JPS6226842Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a record size detection device that detects the size of a record by using a strain gauge.

Conventional record size detection methods can be broadly divided into optical and mechanical methods. Optical methods mainly utilize the fact that the record blocks light, while light sources such as CDS, phototransistors, and lamps are used to detect the size of records through a turntable. The turntables are arranged to face each other, and holes for light transmission are formed at predetermined locations on the turntable. The size of the record is then detected based on whether or not the light source passing through the hole is blocked depending on the size of the record.

The disadvantage of this optical type is that a lamp must be installed on the panel to prevent malfunctions even when used in areas with insufficient light, which increases the number of man-hours and parts. Furthermore, since holes for light transmission are formed in the turntable, there is also a drawback in that the number of man-hours increases.

On the other hand, in the case of a mechanical type, a pin that moves up and down is installed on the turntable, and the position of the up and down pin changes depending on the size of the record placed on the turntable. I am trying to detect the size.

Alternatively, a detection arm is rotated from outside the turntable and brought into contact with the record to detect the size. Such a mechanical detection method not only makes the appearance unsightly, but also tends to damage the record, especially if a pin is used.

This idea was made in order to eliminate the above-mentioned drawbacks of the conventional method, and uses a strain gauge to form a bridge circuit to detect the size of a record from an unbalanced output based on the difference in weight depending on the size of the record. In this way, the appearance will not be spoiled,
Moreover, it is an object of the present invention to provide a record size detecting device that not only does not cause damage to the record, but also does not increase the number of parts and man-hours, and can reduce costs.

Embodiments of the record size detection device of this invention will be described below with reference to the drawings. FIG. 1 is a side view showing the configuration of one embodiment. This first
1 in the figure is a turntable, on which a record (not shown) is placed.

As is well known, a shaft 2 is attached to the center of the turntable 1, and the shaft 2 is supported by a bearing (not shown).
is connected to the motor 3. A strain gauge 5 is attached to a predetermined location of the turntable support mechanism 4, for example, to the base of the motor 3, as shown in FIG. 1, using the motor 3 and bearings. Although one strain gauge 5 may be used, it is more convenient to have two strain gauges 5 because they have a temperature compensation function. Therefore, in the illustrated embodiment, two strain gauges 5, 6 are used.

One strain gauge 5 is attached to a point where the turntable support mechanism 4 extends, and the other strain gauge 6 is attached to a point where the turntable support mechanism 4 contracts. Both strain gauges 5 and 6 are connected to two sides of the bridge circuit 7, respectively, as shown in FIG.

A resistor 8 and a variable resistor 9 are connected to the other two sides of the bridge circuit 7. In this way, the strain gauges 5 and 6, the resistor 8, and the variable resistor 9 constitute a bridge circuit 7. The input end of the bridge circuit 7 is connected to the output end of the oscillator 10. The output terminal of the bridge circuit 7 is connected to the input terminal of the amplifier 11. The output end of the amplifier 11 is connected to an arm drive section (not shown).

Next, the operation of the record size detection device of this invention constructed as described above will be explained. When no record is placed on the turntable 1, the bridge circuit 7 is in a balanced state, and the variable resistor 9 is adjusted so that no voltage is generated at the output terminal of the bridge circuit 7.

Next, when a record is placed on the turntable 1, the weight changes depending on the size of the record, and the resistance values of the strain gauges 5 and 6 change accordingly, causing the bridge circuit 7 to become unbalanced. Therefore, a change in current corresponding to a change in weight due to a change in the size of the record is extracted as a signal. After this signal is amplified by the amplifier 11, it is transmitted to the arm drive section, and the arm drive section is operated according to the size of the record.

As described above, according to the record size detection device of this invention, strain gauges are attached to predetermined locations on the turntable support means, at least one of the strain gauges is connected to one side of the bridge circuit, and When there is no record placed on the
When a record is placed on a turntable, the resistance value of the strain gauge changes as the weight changes depending on the size of the record, causing the bridge circuit to become unbalanced and extracting a signal according to the size of the record. , so there are no factors that could damage the record.

In addition, it is not necessary to form holes for light transmission in the turntable, rubber sheet, etc., and there is no need to attach a lamp, reducing the number of man-hours and parts, and ultimately reducing costs.

Furthermore, unlike conventional mechanical detection methods, the detection method does not disturb the appearance, and since it is a purely electronic method, it has excellent effects such as no mechanical noise.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a strain gauge attached to a turntable support means in an embodiment of the record size detection device of this invention, and Fig. 2 is a circuit diagram of an embodiment of the record size detection device of this invention. be. 1... Turntable, 2... Shaft, 3...
...Motor, 4...Turntable support means, 5,
6...Strain gauge, 7...Bridge circuit, 8
...Resistance, 9 ... Variable resistance, 10 ... Oscillator, 1
1...Amplifier.

Claims (1)

[Scope of utility model registration request] A turntable supporting means of a record player, at least one strain gauge affixed to a predetermined location of the turntable supporting means, and a record disc having the strain gauge on at least one side and a record placed on the turntable. A record size detecting device comprising a bridge circuit that maintains an equilibrium state when the record is not on the turntable, and becomes an unbalanced state when the record is placed on a turntable and generates an output according to the size of the record.