JPS5834026B2 - record play - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a record lead-out groove position detection device for a record player.

In conventional high-grade fully automatic players, the arrival of the squilllus of the pickup into the lead-out groove of the record is detected by an electrical non-contact detection method rather than by a mechanical contact detection method. .

In other words, in the mechanical contact detection method, the detection plate for detecting the speed of movement of the tone arm becomes a mechanical load on the tone arm, which also places a load on the squill, which may cause distortion in the reproduced signal or increase the stylus pressure. The stylus would fly off when there was little.

On the other hand, although the electrical non-contact detection method does not cause the problems encountered with the mechanical contact detection method described above, it has the disadvantage that the apparatus using this method is expensive and the detection means is difficult to adjust.

This latter detection method combines a lamp, a CdS photoconductive cell, and a shutter, and the shutter is attached to the axis of the tonearm, and changes in the amount of light incident on this cell are used to speed up the movement of the tonearm. There are known methods for detecting.

However, this method has the problem that the detection means must be adjusted by darkening the vicinity of the lamp and the CdS photoconductive cell, and the adjustment is difficult.

In view of this, the present invention aims to provide a record lead-out groove position detection device for a record player, which eliminates the above-mentioned drawbacks.

Below, we will discuss one embodiment of the present invention in detail with reference to FIGS. 1 to 5.

FIG. 1 is a plan view of a record lead-out groove position detection device of a record player of the present invention, and FIG. 2 is a rear view of the pickup 1 seen from behind.

Reference numeral 1 denotes a pickup, which is composed of a cartridge 2, a tone arm 3, a bearing portion 4 for holding the tone arm 3, and a counterweight 5.

A shaft 6 is attached to the bearing portion 4 so as to pass through the housing 8, and this is attached to the housing 8 of the record player via the bearing 1.

Inside the housing 8, a U-shaped yoke 9 connects the tone arm 3.
It is attached to the shaft 6 so as to be substantially perpendicular to the axis.

10 is a magnet attached to the lower part of the U-shaped 1 yoke 9.

11 is a detection coil as a first magnetic flux detection means;
When the tone arm 3 rotates, the rotation speed of the tone arm 3 is detected by detecting the magnetic flux generated by the magnet 10 attached to the tone arm 3.

12 is a terminal led out from the detection coil 11.

Reference numeral 14 denotes a detection coil support member, which is attached to the housing 8 with screws 13.

15 is a saturable magnetic core as a second magnetic flux detection means;
It is provided to detect the magnetic flux of the magnet 10 to detect the detectable rotation angle position of the lead-out groove of the tone arm.

16 is a coil wound around the saturable magnetic core 15.

Reference numeral 17 denotes a saturable magnetic core support member, which is attached to the housing 8 with screws.

18 is another saturable magnetic core, and 17 in a record player.
When a cIrt record is played, the position of the introduction groove of the record is detected.

19 is a coil wound around the saturable magnetic core 18.

Reference numeral 20 denotes a saturable magnetic core support member, which is attached to the housing 8 with screws 21.

Reference numeral 22 denotes yet another saturable magnetic core, which is provided to detect the position of the introduction groove of the record when playing a 30 cfn record on a record player.

23 is a coil wound around the saturable magnetic core 22.

24 is a saturable magnetic core support member, which is attached to the housing 8 with screws 25.

Coils 16, 19 and 23 wound around the above-mentioned saturable magnetic cores 15, 18 and 22 are connected to an oscillator via resistors, respectively, and when the saturable magnetic cores 15, 18 and 22 are non-saturated, The level of the oscillation voltage obtained across each of the coils 16, 19, and 23 is set so that the level becomes small when it is saturated, but this is not shown.

Next, with reference to FIG. 3, questions will be asked regarding the electrical system of the record lead-out groove position detection device of the record player of the present invention.

The electric signal detected by the detection coil 11 is amplified by an amplifier 27 and then supplied to one input terminal of an AND circuit 28 .

Further, a detected electric signal from the coil 16 wound around the saturable magnetic core 15 is supplied to the other input terminal of the AND circuit 28 through an inverter circuit 29.

The output of the AND circuit 28 is supplied to an input terminal of a control circuit 30 for a device that returns the tone arm 3.

Next, with reference to FIGS. 3 to 5, we will ask about the operation of the record lead-out groove position detection device of the record player of the present invention.

When a record is played on a record player, the tone arm 3 is first rotated by turning on a function switch.

When the record has a diameter of 30 cIn, when the magnet 10 attached to the yoke 9 reaches the position of the saturable magnetic core 22, the saturable magnetic core 22 is saturated, and the voltage generated in the coil 23 wound around it is as follows. It becomes zero.

This electric signal is supplied to the control circuit, and after stopping the rotation of the tone arm 3, it is lowered, and the stylus attached to the cartridge 2 is placed in the introduction groove of the record.

On the other hand, when the record has a diameter of 17 cr/'L, the saturable magnetic core 18 is saturated when the magnet 10 attached to the yoke 9 reaches the position of the saturable magnetic core 18.
The voltage generated in the coil 19 wound around this becomes zero.

In this case, the saturable magnetic core 22 is also saturated, but for example, if the selector switch for selecting the record size is
By switching toward the saturable magnetic core 18, even if the saturable magnetic core 22 is saturated, the saturable magnetic core 1
An electric signal from 8 is supplied to the control circuit, and the stylus of the cartridge 2 is placed in the introduction groove of the record by the operation of the control circuit.

As the squill attached to the cartridge traces the groove of the record, the tip of the U-shaped yoke 9 approaches the detection coil 11, and eventually the U-shaped yoke 9 is inserted into the detection coil 11. Ru.

Here, the moving speed of the U-shaped yoke 9 is V, and the detection coil 1 is
1, the average length of the detection coil 11 is 1, and the number of turns of the detection coil 11 is N, then the electromotive force e generated between the terminals 12 of the detection coil 11 is as follows: .

e=B・1・V−N=K・■ (However, 1 and・1・N) This electromotive force e changes as the position of the tone arm changes.

FIG. 4 shows the electromotive force e generated in the detection coil 11 when the yoke 9 moves at a constant speed of 1iv.

That is, the cartridge can detect the lead-out groove of the record.

The electromotive force e gradually increases until it reaches the position of 1301 mφ, and then it remains constant for a while and then drops.

On the other hand, the cartridge can detect the introduction groove of the record.

When reaching the position of 130 mrnφ, the magnet 10 approaches the saturable magnetic core 15.

However, when the record is actually played and the cartridge traces the record, the electromotive force e of the detection coil 11 changes as shown in FIG. 5A.

That is, when the needle of the cartridge is at position a of the feed groove between the song recorded on the record, the pitch of the feed groove becomes larger than the pitch of the part where the song is recorded (varies by about 0.1 mm). Therefore, the moving speed of the yoke 9 attached to the tone arm 1 increases, and an electromotive voltage V1 is generated.

Also, when you want to play a song from among the many songs recorded on a record, by turning on the function switch, the tone arm will automatically rotate and the cartridge needle will move to the position of the song. Alternatively, in systems where this operation is not automatic, the tone arm is manually rotated to position the cartridge stylus at the position of the song.

At this time, the moving speed of the yoke 9 attached to the tone arm 1 becomes extremely fast, and the electromotive force v1
An electromotive voltage V2 several hundred times larger than that generated is generated.

Furthermore, when the needle of the car 1-IJ edge traces the lead-out groove C of the record, the pitch in this area becomes 4.
Since the difference is about .about.7 mm, the moving speed of the yoke 9 attached to the tone arm 1 increases, and in this case, an electromotive voltage V3 that is about 1/100th of the electromotive voltage V2 described above is generated.

If the voltage generated by the detection coil 11 is supplied to the amplifier 27 when the stylus of the cartridge 2 is at positions a and b on the record, the voltage is amplified and then directly supplied to the control circuit 30. The control circuit 30 operates, and the tone arm 1 immediately performs the return operation.

Therefore, in order to supply only the detection electric signal generated by the detection coil 11 to the amplifier 27 when the cartridge reaches position C of the lead-out groove of the record, the signal is amplified and then supplied to the control circuit 30. The detection electric signal from the coil 11 and the detection electric signal obtained by detecting the rotation angle position where the lead-out groove of the tone arm can be detected by the saturable magnetic core 15 (the position of 130 degrees φ of the record) are respectively input to the input terminal of the AND circuit 28. These signals are supplied to the input terminals of the AND circuit 28, so that the AND circuit 28 outputs the record groove detection output.

That is, the magnet 10 attached to the tone arm 1 approaches the saturable magnetic core 15 when the cartridge of the tone arm 3 reaches position C of the lead-out groove of the record.
The saturable magnetic core 15 becomes saturated and the voltage generated in its coil 16 becomes zero.

The electrical signal obtained by this coil 16 is transferred to the inverter circuit 2
9 and is inverted, and a voltage of level v4 is generated at the output terminal of the impark circuit 29 as shown in FIG. 5B.

The output voltage of the inverter circuit 29 is supplied to the other input terminal of the AND circuit 28.

In the AND circuit 28, the detection coil 11 is connected to one input terminal of the AND circuit 28.
Even if the detection signal voltage is constantly supplied from the inverter circuit 29, if the voltage shown in FIG. No voltage is generated.

Then, the stylus of the cartridge 2 traces the lead-out groove and the magnet 10 comes close to the saturable magnetic core 15, and only when the voltage shown in FIG. 5B is supplied to the other input terminal of the AND circuit 28. An output voltage as shown in FIG. 5C is generated at the output terminal.

This output voltage is supplied to the control circuit 30.
When the operating level voltage V of 0 is reached, the control circuit 3
The tone arm 3 starts a return operation when the plunger or the like provided at the tone arm 3 is attracted and the cam or the like provided at the tone arm 3 rotates.

Thus, according to the present invention, the first magnetic flux detection means includes a magnet 10 attached to the tone arm 3 and a detection coil 1 that detects the magnetic flux from the magnet 10 to detect changes in the rotational speed of the tone arm 3; A second magnetic flux detecting means detects the magnetic flux of the magnet 10 to detect the detectable rotational angle position of the lead-out groove of the tone arm 3, and a detection electric signal from the first magnetic flux detecting means and a detection electric signal from the second magnetic flux detecting means. The detection means is provided with an AND circuit 28 to which a detection electric signal is supplied, and the record lead-out groove detection output is obtained from the AND circuit 28, so that the detection means can be adjusted in a bright place and the configuration is simple. Therefore, the device is inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an embodiment of the record lead-out groove position detecting device of the record player of the present invention, FIG. 2 is a rear view of the tone arm of FIG. 1 as seen from the rear, and FIG. The system diagrams of the control system, FIGS. 4 and 5, are curve diagrams used for the operation questions in FIG. 1 is a tone arm, 9 is a magnet, 11 is a detection coil as a first magnetic flux detection means, 15 is a saturable magnetic core as a second magnetic flux detection means, and 28 is an AND circuit.

Claims (1)

[Claims] 1. A first magnetic flux detection means consisting of a magnet attached to the tone arm, a detection coil that detects the magnetic flux from the magnet and detects the rotational speed of the tone arm, and a first magnetic flux detection means that detects the magnetic flux of the magnet and detects the rotation speed of the tone arm. A second magnetic flux detection means for detecting the detectable rotation angle position of the lead-out groove of the arm, and a detection electric signal from the first magnetic flux detection means and a detection electric signal from the second magnetic flux detection means are supplied. 1. A record lead-out groove position detecting device for a record player, comprising an AND circuit and configured to obtain a record lead-out groove detection output from the AND circuit.