according to the third aspect, the signal level
Amplifying means as many as the constant width of change divided into multiple areas
The zoom lens device according to claim 1 or 2, wherein
In comparison, cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an electrical outline of a camera using an A / D converter according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a main part of the camera.

FIG. 3 is a perspective view showing the appearance of the camera.

FIG. 4 is a circuit diagram showing an electrical outline of a camera using an A / D converter according to another embodiment of the present invention.

[Explanation of symbols]

 33 resistor 35 slider 39 amplifying circuit 41 multiplexer circuit 43 A / D converter 36 CPU

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H03M 1/18 G02B 7/08 H03M 1/14

Claims (3)

(57) [Claims] The movable cylinder is moved from a retracted position to a telephoto position.
The zoom lens from the retracted position to the tele end position.
In the zoom lens device that moves to the position, the movement of the movable barrel from the retracted position to the telephoto end position is
Analog signal whose signal level changes monotonically within a certain
Signal output means for outputting a signal, an analog signal from the signal output means is input, and
Each area obtained by dividing a certain range of change into multiple areas
Amplify under different reference voltages set for each region
Signal level of the analog signal,
The reference voltage set for the area containing the
Amplification that selects one amplification means and amplifies with the selected amplification means
Selection means, an output signal from the amplification selection means and the signal output means
Analog signals from the
Convert to a digital signal according to the signal level of
Move the A / D converter and zoom lens between the retracted position and the wide-end position.
In the movement range of the movable cylinder to be moved, a plurality of data from the A / D converter
Of the digital signals, the analog signal from the signal output means.
Select the one that corresponds to the number and set the zoom lens to the wide end.
In the range of movement of the movable barrel that moves between the
Is a signal corresponding to the output signal from the amplification selecting means.
A signal selecting means for selecting, based on the digital signal selected by the signal selecting means
Zui by the zoom lens apparatus characterized by comprising: a position specifying means for specifying a movement position of the movable cylinder, the. 2. A movable cylinder is moved from a retracted position to a telephoto position.
The zoom lens from the retracted position to the tele end position.
In the zoom lens device that moves to the position, the movement of the movable barrel from the retracted position to the telephoto end position is
Analog signal whose signal level changes monotonically within a certain
Signal output means for outputting a signal and an analog signal from the signal output means.
That is obtained by partitioning the certain range of change into a plurality of regions.
Different reference voltages are set for each area.
Amplifying means for amplifying the signals, output signals from these amplifying means, and the signal output means
Analog signals from the
Convert to a digital signal according to the signal level of
Move the A / D converter and zoom lens between the retracted position and the wide-end position.
In the movement range of the movable cylinder to be moved, a plurality of data from the A / D converter
Of the digital signals, the analog signal from the signal output means.
Select the one that corresponds to the number and set the zoom lens to the wide end.
In the range of movement of the movable barrel that moves between the
Contains the signal level of the analog signal from the signal output means.
Amplifier with a reference voltage set corresponding to the region
Signal selection means to select the signal corresponding to the output signal from the stage
And a digital signal selected by the signal selecting means.
Zui by the zoom lens apparatus characterized by comprising: a position specifying means for specifying a movement position of the movable cylinder, the. 3. The movable cylinder is moved from a retracted position to a telephoto position.
The zoom lens from the retracted position to the tele end position.
In the zoom lens device that moves to the position, the movement of the movable barrel from the retracted position to the telephoto end position is
Analog signal whose signal level changes monotonically within a certain
Signal output means for outputting a signal, an analog signal from the signal output means is input, and
Each area obtained by dividing a certain range of change into multiple areas
Multiple reference voltage settings different from each other
That is, the area including the signal level of the analog signal is
A reference voltage selecting means for selecting a corresponding reference voltage, and an analog signal from the signal output means,
Amplify under the reference voltage selected by the reference voltage selection means.
Amplifying means, an output signal from the amplifying means and the signal output means.
Analog signals are input, and each signal is
A / A which converts it into a digital signal according to the signal level and outputs it
Move the D-converter and zoom lens between the retracted position and the wide-end position.
In the movement range of the movable cylinder to be moved, a plurality of data from the A / D converter
Of digital signals, analog signals from the signal output means
Select the one that corresponds to the number and set the zoom lens to the wide end.
In the range of movement of the movable barrel that moves between the
Contains the signal level of the analog signal from the signal output means.
Amplifier amplified under the reference voltage corresponding to the
Signal selection means to select the signal corresponding to the output signal from the stage
And a digital signal selected by the signal selecting means.
Zui by the zoom lens apparatus characterized by comprising: a position specifying means for specifying a movement position of the movable cylinder, the.