GB2113449A - Record players - Google Patents

Abstract

A disc record player comprises a support means (14, 15) to support a stylus (13) for tracking movement along a rectilinear track over the surface of a record (12), drive means (15,16,17) to drive the stylus (13) along the track, an element (18) in said drive means (15,16,17) which moves in a predetermined relationship to said tracking movement of the stylus (13), photoelectric means (19,20) to sense the position of said element (18) when said stylus (13) is at any position along said track and to provide a position address for the stylus (13) via the encoder (21), the control device (22) and the digital display device (23), whereby the stylus can be positioned in a selected location by operating the drive means (15,16,17) via a key matrix (25) and a motor control circuit (24) until the element (18) occupies a position corresponding to the position address of said selected stylus location. <IMAGE>

Description

SPECIFICATION Record players This invention relates to disc record players comprising a pick-up arm adapted to receive a stylus for engaging in a groove on a disc record and a motor driven turntable to support and rotate the disc record beneath the stylus, in use. Such record players will be referred to hereinafter as "of the kind specified".

It is desirable for the user of a record player of the kind specified to be able to move the stylus into playing relationship with the record, i.e. cued, without having manually to handle the stylus, which can be easily damaged by mishandling. Automatic cuein disc record players are well known but these do not allow the user of the record player to commence playing the record at any position other than at the beginning of the record.

Further, automatic cue-in record players are known which allow the user to select a particular track of a multi-track record. Alongside the transducer, a sensor is provided which senses smooth spaces on the record between tracks and thus the record player mechanism moves the transducer to the beginning of a selected track. However, such known record players have at least the following two disadvantages.

First in both of the above types of known record players described above, it is not possible automatically to commence playing a record at any selected starting position but only at the beginning of the record or at the beginning of a selected track.

Further, in the latter type, where the record is not multi-tracked or where the tracks are too close together for the sensor to sense the smooth spaces, it is not possible for the user of the record player to select a particular track on the record he wishes to play.

Secondly, in the latter type of record player, it is necessary for the sensor to be carried adjacent the transducer, which sensor, where provided, increases the mass of the pick-up arm, which is undesirable.

It is therefore an object of the present invention to provide a disc record player of the kind specified which permit of a user cueing the pick-up arm so that the stylus is engaged with a predetermined position on the record which can be selected at will.

Accordingly this invention provides a disc record player of the kind specified comprising a support means to support the stylus for tracking movement along a rectilinear track over the surface of the record, drive means to drive the stylus along said track, an element in said drive means which moves in a predetermined relationship to said tracking movement of the stylus, means to sense the position of said element when said stylus is at any position along said track and to provide a position address for the stylus, whereby the stylus can be positioned in a selected location by operating the drive means until the element occupies a position corresponding to the position address of said selected stylus location.

The element may be a rotatable member which rotates a plurality of turns whilst the transducer performs said tracking movement, the position of said element being detected by virtue of determining the extent of angular rotation of said element in bringing the transducer from an irwdexing position to said selected location.

The support means may include a support member connected to the stylus, a feed screw threadedly engaged with the support member, means to rotate the drive screw and means to rotate said rotatable member in a predetermined relationship with rotation of the drive screw.

The rotatable member may be fixed to the drive screw to rotate therewith.

The means to detect the extent of angular rotation of the rotatable member may comprise a light source, a photo sensitive signal providing device and said rotatable member being disposed between the light source and said device and having at least one pair of areas of different light transmissivity so that said device provides a signal corresponding to passage of the or each pair of areaa between the light source and said device.

Preferably, at least four light transmitting areas alternating with four opaque areas are provided.

Said device may comprise a photo transistor.

The signal produced by the photo sensitive device may be supplied to an encoder which produces address signals according to the position of the stylus. Any suitable form of coding may be used such as pulse counting.

The output signal of the encoder may be supplied to a display device.

A user may note the data displayed for a selected stylus location and when it is desired to re-locate the stylus at said selected location, the user operates the drive means until the data displayed by the display device is the same as that noted for the selected location.

The output signal of the encoder may be provided to a-control device which may comprise a microprocessor and the miro-processor may comprise a random access memory and a read ony memory.

The control device may be provided with an information signal related to the stylus position and fed as an input from a key matrix and derived by a user, for example by visual inspection of a display device to which an output signal of the encoder is supplied, or by visual inspection of the location of the stylus directly on the record, or by acoustic inspection, so that a location address for a desired stylus location may be fed into the control device, the control device then causing the drive screw to rotate and comparing the location address signal fed thereto with that keyed in and thus arresting movement of the stylus at the selected location.

Data may be coded in the lead in or lead out groove of a record so as to be detected by the stylus and fed to said control device for comparison with keyed-in information to permit the stylus to be automatically moved to a selected location. Any suitable form of coding may be used such as frequency shift keying. For example, the operator may key in if he desires a fourth track on the record to be played, the control device would then compare the coded information for the fourth track picked up from the record with the address information fed to the control device from the encoder and again stop the stylus at the desired location.

The invention will now be described in more detail by way of example, with reference to the accompanying drawing which is a diagrammatic illustration of a disc reord player embodying the invention.

Referring to the drawing, a disc record player comprises a turntable 10 driven by a motor 11 in conventional manner and carrying a disc record 12.

A stylus 13 is carried on a pick-up arm 14 provided with means to raise and lower the stylus 13 out of and into playing contact with the record, i.e. vertical cue-in.

The pick-up arm 14 is carried by a support member 15 which is threadedly engaged with a drive screw 16 driven by a second motor 17.

The feed screw 16 has fixed thereto to rotate therewith a rotatable element in the form of a plate 18 provided with four equi-angularly spaced openings therein. A rotation position detection photo transistor 19 is positioned on one side of the plate and a light source in the form of a lamp 20 on the other side of the plate so that the photo transistor is illuminated by the lamp 20 only when one of the openings passes therebetween.

The signal thus produced by the photo transistor 19 is fed to an encoder 21 where a pulse counting encoding operation is performed. The encoder 21 is part of a control device 22 comprising a microprocessor, random-access memory and read-only memory as well as other components. The control device 22 provides an output to a digital display device 23 which thus indicates the instantaneous position of the stylus 13 at any position along the rectilinear track it is moved along by the feed screw 16. The digital display device 23 may, for example, be a four digit display, one digit being displayed for each passage of an opening in the disc 18 between the light source and photo transducer 19.

The control device 22 also provides an ouptut to a control circuit 24 which controls the motor 17 and a key matrix 25 is also connected to the control device 22.

In, the present example, where the control device 22 is provided with the above mentioned memory facility, the disc record player is operated by a user noting when the stylus is in a desired position, for example, at the beginning of a passage of music within a track by acoustic inspection of the sound produced by the disc record player. He then notes the display data on the digital display 23 and feeds this data into the control device 22 using the key matrix 25.

This input may be in terms of the digital display itself or may be in terms of an nth input in the range of, for example, ten possible inputs. In other words, the thus selected stylus location is entered into the control device as the nth selected position.

When it is desired to re-position the stylus at said selected position, the control device 22 is instructed via the key matrix 25 to select the desired location, for example by entering said nth position or the appropriate digital data, and then the control device makes a comparison between the thus keyed input and the instantaneous information address provided by the photo transistor 19 and the encoder 21 and causes the motor control circuit 24 to stop the motor 17 when the stylus has reached the thus selected location.

In an alternative embodiment, the record player may be unprovided with a memory in which case the operator would note the digital data on the display 23 for a selected stylus position, and when causing the motor 17 to drive the stylus to the desired position, would note when the data displayed on the digital display in respect of instantaneous position of the stylus was the same as the thus recorded position and then stop the motor 17.

In a further embodiment, the record may be provided, in its lead in or lead out groove with coded information which is detectable by the stylus and fed thereby into the control circuit 22 where the information is stored in the memory facility. The coded information may be that of the beginning and end of the recorded area on the disc and if desired, the beginning of each track of recorded material.

In this case, when a user desires to play a particular part of the record, and hence requires the stylus to move to a selected location, for example the beginning of a fourth track, he would call up the fourth track using the key matrix 25 and the control device 22 would then compare the data inputted from the stylus for track position number four with the instantaneous stylus position data inputted from the encoder 21, and cause the motor 17 to be stopped when the stylus has achieved the selected location.

If desired, the digital display may be of greater capacity, for example an eight digit capacity, in which case two digits could indicate the record side, two digits the number of the track and two digits the position of the stylus.

Because the encoder is provided with a signal for each 90 of rotation of the disc 18 and because the stylus is driven by a relatiely fine screw thread, very fine indication of the position of the stylus is provided of the order of 1/4mm and thus it is possible with the present invention to locate the stylus in a desired record groove. By providing a greater number of opaque/-transparent areas a high degree of position resolution can be achieved.

This is to be contrasted with prior proposals where the degree of accuracy is considerably less and it is merely possible to locate the stylus within the area between two tracks on a record or the area at the beginning of the recorded matter.

Claims (16)

1. A disc record player of the kind specified comprises a support means to support the stylus for tracking movement along a rectilinear track over the surface of the record, drive means to drive the stylus along said track, an element in said drive means which moves in a predetermined relationship to said tracking movement of the stylus, means to sense the position of said element when said stylus is at any position along said track and to provide a position address for the stylus, whereby the stylus can be positioned in a selected location by operating the drive means until the element occupies a position corresponding to the position address of said selected stylus location.

2. A record player according to Claim 1 wherein the element is a rotatable member which rotates a plurality of turns whilst the transducer performs said tracking movement, the position of said element being detected by virtue of determining the extent of angular rotation of said element in bringing the transducer from an indexing position to said selected location.

3. A record player according to Claim 2 wherein the support means includes a support member connected to the stylus, a drive screw threadedly engaged with the support member, means to rotate the drive screw and means to rotate said rotatable member in a predetermined relationship with rotation of the drive screw.

4. A record player according to Claim 3 wherein the rotatable member is fixed to the drive screw to rotate therewith.

5. A record player according to Claim 2,3 or 4 wherein the means to detect the extent of angular rotation of the rotatable member comprises a light source, a photo sensitive signal providing device and said rotatable member being disposed between the light source and said device and having at least one pair of areas of different light transmissivity so that said device provides a signal corresponding to passage of the or each pair of areas between the light source and said device.

6. A record player according to Claim 5 wherein at least four light transmitting areas alternating with four opaque areas are provided.

7. A record player according to Claim 5 or Claim 6 wherein said device comprises a photo transistor.

8. A record player according to any one of Claims 5 to 7 wherein the signal produced by the photo sensitive device is supplied to an encoder which produces address signals according to the position of the stylus.

9. A record player according to Claim 8 wherein the output signal of the encoder is supplied to a display device.

10. A record player according to Claim 8 or Claim 9 wherein the output signal of the encoder is provided to a control device comprising a microprocessor.

11. A record player according to Claim 10 wherein the micro-processor comprises a random access memory and a read only memory.

12. A record player according to Claim 10 or Claim 11 wherein the control device is provided with an information signal related to the stylus position and fed as an input from a key matrix and derived by a user, the control device then causing the drive screw to rotate whilst comparing the location address signal fed thereto with that keyed in and thus arresting movement of the stylus at the selected location.

13. A record player according to any one of Claims 10 to 12 wherein data is coded in the lead in or lead out groove of a record so as to be detected by the stylus and fed to said control device for comparison with keyed-in information to permit the stylus to be automatically moved to a selected location.

14. A record player according to Claim 13 wherein the record coding is frequency shift keying.

15. A record player as hereinbefore described with reference to and as shown in the accompanying drawings.

16. Any novel feature or novel combination of features disclosed herein and/or shown in the accompanying drawings.