JP5745339B2 - Linear motion device controller - Google Patents

Description

  The present invention relates to a control apparatus and control method for a linear motion device (such as an autofocus lens).

A device in which an input signal and a displacement corresponding to the input signal are expressed by a linear function is also called a linear motion device. Examples of the linear motion device include a camera autofocus lens.
FIG. 13 is a diagram illustrating a conventional control apparatus 10 that controls the linear motion device 11. The control device 10 shown in FIG. 13 includes a magnetic field sensor 13, a voltage command signal generation circuit 14, a differential amplifier 15, and an output driver 12. A linear motion device 11 that is feedback-controlled by the control device 10 is denoted by reference numeral 11 in the drawing. The linear motion device 11 includes a coil 18 and a magnet 19.

  The magnetic field sensor 13 generates a signal based on the detected magnetic field and outputs it as an output signal VMO. The voltage command signal generation circuit 14 generates a voltage command signal VCO based on a signal input from an interface (not shown). The output signal VMO and the voltage command signal VCO are input to the normal input terminal and the reverse input terminal of the differential amplifier 15, respectively. From the differential amplifier 15 to which the output signal VMO and the voltage command signal VCO are input, an operation amount signal VEO representing the operation amount (product of deviation and amplification degree) of the output driver 12 is output.

  The current flowing through the output driver 12 changes depending on the magnitude of the manipulated variable signal VEO, and the current flowing through the coil 18 of the linear motion device 11 changes. The position of the linear motion device 11 including the magnet 19 changes (moves) by the current flowing through the coil 18. At this time, the output signal VMO of the magnetic field sensor 13 changes as the magnet 19 moves. The control device 10 detects the position of the linear motion device 11 based on the change in the output signal VMO, and performs feedback control so that this position matches the position indicated by the signal input from the outside.

  FIG. 14 is a diagram showing the relationship between the magnetic field detected by the magnetic field sensor 13 shown in FIG. 13 (hereinafter also referred to as a detected magnetic field) and the position of the linear motion device 11. In FIG. 14, the magnetic field detected by the magnetic field sensor 13 is shown on the left vertical axis in the drawing, and the value of the output signal VMO of the magnetic field sensor 13 is shown on the right vertical axis in the drawing. A voltage command signal VCO is shown on the further right side of the vertical axis showing the output signal VMO in FIG.

  Further, the horizontal axis of FIG. 14 indicates a position measured from a reference point of a predetermined part in the linear motion device 11. According to the control device 10 illustrated in FIG. 13, when the voltage command signal VCM illustrated in FIG. 14 is given, the control device 10 performs feedback control so that the magnetic field sensor 13 obtains the detected magnetic field BM. By the feedback control, the position of the linear motion device 11 obtains the position XMID.

Incidentally, in the linear motion device 11 shown in FIG. 13, the magnetization of the magnet 19 may vary. Further, in the control device 10, variations in the mounting position of the magnetic field sensor 13 may occur. Due to such variations, the position of the linear motion device 11 and the magnetic field detected by the magnetic field sensor 13 differ from the relationship assumed at the time of design.
FIG. 15 is a diagram showing the relationship between the detected magnetic field and the position of the linear motion device 11. The vertical axis on the left side of FIG. 15 shows the detected magnetic field of the magnetic field sensor 13, and the vertical axis on the right side of the figure shows the output signal of the magnetic field sensor 13. A solid line a in FIG. 15 shows the characteristics shown in FIG. 14, and shows the characteristics when the detected magnetic field and the position of the linear motion device 11 are not shifted (as designed values) for comparison. . An alternate long and short dash line b and an alternate long and two short dashes line c indicate characteristics when there is a shift between the detected magnetic field and the position of the linear motion device 11.

As shown in FIG. 15, when the position of the magnetic field sensor 13 is shifted, the detected magnetic field does not indicate the correct position of the linear motion device 11. For this reason, it turns out that the control apparatus 10 becomes unable to feedback-control the linear motion device 11 appropriately.
For example, there is an invention described in Patent Document 1 as a conventional technique for solving such a problem. FIG. 16 is a diagram for explaining the prior art described in Patent Document 1. In FIG. In the prior art described in Patent Document 1, the minimum value is calculated from the maximum value of the output signal VMO of the magnetic field sensor 13 corresponding to the maximum movement width of the linear motion device 11 (XTOP-XBOT shown in FIG. 16, horizontal axis). Divide equally by the number of steps of the voltage command signal. Then, each of the output ranges of the equally divided magnetic field sensor 13 is set as a fixed step of the voltage command signal with respect to the movement width of the linear motion device 11.
According to the prior art described in Patent Document 1, it is possible to correct the deviation between the position of the linear motion device 11 and the output signal VMO of the magnetic field sensor 13 caused by the magnetization variation of the magnet 19 and the mounting position deviation of the magnetic field sensor 13. .

JP 2006-113874 A

The prior art described in Patent Document 1 described above has the following problems. That is, in the prior art described in Patent Document 1, a fixed step of the voltage command signal is defined for the maximum movement width of each linear motion device. However, there are various cases in the amplitude values of the output signal VMO of the magnetic field sensor 13 and the voltage command signal VCO of the voltage command signal generation circuit 14, and are considered to be different for each control device 10.
For this reason, as shown in FIG. 17, the deviation ε (difference between the output signal VMO of the magnetic field sensor and the voltage command signal VCO) input to the differential amplifier 15 and the operation amount VEO (deviation and amplification degree of the output driver 12). Product) also has various cases, and is different for each control device 10.

18 (a) and 18 (b) are diagrams for explaining the problems of the prior art caused by the above points. In FIG. 18A, the vertical axis represents the voltage command signal, and the horizontal axis represents time. FIG. 18B shows the position of the linear motion device 11 when operated according to the voltage command signal shown in FIG. 18A on the vertical axis, and the time on the horizontal axis.
The amplification degree Kp of the differential amplifier 15 is set to a constant value that optimizes the step response time of the linear motion device 11 with respect to the solid line d in FIG. For this reason, as shown in FIG. 18 (a), the value of the voltage command signal VCO deviates from VC / 2 to be originally output, VC / 4 (indicated by a one-dot chain line e), and VC (indicated by a two-dot chain line f). ), As shown in FIG. 18B, an appropriate operation amount VEO is not given to the output driver 12, and the response time increases.

  For example, when the manipulated variable VEO is insufficient as indicated by a one-dot chain line e, the response speed until the linear motion device 11 reaches a desired position is slow, and the response time t1 when indicated by the solid line d is a response. It extends to time t2. On the other hand, as indicated by a two-dot chain line f, when the manipulated variable VEO is excessive, the response time becomes fast and the linear motion device 11 rings. For this reason, it takes time until the linear motion device 11 converges to a desired position, and the response time extends to time t3. Further, when the manipulated variable VEO is excessive, the linear motion device 11 may oscillate depending on the manipulated variable VEO.

  The present invention has been made in view of the above points, and corrects the positional deviation of the linear motion device with respect to the voltage command signal even when the relationship between the detected magnetic field and the position of the linear motion device is different from the design relationship. It is an object of the present invention to provide a controller for a linear motion device that can be used.

The linear motion device controller of the present invention detects a magnetic field generated by a magnet of a linear motion device (eg, the linear motion device 11 shown in FIG. 1) having a magnet (eg, the magnet 19 shown in FIG. 1). A linear motion device control apparatus (for example, the control apparatus 101 shown in FIG. 1) that moves the linear motion device to a position instructed from the outside, detecting a magnetic field generated by the magnet, and detecting the detected magnetic field From a magnetic field sensor (for example, the magnetic field sensor 113 shown in FIG. 1) that outputs a first output signal that responds to the value of, and an input signal (for example, the control signal VCM [2: 0] shown in FIG. 1). A voltage command signal generation circuit (for example, the voltage command signal generation shown in FIG. 1) that generates a voltage command signal associated with the amplitude of the output signal of the magnetic field sensor (for example, the output signal VMO shown in FIG. 1) A road 114), a differential amplifier for generating a second output signal by amplifying the deviation of the first output signal of the magnetic field sensor and said voltage command signal (e.g., a differential amplifier 115 shown in FIG. 1), the second output signal output from the pre-Symbol differential amplifier, and corrected in accordance with the amplitude of the first output signal of the magnetic field sensor, the correction circuit for generating the input signal to the corrected the output driver ( For example, a gain correction circuit 116 shown in FIG. 1 and an output driver (for example, the output driver 112 shown in FIG. 1) that drives the linear motion device in accordance with the value of the corrected input output signal. It is characterized by.

In the linear motion device control device according to the present invention, in the above-described invention, when the correction circuit has an amplitude of the first output signal that is different from a predetermined reference amplitude, the control circuit controls the amplitude of the first output signal. A gain correction circuit (for example, the gain correction circuit 116 shown in FIG. 1) that amplifies the second output signal with the ratio of the reference amplitude is desirable.
In the linear motion device control apparatus according to the present invention, the gain correction circuit includes a resistance element having a variable resistance value (for example, the resistor divider 41 shown in FIG. 4) and the first output signal. And a decoder (for example, the decoder 42 shown in FIG. 4) that generates a control signal that determines the resistance value of the resistance element according to the amplitude of the resistance element.

In the linear motion device control device according to the present invention, in the above-described invention, when the correction circuit has an amplitude of the first output signal that is different from a predetermined reference amplitude, the control circuit controls the amplitude of the first output signal. wherein it is not to demand a PWM modulation circuit for amplifying said second output signal at a reference amplitude ratio (e.g. the PWM circuit 90 shown in FIG. 10).

According to the present invention, even when the value of the detected magnetic field is different from the design value due to a shift in the mounting position of the magnet of the linear motion device or the magnetic field sensor of the control device, the linear motion device is appropriately input from the outside. Can be moved to a position. That is, the controller of the linear motion device of the present invention can correct the displacement of the linear motion device position with respect to the voltage command signal even when the relationship between the detected magnetic field and the position of the linear motion device is different from the relationship at the time of design. A controller for a linear motion device can be provided.
According to the present invention, it is possible to improve the deterioration of the transient response characteristic caused by simply correcting only the detected magnetic field.

It is a figure for demonstrating the linear motion device control apparatus and linear motion device of 1st Embodiment of this invention. FIG. 6 is a diagram illustrating another configuration of the output driver shown in FIG. 1. FIG. 2 is a diagram for explaining a circuit configuration of a voltage command signal generation circuit shown in FIG. 1. FIG. 2 is a diagram for explaining a circuit configuration of a gain correction circuit shown in FIG. 1. It is a figure for demonstrating operation | movement of the control apparatus of the linear motion device of 1st Embodiment of this invention. FIG. 5 is a diagram for explaining a configuration of a resistor divider shown in FIG. 4. It is a figure for demonstrating the effect of the control apparatus of the linear motion device of 1st Embodiment of this invention. FIG. 7 is a diagram for explaining another configuration example of the gain correction circuit shown in FIG. 1. It is a figure for demonstrating the other structural example of the resistive divider shown in FIG. It is a figure for demonstrating the circuit structure of the linear motion device of 2nd Embodiment of this invention. It is a figure for demonstrating more concretely the structure of the PWM modulation circuit shown in FIG. It is the figure which showed the PWM wave produced | generated by the PWM modulation circuit shown to FIG. It is the figure which showed the conventional control apparatus which controls a linear motion device. It is the figure which showed the relationship between the detection magnetic field of the magnetic field sensor shown in FIG. 13, and the position of a linear motion device. It is the figure which showed the other relationship between the detection magnetic field of the magnetic field sensor shown in FIG. 13, and the position of a linear motion device. It is a figure for demonstrating the prior art described in patent document 1. FIG. It is the figure which illustrated deviation (epsilon) input into a general differential amplifier, and the operation amount of an output driver. It is a figure for demonstrating the malfunction which arises in the prior art described in patent document 1. FIG.

Hereinafter, a first embodiment and a second embodiment of the present invention will be described with reference to the drawings.
[First Embodiment]
Circuit Configuration FIG. 1 is a diagram for explaining a control device 101 that controls the linear motion device 11 according to the first embodiment and the linear motion device 11 that is controlled by the control device 101. FIG. 1 shows a linear motion device 11 and a controller 101 that controls the linear motion device 11. Since the linear motion device 11 has the same configuration as that of the linear motion device 11 shown in FIG. 13, the same reference numerals as those shown in FIG. 15 are given, and the description thereof is partially omitted.

  The linear device 11 according to the first embodiment includes a coil 18 and a magnet 19. In the first embodiment, the positions of the magnet 19 and the linear motion device 11 are changed by a magnetic field generated by electromagnetic induction in the coil 18. Further, the coil 18 is supplied with a current from the control device 101, and the magnet 19 and the linear motion device 11 move in accordance with the supplied current. Therefore, the control device 101 controls the position of the linear motion device 11. Can do.

The control device 101 detects a magnetic field generated in the magnet 19 and generates an output signal VMO that responds to the detected magnetic field, and a signal (hereinafter referred to as a signal for moving the linear motion device 11 to a desired position). And a voltage command signal generation circuit 114 that functions as an interface for inputting an input signal from the outside. Since the position of the magnetic field sensor 113 is fixed, the magnetic field detected by the magnetic field sensor 113 indicates a relative position between the magnetic field sensor 113 and the magnet 19.
The voltage command signal generation circuit 114 generates a voltage command signal VCO that associates the input signal with the amplitude of the output signal VMO of the magnetic field sensor 113.

The control device 101 further includes a differential amplifier 115 that inputs the output signal VMO of the magnetic field sensor 113 and the output signal VMO output from the voltage command signal generation circuit 114. The differential amplifier 115 generates and outputs an output signal VEO obtained by amplifying a deviation, which is a difference between the output signal VMO and the voltage command signal VCO, with an amplification factor Kp. The output signal VEO is corrected as described later to become the input signal VAJ. The input signal VAJ is input to an output driver 112 that drives the linear motion device 11.
The output driver 112 includes a MOS switch MN1. The input signal VAJ is applied to the gate of the MOS switch MN1, and controls the value of the current flowing between the source and drain of the MOS switch MN1. The amount of movement of the magnet 19 is determined according to the strength of the magnetic field generated by the coil 18.

Further, the control device 101 corrects the output signal VEO in accordance with the amplitude of the output signal VCO, and the control signals VMH [2: 0] and VML [2: 0] is stored. The input signal VAJ is generated by correcting the output signal VEO by the gain correction circuit 116.
The control signal VMH [2: 0] is a control signal that selects the maximum output voltage VMH of the magnetic field sensor 113. The control signal VML [2: 0] is a control signal for selecting the minimum output voltage VML of the magnetic field sensor 113.

The writing of the control signal VMH [2: 0] and the control signal VML [2: 0] to the memory 17 is performed as follows, for example. That is, the manufacturer that manufactures the control device 101 measures the maximum output voltage VMH and the minimum output voltage VML when the control device 101 is shipped. Then, the voltage command signal generation circuit 114 determines the control signal VMH [2: 0] corresponding to the measured maximum output voltage VMH and the control signal VML [2: 0] corresponding to the minimum output voltage VML to the memory 17. You may make it write.
Further, the magnetic field sensor 113 in FIG. 1 may be a Hall sensor or a magnetoresistive sensor.

i Output Driver The circuit configuration of the output driver 112 is not limited to the configuration described above. For example, the output driver 112 is not limited to one constituted by one MOS switch MN1 as shown in FIG.
FIG. 2 is a diagram illustrating another configuration of the output driver 112. The output driver 112 is configured by an H-bridge driver including output drivers 201 and 202, the output driver 201 is configured to include two MOS switches M1 and M3, and the output driver 202 includes two MOS switches M2 and M4. It may be configured as follows.

ii Voltage Command Signal Generation Circuit FIG. 3 is a diagram for explaining a circuit configuration of the voltage command signal generation circuit 114 shown in FIG. The voltage command signal generation circuit 114 divides resistance elements RM0 to RM5 connected between a positive power source (ie, VDD) and a negative power source (ie, VSS) and a resistor connected between the positive power source and the negative power source. The switches SWH0 to SWH2 for selecting the voltage corresponding to the maximum amplitude of the magnetic field sensor 113, the switches SWL0 to SWL2 for selecting the voltage corresponding to the minimum amplitude of the magnetic field sensor 113, and the voltage follower for inputting the voltage selected by the switches SWH0 to SWH2. A circuit 31, a voltage follower circuit 32 that receives a voltage selected by the switches SWL0 to SWL2, an output signal VMHQ of the voltage follower circuit 31, and an output signal VMQ of the voltage follower circuit 32, RC0 to RC3, and linear To move the exercise device 11 to a desired position A switch SWC0～SWC2 selects the voltage command signal, and inputs the voltage selected by the switch SWC0～SWC2, includes a voltage follower circuit 33 for outputting a voltage command signal VCO, a.

  Such a voltage command signal generation circuit 114 receives a control signal VCM [2: 0] as an input signal input from the outside. The voltage command signal generation circuit 114 generates a voltage command signal VCO that associates the control signal VCM [2: 0] with the amplitude of the output signal of the magnetic field sensor 113. That is, the voltage command signal generation circuit 114 equally divides the range between the maximum amplitude and the minimum amplitude of the magnetic field sensor 113 by the number of steps of the voltage command signal, and sets the voltage command signal as a fixed step. Further, the control signal VCM [2: 0] input from the outside is used as the voltage command signal VCO corresponding to the fixed step.

iii Differential Amplifier The differential amplifier 115 in FIG. 1 may be configured to include at least one of a differential element and an integral element.
iv Gain Correction Circuit FIG. 4 is a diagram for explaining the circuit configuration of the gain correction circuit 116 shown in FIG. The gain correction circuit 116 receives the control signal VMH [2: 0] and the control signal VML [2: 0] stored in the memory 17, and receives the control signal RSEL [ 2: 0], resistor divider 41 divided by the division ratio determined by control signal RSEL [2: 0], and output signal VEO of differential amplifier 115 shown in FIG. An inverting amplifier 44 composed of a resistor divider 41, a feedback resistor element RF1, and a differential amplifier 43, an input resistor element RI2, a feedback resistor element RF2, and a difference between the output signal of the inverting amplifier 44, which inverts and amplifies the signal VAJ. And an inverting amplifier 46 constituted by a dynamic amplifier 45.

Operation Next, the operation of the control apparatus 101 of the linear motion device 11 according to the first embodiment will be described with reference to FIG.
When the magnet 19 of the linear motion device 11 shown in FIG. 1 moves, the relative positions of the magnet 19 and the magnetic field sensor change. The magnetic field sensor 113 detects a magnetic field corresponding to the position of the magnet 19. Based on the detected magnetic field, the magnetic field sensor 113 outputs an output signal VMO.
As described in [Problems to be Solved by the Invention] in this specification, the positional deviation between the detected magnetic field and the linear motion device is caused by variations in the magnetization of the magnet 19 of the linear motion device 11 and the mounting position deviation of the magnetic field sensor 113. Depending on the case.

  In FIG. 16 described above, the positional deviation between the detected magnetic field and the linear motion device is shown in three cases. That is, as shown in FIG. 16, in the case 1 indicated by the solid line a, the position of the linear motion device 11 reaches the maximum movement width when the amplitude of the magnetic field sensor output signal VMO is VM / 2. In case 2 indicated by the alternate long and short dash line b, the position of the linear motion device 11 reaches the maximum movement width when the amplitude of the magnetic field sensor output signal VMO is VM / 4. In case 3 indicated by a two-dot chain line c, when the amplitude of the magnetic field sensor output signal VMO is VM, the position of the linear motion device 11 reaches the maximum movement width.

  The voltage command signal generation circuit 114 shown in FIG. 5 is selected by the voltage selected by the control signal VMH [2: 0] (that is, the maximum output voltage VMH of the magnetic field sensor 113) and the control signal VML [2: 0]. The control signal VCM [2: 0] for moving the linear motion device 11 to a desired position is input to the voltage (that is, the minimum output voltage VML of the magnetic field sensor 113). The voltage command signal generation circuit 114 generates the voltage command signal VCO by switching the switches SWC0 to SWC2 shown in FIG. 3 with the control signal VCM [2: 0].

Since the voltage command signal VCO is generated between the maximum output voltage VMH of the magnetic field sensor 113 and the minimum output voltage VML of the magnetic field sensor 113, the same voltage amplitude as that of the output signal VMO of the magnetic field sensor 113 is obtained.
The differential amplifier 115 shown in FIG. 5 amplifies the deviation ε, which is the difference between the output signal VMO of the magnetic field sensor 113 and the output signal VCO of the voltage command signal generation circuit 114, with the amplification degree Kp, and generates the manipulated variable signal VEO. Generate. That is, the differential amplifier 115 generates the manipulated variable VEO of Kp × ε / 2 in case 1 shown in FIG. 16, while the manipulated variable VEO of Kp × ε / 4 in case 2 and Kp in case 3 A manipulated variable VEO of xε is generated.

  In the gain correction circuit 116 shown in FIG. 4, the inverting amplifier 44 uses a magnetic field sensor based on the input resistance determined by the control signal RSEL [2: 0] for selecting the division ratio of the resistance divider 41 and the feedback resistance element RF1. An amplification degree corresponding to the output amplitude of 113 is determined. Then, the inverting amplifier 46 further inverts the phase and outputs it as a normal signal by inverting the phase output via the inverting amplifier 44 by the input resistance element RI2 and the feedback resistance element RF2.

FIG. 6 is a diagram for explaining the configuration of resistance divider 41 shown in FIG. The resistance divider 41 shown in FIG. 6 is configured to be able to arbitrarily select a resistance value by short-circuiting and opening the switches SRS0 to SRS2 connected in parallel to each of the resistance elements RS0 to RS2. ing.
According to the above configuration, if the operation amount VAJ (ie, Kp × ε / 2) of the output driver 112 in case 1 is optimal, even in case 2 where the magnetic field sensor output amplitude is ½ times that in case 1, The resistance ratio of the resistor divider 41 at which the amplification degree of the inverting amplifier 44 is doubled is selected, and the operation amount VAJ (that is, Kp × ε / 2) of the output driver 112 having the same value as in the case 1 can be obtained.

Further, according to the above configuration, even in the case 3 where the amplitude of the output signal VMO of the magnetic field sensor 113 is twice that in the case 1, the resistance divider 41 in which the amplification degree of the inverting amplifier 44 is ½ times. The resistance ratio is selected, and the operation amount VAJ (that is, Kp × ε / 2) of the output driver 112 having the same value as in the case 1 can be obtained.
That is, in the first embodiment, the gain correction circuit 116 corrects the signal VEO obtained by amplifying the deviation ε obtained from the differential amplifier 115 with the amplification degree Kp, and obtains the optimum operation amount VAJ of the output driver 112. it can. For this reason, according to the first embodiment, even when the relationship between the output signal of the magnetic field sensor 113 and the position of the linear motion device differs from the design due to the variation in magnetization of the magnet 19 and the mounting position shift of the magnetic field sensor 113, the design value A transient response characteristic and a step response time similar to the above can be obtained.

FIG. 7 is a diagram for explaining the effect of the first embodiment. As shown in FIG. 7, according to the first embodiment, the same transient response as in case 1 indicated by the solid line d even in the case 2 indicated by the one-dot chain line e and the case 3 indicated by the two-dot chain line f. It is clear that the characteristic and step response time t1 are obtained.
In the first embodiment, the control for selecting the maximum output voltage VMH of the same magnetic field sensor 113 as the control signal input to the voltage command signal generation circuit 114 and the control signal input to the decoder 42 of the gain correction circuit 116. It is desirable to track the signal VMH [2: 0] and the control signal VML [2: 0] for selecting the minimum output voltage VML of the magnetic field sensor 113. However, in the first embodiment, the control signal input to the voltage command signal generation circuit 114 and the control signal input to the decoder 42 of the gain correction circuit 116 may be independent control signals.

Further, the first embodiment is not limited to the configuration described above. For example, in the first embodiment, the gain correction circuit 116 is configured as shown in FIG. However, the gain correction circuit 116 of the first embodiment may be configured as shown in FIG. 8 by replacing the resistor divider 41 and the feedback resistance element RF1 shown in FIG.
Further, the resistor divider 41 shown in FIGS. 4 and 8 of the first embodiment is not limited to the configuration of FIG. For example, as illustrated in FIG. 9, a resistance selection signal generation circuit 71 that inputs a control signal RSEL [2: 0] for selecting a resistance division ratio and generates a resistance selection switch control signal SSEL [7: 0]; It may be configured to include switches SRP0 to SRP7 that select between the resistance elements RP0 to RP8 to which the control signal SSEL [7: 0] generated by the resistance selection signal generation circuit 71 is input.
The input signal received in the first embodiment may have a bit number of 3 bits. However, the input signal may be 3 bits or less or 3 bits or more.

[Second Embodiment]
Circuit Configuration FIG. 10 is a diagram for explaining a circuit configuration of the linear motion device according to the second embodiment of the present invention. In FIG. 10, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is partially omitted.
In the second embodiment, the manipulated variable VAJ input to the output driver 112 changes linearly as in the first embodiment described above, while using PWM (Pulse Width Modulation) modulation. A feature is that an input signal to the output driver 112 is generated.
As illustrated in FIG. 10, the control device 109 of the linear motion device 11 according to the second embodiment includes a PWM modulation circuit 90 instead of the gain correction circuit 116 illustrated in FIG. 1.

FIG. 11 is a diagram for explaining the configuration of the PWM modulation circuit 90 more specifically. As shown in FIG. 11, the PWM modulation circuit 90 includes a sawtooth wave generation circuit 91 and a comparator 92 that compares the sawtooth wave VRM with the output signal VEO of the differential amplifier 115 to generate a PWM wave.
The sawtooth wave generation circuit 91 receives a control signal VMH [2: 0] for selecting the maximum output voltage VMH of the magnetic field sensor 113 and a control signal VML [2: 0] for selecting the minimum output voltage VML of the magnetic field sensor 113. . Then, a sawtooth wave VRM is generated in which the voltage VMH selected by the control signal VMH [2: 0] has a maximum amplitude value and the voltage VML selected by the control signal VML [2: 0] has a minimum amplitude value.

  According to such a sawtooth wave generation circuit 91, a sawtooth wave VRM having an amplitude associated with the output voltage amplitude of the magnetic field sensor 113 can be generated, and the differential amplifier 115 associated with the output voltage width of the magnetic field sensor 113 can be generated. The PWM wave generated by comparing the output signal VEO and the sawtooth wave VRM has a duty (that is, a linear motion device position that does not depend on the output voltage width of the magnetic field sensor 113 that is different for each device as shown in FIG. , The ratio of the VDD period Ton to the switching period Ts). That is, the gain of the operation amount signal VEO is corrected by the PWM modulation circuit 90, and an optimum operation amount can be given to the output driver 112 regardless of the device.

  12 (a), 12 (b), and 12 (c) show the PWM modulation shown in FIGS. 10 and 11 when the output amplitude of the magnetic field sensor 113 is different for each device as in the case shown in FIG. FIG. 4 is a diagram illustrating PWM waves generated by a circuit 90. For example, assuming that the manipulated variable VPW1 obtained when the maximum output voltage of the magnetic field sensor 113 in FIG. 12A is VMH1 and the minimum output voltage is VML1, it is determined by the output voltage width of the magnetic field sensor 113 that is different for each device. Even when the maximum output voltage of the magnetic field sensor 113 obtained is VMH2 and the minimum output voltage is VML2, as shown in FIG. 12B, the control amount VPW2 given to the output driver 112 is the same operation as the operation amount VPW1. The quantity can be obtained. In FIG. 12C, even when the maximum output voltage VMH3 and the minimum output voltage VML3 of the magnetic field sensor are obtained, the operation amount VPW3 given to the output driver 112 can obtain the same operation amount as the operation amount VPW1.

  The present invention can be applied to any linear motion device that needs to be accurately positioned using a magnet, such as a camera autofocus lens.

DESCRIPTION OF SYMBOLS 11 Linear motion device 18 Coil 19 Magnet 31, 32, 33 Voltage follower circuit 41 Resistance divider 42 Decoder 44, 46 Inverting amplifier 71 Resistance selection signal generation circuit 90 Modulation circuit 91 Sawtooth wave generation circuit 92 Comparator 101, 109 Controller 112 Output Driver 113 Magnetic field sensor 114 Voltage command signal generation circuit 115 Differential amplifier 116 Gain correction circuit 201, 202 Output driver

Claims (4)

A linear motion device controller for detecting a magnetic field generated by the magnet and moving the linear motion device to an externally designated position of a linear motion device having a magnet,
A magnetic field sensor that detects a magnetic field generated by the magnet and outputs a first output signal that responds to the value of the detected magnetic field;
A voltage command signal generation circuit that generates a voltage command signal associated with the amplitude of the output signal of the magnetic field sensor from an input signal input from the outside;
A differential amplifier that amplifies a deviation between the first output signal of the magnetic field sensor and the voltage command signal to generate a second output signal ;
The second output signal output from the pre-Symbol differential amplifier, and a correction circuit for correcting in accordance with the amplitude of the first output signal of the magnetic field sensor, for generating a corrected input signal,
An output driver for driving the linear motion device according to the value of the corrected input signal;
A controller for a linear motion device, comprising: The correction circuit includes:
When the amplitude of the first output signal is different from a predetermined reference amplitude, the gain correction circuit amplifies the second output signal by a ratio of the reference amplitude to the amplitude of the first output signal. The control apparatus for a linear motion device according to claim 1. The gain correction circuit includes:
A resistance element having a variable resistance value;
A decoder for generating a control signal for determining a resistance value of the resistance element according to an amplitude of the first output signal;
The linear motion device control apparatus according to claim 2, comprising: The correction circuit includes:
When the amplitude of the first output signal is different from a predetermined reference amplitude, the PWM modulation circuit amplifies the second output signal by a ratio of the reference amplitude to the amplitude of the first output signal. The control apparatus for a linear motion device according to claim 1.

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