JPS627629B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a linear tracking arm drive device, and more particularly to a linear tracking arm drive device using a linear motor as a drive source.

A linear motor is used as a drive source for a linear tracking arm, which has the advantage of generating extremely little vibration. This linear motor is
It has a guide rail, a movable member that can freely move linearly along the guide rail, and a drive means that drives the movable member by electromagnetic force, and the movable member moves the tone arm in horizontal and vertical planes. A linear tracking arm drive device is constructed by supporting the arm so that it can rotate freely.

In such a linear tracking arm drive device, when the moving member starts moving, that is, when a driving force that exceeds the static friction force between the guide rail and the moving member acts on the moving member, the difference between this driving force and the braking force due to dynamic friction is determined. Since the movement member is large, the movable member starts moving at a high speed, resulting in a disadvantage that smooth movement cannot be achieved.

An object of the present invention is to provide a linear tracking arm drive device that can control the speed of a moving member while electrically applying a braking force to the moving member.

The linear tracking arm driving device according to the present invention includes a pulse generating means that generates a pulse signal according to the moving speed of a moving member that supports a pick-up arm, and a pulse train that measures the pulse width of this pulse signal and generates a pulse train according to the pulse width. comprising a pulse width measuring means for outputting a signal, a moving direction determining means for determining the moving direction of the moving member, and a means for converting the pulse train signal into an analog signal and generating an output signal with a polarity according to the determined direction, The driving means for driving the moving member controls the speed while applying a braking force to the moving member according to the output signal.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a side view, partially in section, of a linear tracking arm assembly using a linear motor as a drive source. In the figure, tone arm 1
is rotatably supported by an arm holder 2 in horizontal and vertical planes, and a counterweight 3 is attached to the rear end of the arm. The arm holder 2 is supported by a moving member 4, and the moving member 4 is configured to be movable along a pair of horizontally provided guide rails 5a and 5b. That is, it has a structure in which rollers 6 and 7 rotatably attached to the moving member 4 are engaged with guide rails 5a and 5b, respectively.

A pair of magnets 8a and 8b as movable elements of a linear motor are fixed to the lower end of the moving member 4 with a predetermined gap therebetween so that the same magnetic poles (for example, N poles) face each other. Furthermore, a yoke 9 constituting a stator is disposed within the gap between the magnets 8a and 8b, and the guide rail 5a
and 5b. A coil 10 is wound around this yoke 9, and the magnetic flux generated from the north poles of the magnets 8a and 8b interlinks with the coil 10. Therefore, by supplying a current of a predetermined direction and a predetermined value to the coil 10, a force acts between the magnets 8a and 8b and the coil portion facing them, and the movable moving member 4 is driven in a predetermined horizontal direction. Therefore, the tone arm 1 performs a tracking operation in a horizontal plane.

Further, for example, a rotating disk 11 having the roller 6 as a central axis is attached to the roller 6, and an optical pattern is formed on the rotating disk 11, for example. This pattern includes, for example, slits 11a arranged at regular intervals in the rotating direction, and two pairs of light emitting elements 12a, such as light emitting diodes, facing each other with the slits of the rotating disk 11 in between.
12b and a light receiving element 13 such as a phototransistor
a and 13b are attached to a mounting member 14 that is integrally constructed with the moving member 4 so as to be spaced apart from each other by a predetermined distance in the direction of rotation of the rotary disk 11. Therefore, since the rotary disk 11 rotates as the moving member 4 moves, pulse-like signals are output from the light receiving elements 13a and 13b in accordance with the moving speed of the moving member 4. Note that the sensor is not limited to an optical sensor, and may be a magnetic or electrostatic sensor.

FIG. 2 is a circuit block diagram of an embodiment of a linear tracking arm drive device according to the present invention.
In the figure, 20 is a position sensor as an identification means that includes two pairs of light emitting elements 12a, 12b and light receiving elements 13a, 13b in FIG. The outputs F _A and F _B are arranged in the rotation direction of the rotary disk 11 so as to have a phase difference of 90 degrees as shown in FIG. The pulse signals F _A and F _B are applied to the pulse width measurement circuit 23 .

This pulse width measuring circuit 23 detects the moving speed of the moving member 4 by measuring, for example, the time T between the rises (or falls) of each pulse signal, and as shown in FIG. Ta
This configuration measures the time T by counting the number of clock pulses b during the period. In other words, if the time required to count one pulse is ΔT and the number of pulses to count is n, then T
≒n△T. If the distance that the moving member 4 moves during the time T is l, the moving speed v is as follows: v=l/T≒l/nΔT∽1/n, and is inversely proportional to the number of pulses n. The present invention attempts to control the speed while applying braking to the movable member 4 according to the number n of pulses, and FIG. 5 shows the characteristic of the number n of pulses, that is, the moving speed versus the braking force.

The pulse width measuring circuit 23 outputs n pulse train signals counted at time T as shown in FIG. 4C. This pulse train signal is sent to the D/A converter 2
4, it is converted into a voltage as an analog quantity corresponding to the number of pulses, and becomes one input of the subtraction circuit 25. In addition to the subtraction circuit 25, the other input is a tracking sensor 2 that corresponds to the deflection angle of the tone arm 1 that follows the sound groove as the record rotates during performance.
6 is applied, and at the time of lead-in or return, a predetermined drive signal is applied from means not shown. The tracking sensor 26 is
For example, it is composed of a combination of a light-emitting element such as a lamp, a light-receiving element such as CdS, and a shutter having a slit interlocked with the tone arm 1 between the light-emitting and light-receiving elements, and an output signal corresponding to the deflection angle of the tone arm 1. occurs. The difference signal of the subtraction circuit 25 drives the coil 10. The signal is supplied to the drive circuit 27. Further, the polarity of the other inputs of the subtraction circuit 25 changes depending on the moving direction of the moving member 4, but in order for the output signal of the D/A converter 24 to act as a braking force, the polarity changes depending on the moving direction. The polarity must change. Therefore, by inputting the pulse signals F _A and F _B from the waveform shaping circuit 21 and determining which pulse is leading in phase, the moving direction of the moving member 4 is determined, and an output signal corresponding to the direction is determined. A moving direction determining circuit 28 is provided, and the D/A converter 24 is configured to generate an output voltage having a polarity corresponding to the output signal of the moving direction determining circuit 28.

According to the linear tracking arm drive device of the present invention configured as described above, since braking can be applied to the moving member electrically, the speed of the moving member can be quickly and reliably controlled. Smooth movement of the moving member can be achieved. Further, such a drive device has a cost advantage because, for example, in a multi-function player equipped with a microcomputer and capable of fully automatic music selection, etc., the microcomputer can have this function.

[Brief explanation of the drawing]

FIG. 1 is a side view including a partial cross section of the linear tracking arm assembly, FIG. 2 is a circuit block diagram of an embodiment of the present invention, and FIGS. 3 and 4 are for explaining the operation of FIG. 2. FIG. 5 is a waveform diagram of moving speed versus braking force. Explanation of symbols of main parts, 1...Tone arm,
4... Moving member, 5a, 5b... Guide rail,
8a, 8b...Magnet, 10...Coil, 20...
Position sensor, 23...Pulse width measurement circuit, 25...
...Subtraction circuit, 26...Tracking sensor.

Claims (1)

[Scope of Claims] 1. a guide rail, a moving member that supports a pickup and is capable of linear movement along the guide rail, means for generating a deflection angle signal corresponding to a deflection angle of the pickup; A linear tracking arm drive device comprising a drive means for driving the moving member according to a deviation angle signal or a predetermined drive signal, and a pulse generating means for generating a pulse signal according to a moving speed of the moving member. and a pulse width measuring means for measuring the pulse width of the pulse signal and outputting a pulse train signal according to the pulse width.
a moving direction determining means for determining the moving direction of the moving member; a means for converting the pulse train signal into an analog signal and generating an output signal having a polarity according to the direction determined by the moving direction determining means; and the deflection angle. 1. A linear tracking arm drive device comprising: subtraction means for subtracting the output signal from a signal or a predetermined drive signal, and the output signal of the subtraction means is used as a drive input of the drive means. 2. The pulse generating means includes a rotating member that rotates in accordance with the movement of the pickup, and optical, electrostatic or magnetic pulse generators arranged on the rotating member at regular intervals in the rotational direction of the rotating member. Claim 1, characterized in that it has an identifiable pattern, and identification means disposed opposite the pattern to optically, electrostatically, or magnetically identify the pattern and output a pulse-like signal. The linear tracking arm drive device according to item 1.