JPS5932068Y2 - Record player linear tracking arm - Google Patents

Description

[Detailed explanation of the invention] This invention is a linear tracking system for record players.
The present invention relates to a linear tracking arm that prevents the tone arm from moving in the direction of the tilt force by generating a force in the system that counteracts the force in the direction of the tilt force applied to the tone arm due to the tilt of the system.

In conventional electromagnetically driven linear tracking arm systems, when the system is tilted, a force is applied to the arm in the direction of the tilt force, especially when the arm is tracing from the outer circumference of the record to the inner circumference. Furthermore, if no drive current is flowing through the drive coil that drives the arm to move linearly in the direction of the axial force, the arm may move in the direction of the inclined force.

In order to avoid this movement, each time the system is installed, the levelness of the system must be measured using a spirit level, etc., and the system must be adjusted to be level each time, which is a hassle.

With this invention, once the horizontality is adjusted on a horizontal table,
After that, we developed a system that can prevent the tone arm from moving in the direction of the tilt force even if the installation location is moved, as long as the installation location does not have an extreme inclination, without the need for adjustment. The purpose is to eliminate the hassle of adjusting the scale.

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings.

Figure 1 is a schematic plan view of a linear tracking arm to which the present invention is applied, and is an example of a mechanism that uses a linear motor to move the fulcrum of arm 1 linearly in the force direction of arrow a (diameter force of the record). It shows.

A fulcrum (not shown) of the tone arm 1 is fixed to an arm support member 2, a hypothetical pickup cartridge 3 is attached to one end of the tone arm 1, and a counter is attached near the other end so that the mounting position can be adjusted. Weight 4 is attached.

In order to guide the arm support member 2 to move left and right along the arrow direction a, two parallel guide rods 5A, 5 are provided.
B is fixed near the end of a turntable board (not shown).

In addition, drive coils 6 are arranged parallel to the guide rods 5A and 5B, respectively.
A and 6B are provided, and the arm support member 2 is moved in the force direction of arrow a by the magnetic field generated by these drive coils 6A and 6B.
A magnet 7 (
The shaded area) is fixed, and in a so-called linear motor type, a force is applied to the tone arm 1 to move it in the diametrical direction of the record by passing a drive current through the drive coils 6A and 6B. .

The horizontal detection weight 8 shown in FIG. 2 is formed into a fan shape, and a bearing hole 8A provided at a position corresponding to the corner of the fan is inserted into a shaft (not shown) fixed to the turntable board. It is a plate-shaped weight configured so that it can freely rotate around the axis, and the center line l of the fan shape always coincides with the vertical line, so that even if the system is tilted, it will always remain horizontal. The direction of force can be detected.

At the lower end of this horizontal detection weight 8, slits 8B and 8C are formed at symmetrical positions with respect to the center line l.

The shapes of the slits 8B and 8C are such that the light beams transmitted through the slits to the light receiving sections 9B and 9C (FIG. 3) differ depending on the inclination of the system.

In addition, in the above, the fan-shaped surface rotating around the bearing hole 8A of the horizontal detection weight 8 corresponds to the movement direction arrow a of the tone arm 1.
The shaft is fixed to the turntable board such that it is parallel to the turntable board.

Next, the 7jth inclination detection section 9 for detecting the direction and amount of the inclination force of the system will be explained with reference to FIG.

Light-receiving elements 9B and 9C and a lamp 9D are fixed with the horizontal detection weight 8 sandwiched in a light-shielding case 9A that blocks external light, and the light beam P from the lamp 9D passes through the horizontal detection weight 8B and 8C. The light reaches the light receiving surfaces of the light receiving elements 9B and 9C.

It is located at J:5.

Next, the inclination of the system and the light flux 9 flash received by the light receiving elements 9B and 9C will be explained with reference to Fig. 4. In the figure, the horizontal axis is centered on the center point O, and the right side R indicates the degree to which the inclination of the system is tilted to the right. Similarly, the left side indicates the degree to which the left side is tilted to the left, and the vertical axis indicates the left and right light receiving elements 9 in the horizontal position with the center point O
It is assumed that the received light fluxes of B and 9C are the same.

In the figure, a dotted line 9B represents the light beam received by the light receiving element 9B, and a solid line 9C represents the light beam received by the light receiving element 9C.

Next, the signal processing circuit according to the present invention will be explained with reference to FIG.
J: The connection point between the resistor r1 and the light receiving element 9B and the connection point between the resistor r2 and the light receiving element 9C of the bridge circuit Q are connected to two input terminals 10A and 10B of the differential amplifier 10, respectively.

Note that the power supply of the bridge Q has a voltage Vcc between it and ground.
is given by.

The output of the differential amplifier 10 is configured to cause a current to flow through the drive coils 6A, 6B in a direction to correct the system inclination by a linear arm drive circuit 11.

The operation of the present invention configured as described above will be explained.

Now when the system is horizontal, light receiving element 9B. Adjust the mounting angle of the light-shielding case 9A so that the received light beams of the light beams 9C are equal, or adjust the values of the resistors r and r2 or the balance of the differential amplifier in FIG. Adjust the correction current flowing to zero.

Next, when the system tilts to the right, the lamp 9D and light receiving elements 9B and 9C shown in FIG. Since it is oriented in the direction of force, the light receiving element 9C
The light flux received by the light receiving element 9B increases, and on the contrary, the light flux received by the light receiving element 9B decreases.

This is illustrated in FIG.

Also, when the system is tilted to the left, the situation is opposite to the case where the system is tilted to the right.

Here, the light receiving element 9B. 9C may be a photoconductive element such as CDS (cadmium sulfide) whose resistance changes depending on the light flux, or a photoelectric element such as a phototransistor whose current changes. A circuit similar to the bridge circuit Q shown can extract the difference in the received light fluxes as a voltage difference.

Therefore, the voltage difference is amplified by the differential amplifier 10, and the system tilt direction and its amount are detected and inputted to the linear arm drive circuit 11 to drive the drive coil 6A.

6B, a correction current flows in a direction to cancel the force applied to the tone arm 1 in the direction of the tilt force due to the tilt of the system, thereby preventing the tone arm from moving in the direction of the tilt force due to the tilt of the register.

In the above, driving of the tone arm in the diametrical direction of the record for playing is performed in a linear motor type by a current from a separately provided drive power source flowing through the drive coils 6A and 6B, and the tilt of the system is A correction current is applied to the drive coils 6A, 6B in a manner superimposed on the current from the drive power source.

As described above, according to the present invention, even if the system is tilted in the direction in which the tone arm can move, that is, in the direction of the driving force of the tone arm, the horizontal detection weight is always maintained in the vertical position, and the horizontal detection weight is The two slits provided on the left and right amplify the difference in photocurrent between the two left and right photodetectors, and the tone is adjusted so as to cancel out the force applied to the direction of movement of the tone arm due to the tilt of the system.・Since current flows through the arm drive coil, once the system is adjusted in the horizontal position, the tone arm will not move in the direction of the tilting force even if the system is installed at a certain degree of inclination. There is no need to adjust the levelness of the system every time you change the level.

[Brief explanation of drawings]

Figure 1 is a schematic plan view of the linear tracking arm.
Fig. 2 is a front view of the horizontal detection weight of the present invention, Fig. 3 is a plan cross-sectional view of the inclination detection unit that detects the direction and amount of inclination force, and Fig. 4 is the same as the inclination of the system and the received light flux of the light receiving element. FIG. 5 is a block diagram of the signal processing circuit. DESCRIPTION OF SYMBOLS 1... Tone arm, 2... Arm support member, 6A, 6B... Drive coil, 7...
...Magnet, 8...Horizontal detection weight, 9
. . . Tilt detection section, 10 . . . Differential amplifier, 11 . . . Arm drive circuit.

Claims (1)

[Scope of utility model registration request] In a linear tracking arm system that is electromagnetically driven by a drive coil and has no drive current flowing through the first drive coil, the system is tilted. an inclination detection mechanism that outputs an electrical output corresponding to the direction and amount of inclination of the system with respect to the horizontal direction of the moving force of the tone arm; A linear record player equipped with a signal processing circuit that causes a correction current to flow through the drive coil using the electrical output so as to cancel the applied force.
tracking arm.