WO1980001619A1

WO1980001619A1 - Automatic research of recorded sequences,particularly on cassette recorders

Info

Publication number: WO1980001619A1
Application number: PCT/FR1980/000011
Authority: WO
Inventors: A Torcheux
Original assignee: A Torcheux
Priority date: 1979-01-30
Filing date: 1980-01-30
Publication date: 1980-08-07
Also published as: FR2448210A1; FR2448210B1

Abstract

A sensor (20) connected to a tape rewind spool (12) supplies pulses to a counter (23); a preliminary recording of digital marks is effected by a coding circuit (24) as a function of the evolution of the content of counter (23). Upon reading, a decoding is effected by the circuit (25) to control consequently the counter (23). During the sequence searching, a logic (28) controls as a function of the desired address a coarse preselection effected in fast motion by means of an estimation counter (26) initially filled with the content of counter (23), and is then up-dated from the output of the sensor (20). Then, a fine selection is effected in slow motion from the output of the recording decoding circuit (25). Application particularly to cassette recorder-readers.

Description

Automatic search of recording sequences, in particular on cassette tape recorder

The present invention relates to the automatic search for sequences recorded on any tape support, in particular in mini-cassettes.

Such an automatic search is generally carried out by locating certain locations on the ribbon, which can then be accessed selectively. The difficulty is to carry out an automatic search which is both precise and reproducible on the one hand, fast and flexible on the other. We know how to satisfy these different requirements by reading the marks worn on the ribbon in rapid scrolling. However, rapid wear must be avoided by abrasion of the ribbon and / or the read heads. This requires very sonic arrangements, most of the time inapplicable to simple devices or fragile tapes such as those of mini-cassettes.

The present invention allows an automatic search which satisfies the four conditions above, which is very simple, and which applies in all cases.

The invention relates essentially to an automatic search device for recording sequences on a support tape, which applies particularly but not exclusively to sound recording on magnetic tape, and more specifically to recording on mini-cassettes. The device of the invention comprises, in combination:

- a motion sensor, linked to one of the tape drive members, and capable of delivering electrical punctuation signals, according to a repetitive function of the movement of this member,

- a reading circuit, capable of reading on the ribbon specific brands, prerecorded on the ribbon to delimit successive sequences there, while defining an address for each sequence, as well as delivering for each mark read a main address signal sequence,

- an input device for selecting a sequence to be obtained in the form of an address signal of desired frequency,

a preselection circuit which receives this desired address signal in order to deduce therefrom an auxiliary address signal offset in a manner chosen in advance with respect to the desired address, means capable on command of producing a scrolling fast ribbon, while constructing an estimated address signal from a value of the main address which was read before the rapid scrolling and punctuation signals then delivered by the motion sensor, and this until what the estimated address signal corresponds to the auxiliary address, and

means connected to the reading circuit and solicited after the stop of the preceding means for advancing the ribbon in slow movement in a predetermined direction, until the main address delivered by the reading circuit corresponds exactly to the address desired.

According to the invention, a preliminary marking of the ribbon is thus used, which did not need This needs to be done strictly periodically on the tape. It suffices simply that this marking has a distribution whose deviations from the rigorous linearity are determinable. Then, we make a kind of coarse positioning of the ribbon, starting from an address already read on the ribbon with certainty during slow scrolling, and advancing this address according to the punctuation signals defined by a motion sensor related to the ribbon drive. Again, it is not necessary that the motion sensor is strictly linked to the linear speed of the ribbon drive, and the sensor can be mounted on a ribbon drive coil, the winding diameter of which varies, and whose consequently, the speed of rotation is not constantly linked to the speed of linear movement of the ribbon. The preselection circuit defines an auxiliary address whose offset is chosen taking into account the distribution chosen for the brands, as well as the way in which the motion sensor will deliver these punctuation signals as a function of the scrolling of the ribbon. Those skilled in the art will understand that under these conditions it is always possible to choose the auxiliary address signal so as to fall without fail upstream of the desired address on the ribbon, for example. Then, the ribbon is driven in slow movement while comparing the real addresses written in advance on the ribbon to the desired address, until the latter is obtained. The device has then reached exactly the desired sequence.

Very advantageously, the registration of marks is carried out beforehand according to the punctuation signals which the motion sensor delivers. This feature improves consideration the correspondence between the estimated addresses and the address actually entered on the ribbon. Thus, the device of the invention may comprise a mark recording circuit, mounted between the sensor and the recording head, and capable, on command, of performing on the tape a preliminary recording of the sequence of marks, in correspondence with punctuation marks.

This recording can be done at the same time as the recording of the useful signals, sound for example, or even separately. Without the mark registration circuit which has just been defined, the apparatus can be used for playing mini-cassettes where the marks have been prerecorded at the same time as the useful signal or separately.

In a preferred application, devoted to magnetic recordings, the marks consist of digital pulse coding, or PCM, using bipolar pulses whose frequency is for example close to 600 Hz. Advantageously, the marks are recorded on one track and the audio signals on another. Marks recorded as indicated above at the level of - 15 dB are sufficient to allow the automatic search for sequences. According to another characteristic of the invention, the sensor is connected to the shaft of a ribbon drive coil, and provides all-or-nothing signals of closed or open contacts, depending on the rotation of this shaft. Other characteristics and advantages of the invention will appear on reading the detailed description which follows, given with reference to the appended drawing, the single figure of which illustrates, without limitation, a preferred embodiment of the present invention. In the figure, the reference numeral 10 generally designates a cassette recorder-player, comprising a supply reel 11 mounted on a shaft 110 and a take-up reel 12 mounted on a shaft 120. Between the two reels, the strip turns around two guide rods 131 and 132 which define a linear path portion where it comes into contact with a read recording head 13. There is provided in the linear part of the tape a means of driving the latter using a capstan, (not shown). Schematically, the tape running assembly is illustrated by block 16, which is in the separate drawing of block 10, and comes in mechanical cooperation with the two wound and the capstan.

In a manner known per se, there is associated with the recording-reading head 13 a recording preamplifier 141 and a playback preamplifier 151. The same head reads the audio frequency signal on another track.

According to the invention, a sensor 20 is mechanically linked to the take-up reel 12. The sensor comprises a shaft 210 connected for example by belt 211 to the shaft 120 of the take-up reel. The sensor itself is composed, like a coding wheel, of eight all-or-nothing contacts distributed evenly around the axis of rotation of the shaft 210. Thus, one in eight of the contacts will be closed for each angular position of the shaft and there is therefore obtained at the output of the sensor 20 a punctuation signal which is a function of the rotation of the shaft 210 and consequently of that of the shaft 120, at the rate of 8 points per turn. Of course, one can also mount the sensor 20 directly on the spool shaft 12, or even connect it to any other drive moven ribbon.

The output of the sensor 20, consisting of all or nothing signals, is shaped by a circuit 22 which makes the electrical punctuation signals compatible with TTL logic for example.

A TTL logic counter, referenced 23, is capable of being connected by a contact 231 to the output of the shaping circuit 22, in order to receive the punctuation signals. These signals are applied to the counting input of the counter, which then allows them to advance the counter at the rate of 8 steps per revolution of the take-up reel. The parallel outputs representing the content of the counter 23 are applied using a plurality of contacts shown diagrammatically at 232 to a recording coding circuit 24 which energizes the preamplifier 141, so as to be able to record on the tape specific marks which delimit successive sections, while defining for each section an address depending on the state of the counter 23.

In the opposite direction, the marks will be read by the head 13, and applied via the preamplifier 151 to a read decoding circuit 25 provided with an address buffer memory. We will see below the practical characteristics of coding and decoding.

Furthermore, the device includes a dead count 26, capable of being connected by a contact 261 to the output of the shaping circuit 22, and also of receiving the parallel outputs of the counter 23, which then serve to preload or hang the esteem counter. The output of the estimate counter 26 is connected to a comparator primary 271. On the other hand, the output of the reading decoding circuit 25 is connected to a secondary comparator 272. A control logic with direct access memory, or RAM, referenced 28, cooperates with the primary comparator circuits 271 and 272, as well as with the scrolling control circuit 16, in order to control the automatic search for recording sequences as a function of the indications given by an input device, such as a sequence selection keyboard 29. The logic also helps to define the state of the various switches, in particular 231, '232, 233 and 261.

The present invention requires a preliminary inscription of the marks on the strip. This first step is carried out initially, before or during the recording on the tape of the sound signals, the contacts 231 and 232 being closed, under the effect of a preliminary recording signal EP which can be supplied by the logic 28, or by a separate command on the recorder-player. The strip then passes in slow movement, and the sensor 20 provides 8 successive punctuation signals for each revolution of the take-up reel. These signals are applied through the shaping circuit 22 to advance the counter 23, which then energizes the recording coding circuit. The latter then performs a coding of the content of the counter, in response to each change of state thereof, in the form of pulses with digital coding or PCM, pulses which are produced in bipolar form, and applied as modulation of a frequency of 600 Hz at the recording head 13. The detailed characteristics of this coding can be chosen from the recording codes well known under the name NRZ or even NRZm. So after wedging of the strip at the start of the strip, when it is practically entirely in the supply reel 11, marks are started on the strip which are linked to the change in state of the contacts of the sensor 20, and each bear a number.

As the winding diameter on the take-up reel 12 increases, the marks will be progressively more and more spaced. However, marking at a rate of 8 steps per revolution is sufficient, even at the maximum winding diameter on the coil 12, in the majority of applications. If necessary, a sensor can be used with a greater number of marks per revolution, or even provide for subdivisions which will be recorded on the tape without being defined by the sensor itself, using an auxiliary counter circuit which would interpolate between changes counter 23.

It is the preliminary registration of the marks thus carried out which is then used for the automatic search for sequences on the magnetic tape. When the recorder-reader 10 is in the reading phase, the switch 233 is closed, and the marks read as the tape runs are applied to the reading decoding circuit 25, which then directly controls the parallel inputs counter 23; provided with a digital display, this then permanently indicates to the user where the tape is running, in the manner of a conventional counter. It will simply be noted that in the present case, the counter is directly linked to the running of the strip, and therefore provides highly repetitive indications, but which are not entirely regular depending on the running.

We will now describe an operation of automatic search for a sequence on the tape. The esteem counter 26 is loaded by the content of the counter 23 either permanently or only when a sequence search is to be carried out. Then, the switch 233 is open, and the counter 23 will no longer change state. The esteem account 26 therefore remains at the value previously defined during a slow-scrolling reading phase. The memory logic 28 then defines for the primary comparator 271 a coarse preset address, chosen so that it is certainly upstream of the desired address, for example by decreasing the desired address by a number preset. The switch 261 is then closed by the order of searching for the RSEQ sequences, so that the estimate counter now receives the pulses from the sensor 20 through the shaping circuit 22. The logic 28 then controls the member 16 so as to produce a rapid scrolling of the ribbon, scrolling during which the recording / reading head 13 is generally no longer in contact with the ribbon. The estimate counter is then updated using the sensor output pulses, and the rapid scrolling continues until the primary comparator 271 indicates to logic 28 that the content of the estimate counter corresponds to the coarse preset value. The fast scrolling is then stopped, and the logic 28 commands a slow scrolling, the read recording head 13 coming back into contact with the ribbon.

During this slow scrolling, the marks written on the tape can then be read in the usual way, and the reading decoding circuit 25 applies the marks to the secondary comparator 272. The logic 28 applies to this same comparator 272 the exact value of the desired address, and the slow scrolling continues until the comparator 272 indicates that the desired address has been reached, after which the logic 28 stops the scrolling members or continuously switches to the audio signal reading phase. As of the slow scrolling, the switch 233 is again closed, and the counter 23 then resumes the display of a precise indication as to the running state of the strip, from the marks actually read thereon.

Of course, the present invention is susceptible of numerous variants easily accessible to those skilled in the art. It is for example easy to make a registration of marks on only part of the tape, which is in an initial phase alone intended to receive a recording, and to continue recording marks on the tape at the same time as the we complete the sound recording that she must wear. In addition, when the desired new sequence is very close to the previous sequence, it is obviously very easy to arrange the logic 28 so that it can retract the slow scrolling phase. Furthermore, it was indicated previously that the rough preselection could be done by removing a predetermined number at the desired address.

In practice, it suffices that the coarse preselection takes into account the maximum error which can occur from the fact that the counter is not following the values of marks actually present on the strip, but an estimate defined by the output of the sensor 20. To obtain better speed, it is possible to make the coarse preselection dependent on the value of the desired address, the dependency being recorded in a memory which can be direct access or even a read only memory.

In addition, when, at the end of the slow scrolling, the reading of the main address shows that the desired address has been exceeded, it suffices to refresh the estimate counter 26, and to make a brief rapid scrolling in reverse.

It will also be noted that with very simple switching operations, it is possible to use a single counter instead of the counters 23 and 26 shown separately. The practical realization of the sensor 20 can be done using switches with flexible blades controlled magnetically or even by opto-electronic means.

By choosing to register the marks a very high or very low frequency, situated at the limits of the useful signal band, one can register the useful signal and the marks on the same track. This is still possible with an unused part of the useful signal band.

Furthermore, it is very easy to provide for a modification of the registered marks to define the beginning or preferably the end of the sequences actually recorded, or even of the intermediate parts of these sequences. A sequence end code will stop playback and then search for the next sequence to play.

A sequence interrupt code will only stop playback.

Finally, the present invention applies very particularly to the case of cassette tape recorders, of the 1/8 inch (3.175 mm) Philips Compact Cassette type, but it also more generally extends to any type of tape recorder player while scrolling. ment, whether it is a magnetic tape or any other type of tape serving as an information carrier.

The invention also applies to the search for a sequence in video recorders, of the U-MATIC or VHS type in particular, by using their sound track or one of these, for example.

Claims

1. An automatic search device for recording sequences on a support tape, characterized in that it comprises, in combination: - a motion sensor, linked to one of the tape drive members, and capable of delivering electrical punctuation signals, according to a repetitive function of the movement of this organ, - a reading circuit, capable of reading on the ribbon specific marks, prerecorded on the ribbon to delimit successive sequences, while defining a address for each sequence, as well as delivering for each mark read a main sequence address signal,

- an input device for selecting a sequence to be obtained in the form of a desired sequence address signal,

a preselection circuit which receives this desired address signal in order to deduce therefrom an auxiliary address signal shifted in a manner chosen in advance with respect to the desired address,

means capable on command of producing a rapid scrolling of the ribbon, while constructing an estimated address signal from a value of the main address which has been read before the rapid scrolling and punctuation signals subsequently delivered by the motion sensor, until the estimated address signal corresponds to the auxiliary address, and

means connected to the reading circuit and called upon after the stop of the preceding means to advance the ribbon in slow movement of predetermined direction, until the main address delivered by the read circuit corresponds exactly to the desired address.

2. Device according to claim 1, characterized in that it also comprises a mark recording circuit, mounted between the sensor and the recording head, and capable on command of performing on the tape a preliminary recording of following marks, in correspondence with punctuation marks.

3. Device according to one of claims 1 and 2, wherein the tape is intended for magnetic recording, characterized in that the marks consist of digital coding by pulses, using bipolar pulses.

4. Device according to claim 3, characterized in that the frequency modulated by the pulses is close to 600 Hz.

5. Device according to one of claims 1 to 4, characterized in that the sensor is connected to the shaft of a ribbon drive coil, and that it provides all or nothing signals with closed contact or open, depending on the rotation of this tree.