JP2000356733A - Camera device - Google Patents

Abstract

(57) [Summary] [Problem] Even when the output from an MR sensor fluctuates,
The output of the MR sensor is made constant by adjusting the gain and the offset. A drive mechanism (13) for moving a movable lens (25) in the optical axis direction, a magnet group (31) attached to the movable lens (25) moved by the drive mechanism (13), and an MR mounted on a lens barrel facing the magnet group (31). Sensor 3
2 and D / A for adjusting the gain of the output of the MR sensor 32
A converter 36, a differential amplifier 33 for adjusting the offset of the output of the sensor 32, and gain control data and a differential amplifier 3 for controlling the output gain of the sensor 32 to a predetermined gain.
3 generates offset control data that does not apply an offset voltage such that the output of the sensor 32 is output as it is,
A position detection circuit that supplies the gain control data to the D / A converter and supplies the offset control data to the differential amplifier 33;

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detection magnetic head and a magnet mounting position at the time of manufacturing by adjusting a gain and an offset of a sensor using a position detection magnetic head used for position detection of a movable lens. The present invention relates to a camera device that can obtain substantially the same output of a position detecting magnetic head without depending on the variation of the position detection magnetic head.

[0002]

2. Description of the Related Art In a video camera apparatus, an objective lens and an image pickup device are provided in a lens barrel, and a movable lens such as a zoom lens and a focus lens is provided between the objective lens and the image pickup device. ing. The detection of the position of the movable lens is performed by a position detection sensor including a position detection element attached to the lens barrel serving as a fixed portion and a magnet group attached to the movable lens.

In order to accurately detect the position of a movable lens, it is necessary to accurately attach a position detecting element and a group of magnets to predetermined positions. Therefore, the video camera device is provided with a mechanical adjustment mechanism for finely adjusting the mounting positions of the position detection element and the magnet group. At the time of manufacture, the video camera device was shipped after adjusting the mounting positions of the position detecting element and the magnet group one by one while observing the output of the position detecting element.

[0004]

However, as described above, when adjusting the mounting position of the position detecting element and the magnet group constituting the sensor by using the mechanical adjustment mechanism, each of the video camera devices is provided with a mechanical device. It is necessary to provide a dynamic adjustment mechanism, and to adjust the mounting position of the position detection element and the magnet group for each video camera device. For this reason, it has not been possible to reduce the size, simplification, and cost of the video camera device.

The output of the position detecting element of the sensor may fluctuate due to temperature changes during the day and night, summer and winter, and aging of characteristics. In this case, the position of the movable lens cannot be accurately detected due to the output fluctuation of the position detecting element. However, the adjustment of the mounting position of the position detecting element and the magnet group is only performed by the adjusting mechanism while observing the sensor output at the time of manufacturing, and it is troublesome to readjust the output of the position detecting element.

In particular, in recent years, the video camera device has been increased in the number of pixels and downsized. For this reason, in this type of video camera device, since it is required to move the movable lens to a desired position with high accuracy in a short time as possible, position detection of the movable lens is very important. High accuracy is required for the detection.

In view of the above, the present invention makes the output of the position detecting magnetic head constant by adjusting the gain and the offset even when the output from the position detecting magnetic head fluctuates due to temperature change and aging. It is an object to provide a camera device that can accurately detect the position of a movable lens.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a camera device according to the present invention has a lens driving means for moving at least one movable lens in the direction of the optical axis, and a lens driving means for moving the movable lens. A magnet attached to a movable lens or a lens barrel provided with a movable lens, a position detecting magnetic head opposed to the magnet and attached to the lens barrel or a movable lens, and an output gain of the position detecting magnetic head are adjusted. And a control means for generating gain control data so that the output gain of the position detecting magnetic head becomes a predetermined gain, and supplying the generated gain control data to the gain adjustment means.

In order to solve the above-mentioned problems, a camera device according to the present invention has a lens driving means for moving at least one movable lens in an optical axis direction, and a movable lens or a movable lens moved by the lens driving means. A magnet attached to a barrel provided with a movable lens, a position detecting magnetic head opposed to the magnet and attached to the barrel or the movable lens, and offset adjusting means for adjusting an output offset of the position detecting magnetic head And offset control means for generating offset control data such that the offset of the output of the position detecting magnetic head becomes a predetermined voltage, and supplying the offset control data to the offset adjustment means.

Further, in order to solve the above-mentioned problems, a camera device according to the present invention has a lens driving means for moving at least one movable lens in an optical axis direction, and a movable lens or a movable lens which is moved by the lens driving means. A magnet attached to a lens barrel provided with a movable lens, a position detecting magnetic head opposed to the magnet and attached to the lens barrel or the movable lens, and gain adjusting means for adjusting an output gain of the position detecting magnetic head And offset adjustment means for adjusting the output offset of the position detection magnetic head; and generating gain control data such that the output gain of the position detection magnetic head becomes a predetermined gain, and supplying the generated gain control data to the gain adjustment means. The offset control means controls the offset control data so that the output offset of the position detecting magnetic head becomes a predetermined voltage. It generates data, and a control means for supplying the offset adjusting unit.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a video camera device to which the present invention is applied will be described with reference to the drawings.

This video camera device is reduced in size to a portable size, and is formed in a substantially rectangular shape as a whole.
An imaging unit 1 for imaging a subject is provided on a front surface of the video camera device. This imaging unit 1 is configured as shown in FIG.
As shown in (1), a plurality of fixed lenses and a movable lens are arranged in a lens barrel 2 serving as a fixed portion so that their optical axes are aligned.
Specifically, an objective lens 3 as a fixed lens and a fixed lens group 4 including a plurality of fixed lenses are disposed in the lens barrel 2, and a movable lens is provided between the objective lens 3 and the fixed lens group 4. Is provided, and a fixed lens group 4 is provided.
A focus lens 7, which is a movable lens, is provided between the camera and the image sensor 6.

The objective lens 3, which is a fixed lens, is mounted on a mounting plate 3a. The mounting plate 3a is mounted on the lens barrel 2 so as to face outward from the lens barrel 2. The fixed lens group 4 is also attached to the attachment plate 4a, and attached to the lens barrel 2 by an attachment mechanism (not shown). The image sensor 6 is, for example, a CCD (charge cou
and is fixedly attached to the attachment plate 6a.

The zoom lens 5, which is a movable lens, is mounted on a mounting plate 5a. A guide hole (not shown) is formed at one end of the mounting plate 5a, and a guide shaft 8 disposed substantially parallel to the optical axis in the lens barrel 2 is inserted into the guide hole. A guide member 9 is attached to the other end of the mounting plate 5a, and a guide shaft 11 arranged in the lens barrel 2 in parallel with the optical axis is inserted through the guide member 9. The focus lens 7 which is a movable lens is
It is attached to the attachment plate 7a. A guide hole (not shown) is formed at one end of the mounting plate 7a, and a guide shaft 8 is inserted into the guide hole. The guide member 12 is attached to the other end of the attachment plate 7a.
The guide shaft 11 is inserted through the guide member 12. That is, the zoom lens 5 and the focus lens 7
Is mounted in the lens barrel 2 so as to be movable in the optical axis direction in the lens barrel 2 by being supported by guide shafts 8 and 11 parallel to the optical axis via mounting plates 5a and 7a.

The zoom lens 5 and the focus lens 7 are moved in the optical axis direction by driving mechanisms 13 and 14 as shown in FIG. The drive mechanism 13 for moving the zoom lens 5 and the drive mechanism 14 for moving the focus lens 57 are disposed on the guide shaft 11 side, and both are composed of linear motors. Since the driving mechanism 13 and the driving mechanism 14 have the same configuration, the same reference numerals will be given below for the description.

The driving mechanisms 13 and 14 include guide members 9 and 1
2, the voice coils 15, 15 attached to the
, And a magnetic circuit portion 16, which is composed of a magnet and a yoke attached to the magnetic circuit portion. When the driving signals are supplied to the voice coils 15, the driving mechanisms 13, 14 generate a driving force (Lorentz force) in the optical axis direction, and move the zoom lens 5 and the focus lens 7 in the optical axis direction.

The current flowing through the voice coils 15 constituting the driving mechanisms 13 is supplied to the zoom lens 5.
And the position of the focus lens 7 is controlled based on the outputs of the position detection mechanisms 21 and 22 respectively. That is, in the video camera device to which the present invention is applied, the current position, moving speed, acceleration, and the like of the zoom lens 5 and the focus lens 7 are calculated based on the outputs of the position detection mechanisms 21 and 22, and these data are fed back. While performing servo control to control the drive current. Since it is required that the zoom lens 5 and the focus lens 7 be accurately moved to desired positions in the shortest possible time, the positions of the zoom lens 5 and the focus lens 7 are very important. Requires high precision.

Here, these position detecting mechanisms 21 and 22 are used.
Will be described. Since the position detection mechanism 21 for the zoom lens and the position detection mechanism 22 for the focus lens have the same structure, they are simply described as a position detection mechanism 30 as shown in FIG. The lens 7 is simply the movable lens 2
Explanation is made as 5.

As shown in FIGS. 2 and 3, the position detecting mechanism 30 includes a magnet group 31 connected to the movable lens 25.
And sensors 32 a and 32 b provided in the lens barrel 2 so as to face the magnet group 31. Then, the magnet group 31 moves with the movement of the movable lens, whereby the magnet group 31 and the sensors 32a and 32b relatively move.

The magnet group 31 includes, as shown in FIG.
Each of the magnets 31a has a width of λ / 2, and the adjacent magnets 31a are arranged in close contact with each other so that the directions of magnetization are opposite. Considering the fine adjustment required for the movable lens 25, λ is 200 μm
３２０320 μm, for example, 200 μm. The entire length of the magnet group 31 is the same as that of the movable lens 2.
5, ie, the movable range of the zoom lens 5 or the focus lens 7.

As shown in FIG. 3, the sensor 32a includes two magnetoresistive elements (hereinafter, referred to as MR elements) 32a ₁ and 32a ₂ formed on the substrate 29, for example, as thin films, and these are connected in series with each other. Connected, one end of which is power supply V
cc, the other end is connected to ground G,
The connection point of the _two MR elements 32a ₁ and 32a ₂ is the sensor 32a
Output. Similarly, the sensor 32b also includes two MR elements 32b ₁ and 32b ₂ connected in series, one end of which is connected to the power supply Vcc, the other end is connected to the ground G, and the connection point is the output of the sensor 32b. I have. Also,
As shown in FIG. 4, assuming that λ / 4 is 360 degrees, the MR elements 32a ₁ and 32b ₁ and the MR elements 32a ₂ and 32b ₂ are arranged 360 degrees, that is, λ / 4 apart, and The MR element 32a ₁ and the MR element 32b ₁
Degrees, that is, λ / 16. Specifically, the distance between the MR element 32a ₁ and the MR element 32 b ₁ is approximately 50 [mu] m.

As shown in FIG. 5, the position detecting mechanism 30 includes a differential amplifier 3 for applying an offset voltage to the outputs of the sensors 32a and 32b (hereinafter simply referred to as the sensor 32).
3, an analog / digital converter (hereinafter, referred to as an A / D converter) 34 for converting the output of the differential amplifier 33 into position data, and a driving mechanism based on the position data from the A / D converter 34. Voice coil 1 that constitutes 13 and 14
A position calculation circuit 35 that controls the drive current flowing through the sensors 5 and 15 and outputs control data for controlling the power supply voltage and offset voltage of the sensor 32, and converts the control data from the position calculation circuit 35 into an analog voltage. A digital / analog converter (hereinafter, referred to as a D / A converter) 36.

Then, for the sensors 32a and 32b,
When the magnet group 31 is relatively moved, the sensor 32
a and 32b, as shown in FIG.
A signal (hereinafter, referred to as an A-phase signal and a B-phase signal) that is approximately 0 degrees shifted and approximately approximated to a sine wave with a period of λ is output. These A-phase signal and B-phase signal are supplied to a differential amplifier 33 as shown in FIG.

The differential amplifier 33 subtracts an offset voltage to be described later from the A-phase signal and the B-phase signal, and outputs the result of the subtraction to the A / D signal.
It is supplied to a converter 34. The A / D converter 34 converts the A-phase signal and the B-phase signal to which the offset voltage is added, for example, into 8-bit data, and supplies the data to the position calculation circuit 35.

The position calculation circuit 35 is composed of, for example, a microprocessor, and switches the two-phase data based on the data from the A / D converter 34 at the intersection thereof, for example, the position, movement direction, and movement of the movable lens. The speed and acceleration are calculated, and zoom control data for moving the zoom lens 5 is generated so that the angle of view is set, for example, by a user operation, and the output of a focus sensor (not shown) is set to 0. Then, focus control data for moving the focus lens is generated. That is, when the output level of the sensor is close to the maximum value, the change in the output level of the sensor is small with respect to the change in the position of the movable lens. However, in this video camera to which the present invention is applied, two sensors 3 are used.
2a and 32b are arranged so that the output phase is 90 degrees, and the outputs of the sensors 32a and 32b are intersected at their intersections.
The switching is performed so that a signal having high sensitivity to the position is always obtained. Thereby, the movable lens 25 can be accurately moved to a target position.

Further, the position calculation circuit 35 determines whether the mounting of the sensor 32 and / or the magnet group 31 is different for each video camera device, and the MR elements 32a ₁ , 32a ₂ , 32b ₁ , 32.
In consideration of the temperature characteristics of b ₂ and / or the temperature characteristics of the magnet 31a and aging, gain control data and offset control data for controlling a gain and an offset voltage of the sensor 32 described later are generated.

The D / A converter 35 converts these control data into analog voltages, applies them to the sensors 32a and 32b, and supplies them to the differential amplifier 33. The microprocessor may be of a type having a built-in A / D converter or D / A converter. In this case, an external A / D converter 34 and / or a D / A converter may be used. 36 is unnecessary.

The specific operation of the position detection circuit 35 will be described with reference to the flowchart shown in FIG.

For example, when the user turns on the power of the video camera device, in step S1, the position calculation circuit 35 is turned on.
Is the gain control data V _gain1 such that the gain of the sensor 32 becomes a predetermined gain, and the differential amplifier 33
The offset control data _Voffset0 which does not add the offset voltage which outputs the output of the second as it is is generated,
It is supplied to the D / A converter 36. The D / A converter 36 receives the gain control data V _gain1 , the offset control data V
_offset0 were each converted to a voltage analog, and supplies the sensor 32 a voltage based on the gain control data V _gain1 as a power supply voltage, the offset control data V
A voltage based on _offset0 , that is, 0 volt, is supplied to the negative input terminal of the differential amplifier 33.

By the way, the output of sensor 32 is proportional to the voltage applied to the MR element 32a ₁ ~32b _2. Therefore, the voltage applied to the sensor 32 immediately after the power is turned on is constant in any video camera device. However, as described above, the attachment of the sensor 32 and / or the magnet group 31 is different for each video camera device. Since they are different, the output of the sensor 32 for each video camera device, that is, the data input to the position calculation circuit 35 is different.

In step S2, the position calculation circuit 35
Moves the movable lens 25 at least two times from the reference position.
At this time, control is performed so as to obtain 00 μm, that is, an A-phase signal and a B-phase signal for at least one cycle, and the maximum value and the minimum value of the output of the sensor 32 obtained at this time are stored as MAX ₁ and MIN ₁ . .

In step S3, the position calculation circuit 35
Generates the _gain control data V _gain2 and the offset control data V _offset0 and supplies them to the D / A converter 36.

In step S4, the position calculation circuit 35
Performs the control to move the movable lens 25 again so as to obtain the A-phase signal and the B-phase signal for at least one cycle, and determines the maximum value and the minimum value of the output of the sensor 32 obtained at this time by MAX ₂ and MIN. Remember as ₂ .

In step S5, the position calculation circuit 36
Calculates the gain V _gain according to the following equation 1, supplies the gain V _gain to the D / A converter 36 as gain control data,
The offset voltage V _offset is calculated according to the following equation 2 and supplied to the negative input terminal of the differential amplifier 33 as offset control data.

V _gain = {(V _top −V _bottom ) − (MAX ₁ −MIN ₁ )} {(MAX ₂ −MIN ₂ ) − (MAX ₁ −MIN ₁ )} × (V _{gain 2} −V _{gain 1} ) + V _gain1 · · · formula _{1 V offset = (V top +} V bottom) / 2- (V gain -V gain1) ÷ (V gain1 -V gain2) × {(MAX 1 + MIN 1) / 2 - (MAX 2 + MIN 2) / 2｝ + (MAX ₁ + MIN ₁ ) / 2 + V _{offset 0} Equation 2 Here, V _top and V _bottom are predetermined voltages required for the output of the sensor 32. That is, the position calculation circuit 36
_{Calculates the} rate of increase in the output amplitude of the sensor 32 when the gain control data is changed from _Vgain1 to _Vgain2 , as shown in FIG. Gain control data V _gain and offset control data V for setting the output amplitude to (V _top −V _{bot tom} )
_{Find offset} . Thus, the sensor 32 during manufacture
Even if the mounting of the magnet group 31 and the like vary for each video camera device, after the power is turned on and the above-described processing is performed, substantially the same sensor output is obtained in all the video cameras. . In other words, the mechanical adjustment of the attachment of the sensor 32 and the magnet group 31, which is conventionally required at the time of manufacturing, can be eliminated. Further, for example, fluctuations in sensor output due to temperature changes during the day and night, summer and winter, and aging of characteristics can be constantly calibrated at the time of use.

Then, the position calculation circuit 35 controls the sensor 32 calibrated as described above, that is, the sensors 32a and 32a.
2b, the position, the moving direction, the moving speed, and the acceleration of the movable lens 25 are detected as described above based on the A-phase signal and the B-phase signal, and the movable lens 25 is moved to a desired position as quickly as possible. Control to move with high accuracy. More specifically, the position calculation circuit 35 uses a high-accuracy portion of the A-phase signal and the B-phase signal, that is, switches a signal used at the intersection of the A-phase signal and the B-phase signal to remove a steep portion. Control to accurately move the movable lens to a target position.

In order to take the data of the A-phase signal and the B-phase signal into the position calculation circuit 35, the A / D converter 34
Is used, the fetched data is discrete, and depending on the sampling frequency of the A / D converter 34, the intersection of the A-phase signal and the B-phase signal may not be accurately detected. Therefore, in the video camera device to which the present invention is applied, the number of samples held in the position calculation circuit 35 is at least one cycle of the A-phase signal and the B-phase signal,
As shown in FIG. 6 described above, the switching level between the A-phase signal and the B-phase signal is determined based on the switching level above the A phase, the switching level below the A phase, the switching level above the B phase obtained by interpolation, B obtained by interpolation
It is performed at the switching level below the phase. In the video camera device to which the present invention is applied, for example, the magnet group 31 is mounted obliquely with respect to the sensor 32, and the difference in the relative position of the sensor 32 with respect to the magnet group 31 causes the difference between the A-phase signal and the B-phase signal. In order to prevent the maximum value (amplitude) from fluctuating, the A-phase signal and the B-phase signal are always normalized by, for example, 256 bits by associating the maximum value and the minimum value with 0 and 255, for example.

Here, a specific example of the normalization and switching operation of the A-phase signal and the B-phase signal in the position calculation circuit 35 will be described with reference to the flowchart shown in FIG.

In step S11, the position calculation circuit 3
5 is a differential amplifier 3 for offset adjustment from the sensor 32.
3 and the data of the A-phase signal and the B-phase signal input through the A / D converter 34 (hereinafter, each data is referred to as a sample value) for at least one cycle or more, and the A-phase signal And whether each sample value of the B-phase signal is larger than the respective maximum value obtained before (hereinafter, referred to as the A-phase previous maximum value and the B-phase previous maximum value), The process proceeds to S12, and if not, the process proceeds to step S13.

In step S12, the position calculation circuit 3
5 holds the sample values of the A-phase signal and the B-phase signal larger than the previous maximum value of the A-phase and the B-phase, respectively, as new maximum values, and proceeds to step S13.

In step S13, the position calculation circuit 3
5 determines whether each sample value of the A-phase signal and the B-phase signal is smaller than the preceding minimum value of the A-phase and the preceding minimum value of the B-phase, respectively. If so, the process proceeds to step S15.

In step S14, the position calculation circuit 3
5 holds the sample values of the A-phase signal and the B-phase signal smaller than the previous minimum value of the A phase and the minimum value of the B phase, respectively, as new minimum values, and proceeds to step S15.

In step S15, the position calculation circuit 3
5 normalizes each sample value of the A-phase signal and the B-phase signal based on the maximum value and the minimum value obtained in steps S12 and S14, and proceeds to step S16. In other words, the position calculation circuit 35 is mounted, for example, with the magnet group 31 and the sensor 32 inclined relative to each other by the processing of steps S11 to S15, and by the difference in the relative position of the sensor 32 with respect to the magnet group 31, Even when the output amplitude fluctuates, it is possible to obtain an A-phase signal and a B-phase signal whose maximum value and minimum value are always constant.

Steps S11 to S1
In the process 4, there is a possibility that noise larger than the maximum value is erroneously held. Therefore, the following processing is provided in the video camera device to which the present invention is applied.

That is, in step S16, the position calculation circuit 35 determines whether or not the sample value of the A-phase signal is the center value of the amplitude of the A-phase signal.
If not, go to step S19.

In step S17, the position calculation circuit 3
5 determines whether the sample value of the B-phase signal corresponding to the sample value of the A-phase signal, which is the center value of the amplitude, is greater than the center value of the amplitude of the B-phase signal.
The process proceeds to step S19, and if not, the process proceeds to step S19.

In step S18, the position calculation circuit 3
Step 5 sets the current sample value of the B-phase signal as the maximum value of the B-phase signal, and proceeds to step S19.

In step S19, the position calculation circuit 3
Step 5 determines whether the sample value of the B-phase signal is the center value of the amplitude of the B-phase signal. If the sample value is applicable, the process proceeds to step S20; otherwise, the process proceeds to step S22.

In step S20, the position calculation circuit 3
5 judges whether the sample value of the A-phase signal corresponding to the sample value of the B-phase signal, which is the center value of the amplitude, is larger than the center value of the amplitude of the A-phase signal.
The process proceeds to step S1, and if not, the process proceeds to step S22.

In step S21, the position calculation circuit 3
5 sets the current sample value of the A-phase signal as the maximum value of the A-phase signal, and proceeds to step S22.

In step S22, step S18
And the maximum and minimum values obtained in step 21,
After normalizing each sample value of the phase signal and the B-phase signal, the process proceeds to step S23. That is, since the phase of the A-phase signal and the phase of the B-phase signal differ by 90 degrees, when one of them is the center value of the amplitude, the other is the maximum value or the minimum value. Therefore, the position calculation circuit 35 performs steps S11 to S11.
Even if the noise is mistakenly held as the maximum value of the A-phase signal or the B-phase signal in the processing of step 15,
Through the processing of Step 21, the correct maximum value of each phase signal can be obtained.

As described above, the A-phase signal and the B-phase signal are fetched into the position calculation circuit 35 as discrete sample values, and it is possible to accurately specify the intersection of the A-phase signal and the B-phase signal. Can not. Therefore, in the video camera to which the present invention is applied, switching between the A-phase signal and the B-phase signal is performed by the following processing.

In step S23, the position calculation circuit 3
5, as shown in FIG. 10, as compared to the switching level CrossA ₁ on the A-phase of each sample value is sequentially predetermined level, when the current sample value to determine over a switch level CrossA _1, the appropriate Proceeds to step S24, otherwise proceeds to step S27.

In step S24, the position calculation circuit 3
Step 5 determines whether the current sample value of the B-phase signal is larger than the center value of the amplitude of the B-phase signal. If the current sample value is applicable, the process proceeds to step S25, and if not, the process proceeds to step S26.

In step S25, the position calculation circuit 3
5, before the sample value and interpolation of the current sample value, for example, by the following equation 3, and calculates the switching level CURB ₁ on the B-phase, the process proceeds to step 27.

CurB ₁ = curB − {(crossA−curA) (curB−prevB)} / {(prevA−curA)} Equation 3 where crossA is the switching level of the A phase, and FIG. switching level CrossA ₁ or switching level CrossA ₂ below the top of the a-phase indicated is substituted, Preva, p
As shown in FIG. 10, revB, curA, and curB are a previous sample value of the A phase, a previous sample value of the B phase, a current sample value of the A phase, and a current sample value of the B phase.

On the other hand, in step S 26, the position calculation circuit 35 calculates the lower switching level “cur” of the B-phase according to Expression 3.
To calculate the B _2, the process proceeds to step S27.

In step S27, the position calculation circuit 3
5, compared with the switching level CrossA ₂ below the A phase of each sample value is sequentially predetermined level, it is determined whether the current sample value is below the switching level CrossA _2, applicable when the process proceeds to step S28, the corresponding If not, the process proceeds to step S31.

In step S28, the position calculation circuit 3
Step 5 determines whether the current sample value of the B-phase signal is larger than the center value of the amplitude of the B-phase signal. If the current sample value is applicable, the process proceeds to step S29. If not, the process proceeds to step S30.

In step S29, the position calculation circuit 3
5 calculates the upper switching level curB ₁ above the B phase by the equation 3, and proceeds to step 31.

On the other hand, in step S30, the position calculation circuit 35 calculates the lower switching level cur of the B phase according to the equation (3).
To calculate the B _2, the process proceeds to step S31.

In step S31, the position calculation circuit 3
5 shows the sample values of the A-phase signal and the B-phase signal
Normalization is performed at the upper and lower switching levels of the phase to obtain position data.

That is, in the video camera to which the present invention is applied, two initializations, ie, normalization based on the maximum value and the minimum value and normalization based on the upper and lower switching levels are performed, and the A-phase after the first normalization is performed. And the voltage at the position where the values of the B and B phases are substantially the same, that is, the voltage is held as the switching level of the A phase, and during the normal operation after the initialization operation, the switching level of the A phase is updated. Absent. And the switching level of the B phase is
A comparison is made between the previous sample value obtained in the previous normalization of the A phase during the normal operation and the current sample value, and this is set as the level when the switching level of the A phase is straddled.

Since the video camera apparatus switches the A-phase signal and the B-phase signal as described above, the position of the movable lens 25 can be accurately detected. Accordingly, the movable lens 30 can be moved smoothly, and generation of acoustic noise due to deterioration of the positional accuracy of the movable lens 30 can be prevented. In particular, in a video camera device which is miniaturized to a portable size and in which the positions of the drive mechanisms 13 and 14 and the microphones are extremely close to each other, acoustic noise is not collected by the microphones. is there.

The video camera apparatus to which the present invention has been applied has been described with reference to the drawings. However, the present invention is not limited to this, and may be applied to a so-called digital camera apparatus for photographing a still image. Can be. Also,
In the above-described example, the case where the sensor is attached to the lens barrel 2 and the magnet group is attached to the movable lens has been described. On the contrary, the sensor is attached to the movable lens and the magnet group is attached to the lens barrel. You may do it.

[0066]

According to the present invention, gain adjustment means for adjusting the output gain of the position detection magnetic head and / or offset adjustment means for adjusting the output offset of the position detection magnetic head are provided. Therefore, the output of the magnetic head for position detection can be made constant. Therefore, even if there is a variation in the mounting of the position detecting magnetic head and / or the magnet at the time of manufacturing for each camera device, it is possible to obtain the output of the position detecting magnetic head substantially equal to all the camera devices. Therefore, the mechanical adjustment of the mounting of the position detecting magnetic head and / or the magnet which is conventionally required at the time of manufacturing can be eliminated,
In addition, since the output fluctuation of the position detecting magnetic head due to a temperature change, a secular change of characteristics, and the like can be calibrated at the time of use, the position of the movable lens can be accurately detected.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a lens barrel of a video camera device to which the present invention has been applied.

FIG. 2 is a side view of a main part of a driving mechanism of the movable lens.

FIG. 3 is a perspective view of a position detection mechanism that detects a position of a movable lens.

FIG. 4 is a side view showing a relationship between a sensor constituting a position detecting mechanism and a magnet group.

FIG. 5 is a block diagram illustrating a control system of a position detection mechanism.

FIG. 6 is a diagram showing output characteristics of a two-phase sensor.

FIG. 7 is a flowchart showing a procedure for adjusting a gain / offset.

FIG. 8 is a diagram showing a gain of a sensor and an output level of the sensor.

FIG. 9 is a flowchart illustrating a switching procedure of a two-phase sensor.

FIG. 10 is a diagram illustrating an example of calculating a B-phase switching voltage.

[Explanation of symbols]

Reference Signs List 1 imaging unit, 2 lens barrel, 3 objective lens, 4 fixed lens group, 5 zoom lens, 6 image sensor, 7 focus lens, 13, 14 drive mechanism (linear motor), 2
1, 22 position detecting mechanism, 31 magnet, 32a,
32b MR element, 34 A / D converter, 35 position detection circuit, 36 D / A converter

[Procedure amendment]

[Submission date] July 22, 1999 (July 7, 1999
2)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

[Title of the Invention] Camera device

[Claims]

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detection magnetic head and a magnet mounting position at the time of manufacturing by adjusting a gain and an offset of a sensor using a position detection magnetic head used for position detection of a movable lens. The present invention relates to a camera device that can obtain substantially the same output of a position detecting magnetic head without depending on the variation of the position detection magnetic head.

[0002]

2. Description of the Related Art In a video camera apparatus, an objective lens and an image pickup device are provided in a lens barrel, and a movable lens such as a zoom lens and a focus lens is provided between the objective lens and the image pickup device. ing. The detection of the position of the movable lens is performed by a position detection sensor including a position detection element attached to the lens barrel serving as a fixed portion and a magnet attached to the movable lens.

In order to accurately detect the position of a movable lens, it is necessary to accurately attach a position detecting element and a magnet to predetermined positions. Therefore, the video camera device is provided with a mechanical adjustment mechanism for finely adjusting the mounting position of the position detecting element or the magnet. At the time of manufacturing, the video camera device was shipped after adjusting the mounting positions of the position detecting element and the magnet one by one while observing the output of the position detecting element.

[0004]

However, when the position of the position detecting element or the magnet constituting the sensor is adjusted by using the mechanical adjustment mechanism as described above, each of the video camera devices is mechanically adjusted. It is necessary to provide a simple adjustment mechanism, and to adjust the mounting position of the position detecting element and the magnet for each video camera device. For this reason, it has not been possible to reduce the size, simplification, and cost of the video camera device.

The output of the position detecting element of the sensor may fluctuate due to temperature changes during the day and night, summer and winter, and aging of characteristics. In this case, the position of the movable lens cannot be accurately detected due to the output fluctuation of the position detecting element. However, the adjustment of the mounting position of the position detecting element and the magnet is only performed by the adjusting mechanism while observing the sensor output at the time of manufacturing, and it is troublesome to readjust the output of the position detecting element.

In particular, in recent years, the video camera device has been increased in the number of pixels and downsized. For this reason, in this type of video camera device, since it is required to move the movable lens to a desired position with high accuracy in a short time as possible, position detection of the movable lens is very important. High accuracy is required for the detection.

In view of the above, the present invention makes the output of the position detecting magnetic head constant by adjusting the gain and the offset even when the output from the position detecting magnetic head fluctuates due to temperature change and aging. It is an object to provide a camera device that can accurately detect the position of a movable lens.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a camera device according to the present invention has a lens driving means for moving at least one movable lens in the direction of the optical axis, and a lens driving means for moving the movable lens. A magnet attached to a movable lens or a lens barrel provided with a movable lens, a position detecting magnetic head opposed to the magnet and attached to the lens barrel or a movable lens, and an output gain of the position detecting magnetic head are adjusted. And a control means for generating gain control data so that the output gain of the position detecting magnetic head becomes a predetermined gain, and supplying the generated gain control data to the gain adjustment means.

In order to solve the above-mentioned problems, a camera device according to the present invention has a lens driving means for moving at least one movable lens in an optical axis direction, and a movable lens or a movable lens moved by the lens driving means. A magnet attached to a barrel provided with a movable lens, a position detecting magnetic head opposed to the magnet and attached to the barrel or the movable lens, and offset adjusting means for adjusting an output offset of the position detecting magnetic head And offset control means for generating offset control data such that the offset of the output of the position detecting magnetic head becomes a predetermined voltage, and supplying the offset control data to the offset adjustment means.

Further, in order to solve the above-mentioned problems, the camera device according to the present invention has a lens driving means for moving at least one movable lens in the optical axis direction, and a movable lens or a movable lens moved by the lens driving means. A magnet attached to a lens barrel provided with a movable lens, a position detecting magnetic head opposed to the magnet and attached to the lens barrel or the movable lens, and gain adjusting means for adjusting an output gain of the position detecting magnetic head And offset adjustment means for adjusting the offset of the output of the position detection magnetic head; and generating gain control data so that the output gain of the position detection magnetic head becomes a predetermined gain, and supplying the generated gain control data to the gain adjustment means. The offset control means controls the offset control data so that the output offset of the position detecting magnetic head becomes a predetermined voltage. It generates data, and a control means for supplying the offset adjusting unit.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a video camera device to which the present invention is applied will be described with reference to the drawings.

This video camera device is reduced in size to a portable size, and is formed in a substantially rectangular shape as a whole.
An imaging unit 1 for imaging a subject is provided on a front surface of the video camera device. This imaging unit 1 is configured as shown in FIG.
As shown in (1), a plurality of fixed lenses and a movable lens are arranged in a lens barrel 2 serving as a fixed portion so that their optical axes are aligned.
Specifically, an objective lens 3 as a fixed lens and a fixed lens group 4 including a plurality of fixed lenses are disposed in the lens barrel 2, and a movable lens is provided between the objective lens 3 and the fixed lens group 4. Is provided, and a fixed lens group 4 is provided.
A focus lens 7, which is a movable lens, is provided between the camera and the image sensor 6.

The objective lens 3, which is a fixed lens, is mounted on a mounting plate 3a. The mounting plate 3a is mounted on the lens barrel 2 so as to face outward from the lens barrel 2. The fixed lens group 4 is also attached to the attachment plate 4a, and attached to the lens barrel 2 by an attachment mechanism (not shown). The image sensor 6 is, for example, a CCD (charge cou
and is fixedly attached to the attachment plate 6a.

The zoom lens 5, which is a movable lens, is mounted on a mounting plate 5a. A guide hole (not shown) is formed at one end of the mounting plate 5a, and a guide shaft 8 disposed substantially parallel to the optical axis in the lens barrel 2 is inserted into the guide hole. A guide member 9 is attached to the other end of the mounting plate 5a, and a guide shaft 11 arranged in the lens barrel 2 in parallel with the optical axis is inserted through the guide member 9. The focus lens 7 which is a movable lens is
It is attached to the attachment plate 7a. A guide hole (not shown) is formed at one end of the mounting plate 7a, and a guide shaft 8 is inserted into the guide hole. The guide member 12 is attached to the other end of the attachment plate 7a.
The guide shaft 11 is inserted through the guide member 12. That is, the zoom lens 5 and the focus lens 7
Is mounted in the lens barrel 2 so as to be movable in the optical axis direction in the lens barrel 2 by being supported by guide shafts 8 and 11 parallel to the optical axis via mounting plates 5a and 7a.

The zoom lens 5 and the focus lens 7 are moved in the optical axis direction by driving mechanisms 13 and 14 as shown in FIG. A drive mechanism 13 for moving the zoom lens 5 and a drive mechanism 14 for moving the focus lens 7 are disposed on the guide shaft 11 side, and both are composed of linear motors. Since the driving mechanism 13 and the driving mechanism 14 have the same configuration, the same reference numerals will be given below for the description.

The driving mechanisms 13 and 14 include guide members 9 and 1
2, the voice coils 15, 15 attached to the
, And a magnetic circuit portion 16, which is composed of a magnet and a yoke attached to the magnetic circuit portion. When the driving signals are supplied to the voice coils 15, the driving mechanisms 13, 14 generate a driving force (Lorentz force) in the optical axis direction, and move the zoom lens 5 and the focus lens 7 in the optical axis direction.

The current flowing through the voice coils 15 constituting the driving mechanisms 13 is supplied to the zoom lens 5.
And the position of the focus lens 7 is controlled based on the outputs of the position detection mechanisms 21 and 22 respectively. That is, in the video camera device to which the present invention is applied, the current position, moving speed, acceleration, and the like of the zoom lens 5 and the focus lens 7 are calculated based on the outputs of the position detection mechanisms 21 and 22, and these data are fed back. While performing servo control to control the drive current. Since it is required that the zoom lens 5 and the focus lens 7 be accurately moved to desired positions in the shortest possible time, the positions of the zoom lens 5 and the focus lens 7 are very important. Requires high precision.

Here, these position detecting mechanisms 21 and 22 are used.
Will be described. Since the position detection mechanism 21 for the zoom lens and the position detection mechanism 22 for the focus lens have the same structure, they are simply described as a position detection mechanism 30 as shown in FIG. The lens 7 is simply the movable lens 2
Explanation is made as 5.

The position detecting mechanism 30 includes a magnet 31 connected to the movable lens 25, as shown in FIGS.
And sensors 32 a and 32 b provided in the lens barrel 2 so as to face the magnet 31. Then, the magnet 31 moves with the movement of the movable lens, whereby the magnet 31 and the sensors 32a and 32b move relatively.

As shown in FIG. 3, the magnet 31 is composed of a plurality of magnetic poles 31a each having a width of λ / 2, and the adjacent magnetic poles 31a have magnetization directions opposite to each other. Considering the fine adjustment required for the movable lens 25, λ is 200 μm to 320 μm, for example, 2 μm.
00 μm. Further, the entire length of the magnet 31 corresponds to the movable range of the movable lens 25, that is, the movable range of the zoom lens 5 or the focus lens 7.

As shown in FIG. 3, the sensor 32a includes two magnetoresistive elements (hereinafter, referred to as MR elements) 32a1 and 32a2 formed on the substrate 29, for example, as thin films, which are connected in series with each other. , One end of which is power supply V
cc, the other end is connected to ground G,
The connection point of the two MR elements 32a1 and 32a2 is the sensor 32
a. Similarly, the sensor 32b includes two MR elements 32b1 and 32b2 connected in series.
One end is connected to the power supply Vcc, the other end is connected to the ground G, and the connection point is the output of the sensor 32b. As shown in FIG. 4, if λ / 4 is 180 degrees, M
R elements 32a1, 32b1 and MR elements 32a2, 32b
2 are arranged at an integer multiple of 180 degrees, that is, at an integer multiple of λ / 4.
And the MR element 32b1 are arranged at a distance of 90 degrees, that is, an integer multiple of λ / 8. Specifically, the MR element 32a1
And the distance between the MR element 32b1 is approximately 50 μm.

As shown in FIG. 5, the position detecting mechanism 30 includes a differential amplifier 3 for applying an offset voltage to the outputs of the sensors 32a and 32b (hereinafter simply referred to as the sensor 32).
3, an analog / digital converter (hereinafter, referred to as an A / D converter) 34 for converting the output of the differential amplifier 33 into position data, and a driving mechanism based on the position data from the A / D converter 34. Voice coil 1 that constitutes 13 and 14
A position calculation circuit 35 that controls the drive current flowing through the sensors 5 and 15 and outputs control data for controlling the power supply voltage and offset voltage of the sensor 32, and converts the control data from the position calculation circuit 35 into an analog voltage. A digital / analog converter (hereinafter, referred to as a D / A converter) 36.

Then, for the sensors 32a and 32b,
When the magnet 31 is relatively moved, the sensors 32a,
From FIG. 32b, as shown in FIG. 6, a signal whose phase is shifted from each other by 90 degrees and whose period is approximately approximated to a sine wave of λ (hereinafter, A
A phase signal is called a B-phase signal. ) Is output. These A
The phase signal and the B-phase signal are, as shown in FIG.
3 is supplied.

The differential amplifier 33 subtracts an offset voltage to be described later from the A-phase signal and the B-phase signal, and outputs the result of the subtraction to the A / D signal.
It is supplied to a converter 34. The A / D converter 34 converts the A-phase signal and the B-phase signal to which the offset voltage is added, for example, into 8-bit data, and supplies the data to the position calculation circuit 35.

The position calculation circuit 35 is composed of, for example, a microprocessor, and switches the two-phase data based on the data from the A / D converter 34 at the intersection thereof, for example, the position, movement direction, and movement of the movable lens. The speed and acceleration are calculated, and zoom control data for moving the zoom lens 5 is generated so that the angle of view is set, for example, by a user operation, and the output of a focus sensor (not shown) is set to 0. Then, focus control data for moving the focus lens is generated. That is, when the output level of the sensor is close to the maximum value, the change in the output level of the sensor is small with respect to the change in the position of the movable lens. In this video camera device to which the present invention is applied, the two sensors 32a and 32b are connected. The output of each sensor 32a, 32b is switched at the intersection thereof so that a signal with high position sensitivity is always obtained. Thereby, the movable lens 25 can be accurately moved to a target position.

The position calculation circuit 35 is used to determine whether the sensors 32 and / or the magnets 31 vary from one video camera device to another, and the MR elements 32a1, 32a2, 32b1, 32
In consideration of b2 and / or temperature characteristics and aging of the magnet 31, gain control data and offset control data for controlling a gain and an offset voltage of the sensor 32 described later are generated.

The D / A converter 35 converts these control data into analog voltages, applies them to the sensors 32a and 32b, and supplies them to the differential amplifier 33. The microprocessor may be of a type having a built-in A / D converter or D / A converter. In this case, an external A / D converter 34 and / or a D / A converter may be used. 36 is unnecessary.

The specific operation of the position detection circuit 35 will be described with reference to the flowchart shown in FIG.

For example, when the user turns on the power of the video camera device, in step S1, the position calculation circuit 35 is turned on.
Generates gain control data Vgain1 such that the gain of the sensor 32 becomes a predetermined gain, and offset control data Voffset0 that does not apply an offset voltage such that the differential amplifier 33 outputs the output of the sensor 32 as it is, It is supplied to the D / A converter 36. The D / A converter 36 converts the gain control data Vgain1 and the offset control data Voffset0 into analog voltages, respectively, supplies a voltage based on the gain control data Vgain1 to the sensor 32 as a power supply voltage, and supplies the offset control data Voffset0 to the offset control data Voffset0. A voltage based on the voltage, that is, 0 volt, is supplied to the negative input terminal of the differential amplifier 33.

The output of the sensor 32 is proportional to the voltage applied to the MR elements 32a1 to 32b2. Therefore, the voltage applied to the sensor 32 immediately after the power is turned on is constant in any video camera device. However, as described above, the attachment of the sensor 32 and / or the magnet 31 differs for each video camera device. Therefore, the output of the sensor 32 for each video camera device, that is, the data input to the position calculation circuit 35 is different.

In step S2, the position calculation circuit 35
Moves the movable lens 25 at least two times from the reference position.
Control is performed to move the sensor 32 so as to obtain 00 μm, that is, an A-phase signal and a B-phase signal for at least one cycle, and the maximum and minimum values of the output of the sensor 32 obtained at this time are stored as MAX1 and MIN1.

In step S3, the position calculation circuit 35
Generates the gain control data Vgain2 and the offset control data Voffset0 and supplies them to the D / A converter 36.

In step S4, the position calculation circuit 35
Performs control to move the movable lens 25 again so as to obtain an A-phase signal and a B-phase signal for at least one cycle. The maximum value and the minimum value of the output of the sensor 32 obtained at this time are defined as MAX2 and MIN2. Remember.

In step S5, the position calculation circuit 36
Calculates the gain Vgain according to the following equation 1, supplies the gain Vgain to the D / A converter 36 as gain control data, calculates the offset voltage Voffset according to the following equation 2, and uses the negative input terminal of the differential amplifier 33 as the offset control data. To supply.

Vgain = {(Vtop−Vbottom) − (MAX1-MIN1)} {(MAX2-MIN2) − (MAX1-MIN1)} × (Vgain2−Vgain1) + Vgain1 (1) Voffset = (Vtop + Vbottom) / 2- (Vgain-Vgain1) {(Vgain1−Vgain2) × {(MAX1 + MIN1) / 2− (MAX2 + MIN2) / 2} + (MAX1 + MIN1) / 2 + Voffset0 where Vtop and Vbottom are sensors 32 This is a predetermined voltage required for output. That is, the position calculation circuit 36 calculates the rate of increase in the output amplitude of the sensor 32 when the gain control data is changed from Vgain1 to Vgain2 as shown in FIG. , The output amplitude of the sensor 32 is (Vto
p-Vbottom) gain control data Vgai
n and offset control data Voffset are obtained. Thus, even if there is a variation in the attachment of the sensor 32 and / or the magnet 31 at the time of manufacturing for each video camera device, after the power is turned on and the above-described processing is performed,
Substantially equal sensor outputs are obtained in all video camera devices. In other words, the mechanical adjustment of the attachment of the sensor 32 and the magnet 31, which is conventionally required at the time of manufacturing, can be eliminated. Further, for example, fluctuations in sensor output due to temperature changes during the day and night, summer and winter, and aging of characteristics can be constantly calibrated at the time of use.

Then, the position calculation circuit 35 controls the sensor 32 calibrated as described above, that is, the sensors 32a and 32a.
2b, the position, the moving direction, the moving speed, and the acceleration of the movable lens 25 are detected as described above based on the A-phase signal and the B-phase signal, and the movable lens 25 is moved to a desired position as quickly as possible. Control to move with high accuracy. More specifically, the position calculation circuit 35 uses a high-accuracy portion of the A-phase signal and the B-phase signal, that is, switches a signal used at the intersection of the A-phase signal and the B-phase signal to remove a steep portion. Control to accurately move the movable lens to a target position.

In order to take the data of the A-phase signal and the B-phase signal into the position calculation circuit 35, the A / D converter 34
Is used, the fetched data is discrete, and depending on the sampling frequency of the A / D converter 34, the intersection of the A-phase signal and the B-phase signal may not be accurately detected. Therefore, in the video camera device to which the present invention is applied, the number of samples held in the position calculation circuit 35 is at least one cycle of the A-phase signal and the B-phase signal,
As shown in FIG. 6 described above, the switching level between the A-phase signal and the B-phase signal is determined based on the switching level above the A phase, the switching level below the A phase, the switching level above the B phase obtained by interpolation, B obtained by interpolation
It is performed at the switching level below the phase. Further, in the video camera device to which the present invention is applied, for example, the magnet 31 is mounted obliquely with respect to the sensor 32, and the maximum value of the A-phase signal and the B-phase signal depends on the relative position of the sensor 32 with respect to the magnet 31. In order to prevent the (amplitude) from fluctuating, the A-phase signal and the B-phase signal are always normalized with 256 bits by associating the maximum value and the minimum value with 0 and 255, for example.

Here, a specific example of the normalization and switching operation of the A-phase signal and the B-phase signal in the position calculation circuit 35 will be described with reference to the flowchart shown in FIG.

In step S11, the position calculation circuit 3
5 is a differential amplifier 3 for offset adjustment from the sensor 32.
3 and the data of the A-phase signal and the B-phase signal input through the A / D converter 34 (hereinafter, each data is referred to as a sample value) for at least one cycle or more, and the A-phase signal And whether each sample value of the B-phase signal is larger than the respective maximum value obtained before (hereinafter, referred to as the A-phase previous maximum value and the B-phase previous maximum value), The process proceeds to S12, and if not, the process proceeds to step S13.

In step S12, the position calculation circuit 3
5 holds the sample values of the A-phase signal and the B-phase signal larger than the previous maximum value of the A-phase and the B-phase, respectively, as new maximum values, and proceeds to step S13.

In step S13, the position calculation circuit 3
5 determines whether each sample value of the A-phase signal and the B-phase signal is smaller than the preceding minimum value of the A-phase and the preceding minimum value of the B-phase, respectively. If so, the process proceeds to step S15.

In step S14, the position calculation circuit 3
5 holds the sample values of the A-phase signal and the B-phase signal smaller than the previous minimum value of the A phase and the minimum value of the B phase, respectively, as new minimum values, and proceeds to step S15.

In step S15, the position calculation circuit 3
5 normalizes each sample value of the A-phase signal and the B-phase signal based on the maximum value and the minimum value obtained in steps S12 and S14, and proceeds to step S16. In other words, the position calculation circuit 35 is mounted in such a manner that the magnet 31 and the sensor 32 are attached to the sensor 31 in a relatively inclined manner by the processing of steps S11 to S15.
Even if the output amplitude of the sensor 32 fluctuates due to the difference in the relative position with respect to, the A-phase signal and the B-phase signal whose maximum value and minimum value are always constant can be obtained.

Steps S11 to S1
In the process 4, there is a possibility that noise larger than the maximum value is erroneously held. Therefore, the following processing is provided in the video camera device to which the present invention is applied.

That is, in step S16, the position calculation circuit 35 determines whether or not the sample value of the A-phase signal is the center value of the amplitude of the A-phase signal.
If not, go to step S19.

In step S17, the position calculation circuit 3
5 determines whether the sample value of the B-phase signal corresponding to the sample value of the A-phase signal, which is the center value of the amplitude, is greater than the center value of the amplitude of the B-phase signal.
The process proceeds to step S19, and if not, the process proceeds to step S19.

In step S18, the position calculation circuit 3
Step 5 sets the current sample value of the B-phase signal as the maximum value of the B-phase signal, and proceeds to step S19.

In step S19, the position calculation circuit 3
Step 5 determines whether the sample value of the B-phase signal is the center value of the amplitude of the B-phase signal. If the sample value is applicable, the process proceeds to step S20; otherwise, the process proceeds to step S22.

In step S20, the position calculation circuit 3
5 judges whether the sample value of the A-phase signal corresponding to the sample value of the B-phase signal, which is the center value of the amplitude, is larger than the center value of the amplitude of the A-phase signal.
The process proceeds to step S1, and if not, the process proceeds to step S22.

In step S21, the position calculation circuit 3
5 sets the current sample value of the A-phase signal as the maximum value of the A-phase signal, and proceeds to step S22.

In step S22, step S18
And the maximum and minimum values obtained in step 21,
After normalizing each sample value of the phase signal and the B-phase signal, the process proceeds to step S23. That is, since the phase of the A-phase signal and the phase of the B-phase signal are different from each other by 90 degrees, when one of them is the center value of the amplitude, the other is the maximum value or the minimum value. Therefore, even if the noise is erroneously held as the maximum value of the A-phase signal or the B-phase signal in the processing of steps S11 to S15,
The correct maximum value of each phase signal can be obtained by the processes from 6 to 21.

As described above, the A-phase signal and the B-phase signal are fetched into the position calculation circuit 35 as discrete sample values, and it is possible to accurately specify the intersection of the A-phase signal and the B-phase signal. Can not. Therefore, in the video camera device to which the present invention is applied, switching between the A-phase signal and the B-phase signal is performed by the following processing.

In step S23, the position calculation circuit 3
5, as shown in FIG. 10, each sample value is sequentially compared with the switching level crossA1 above the A-phase which is a predetermined level, and it is determined whether the current sample value has exceeded the switching level crossA1. Proceed to step S24,
If not, the process proceeds to step S27.

In step S24, the position calculation circuit 3
Step 5 determines whether the current sample value of the B-phase signal is larger than the center value of the amplitude of the B-phase signal. If the current sample value is applicable, the process proceeds to step S25, and if not, the process proceeds to step S26.

In step S25, the position calculation circuit 3
5 calculates the switching level curB1 above the B phase by interpolation of the previous sample value and the current sample value, for example, by the following equation 3, and proceeds to step 27.

CurB1 = curB-{(crossA-curA) (curB-prevB)} / {(prevA-curA)} Equation 3 where crossA is the switching level of the A phase and is shown in FIG. The upper switching level crossA1 or the lower switching level crossA2 of the A phase is substituted, and prevA, p
As shown in FIG. 10, revB, curA, and curB are a previous sample value of the A phase, a previous sample value of the B phase, a current sample value of the A phase, and a current sample value of the B phase.

On the other hand, in step S 26, the position calculation circuit 35 calculates the lower switching level “cur” of the B-phase according to Expression 3.
B2 is calculated, and the process proceeds to step S27.

In step S27, the position calculation circuit 3
5 sequentially compares each sample value with the switching level crossA2 below the predetermined phase A, and determines whether or not the current sample value has fallen below the switching level crossA2. Goes to step S31.

In step S28, the position calculation circuit 3
Step 5 determines whether the current sample value of the B-phase signal is larger than the center value of the amplitude of the B-phase signal. If the current sample value is applicable, the process proceeds to step S29. If not, the process proceeds to step S30.

In step S29, the position calculation circuit 3
5 calculates the switching level curB1 above the B phase by using the equation 3, and proceeds to step 31.

On the other hand, in step S30, the position calculation circuit 35 calculates the lower switching level cur of the B phase according to the equation (3).
B2 is calculated, and the process proceeds to step S31.

In step S31, the position calculation circuit 3
5 normalizes each sample value of the A-phase signal and the B-phase signal by the upper and lower switching levels of the A-phase and the B-phase to obtain position data.

That is, in the video camera apparatus to which the present invention is applied, two initializations, ie, normalization based on the maximum value and the minimum value and normalization based on the upper and lower switching levels are performed, and A after the first normalization is performed. The level at the position where the values of the phase and the B phase are substantially the same, that is, the voltage is held as the switching level of the A phase, and during the normal operation after the initialization operation, the switching level of the A phase is updated. Not performed. The switching level of the B phase is compared with the previous sample value obtained by the previous normalization of the A phase during the normal operation and the current sample value, and the level when the switching level of the A phase is straddled is compared. And

Since the video camera apparatus switches the A-phase signal and the B-phase signal as described above, the position of the movable lens 25 can be accurately detected. Accordingly, the movable lens 30 can be moved smoothly, and generation of acoustic noise due to deterioration of the positional accuracy of the movable lens 30 can be prevented. In particular, in a video camera device which is miniaturized to a portable size and in which the positions of the drive mechanisms 13 and 14 and the microphones are extremely close to each other, acoustic noise is not collected by the microphones. is there.

The video camera apparatus to which the present invention has been applied has been described with reference to the drawings. However, the present invention is not limited to this, and may be applied to a so-called digital camera apparatus for photographing a still image. Can be. Also,
In the above-described example, the case where the sensor is attached to the lens barrel 2 and the magnet is attached to the movable lens has been described. Conversely, the sensor is attached to the movable lens, and the magnet is attached to the lens barrel. May be.

[0066]

According to the present invention, gain adjustment means for adjusting the output gain of the position detection magnetic head and / or offset adjustment means for adjusting the output offset of the position detection magnetic head are provided. Therefore, the output of the magnetic head for position detection can be made constant. Therefore, even if there is a variation in the mounting of the position detecting magnetic head and / or the magnet at the time of manufacturing for each camera device, it is possible to obtain the output of the position detecting magnetic head substantially equal to all the camera devices. Therefore, the mechanical adjustment of the mounting of the position detecting magnetic head and / or the magnet which is conventionally required at the time of manufacturing can be eliminated,
In addition, since the output fluctuation of the position detecting magnetic head due to a temperature change, a secular change of characteristics, and the like can be calibrated at the time of use, the position of the movable lens can be accurately detected.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a lens barrel of a video camera device to which the present invention has been applied.

FIG. 2 is a side view of a main part of a driving mechanism of the movable lens.

FIG. 3 is a perspective view of a position detection mechanism that detects a position of a movable lens.

FIG. 4 is a side view showing a relationship between a sensor constituting a position detection mechanism and a magnet.

FIG. 5 is a block diagram illustrating a control system of a position detection mechanism.

FIG. 6 is a diagram showing output characteristics of a two-phase sensor.

FIG. 7 is a flowchart showing a procedure for adjusting a gain / offset.

FIG. 8 is a diagram showing a gain of a sensor and an output level of the sensor.

FIG. 9 is a flowchart illustrating a switching procedure of a two-phase sensor.

FIG. 10 is a diagram illustrating an example of calculating a B-phase switching voltage.

[Description of Signs] 1 imaging unit, 2 lens barrel, 3 objective lens, 4 fixed lens group, 5 zoom lens, 6 image sensor, 7 focus lens, 13, 14 drive mechanism (linear motor), 2
1, 22 position detecting mechanism, 31 magnet, 32a,
32b MR element, 34 A / D converter, 35 position calculation circuit, 36 D / A converter

Claims (6)

[Claims] 1. A lens driving means for moving at least one movable lens in the optical axis direction; a magnet attached to the movable lens moved by the lens driving means or a lens barrel provided with the movable lens; A position detecting magnetic head attached to the lens barrel or the movable lens so as to face the magnet, gain adjusting means for adjusting a gain of an output of the position detecting magnetic head, and an output of the position detecting magnetic head. A camera device comprising: a control unit that generates gain control data such that the gain becomes a predetermined gain and supplies the data to the gain adjustment unit. 2. The apparatus according to claim 1, wherein said gain adjusting means comprises a digital / analog converter for adjusting a voltage applied to said magnetic head for position detection based on said gain control data from said control means. Camera device. 3. A lens driving means for moving at least one movable lens in the optical axis direction; a magnet attached to the movable lens moved by the lens driving means or a lens barrel provided with the movable lens; A position detecting magnetic head attached to the lens barrel or the movable lens so as to face the magnet; an offset adjusting unit for adjusting an offset of an output of the position detecting magnetic head; A camera device comprising: a control unit that generates offset control data such that an offset of an output of a magnetic head becomes a predetermined voltage and supplies the offset control data to the offset adjustment unit. 4. The offset adjusting means comprises a differential amplifier to which an output of the magnetic head for position detection is inputted to one input terminal and a DC voltage is inputted to another input terminal. Item 4. The camera device according to item 3. 5. A lens driving means for moving at least one movable lens in an optical axis direction; a magnet attached to the movable lens moved by the lens driving means or a lens barrel provided with the movable lens; A position detecting magnetic head attached to the lens barrel or the movable lens so as to face the magnet; gain adjusting means for adjusting a gain of an output of the position detecting magnetic head; and an output of the position detecting magnetic head. Offset adjusting means for adjusting the offset; and generating gain control data such that the gain of the output of the position detecting magnetic head becomes a predetermined gain, and supplying the generated gain control data to the gain adjusting means. Generates offset control data so that the output offset of the magnetic head for detection becomes a predetermined voltage A camera device and a control means for supplying said offset adjusting means. 6. The gain adjusting means comprises a digital / analog converter for adjusting a voltage applied to the position detecting magnetic head with the gain control data from the control means. 6. The camera device according to claim 5, further comprising a differential amplifier to which an output of the magnetic head for position detection is input to an input terminal and a DC voltage is input to another input terminal.