JPS6377366A - Voice coil type linear motor - Google Patents

Abstract

PURPOSE:To mount an image sensing element on the side of a coil bobbin, and to attain stable drive by installing a pair of permanent magnets holding a core and a guide shaft for sliding the coil bobbin and fixing a base plate, on which the image sensing element, etc., are loaded, to the coil bobbin. CONSTITUTION:When predetermined currents are caused to flow through a coil 50 for a linear motor 5, a bobbin 51 is guided by a guide shaft 54 and moved to the right or the left between the opposed sections of a pair of permanent magnets 57, and a base plate 52 is shifted together with the bobbin 51. An image sensing drive has the linear motor 5, a linear encoder 6, a drive circuit 7 and an image sensing element 4 fitted to an arm 59 backward projected from the base plate 52. The linear encoder 6 consists of a scale 61 and a position-signal generating section 62 set up in front of the base plate 52, and a signal corresponding to the travel of the base plate 52 is outputted from the signal generating section 62. When the output signal is fed back to the drive circuit 7, the linear motor 5 driven by closed-loop control is transferred at uniform velocity, and the image sensing element 4 can be moved at a uniform rate.

Description

[Detailed Description of the Invention] [Summary] This is a voice coil type linear motor (hereinafter referred to as a linear motor) in which the voice coil moves parallel to the core, and is provided with a pair of permanent magnets that sandwich the core and a guide shaft for sliding the coil bobbin. A stage for mounting a required image sensor, etc. is fixed to the coil bobbin, and the image sensor, etc. can be attached to the side of the coil bobbin, thereby shortening the overall length and achieving stable drive.

[Industrial application field]

The present invention relates to improvements in voice coil type linear motors, particularly voice coil type linear motors that are used in image processing devices to move an image sensor, etc.

Among image sensors that convert various information images into electrical signals, those that can detect shading from a two-dimensional image and sequentially convert it into electrical signals, such as a television camera, do not need to move the image sensor. However, when the image sensor detects only shading arranged on a straight line, it is necessary to move the image sensor in a direction perpendicular to the straight line.

When such an image sensor is moved, if there is a variation in the moving speed, the interval between signals output from the image sensor will be disturbed, making it impossible to obtain accurate images.

[Conventional technology]

FIG. 4 is a perspective view showing the main parts of a conventional image sensor driving device.

In FIG. 4, the device includes a pulse motor 1, a movable part 2, a power transmission system 3 for moving the movable part 2 by rotation of the pulse motor 1, and an image sensor 4 attached to the movable part 2,
The power transmission system 3 is composed of gears 31 and 32 and a ball screw 33. The movable part 2 includes a female thread (not shown) that fits into a ball screw 33, and the image sensor 4 is attached to an arm 22 that projects laterally.

In such a device, when the pulse motor 1 rotates, the ball screw 33 rotates via the gears 31 and 32, and the movable part 2 (image sensor 4) moves along the ball screw 33.

[Problem that the invention seeks to solve]

In the conventional image sensor driving device, the pulse motor 1
is attached to the side of the movable part 2, so it is large in size, and noise is emitted from the power transmission system 3 and the fitting part between the ball screw 33 and the female thread, and the moving speed of the movable part 2 (image sensor 4) is pulsed. It is controlled by the period of the pulse signal applied to the motor 1, and when the load changes, the rotation speed of the pulse motor 1 changes.

In addition, backlash is necessary for the meshing of the gears 31 and 32, and the gear 3L32 "
If there is a bias or if there is a bias between the ball screw 33 and the fitting screw of the movable part 2, there is a problem in that the moving speed of the movable part 2 fluctuates.

On the other hand, there is a linear motor that can occupy a much smaller space than the pulse motor 1. However, in the conventional linear motor, when a necessary object such as the image sensor 4 is supported so as to protrude to the side of the linear motor, an uneven load is applied to the movable element corresponding to the movable part 2 due to the necessary object. There was a problem with the lack of stability in movement.

[Means for resolving issues]

According to FIG. 1, the present invention aims to eliminate the above-mentioned problems. According to FIG. A frame-shaped yoke, a pair of permanent magnets 57 each fixed to a pair of plate parts 56 and facing the core, a pair of guide shafts 54 supported in parallel with the core 55 in between, and a pair of guide shafts 54 A bobbin 51 is provided with a through hole 58 that slides along the core 55 and that the core 55 passes through without contacting the bobbin 51.
This is a voice coil type linear motor characterized by comprising a coil 50 wound around the coil 50 and coaxial with a through hole 58, and a stage 52 mounted on a bobbin 51.

[Effect]

According to the above means, mechanical drive means such as ball screws and gears are not required, so noise and speed fluctuations that occur in the past do not occur, and the center of gravity of the movable body can be easily balanced, so stable drive is possible. Close.

〔Example〕

Below, a voice coil type linear motor according to the present invention will be explained using the drawings.

FIG. 1 is a perspective view of a voice coil type linear motor according to an embodiment of the present invention, FIG. 2 is a perspective view showing essential parts of an image sensor driving device using the voice coil type linear motor of FIG. This figure is a block diagram showing the drive circuit of FIG. 2.

In FIG. 1, the voice coil type linear motor 5 includes a core 55 having a rectangular cross section, and a pair of yoke flanges 53. which are connected to both longitudinal end surfaces of the core 55. A pair of yoke plates (a frame-shaped yoke consisting of plate parts 56 and a pair of permanent magnets 57 fixed to the inside of the yoke plate 56 and parallel to the front and rear of the core 55 and fixed to the flange 53 in parallel to the top and bottom of the core 55). A pair of guide shafts 54, a bobbin 51 that slides along the pair of guide shafts 54 and has a through hole 58 through which the core 55 passes through without contacting it, and a coil 50 that is wound around the bobbin 51 and is coaxial with the through hole 58. , and a stage 52 attached to the upper surface of the bobbin 51 and extending in the front-rear direction of the core 55.

In the near motor 5 configured in this way, when a predetermined current is passed through the coil 50, the bobbin 51 is guided by the guide shaft 54 and moves to the right or left between the pair of opposing permanent magnets 57. The stand 52 comes to move together with the bobbin 51.

In FIG. 2, the image sensor driving device includes a voice coil type linear motor 5, a linear encoder 6, a driving circuit 7, and an arm 5 that projects rearward from a stage 52 of the linear motor 5.
The image pickup device 4 is attached to the image pickup device 9. The linear encoder 6 consists of a scale 61 fixed appropriately and a position signal generating section 62 mounted in front of the stage 52.
A signal corresponding to the moving distance of 2 is now output from the signal generating section 62.

However, consideration is given so that the rotational torque applied to the bobbin 51 by the image pickup device 4 when attached to the arm 59 is approximately equal to the rotational torque applied to the bobbin 51 by the signal generation section 62.

In FIG. 3, a drive circuit 7 for driving the linear motor 5 is a device composed of a pattern generator 71 for inputting movement signals to the linear motor 5, and a linear encoder 6 for inputting movement signals output from the pattern generator 71. A deviation counter 72 that corrects based on an information signal, a DA conversion circuit 73 that converts the output signal of the deviation counter 72 into a voltage, and a guarantee circuit 74 that corrects, amplifies, and corrects the waveform of the voltage output from the DA conversion circuit 73, and an amplification circuit. It includes a circuit 75.

In such a device, when the output signal of the linear encoder 6 is fed back to the drive circuit 7, the linear motor 5 driven by closed loop control moves at a constant speed,
The image sensor 40 can be moved at a constant speed.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to realize uniform velocity movement of an image sensor, etc., and it has the effect that accurate image information can be obtained when used in an image processing device.

[Brief explanation of the drawing]

1 is a perspective view of a voice coil type linear motor according to an embodiment of the present invention; FIG. 2 is a perspective view showing essential parts of an image sensor driving device using the voice coil type linear motor of FIG. 1; The figure is a block diagram showing the drive circuit of FIG. 2, and FIG. 4 is a perspective view showing main parts of a conventional image pickup device drive device. In the figure, 4 is an image sensor, 5 is a voice coil type linear motor, 6 is a linear encoder, 7 is a drive circuit, 50 is a coil, 51 is a bobbin, 52 is a stage, 53 is a yoke flange, and 54 is a guide shaft , 55 is a core, 56 is a yoke plate (plate portion), 57 is a permanent magnet, and 58 is a through hole. , again, turn Y number and claw 1 block kunicho 3 flash

Claims (1)

[Scope of Claims] A square frame-shaped yoke connected to both longitudinal end surfaces of a core (55) with a square cross section, and a pair of plate parts (56) parallel to each other with the core (55) sandwiched therebetween; A pair of permanent magnets (57) each fixed to the plate portion (56) and facing the core; a pair of guide shafts (54) supported in parallel with the core (55) in between; The core (55) slides along the guide shaft (54).
A bobbin (
51), a coil (50) wound around the bobbin (51) and coaxial with the through hole (58), and a stage (52) attached to the bobbin (51). voice coil type linear motor.