JP3387658B2 - Lens drive - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a lens driving device used for a camera such as a lens shutter camera.

[0002]

2. Description of the Related Art With the recent miniaturization of cameras, various improved cameras have been proposed. Among them, various mechanisms have been proposed for detecting absolute positions of photographing lenses, focus lenses and the like. Proposals are being made.

For example, as shown in FIG. 4, as a means for detecting the absolute position of a zoom lens, a plurality of switches (hereinafter referred to as "switches") attached with a conduction pattern 4 on a member interlocking with the taking lens barrel 2 and sliding thereon. , Abbreviated as SW), which is provided with a section 3 is well known.

The states of the plurality of SW sections 3 are detected by the control circuit side of the microprocessor 1 or the like, and the absolute position of the taking lens barrel 2 which normally has two or more states is determined. What is schematically shown in FIG. 4 is three SW sections 3 (Z
This is an example using M1, ZM2, ZM3). The SW segment 3 slides on the conduction pattern 4 according to the position of the taking lens barrel 2, and a maximum of eight types of absolute lens positions can be discriminated by distinguishing the conduction and non-conduction patterns.

In FIG. 4, 5 is a CPU, and 6 is a ROM (Read Onl) for storing control programs and control constants.
y Memory), 7 is a RAM (Random Access Memory) for storing calculation results and temporary data, and 8 is a known PWM
PWM (Pulse Widht Modula) for generating energization signal
circuit, 9 is a driver circuit for driving a large current into the lens barrel drive motor 12 by using a PWM energization signal as an input signal, 10 is a timer circuit for measuring time, and 11 is an external input signal and a microprocessor. CPU5 in 1
I / O, such as a multiplexer, between 16 and C
A register provided in the PU 5, 18 is a TELE-SW linked with a telescopic zoom operation button (not shown), and 19 is a WIDE-SW linked with a wide-angle zoom operation button (not shown).

Further, as shown in FIG. 5, a variable resistor 15 interlocking with the taking lens barrel 2 is installed in place of the above-mentioned conduction pattern, and the analog voltage output of this variable resistor 15 is ADIN of the microprocessor 1. It is proposed that the absolute position of the lens is detected by inputting it to a terminal and converting it into a digital value using a known A / D converter 13.

In this case, the mechanism that operates over the entire driving area of the taking lens barrel 2 is only the interlocking portion of the variable resistor 15 and the lens barrel driving mechanism (not shown). Further, it is not necessary to provide a plurality of SW intercept input signal terminals. That is, since only one signal line is required to be input to the microprocessor 1, layout design is facilitated in a camera with many wiring restrictions. In addition, in FIG. 5, 14 is an EEPROM.

Further, as shown in FIG. 6, in addition to the conventional example of FIG. 5, a known D / A converter 16 and the D / A converter are provided.
A configuration in which the output of the converter 16 is used as one input signal and the other input signal is used as an analog voltage signal linked to the variable resistor 15, and the output signal of the comparator 17 is connected to the I / O 11 of the microprocessor 1. Device has been proposed.

In this case, the single signal line to be input to the microprocessor 1 is the same, and it is the same in that the layout design is easy in a camera having many restrictions on wiring and arrangement space. Microprocessor 1
The difference is that the signal input to is a digital logic signal. That is, in the processing program installed in the microprocessor 1, the data corresponding to the desired voltage value calculated in advance by the calculation process is set in the comparator 17 via the D / A converter 16, and the desired data is set in the comparator 17. The voltage value and the analog voltage signal linked to the absolute position of the photographic lens barrel 2 are compared, and the output logic signal is “true”.
This is a method in which only the'false 'judgment is detected by the processing program. Here, the comparator 17 and the D / A converter 1
Since 6 and the like can be integrated on the same chip as the peripheral circuit of the microprocessor 1, no extra space in the camera is required.

FIG. 7 is a flow chart showing the processing during the zooming operation of the microprocessor 1 of FIG. 6, and the sequence will be briefly described below based on this flow chart.

When the TELE-SW 18 linked with a telephoto zoom operation button (not shown) is operated, the microprocessor 1 starts the "ZOOMING TELE" process.

First, in step 701, ADIN
The signal input through the terminal is A / D converted by the A / D converter 13, and in the following step 702, the data corresponding to the current position of the taking lens barrel 2 is written to a location called ZOOM_POS on the RAM 7. . Then, in steps 703 and 704, the value stored in the ZOOM_POS is compared with the data ZOOM_WIDE and ZOOM_TELE corresponding to the WIDE end and the TELE end. Here, these values may be values that have been subjected to a correction calculation using the data of the EEPROM 14 or the like.

As a result of the above comparison, the taking lens barrel 2 is WI.
If it is not between the DE end and the TELE end, "Error routine" is executed in order to execute error processing (not shown).
e ". On the other hand, if it is between the WIDE end and the TELE end, the process proceeds to step 705, and energization of the lens barrel driving motor 12 through the driver circuit 9 in the TELE direction is started. Then, in step 706, the data ZOOM_TELE corresponding to the TELE end is D / A converted.
As a result, one input terminal of the comparator 17 shown in FIG. 6 is set.

Then, in step 707, the TELE-
Check whether SW18 is OFF. As a result, if it is not OFF, the operation button is still pressed, so the process proceeds to step 708, and the output signal of the comparator 17 is checked. If the output of the comparator 17 is inverted, it means that the taking lens barrel 2 has reached the TELE end. Therefore, in steps 709 and 710, the brake energization / energization stop processing is sequentially executed, and this processing ends.
Further, in the above step 707, TELE- (not shown)
If the SW is OFF, immediately step 709,
Proceeding to 710, brake energization and energization stop processing are sequentially executed, and this processing is ended.

That is, when the TELE end is reached,
The brake is energized and the process is terminated at an earlier timing when the SW18 is turned off.

[0016]

By the way, as shown in FIG. 4, a conductive pattern 4 is attached to a member interlocking with the taking lens barrel 2 and a plurality of SW sections 3 which slide on the conductive pattern 4 are provided. Is a simple means as an absolute position detection signal when step-driving the photographing lens barrel 2,
It has the following drawbacks.

1) An error in attaching the conduction pattern 4 to the photographing lens barrel 2 directly affects the lens control. Therefore, an adjusting member or adjustment for mechanically positioning the photographing lens barrel 2 is performed. A process was needed.

2) Providing the conductive pattern 4 and the SW segment 3 was a great constraint in layout design when the camera was downsized.

3) In order to improve the resolution of absolute position detection, the number of SW intercepts 3 must be increased, and 4 to 5
Having a large number of lines is not a practical method in view of the above two points.

Further, as shown in FIG. 5, a variable resistor 15 interlocking with the taking lens barrel 2 is installed, and an analog voltage output of the variable resistor 15 is inputted to the microprocessor 1 to make a known A / D. In the case of detecting the absolute position of the lens by converting it into a digital value by using the converter 13 or the like, the positioning of the photographing lens barrel 2 is performed by electrical signal processing (for example, data stored in the EEPROM 14 is used. Since it is a simple means as an absolute position detection signal of the taking lens barrel 2, it has the following drawbacks when performing step driving.

1) Generally, the photographic lens barrel 2 is driven by a motor 12 and a driver circuit 9 driven by a known PWM circuit 8. These large current load and high frequency noise component generation source operate. In this state, the analog voltage signal interlocked with the variable resistor 15 is also affected by noise and power supply fluctuation, and its reliability accuracy is reduced.

2) This analog voltage signal is usually sampled by the A / D converter 13 in the microprocessor 1.
Although it is converted into a digital value and processed by a software program, as described above, the taking lens barrel 2
Since the reliability of the data during the driving of the
It is necessary to repeatedly perform D conversion and confirm the signal change, and as a result, the control program tends to be complicated.

Further, in the case where the D / A converter 16 and the comparator 17 are added to detect the absolute position of the lens as shown in FIG. It is not necessary to repeatedly perform D conversion or to confirm the signal change, and only the output signal of the comparator 17 needs to be monitored. Therefore, the control program is simplified, and the device eliminates the above-mentioned drawbacks of the conventional examples. However, there are the following problems when performing the step drive.

Data to be set in the D / A converter 16 is
There is a problem that it takes time because it needs to be calculated by calculation according to the current absolute position information of the taking lens barrel 2 and adjustment data unique to the camera. In particular, this problem is serious when a microprocessor that is slow and has poor calculation capability is used as a control circuit, and the calculation time limits the resolution of the lens step drive.

(Object of the Invention) An object of the present invention is to provide a lens driving device capable of performing lens driving control without impairing the responsiveness during step driving.

[0026]

In order to achieve the above object, the present invention provides a lens driving means for driving a lens in the optical axis direction, and a variable resistor for outputting a different voltage depending on the position of the lens. And a plurality of lenses over the entire drive range of the lens
Calculation means for calculating data according to the step driving point of, the storage means for storing the output of the calculation means, the D / A conversion means for D / A converting the data stored in the storage means, and the variable more a comparator for comparing the output of the resistor and the output of the D / a converting means, the said calculating means prior to driving the lens over the driving entire area of the lens
Data corresponding to the step driving point is calculated and output to the storage means, and the stored data is sequentially transferred to the D / D circuit each time the output of the comparator is inverted when the lens is driven.
It is characterized by having control means for controlling so as to output to the A conversion means.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the illustrated embodiments.

FIG. 1 is a block diagram showing a schematic structure of a lens driving device according to a first embodiment of the present invention. The circuit structure is the same as that of FIG. 6 except for the operation (processing) of a microprocessor. Therefore, each constituent element is shown in the 100 series here, and the description thereof is omitted.

FIG. 2 is a flow chart showing the zooming operation of the microprocessor 101 of FIG. 1, which will be described below based on this flow chart.

When the TELE-SW 118 linked with a telephoto zoom operation button (not shown) is operated, the "ZOOM"
"ING TELE" is started.

First, in step 201, ADIN
The signal input through the terminal is A / D converted by the A / D converter 113, and in the subsequent step 202, data corresponding to the current position of the taking lens barrel 102 is stored in the RAM.
Write to the location ZOOM_POS on 107. Then, in steps 203 and 204, the ZOOM
The value stored in _POS and the data ZOOM_WIDE, ZOOM_TEL corresponding to the WIDE end and the TELE end
Compare with E. Here, these values are stored in the EEPROM.
It may be a value that has been corrected using data such as 114. As a result of the above comparison, the taking lens barrel 102 is the WID.
If it is not between the E end and the TELE end, "Error routine" is executed to execute error processing (not shown).
e ".

On the other hand, if it is between the WIDE end and the TELE end, the process proceeds to step 205, and the division number N of the lens barrel stop position (step drive) is determined. This value is ROM1
06 or a predetermined constant stored in the EEPROM 114 or the like, or a value that is variable according to temperature information, power source information, or the like (not shown). Next, in step 206, the RAM 10 is provided with an area for storing the array data ZOOM (i) set in the D / A converter 116.
Secure on 7. Then, the process proceeds to step 207, and the array parameter i is initialized to 1. Then, step 208
In, the value of ZOOM (i), that is, ZOOM (1) is calculated when this step is first reached.

This calculation formula is not particularly limited. For example, if the TELE end and the WIDE end are equally divided, ZOOM (i) = ZOOM_WIDE + (ZOOM_TELE-ZOOM_WIDE) × (i / N) (i = It may be defined by a linear expression such as 1, 2, ..., N).

In step 209, the content of the array parameter i is incremented by 1, and in the next step 210, it is checked whether or not this i exceeds N. N
The above steps 208 to 210 are repeated until the number of times exceeds, but by repeating this (i = 1, 2, ..., N), the array data ZOOM (1) to
ZOOM (N) is sequentially calculated and stored in predetermined addresses.

Then, in step 220, the array parameter is initialized to 1 again. And step 22
1, the A / D corresponding to the current absolute position of the taking lens barrel 102 obtained in steps 201 and 202 above.
The converted data ZOOM_POS and ZOOM (i) are compared. In this example, since the data value increases in the TELE direction, ZOOM (i) becomes ZOOM.
Step 2 until _POS is exceeded or "i>N"
Steps 21, 223 and 224 are repeated. (Here, step 2
Although the check that "i>N" is checked in 24, in step 204, "ZOOM_TELE (= Z
(OOM (N))> ZOOM_POS ”has been confirmed, so it is not always necessary.) Thus, the array parameter i is“ ZOOM (i)> Z
It is set to the minimum value that satisfies "OMM_POS". Next, at step 222, the lens barrel driving motor 112 is energized in the TELE direction via the driver circuit 109. As a result, the taking lens barrel 102 becomes TEL.
Start moving in the E direction. Then, the process proceeds to step 225, and the data of ZOOM (i) designated by the array parameter i is set in the D / A converter. In the following step 226, the output signal of the comparator 117 is checked and waits until it is inverted.

When the taking lens barrel 102 moves in the TELE direction, the partial pressure value of the variable resistor 115 interlocked with this movement rises, and the output of the comparator 117 is inverted, the taking lens barrel 102 moves the ZOOM (i ), The process exits the waiting loop and proceeds to step 227. In step 227, the content of the array parameter i is incremented by 1, and in the next step 228, it is checked whether this i exceeds N. If it does not exceed N, proceed to step 229 and make TELE-S.
It is checked whether W118 is OFF. If it is not OFF, the operation button continues to be pressed. Therefore, the procedure returns to step 225 again, and the above-described procedure is repeated. That is,
As long as the array parameter i does not exceed N, the D / A conversion is sequentially performed each time the output of the comparator 117 is inverted.

The time required for this procedure is set in advance in the array ZOO.
Only the time required to output the calculated value of M (i) by D / A conversion is sufficient. In other words, there is no need to perform recalculation during energization (during lens driving), so that it can be performed at high speed.

Thus, at the timing when the output of the comparator 117 is inverted, the taking lens barrel 2 is set to TEL.
When the end of E is reached or the timing when the TELE-SW 118 is turned off is earlier, brake energization is performed in step 230, and energization stop processing is performed in step 231, and this "ZOOMING TELE" ends.

(Second Embodiment) In the above embodiment, D /
The array data ZOOM (i) to be A-converted is secured in the RAM 107, but if the array is relatively small, it may be secured in the general-purpose register 116 'in the microprocessor 101 as shown in FIG.

In general, transferring the data in the register is faster and more effective than transferring the data in the RAM 107.

According to each of the above-mentioned embodiments, the lens drive control (the absolute position of the lens is controlled by the output signal of the comparator that receives the analog voltage signal from the taking lens barrel and the output signal of the D / A converter as input signals). In the device for detecting), a plurality of data to be set in the D / A converter at the time of step driving are all calculated before the start of energization, and stored in a high-speed access RAM or register, etc. Since this stored value is sometimes used for setting in the D / A converter 117, it becomes possible to perform lens drive control without impairing responsiveness.

(Correspondence between Invention and Embodiment) In this embodiment, the CPU 105 is the calculation means and control means of the present invention.
In addition, the RAM 107 and the register 116 'are the storage means of the present invention.
In addition, the D / A converter 116 is the D / A conversion means of the present invention.
, Respectively .

The above is the correspondence relationship between each configuration of the embodiments and each configuration of the present invention, but the present invention is not limited to the configurations of these embodiments, and the functions or embodiments shown in the claims or the embodiments It goes without saying that any structure may be used as long as it can achieve the function of.

(Modification) The present invention is described as applied to a camera such as a single-lens reflex camera, a lens shutter camera, a video camera, etc. However, other optical devices and other devices,
Furthermore, it can be applied as a constituent unit.

[0045]

As described in the foregoing, according to the present invention, before driving the lens, driving calculation means of the lens
Data corresponding to a plurality of step driving points over the entire moving area is calculated and output to the storage means, and the stored data is sequentially D / D each time the output of the comparator is inverted when the lens is driven.
It is controlled to output to the A conversion means.

Therefore, during lens driving, the position of the lens
No need to calculate data to detect
Even when a microprocessor with a weak force is used, the responsiveness during step driving is not impaired.

[Brief description of drawings]

FIG. 1 is a block diagram showing a lens driving device according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a zooming operation of the microprocessor of FIG.

FIG. 3 is a block diagram showing a lens driving device in a first embodiment of the present invention.

FIG. 4 is a block diagram showing an example of a conventional lens driving device.

FIG. 5 is a block diagram showing another example of a conventional lens driving device.

FIG. 6 is a block diagram showing another example of a conventional lens driving device.

7 is a flowchart showing a zooming operation of the microprocessor of FIG.

[Explanation of symbols]

101 microprocessor 102 Photography lens barrel 105 CPU 106 ROM 107 RAM 109 driver circuit 112 Lens barrel drive motor 115 Variable resistor 116 'register

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G02B ⁷ /02-7/105

Claims (3)

(57) [Claims] 1. A lens driving means for driving a lens in an optical axis direction, a variable resistor for outputting a different voltage depending on the position of the lens, and a plurality of switches over the entire driving range of the lens .
Calculation means for calculating data according to the step driving point, storage means for storing the output of the calculation means, D / A conversion means for D / A converting the data stored in the storage means, and the variable resistor A comparator for comparing the output of the device with the output of the D / A conversion means, and a plurality of switches over the entire driving range of the lens by the calculation means before driving the lens .
Control is performed such that data corresponding to the step driving point is calculated and output to the storage means, and the stored data is sequentially output to the D / A conversion means each time the output of the comparator is inverted when the lens is driven. And a control means for controlling the lens drive device. 2. The lens driving device according to claim 1, wherein the storage unit is a RAM. 3. The lens driving device according to claim 1, wherein the storage means is a register of a microprocessor.