JP2003114370A - Zoom lens device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make detectable and also correctable a step-out caused by an external load, etc., in a zoom lens device equipped with a collapsible lens which is driven by a stepping motor. SOLUTION: The zoom lens device is provided with a control part 21 for performing an initialization processing of moving the collapsible lens to an initial position when a power source is turned on based on a detection signal by a potentiometer 15 for detecting a zoom position. The comparison of the present zoom position information detected by the potentiometer 15 with zoom position information stored by an EEPROM 28 is performed by the control part 21 at a zooming operation, and in the case the difference is equal to or exceeding a threshold, the zoom position correcting processing is performed by the control part 21.

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 mounted on an image pickup device such as a single-lens reflex camera, a digital still camera and a video camera having a zoom function for changing an angle of view, and more particularly to a collapsible lens driven by a stepping motor. The present invention relates to a zoom lens device equipped with an adjustable lens.

[0002]

2. Description of the Related Art Conventionally, image pickup devices such as single-lens reflex cameras, digital still cameras and video cameras having a zoom function for changing the angle of view have been known.

In an image pickup apparatus having the above zoom function, a collapsible zoom lens apparatus that has been put into practical use in the past has a retractable lens barrel, a stepping motor for driving the lens barrel, and a lens barrel position. It is composed of a detection element for detecting.

[0004]

By the way, from the past,
In the collapsible zoom lens device having the above-described configuration used in the image pickup apparatus having the zoom function, when an external force is applied to the lens barrel, 1. If an external force is applied at startup, the zoom position will not reach the startup position. 2. When an external force is applied during the normal zoom operation, the normal zoom magnification may not be achieved and the focus may not be focused. 3. If external force is applied at the end, the lens barrel is not stored. There was a problem such as.

Further, since the position is not fixed until the lens barrel position detecting element is detected, in a lens in which the positional relationship between the focus lens and the zoom lens interferes, the initial time at power-on becomes long, etc. There was a problem.

Therefore, an object of the present invention is to detect step-out caused by an external load in a zoom lens device equipped with a retractable lens driven by a stepping motor,
It is possible to make further correction.

[0007]

According to the present invention, in a zoom lens device equipped with a retractable lens driven by a stepping motor, an analog position detecting element capable of detecting the absolute zoom position is used to generate an external load. It is possible to detect a step out that occurs and further correct it.

According to the present invention, in a zoom lens device equipped with a collapsible lens driven by a stepping motor, an analog position detecting element for detecting a zoom position and a signal detected by the analog position detecting element when the power is turned on are used. And a control means for performing an initialization process for moving the retractable lens to the initial position.

The zoom lens device is provided with a storage means for storing zoom position information previously detected by the analog position detecting element, and the control means controls the current position detected by the analog position detecting element during zoom operation. The zoom position information is compared with the zoom position information stored in the storage means, and if there is a difference equal to or larger than the threshold value, the zoom position correction process is performed.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

The zoom lens device according to the present invention has a retractable lens driven by a stepping motor, and is moved in the optical axis direction by a focus motor 11 using a stepping motor, as shown in FIG. 1, for example. A focus lens 12, a zoom lens 14 moved in the optical axis direction by a zoom motor 13 using a stepping motor, and a potentiometer 15 as an analog position detecting element for detecting the zoom position of the zoom lens 14. Be prepared.

The zoom lens device 10 is mounted on a digital still camera (not shown), and the focus control motor 11 and the zoom motor 13 are drive-controlled by the drive control circuit 20 having the configuration shown in FIG.

The drive control circuit 20 includes a control unit 21 using a CPU, a focus pulse generation circuit 22 for converting a focus drive instruction from the control unit 21 into a pulse, and a focus pulse generated by the focus pulse generation circuit 22. Accordingly, a focus drive circuit 23 for driving the focus motor 11 and a zoom pulse generation circuit 2 for pulse-converting a zoom drive instruction from the control unit 21.
4. A zoom drive circuit 25 for driving the zoom motor 13 in response to a zoom pulse generated by the zoom pulse generation circuit 24. An analog detection signal of the zoom position by the potentiometer 15 is digitized to control the control section 2 described above.
1 is composed of an AD conversion circuit 26, a RAM 27 and an EEPROM 28 connected to the control unit 21.

FIG. 3 shows a graph of the potentiometer output at each zoom position. FIG. 3 illustrates the potentiometer output from the retracted end to the wide end to the telephoto end of the retractable lens, which usually has a hysteresis characteristic due to mechanical clearance or the like.

The step-out detection in the drive control circuit 20 of the zoom lens apparatus 10 is carried out when the difference between the potentiometer output in each zoom position and zoom direction and the zoom position based on the conventional position detecting element is equal to or more than a threshold value. , By changing to the zoom position based on the potentiometer output.

That is, the control unit 21 in the drive control circuit 20 of the zoom lens device 10 performs a series of control operations shown in the flowcharts of FIGS.

Since the output of the potentiometer output at each zoom position differs for each set due to variations in mounting on the lens and the like, the control unit 21 in the drive control circuit 20 of this zoom lens device 10 is shown in FIG. According to the procedure shown in the flowchart, the potentiometer output at each zoom position is measured and stored in the nonvolatile RAM. That is, the control unit 21 in the drive control circuit 20 of the zoom lens device 10 activates the zoom reset sensor in the first processing step S1 and adjusts the zoom lens 14 in the next processing step S2 at the time of factory adjustment. It is moved to the wide end, and the potentiometer output P1 at the wide end is read in the next processing step S3.

Then, in the next processing step S4, the zoom lens 14 is moved to the telephoto end at the zoom position Zmn (n = 2, 3).
... n), and the potentiometer output Pn at the zoom position Zmn is read in the next processing step S5.

In the next processing step S6, it is determined whether or not the zoom lens 14 has reached the telephoto end position. When the determination result in this processing step S6 is NO, that is, when the tele end position has not been reached, the processing returns to the processing step S4, and the processing steps S4 to S6 are repeated. When the determination result in the processing step S6 is YES, that is, when the tele end position is reached, the process proceeds to the next processing step S7.

In processing step S7, the zoom lens 14
Zoom position Zm '(n) from the tele end to the collapse end
It is moved to (n = n−1 ... 1, 0), and the potentiometer output P ′ (n) at the zoom position Zmn ′ is read in the next processing step S8.

In the next processing step S9, it is determined whether or not the zoom lens 14 has reached the retracted end position. When the determination result in this processing step S9 is NO, that is, when the collapsing end position has not been reached, the processing returns to the processing step S7, and the processing steps S7 to S9 are repeated. Then, when the determination result in the processing step S9 is YES, that is, when the collapsing end position is reached, the process proceeds to the next processing step S10.

Then, in processing step S10, the control section 21 controls the potentiometer outputs P0 to Pn, P corresponding to the respective zoom positions Zm0 to Zmn, Zm'n-1 to Zm'0 read as described above. 'n-1 to P'0 are stored in the EEPROM 28, and the shipping adjustment process is completed.

Further, the control unit 21 in the drive control circuit 20 of the zoom lens apparatus 10 performs the power-on process of the digital still camera according to the procedure shown in the flowchart of FIG. FIG. 5 shows, as an example, the flow when moving to the wide end for zoom and to the infinite position for focus. In the case of a lens in which zoom and focus interfere with each other, it takes time for the same process because the absolute position cannot be determined until the position detection sensor is detected only by the conventional position detection element having only a photo interrupter. However, in this zoom lens device 10, since the position can be determined immediately after the power is turned on by mounting the potentiometer 15, that is, the analog type position detecting element, the processing time can be shortened.

That is, the control unit 21 in the drive control circuit 20 of the zoom lens device 10 is in the interference region shown in FIG. 1 in the first process step S11 in the power-on process of the digital still camera. Determine whether or not. If the determination result in this processing step S11 is YES, that is, if the zoom lens 14 is located in the interference region, the process proceeds to the next processing step S12 and the process shown in FIG.
The zoom lens 14 is evacuated to the stable region shown in (4) and the process proceeds to the next processing step S13. Also, the above processing step S
The determination result in 11 is NO, that is, the zoom lens 14
Is not in the interference area, the processing step S13 is immediately performed.
Proceed to.

Then, in processing step S13, the focus lens 12 is moved from the retracted end position in the tele end direction to perform focus reset detection.

In the next processing step S14, the focus lens 12 is evacuated to a stable area.

In the next processing step S15, zoom reset detection is performed.

Then, the control section 21 moves the zoom lens 14 to the initializing position in the next processing step S16, and further moves the focus lens 12 to the initializing position in the next processing step S17 to turn on the power source. The processing at the time of input is ended.

As described above, the control unit 21 in the drive control circuit 20 of the zoom lens device 10 can determine the lens position immediately after the power is turned on, so that the time for the lens initialization process when the power is turned on can be shortened.

Further, the control unit 21 in the drive control circuit 20 of the zoom lens device 10 performs the step-out correction process according to the procedure shown in the flowchart of FIG. 6 during the zoom operation of the digital still camera.

That is, the control unit 21 in the drive control circuit 20 of the zoom lens device 10 first performs the first processing step S when zooming the digital still camera.
In 21, it is determined whether or not it is during the period exhibiting the hysteresis characteristic. If the determination result in this processing step S21 is NO, that is, if it is not during the hysteresis period, the process ends without performing the step-out correction process.
Then, the determination result in this processing step S21 is Y
If ES, that is, during the hysteresis period, the process proceeds to the next process step S22 to determine the zoom direction.

As a result of the determination in the processing step S22, when the zoom operation is performed from the tele end side to the wide end side, P'which is stored in the EEPROM 28 as potentiometer adjustment data in the processing step S23.
With reference to n-1 to P'0, the adjusting potentiometer value Pm at the current zoom position is obtained in processing step S25. Further, when the zoom operation is performed from the wide end side to the tele end side, P0 to Pn stored in the EEPROM 28 as the potentiometer adjustment data are referred to in the processing step S24, and the current processing is performed in the processing step S25. An adjustment potentiometer value Pm at the zoom position is obtained.

In the next processing step S26, the absolute value D = ABS (Pm-Pn) of the difference between the potentiating value Pm during adjustment and the potentiating value Pn at the current zoom position is calculated. In S27, the absolute value D
Is greater than or equal to the threshold value.

Then, if the determination result in the processing step S27 is YES, that is, if the absolute value D is equal to or more than the threshold value, the control section 21 determines that zoom out-of-step has occurred, and the next processing step S28. In step S3, step out correction is performed by changing the zoom position, and the step out correction processing ends. If the determination result in the process step S27 is NO, that is, if the absolute value D is not equal to or more than the threshold value, the process ends without performing the step-out correction.

As described above, the controller 21 in the drive control circuit 20 of the zoom lens device 10 compares the difference between the potentiometer output at the current zoom position and the potentiometer output data at the time of shipment to determine the threshold value. If there is a difference equal to or more than the value, it is determined that zoom out-of-step has occurred and step-out correction is performed. The shipping potentiometer output at an arbitrary zoom position can be calculated, for example, by calculation such as linear interpolation. By this operation, the position correction in the stepping motor, which was the conventional open loop control, becomes possible. That is, by comparing the potentiometer output at the time of shipment with the potentiometer output of the current zoom lens device 10, it is possible to correct the step-out which occurs when an external load is applied to the lens. Therefore, it becomes possible to prevent the zoom position shift in the stepping motor.

[0036]

As described above, according to the present invention,
By providing the analog output position detection element, the zoom position can be fixed at all times (even before the origin is detected), so the initial processing when turning on the power of the lens that has a structure where the zoom and the focus interfere is accelerated. can do. Further, it becomes possible to perform zoom position correction for step-out that occurs when an external load is applied to the lens.

[0037]

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a configuration of a main part of a zoom lens device according to the present invention.

FIG. 2 is a block diagram showing a configuration of a device drive control circuit of the zoom lens.

FIG. 3 is a graph of potentiometer output at each zoom position of the zoom lens device.

FIG. 4 is a flowchart showing a procedure of a shipping adjustment process executed by a control unit in the shipping adjustment of the zoom lens device.

FIG. 5 is a flowchart showing a procedure of power-on processing executed by the control unit when the digital still camera equipped with the zoom lens device is powered on.

FIG. 6 is a flowchart showing a procedure of step-out correction processing executed by the control unit during a zoom operation of a digital still camera equipped with the zoom lens device.

[Explanation of symbols]

10 zoom lens device, 11 focus motor, 1
2 focus lens, 13 zoom motor, 14 zoom lens, 15 potentiometer, 20 drive control circuit, 21 control unit, 22 focus pulse generation circuit,
23 focus drive circuit, 24 zoom pulse generation circuit, 25 zoom drive circuit, 26 AD conversion circuit, 27
RAM, 28 EEPROM

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03B 17/04 G03B 17/04 F term (reference) 2H044 DA02 DB03 DC01 EC01 2H100 EE00 2H101 BB07 DD51

Claims (2)

[Claims] 1. A zoom lens having a retractable lens driven by a stepping motor, wherein the retractable lens is based on an analog position detecting element for detecting a zoom position and a detection signal from the analog position detecting element when the power is turned on. A zoom lens device comprising: a control unit that performs an initialization process of moving a lens to an initial position. 2. A storage means for storing zoom position information previously detected by the analog position detection element, wherein the control means is present zoom position information detected by the analog position detection element during a zoom operation. 2. The zoom lens device according to claim 1, wherein the zoom position information is compared with the zoom position information stored in the storage unit, and if there is a difference equal to or more than a threshold value, a zoom position correction process is performed. .