DE2529151A1 - Data recorder and reproducer - operates whilst tape is accelerating and decelerating to or from normal running speed - Google Patents

Abstract

A recording/reading system uses magnetic tape as an input/output unit for a data processor in which recording/reproduction can be undertaken whilst the tape is starting up travel, without waiting for normal running speed to be reached. A tachometer is coupled to the tape drive roller which feeds pulse train representing the instantaneous tape speed to a detector which acts as a threshold detector to feed a switching-on signal to a fixed phase oscillator when the speed is above a critical minimum value. The fixed phase oscillator together with a phase comparator controls the flow of data from the source to the recording head according to the speed as represented by the pulse train from the tachometer.

Description

Arrangement for recording and reading data on and from one magnetic variable speed tape The invention relates to a device for recording digits on a magnet, which is used by the data processor Facilities is used and in these serves as input devices.

When recording or reading, those normally present as bits Digits can start and stop the tape several times per second will. During start-up, writing or reading is suppressed as long as until the tape has reached a certain speed. The same applies to shutdown during the period in which you see the tape slows down. As a result of oppression of the write process at m start and stop occurs between the on the tape recorded data blocks an empty space, also known as the "gap between the blocks" and so far normally 0.6 inches ica, 16 mm) wide nst. In the last One went over to a gap width of 0.3 inches (<a 8 mm). If the Read / write head is located in the middle of the gap when the tape is stopped, means this narrow gap width that ntcr still a distance of 0.15 inches (3.8 mm) ur Acceleration of the tape is available until there is space for the next data block shows up. Accordingly, belt speeds of 300 inches sec (7.6 m / sec) are used, which experienced an acceleration of 300,000 inches / sec2 (7.6 km / sec2 must be assigned; when stopping, the delay is of the same order of magnitude. This in turn includes motors for winding and unwinding the tape and drive circuits linked that have an enormous amount of electricity consumption. Indeed the power consumption increases non-linearly with acceleration or deceleration bzy. which depends on the gap width and the band speed of the arrangement are. There is no further requirement imposed on a hand-held device with the construction of the Read circuit is related, is that the data bits with a constant Density of z Bo 6000 bits inches (2360 bits / cm) must be recorded.

If, however, the tape system 30 is constructed, that is the data transfer A wide range of belt speeds can take place at startup and stopping, lower accelerations or decelerations are possible. The activity an arrangement. record the data bits at reduced speeds and reading can thus help reduce the mechanical stresses and reduces power consumption for the coil drive and associated circuitry will.

The invention is based on the object of specifying an arrangement in which the data are recorded or read at tape speeds can that only have a predetermined fraction of normal drive speeds of the tape, so that the power consumption of the motor for the reel drive and the mechanical stress on the belt is greatly reduced.

According to the invention, a tachometer is used as a sensor for the belt speed coupled to the transport mechanism of the belt and provides a signal whose Frequency is proportional to the belt speed. A phase start oscillator which controls the writing speed of the data bits is connected to the tachometer, whose frequency is locked to that of the oscillator, reducing the writing speed of the tape speed bits is recorded so that when the tape speeds change the recording density of the bits is kept constant. Kit the speedometer and the fixed phase Oscillator is connected to a threshold circuit which switches on the latter as soon as the belt speed is above a predetermined one Proportion of its full speed. As a result, cores when the belt starts up already duration. recorded before the tape reaches a certain speed has, and when stopped, the writing can continue until the tape speed drops below a fixed value. Another phase-locked oscillator, its frequency against which the data reading is recorded from the tape controls the circuit o to recover the data and is also dependent on the aforementioned threshold value circuit switched on £ your connection to this second oscillator is like this. designed that the latter a short time after the first oscillator is switched on, is also switched on by the threshold circuit.

An error voltage. The one phase comparator of the first Oxaillator is taken, is fed to the second phase-fixed oscillator whose frequency, if it is switched on .qst, instantly with the reading speed of the data bits is synchronized.

An embodiment of the invention is shown in the accompanying drawings and is explained in detail below. The figures show: FIG. 1 schematically the transport mechanism of a magnetic tape.

in which the invention is applied, FIG. 2 is a block diagram the circuit according to the invention, FIG. 3 the block diagram of a detector 37 for the perception of a threshold value of the tape speed, which is in the circuit of FIG. 2 is applied, and FIG. 4 has several diagrams for illustration the operation of the circuit according to the invention.

According to FIG. 1, the mechanism for transporting the tape has two Reels 10 and 11 on which a magnetic tape 10a is unwound and wound up, a drive roller 14 and a reversible motor 12 for the further conveyance of the magnetic tape 1Ca next to which a read / write head 20 is arranged; Furthermore, the magnetic tape runs 10a over an idle mechanism 19 and forms two slack loops lr; / trend 18 A circuit 21 is connected to the read / write head 20 from the the data appearing on a line 22 is recorded on the magnetic tape TOa.auB while the data read from this occur in a line 23. Coupled with the drive roller 14 St via a shaft 16 is a tachometer 15 which preferably works digitally and optically or magnetically0 It delivers on one Line 24 pulse-shaped signals, the repetition rate of which corresponds to the speed of the drive roller 14 is proportional to 0 The usual work of the transport mechanism of the figure 1 is the following: A start signal is sent to the motor 12 via a line 13, which excites him and thus causes the Anlaufc-n of the drive roller 14, which the magnetic tape 10a passes the read / write head ao. The direction of movement is determined by a "forward" or "reverse" signal, which is also supplied to the motor 12.

As soon as the movement of the magnetic tape 10a on the read / write head 20 begins, the loop 17 or 18 disappears and the other increases accordingly. The respective length of the loops 17 and 18 is determined by scanning devices (not shown) perceived that each one of the coil 10 or 11 assigned motor (not shown) affect the direction of rotation of the coil, as well as its speed in such a way, that the lengths he loops 17 and 18 in a predetermined relationship to each other stand. After the magnetic tape 10a has been brought to its full speed, the data are read out or written in by him with the aid of the circuit 21. This transport of the magnetic tape 10a is shown in the plots in FIGS 4b made clear.

FIG. 4a shows a cross section through the magnetic tape 10a, over which the one direction of tape movement relative to the read / write head by one Arrow is indicated. A point C is assumed to be the position of the read / write head 20 opposite the stationary magnetic band 17a considered, As soon as the start signal reaches motor 12, the Magretb and lOa bi.s is accelerated to tendon full speed, like is shown in Figure 4b by line C-8. At full speed which is reached at point B, a data block .n the magnetic tape 10a can be written or can be read out from it. The motor 12 then receives e: n stop signal, as a result of which the magnetic tape 10a is delayed as indicated by a line A-C in Figure 4b. until it comes to a standstill at point C.

As can be readily seen, these are imposed on the engine 12 Accelerations or decelerations increased when the width of the gap A-3 decreases and / or increases the full speed of the magnetic tape 10a will. In the latter case, the motor 12 consumes significantly more power, and besides the mechanical stresses that the transport mechanism of the Magnetic tape 10a itself is subject to the aid of the subject matter of the invention the accelerations and decelerations to which the arrangement is subjected are smaller be held when data transfer is at a speed of the magnetic tape lOa takes place, which only a given proportion z.

B. 50% of the previously specified full speed or

If this threshold value exceeds the speed, as can be seen from FIG. 4c, there are smaller accelerations or decelerations possible as indicated by lines C-Bv and As-C, while the desired Width of the gap A-B between the data blocks is maintained. Of course you can according to the invention also the recording speed of the bits accordingly the belt speed can be changed, so that the requirement to maintain a constant bit sequence can be fulfilled.

In the figure 2 are a first phase-locked oscillator 28 for control the writing speed of the bits tape a second phase-fixed oscillator 27 for the establishment of the circuits for the recovery of the bits shown by a detector 37 of the speed threshold value can be switched on. Door no inner Structure is z. As explained in U.S. Patent No. 3,577,132. To the oscillator 28 belongs e.g. B. a voltage-controlled oscillator 32, the frequency of which depends on its control input terminal is affected. those of one Phasenkompa @ a @ or 35, the z. 3. Disclosed in U.S. Patent No. 3,701,039 is fed in via a low-pass filter 34 and an amplifier 33. The low-pass filter 34, preferably according to a Bessel structure, has an approximately equal to the pulse frequency of the tachometer 19 matching blocking frequency when the tachometer 15 at the half speed works. The one input terminal of the phase comparator 35 becomes fed via line 24 from tachometer 15, while the other via a frequency divider 36 is connected to the output terminal of the voltage controlled oscillator 32. In practice, the recording speed of the bits can be several times the frequency the speedometer exceed 15; therefore the frequency divider 36 is the frequency of the voltage controlled oscillator 32 is reduced to a value equal to the tachometer frequency at full belt speed, is. If the normal one supplied by the tachometer 15 Signal frequency at full tape speed, for example 32 kHz and the normal output frequency of the voltage-controlled oscillator is 32 640 kHz, the frequency divider 36 divides the latter by a factor of 20.

The structure of the second phase-fixed oscillator 27 is the same as the first Oscillator 28 is similar and therefore also contains a voltage controlled oscillator 43 and a phase comparator 40, the error signal of which a low-pass filter 41 and is fed to this downstream summing amplifier 42, the Output terminal connected to the control terminal of the voltage-regulated oscillator 43 is.

The phase comparator 40 also receives two signals similar to that Phase comparator 35. One comes from the voltage controlled oscillator 43 while the other from a data output line 25a of a decoder 25 for retrieval the dater is brought in. The construction of the decoder 25 is dependent chosen by the structure of an encryptor 30, which is used for the arrangement for recording the Data belongs to the magnetic tape 10a.

Even the structure of the two phase-fixed oscillators 27 and 28, superficially, is almost the same. there is at least one significant one Difference, namely the summing amplifier L2 of the oscillator 27, which is connected to the Place of the amplifier 33 occurs.

While the one input to summing amplifier 42 is from Formed via the @ Tiefpaßfi.lter 41 led error signal of the phase comparator 40 is, the other input signal comes over as an error signal of the phase comparator 35 Low-pass filters 34 and 44, both of which are preferably constructed in the manner of Bessel and of which the latter has a slightly lower cut-off frequency than the former having. The purpose of connecting the summing amplifier 42 through the low pass filters 34 and 44 to the phase comparator 35 will be explained below during operation the phase-locked oscillators 27 and 28 from the detector 37 of the speed threshold value switched on, the one coming from the tachometer 15 with its input terminal Line 24 and with its output terminals 45 and 46 to the phase comparators 35 and 40 left. In this way he can increase the speed of the magnetic tape 10a perceive; when it excites a predetermined proportion of full speed the two phase-fixed oscillators 27 via its output terminals 45 and 46 and 28. The output terminal 46 is also on the voltage controlled oscillator 32, am Low-pass filter 34 and connected to the phase comparator 35.

The same applies to the output terminal 45, which is connected to the corresponding Elements of the phase-fixed oscillator 27 is connected, the connection of these output terminals 45 and 46 to the phase comparators 35 and 40 and to the low-pass filters 34 and 41 is used to set the initial conditions in these components, while the Connection to the voltage controlled oscillators 32 and 43 is provided so that the latter are fixed in a built-up phase state in the detector 37 of the speed threshold are two monoflops 47 and 48 and two flip-flops 53 and 54. The line 24 coming from the tachometer 15 is according to the figure 3 in parallel at the two triggering inputs of the monoflop 47 and 48 and also to two logic elements 49 and 50, which are the set and reset input terminals of the flip-flop 53 are connected downstream, as well as two further logic elements 51 and 52, to which the set or Rtokstelleinputklemme of the second flip-flop 54 is connected. The signals emitted by the monoflop 47 reach the second Input terminal of logic elements 49 and 50; the same applies to the monoflop 48 and the linkage elements 51 and 52. As soon as the monoflop 47 is triggered is, the logic element 49 receives a switch-on signal and the logic element 50 a lock signal; The signal feed is in the inactive state of the monoflop 47 umgelarhrt.

The monoflop 48 and the two link elements 51 and 52 act together in a corresponding manner. The two monoflops 47 and 48 become common from the trailing edge of the pulses coming from the tachometer 15 via the line 24 triggered; only the monoflop 48 remains set a little longer than the monoflop 47. In practice, the monoflop 48 remains active for a period State set, which is approximately the distance between the impulses of the speedometer 15 when the tape speed is half of its full value. If the repetition period of the pulses emitted by the tachometer 15 at the full tape speed is 30 msec, the excitation time of the monoflop would 48 to about 60 msec, while with the monoflop 47 this Time span could be 50 msec, the detector 37 of the speed threshold value works as follows: The trailing edge of the pulses appearing in line 24 from the tachometer 15 trigger the two monoflops 47 and 48, which during their active period of time bring a switch-on signal to logic element 49 or 51, However, before the magnetic tape reaches half of its full speed, the distance between the pulses of the tachometer 15 is so great that the two MoroSlopF 47 and 48 adopt their inactive state in this case.

are the two links 50 tüld 52 excited so that the after switched flip-flops 53 and 54 remain in the reset state, as soon as the Belt speed reaches 50% of its full value, the distance between the successive pulses of the tachometer 15 so far decreased that they arrive at the set input terminal of the logic element 51 before the monoflop 48 recovered.

The logic element 51 allows the pulses from the tachometer 15 to be sent to the set input terminal of the flip-flop 54 go through so that the output terminal 46 is activated, the turn on the phase-fixed oscillator 28. With a constant increase the distance between the successive pulses decreases with the belt speed of the tachometer 15 so far that they arrive at the link 49 before the monoflop 47 receives. When this occurs, the flip-flop 53 is set and the Output terminal 45 energized, whereby the phase-fixed oscillator 27 is switched on. The two flip-flops 53 and 54 then remain set until the speedometer 15 falls below half the value of the full tape speed, causing the flip-flops 53 and 54 are reset by the pulses now coming from the tachometer 15 pass through links 50 and 52. With the resetting of the oscillators 53 and 54, the phase-fixed oscillators 27 and 28 are switched off, whereby the transmission of the data ceases In summary, works The arrangement of Figure 2 when recording bits is as follows: The motor 12 (Figure 1) wiro erIl start signal supplied and with this the movement of the Magnetbaii s 10a initiated via the read / write head 20, with pulses from the tachometer 15 reach the detector 37 (FIG. 2) and the phase comparator 35 via the line 24. As soon as the speed of the speedometer 15 reaches about half of its full value, where you can also count another fraction of the full value, activated de7 detector 37 via its output terminal 46 the phase comparator 35, the low-pass filter 34 and the voltage-controlled oscillator 320 The comparator now compares 35 the pulse frequency of the tachometer pulses with the one emitted by the oscillator 32, divided frequency and produces an error voltage that is the difference between corresponds to its two input frequencies. This error voltage runs across the Low-pass filter 34 and the amplifier 33 to the control terminal of the voltage-regulated Oscillator 32 to keep the frequency of the oscillator 32 on that of the tachometer 15. The data signals are from the data signals from the data quality from the Misgangs impulses of the oscillator 32 le 29 is placed on the line 22 at the right time via the locker 30 and thus supplied to the read / write circuits 21. This encryptor 30 is activated by a write signal on line 26 for the circuits 21 the data is recorded on the magnetic tape 10a. At the end of the writing process the motor 12 receives a stop signal from which it is decelerated and brought to a standstill. When the magnetic tape 10a slows down, the writing process continues until the Tachometer 15 shows the drop in speed to below half of the full value achieved. In this case the signal from the output terminal 46 of the detector 37 removed, whereby the phase-fixed oscillator 28 is switched off.

and the recording is stopped. From the encryptor 30, which does not have a Forming part of the invention, the data coming from the data source 29 are encrypted, before they are recorded on the magnetic tape 10a, During the reading process the magnetic tape 10a is started in the same way as described above, and the fixed phase oscillator 28 operates in the same way; just the encryptor 30 is still held inactive. so no signal zugelei-T-eG on line 26 Once the magnetic tape 113a has reached a predetermined fraction of its full speed has reached the detector via its output terminal 45 the phase-fixed Oscillator 27, so switches this on. From the read-write circuits 21 takes the decoder 25 receives the data via the line 23 and carries it out after it has been decrypted on line 25a of one input terminal of phase comparator 40. the for phase-solid Oxsillator 27 belongs. In the phase comparator 40, the voltage controlled by the Oscillator 43 emitting frequency with the frequency coming from decoder 25 Compare data signals. and there is an error signal that passes through the low-pass filter 41 and the summing amplifier 42 goes to the Steuerklem me of the oscillator 43, so that this keeps the sequence of data pulses from the decoder 25, Since the speed also a function of the for the recovery of the data from the magnetic tape 10a The speed of the magnetic belt is a component of the belt speed added to the error voltage received from the phase comparator S0 in such a way that that the output from the phase comparator 35 signal through the low-pass filter 34 and 44 is fed to the second input terminal of the su = iierenden amplifier 42, The The output terminal of the latter is in turn connected to the control terminal of the voltage-regulated Oscillator 43; in this way the frequency of this oscillator 43 will be of both its own phase comparator 40 as well as that of the tachometer 15 associated Comparator 35 influenced. The error voltage of the phase comparator 35 is already developed at a time before output terminal 45 is energized; when the output terminal 45 of the detector 37 of the speed threshold value is activated. around the solid phase Turning on oscillator 27 is therefore dependent on the span voltage-regulated Oscillator 43 has an instantaneous error voltage available to it quickly brings to the data bits which come from the decoder 25 over the line 25a. In addition, the introduction of the error voltage emitted by the phase comparator 35 has the effect from the phase-least oscillator '28 to the summing amplifier 42, the phase-fixed Oscillator 27 is responsible for imparting a speed component to the latter so that he better foler the speed changes of the magnetic tape 10a can.

In conclusion, the device explained above allows one Transmission of digital data to or from a magnetic tape below its full running speed. A phased oscillator follows the belt speed and influences the Data transfer to the tape. Furthermore, the belt speed is followed by a higher one Fixed phase oscillator that controls the transfer of data from the magnetic tape.

The belt speed is determined by a detector that is set to a threshold value responding to speed, perceived; if this is a certain fraction the two phase-fixed oscillators switched on. This means that there are fewer accelerations and decelerations when starting up and stopping of the magnetic tape possible.

Claims (6)

T A T E N T A N 5 P R U C H E Circuit for controlling the events taking place on or from a magnetic tape Transmission of digital data during startup at a given fraction the full drive speed begins or during the stopping process until to this fraction persists, with one on the drive roller of the magnetic tape coupled speedometer, one of which is the respective drive speed of the Drive roller proportional countless impulses per unit of time can be fed to a detector is that the detector (37) acts as a threshold value sensor at least above the specified fraction of the full drive speed a switch-on signal is fed to a phase-fixed oscillator (28, 27) which, in cooperation with a phase comparator (35 and / or 40) the data flow between the read / write head (20) and a data source (29) or an evaluation device as a function of the number of pulses per unit of time fed to the detector (37). 2. A circuit according to claim 1, d a d u r c h g e -k e n n z e i c h n e t that a phase-fixed oscillator (28) for recording the data on the magnetic tape (10a) and another oscillator (27) for recovery the data from the magnetic tape (10a) are provided. 3. A circuit according to claim 2, d a d u r c h g e -k e n n z e i c h n e t that the phase comparator (35) of the first phase-fixed oscillator (28) the impulses coming from the tachometer (15) and fed back from the oscillator output Pulses can be fed, and that from the phase comparator (35) from the fed pulses an error voltage can be generated, which together with the switch-on signal from the Detector (37) can be fed to a voltage-regulated oscillator section (32), whose output signal the data flow between the data source and the magnetic tape (lOa) adjusts. 4. Circuit according to claims 2 and 3, d a d u r c h g e k e n n z e i c h n e t that from the phase comparator (35) of the first phase-fixed oscillator (28) generated error voltage common to the further phase-fixed oscillator (27) with the switch-on signal of the detector (37) as the input signal of a voltage-regulated Oscillator section (43) can be fed, its output signals both are fed back to the associated phase comparator (40) as well as the data flow adjust between the magnetic tape (10a) and an evaluation device. 5. A circuit according to claim 4, d a d u r c h g e -k e n n z e i c h n e t that the second phase-fixed oscillator (27) with a summing amplifier (42) works, via which the error voltage generated by the associated phase comparator (40) after adding them to the error voltage coming from the other phase comparator (35) the voltage-regulated oscillator section (43) can be fed. 6. A circuit according to claim 2, d a d u r c h g e -Ic e n n z e i c h n e t that the switch-on signal fed to the first phase-fixed oscillator (28) somewhat longer than the switch-on signal fed to the second phase-fixed oscillator (27) persists. L e r s e i t e