JPS5853425B2 - Tone arm movement detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting the absolute position of a tone arm in a player device corresponding to all rotational positions on a record, that is, all positions of the record sound groove. It is possible to provide positional information that helps the player device to introduce the tone arm to an arbitrarily selected position on the record.

An embodiment of the tone arm movement detection device of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the tone arm movement detection device of the present invention, FIG. 2 is a plan view of the movable slit plate of the same, and FIG. 3 is a plan view of the fixed slit plate of the same. Figures 4A and B are the output waveform diagrams when the tone arm moves toward the inner circumference of the record, and Figures 5A and B are the output waveform diagrams when the tonearm moves in the opposite direction to Figure 4A and B. Figures 6 and 7 show the configuration of the same embodiment of the light source and slit plate, and Figure 8 shows the configuration of another embodiment of the light source. .

Click the button in Figure 1, 1 is the tone arm, 2 is the record,
3 is a movable slit plate provided on the same axis of the tone arm; 4
5 is a light source, 5 is light emitted from the light source 4, 6 is a fixed slit plate, and 7 is a light receiving element.

Now, if the tone arm 1 rotates in the inner circumferential direction of the record disc 2, the movable slit plate 3 similarly rotates in the inner circumferential direction of the chord disc 2.

In other words, here, the tone arm 1 can be rotated by driving the shaft on which the movable slit plate and the tone arm 1 are provided by an external driving source, and the tone arm 1 can also be rotated by driving the shaft on which the movable slit plate and the tone arm 1 are provided.
It is rotated by the force received from the record disc 2 via the cartridge as the record disc 2 rotates.

At this time, the light 5 from the light source 4 passes through the slit 3' of the movable slit plate 3 and the slit 6' of the fixed slit plate 6, reaches the light receiving element 7, and the slit pattern of the movable slit plate 3,
The slit pattern of the fixed slit plate 6 is used to detect digital amounts corresponding to changes in brightness and darkness.

Here, the slit pattern of the movable slit plate 3 and the slit pattern of the fixed slit plate 6 are such that a phase difference of at least 900 can be detected, as shown in FIGS. When the arm 1 rotates in the direction of the inner circumference of the record 2, an output waveform with a phase difference of 900 is obtained from the light receiving elements 7 and 7 as shown in FIGS. 4A and 4B.
Conversely, when the tone arm 1 rotates toward the outer circumference of the record 2, as shown in FIGS. 5A and 5B, the light receiving elements 7 and 2
An output waveform with a 70° phase difference is obtained.

One of the outputs obtained in this way is 00,900,180°, 2700°360 in FIGS. 4 and 5.
The signal level E1.0 at 900 pitches. E2.
E3. By providing each level detector that generates a pulse when E4 is detected and also providing a counter that counts the pulses from this level detector, the count content of the counter means 10 rotation angles of the tone arm,
In other words, if the rotation range of tone arm 1 is divided into predetermined addresses, the current absolute address of the tone arm can be interpreted as (
The stylus of the tone arm detects (designates) the absolute address along the radial direction on the record, and is obtained as position information displayed as an absolute address.

Furthermore, by introducing the above two outputs into the phase discrimination circuit, it is possible to discriminate between the phase relationship shown in FIG. 4 or the phase relationship shown in FIG.
The direction of rotation (rightward or leftward) can be known.

It goes without saying that the counter can be configured to add when the direction of rotation of the tone arm 1 is a predetermined direction, for example, toward the inner circumference of the record disc 2, and to subtract when the direction is reversed.

It will be understood that in this way, the current absolute address and direction of rotation can be determined by passing the output through a control circuit including, for example, a level detector, a counter, a phase discrimination circuit, etc.

In addition, the movable slit plate 3 has a diameter of O in order to detect the minimum detection width of the tone arm 1 on the record with an accuracy of approximately 100μ.
o, 900, 180', 270°.

By reading at a pitch of 3600 to 900, the number of slits 3' can be reduced and the pitch width can be easily manufactured.

However, from the above output, the rotation angle, in other words, the address as an absolute position, that is, the position information is determined by the output levels of 0°, 90°, 180°, and 270° as shown in Figures 4 and 5 above. It is obtained by counting the pulses obtained by detecting E1, E2, E3, and E4, but it is not limited to this. For example, it can be obtained by counting only the pulses obtained by detecting level E2. It is clear that

Since various circuit means for generating pulses by level detection and circuit means for counting pulses are known, their explanation will be omitted here.

It goes without saying that the phase detection means, addition and subtraction means are well known, and will therefore be omitted.

Furthermore, although the number of slits 6' in the fixed slit plate 6 that correspond to the same phase is two as shown in FIG.
The negative effects of pitch width errors can be reduced and even absorbed.

By the way, the above-mentioned absolute address as the position information can be used, for example, in the automatic player device as follows.

That is, the player device is configured to be able to store in advance the address corresponding to the song that the user wishes to play, and the current address detected as the tone arm rotates is set to the stored address. By making it possible to lower the arm when a match is made, and raising the arm when the current address matches the address corresponding to the end of the performance, it is possible to play any song. You can start and end the performance after the end of any song.

Further, according to the above configuration, as shown in FIG. 6, there is a gap between the movable slit plate 3 and the fixed slit plate 6, and the light 5 from the light source 4 is not a parallel beam, so that the light passing through the movable slit plate 3 is It is desirable to increase the pitch width of the slits 3 of the fixed slit plate 6 by tanθ×a so that the light passes through the fixed slit plate 6 effectively, and also to provide a lens 8 in front of the light source 4 as shown in FIG. Therefore, the light 5 becomes a parallel beam, and it is desirable to effectively receive the light 5 without changing the pitch width of the fixed slit plate 6 from that of the movable slit plate 3.Also, when the light source 4 is a lamp, the fixed slit plate 6 is fixed as shown in Fig. 8. Light can be effectively received by aligning the longitudinal direction of the slit 6' of the slit plate 6 with the longitudinal direction of the filament 10 of the lamp.

According to the tone arm movement detection device of the present invention, it is possible to detect absolute positions corresponding to all movement positions of the tone arm on the record, that is, all positions of the tone groove of the record. It has the effect of being able to obtain the necessary information when introducing it to an arbitrarily selected position on a record, an effect that could not be expected until now.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a block diagram of an embodiment of the tone arm movement detection device of the present invention, Fig. 2 is a plan view of the movable slit plate of the above, and Fig. 3 is the same as the above. FIGS. 4A and 4B show the output waveform diagrams when the tone arm moves in the inner circumferential direction of the record, and FIGS.
Figures A and B show output waveform diagrams when moving in the opposite direction, Figures 6 and 7 are configuration diagrams of the same embodiment of the light source and slit plate, and Figure 8 is another embodiment of the light source. The configuration diagrams of each are shown. 1 is a tone arm, 3 is a movable slit plate, 4 is a light source, 6
is a fixed slit plate, and 7 is a light receiving element.

Claims (1)

[Claims] 1. A fixed slit plate having a first slit is provided between the light source and the light receiving element, and a movable slit plate having a second slit interlocked with the movement of the tone arm in the middle of the optical path consisting of the light source, the light receiving element and the fixed slit plate. and the second slit is formed of a plurality of slits arranged in parallel along the moving direction of the movable slit plate to increase or decrease the amount of light received by the light receiving element according to the movement, and to adjust the amount of light received by the light receiving element according to the movement. A level detector is provided to output a proportional signal and generates a pulse each time a specific signal level of such signal is detected, and a counter is provided to count the pulses output from the level detector. In the device in which the count content of the counter is the absolute position of the tone arm, at least two of the light receiving elements are provided, and the first slit of the fixed slit plate receives the light passing through the second slit. The structure is such that a phase difference is given to each element, and the phase difference between the output waveforms of the two light receiving elements is made different according to the difference in the moving direction of the movable slit plate, and the difference in the phase difference is used to generate the counter. A tone arm movement detection device characterized by adding and subtracting.