JPS592977B2 - Magnetic head feeding device using pulse motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic head feeding device using a pulse motor for moving and positioning a magnetic head to a predetermined track position on a magnetic medium.

5. In storage devices such as magnetic drums or magnetic disks, it is necessary to move a magnetic head to a predetermined track position on a magnetic medium to write or read information.

For example, in a floppy disk device, as shown in FIG. 1, a floppy disk 1 having tracks arranged in a concentric 10-circle pattern is used as a magnetic medium, and is inserted into a spindle 2 and rotated. The magnetic head 3 is connected to a write circuit or a read circuit (not shown), is supported by a carriage 4, and is moved radially over the 15 floppy disk 1 by the rotational movement of a lead screw 5. The lead screw 5 is rotated by a pulse motor 7 via a coupling part 6 consisting of a gear and a joint, and the pulse motor 7 receives output signals φ1, φ1, φ2, φ from a clock generation circuit 8.
2 is excited via the drive circuit 9 and step-driven. For example, in the case of two-phase excitation, as shown in the timing chart shown in FIG. 2, when signal a is input to the clock generation circuit 8 as a step command, n pulses (n is a positive integer) are generated for each pulse. A signal 25φ,
, T, φ2, -T are generated while being switched according to the order determined by the signal b. Signal φ2 for signal φ1
is delayed by 900 phase, and the signals φ1 and φ2 are the same as the signal φ1.
, φ2 are polarity inverted signals, so that the signal φ1 lags the signal φ1 by 1800 phases and 30 phases, and the signal φ2 lags the signal φ1 by 2700 phases. Signals φ1, n, φ2, φ2 are φ1・7→φ1・T−φ10
When switched and repeatedly generated in the order of φ2-drunk゜φ2→T-7, each pulse cycle of each signal takes one step and 3
5, the pulse motor 7 is driven in n steps, rotates the lead screw 5 via the coupling portion 6, moves the carriage 4, and sends the magnetic head 3 one track in the radial direction over the floppy diskette housing 1.

A predetermined number of tracks can be sent depending on the number of pulses of signal a. Furthermore, if the above case is to send the magnetic head inward, by changing the command direction of signal b, the signals φ1, nail, φ2 generated from the clock generation circuit 8 can be
，? What is the order of occurrence?・? →?・φ2→φ1・φ2→φpi=→? - If G, the rotation direction of the pulse motor 7 is reversed, and the magnetic head 3 can be moved toward the outer circumference of the floppy disk 1. Conventionally, when a pulse motor is used to position a magnetic head on a predetermined track of a magnetic medium, this is done by driving the pulse motor in multiple steps per track to move from the previous track to the next track. I was on the move.

However, with magnetic media such as floppy disks made from flexible mylar, the amount of movement of the magnetic head is limited, even though the magnetic media expands and contracts depending on the surrounding temperature, humidity, etc. Since the magnetic head is determined without regard to its expansion and contraction, there is a drawback that the stop position of the magnetic head deviates from the target stop position, that is, on a predetermined track. In order to compensate for such positional deviations, it is necessary to widen the track width, making it impossible to increase the track density, which is a factor that limits the amount of stored information. This invention was made in view of the above points, and when the magnetic medium expands due to ambient temperature, humidity, etc., the number of driving steps of the pulse motor per track is increased, and vice versa. The present invention provides a magnetic head feeding device using a pulse motor that correctly positions the head at a target position by reducing the number of drive steps when the magnetic medium contracts.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a magnetic head feeding position with respect to a floppy disk will be described below with reference to the accompanying drawings. FIG. 3 is an explanatory diagram of the deviation of the track on the floppy disk 1, in which the pulse motor is driven in n steps in a certain state with point A as a reference, and the magnetic head 3 is
When one track is sent, the amount of movement is D1, and the point B
Suppose that data is written at a location. Next, the floppy disk 1 expands and the point B moves to the point w, that is, a distance D2 from the point A, but the amount of movement of the magnetic head 3 remains D1.
Therefore, a deviation of D2-D1 occurs per track,
A deviation of m (D2-D1) occurs between m tracks (m is a positive integer). The track pitch of a typical floppy disk is about 500 .mu.ml, and there is a maximum track deviation of about 80 .mu.m due to various factors, and the largest factor of this deviation is about 50 .mu.m due to expansion and contraction of the floppy disk. FIG. 4 is a top view of the floppy disk 1, in which tracks 10 are arranged concentrically at equal pitches, and a typical floppy disk has 77 tracks, with the track number N being the outermost track O, The innermost track is named 76. The floppy disk 1 expands and contracts in the radial direction as shown by arrow R due to changes in temperature, humidity, etc., and each track shifts in the radial direction in proportion to the distance from the center C.
The position of does not change. Therefore, if the number of tracks distance from the center C is indicated as the track position M, the track positioning becomes easier. Now, if the distance k from the center C to the innermost track is an integer converted in track pitch, then the track position M for the track number N is M=k+76-N, and the drive of the pulse motor 7 for one track is If the number of steps D is changed according to the expansion and contraction of the floppy disk, the pulse motor 7 is driven by the number of steps DM, and the magnetic head 3
When moving from the center C position, the track position M
It will be placed at the top. Table 1 shows track number N.
The relationship between the number of driving steps MXD of the pulse motor 7 when the magnetic head 3 is moved from the center C to the track position M according to the track position M and the expansion and contraction of the floppy disk 1 is shown. FIG. 5 is a block diagram showing one embodiment of the present invention, and the same parts as in FIG. 1 are given the same reference numerals. In FIG. 5, reference numeral 11 denotes an image sensor as an expansion/contraction detector, which has an optically detectable mark 28 attached near the outer periphery of the magnetic medium 1, and is provided opposite to this mark 28. A charge transfer device such as a CCD in which light receiving elements are arranged in a row is used, and the direction of the row is made to coincide with the radial direction of the floppy disk 1. When the low bit side of the image sensor 11 is placed inside the floppy disk 1, the mark 28 shifts outward due to expansion, so that the mark 28 is detected from the high bit side of the image sensor 11. According to the detected value of the image sensor 11, which is an expansion/contraction detector, a converter 12, which is a converting means, converts the number of drive steps per track of the pulse motor 7 from the number of drive steps in the reference state to the number of drive steps on the floppy disk 1, which is a magnetic medium. Converts to a value that includes non-integers and outputs it so that it increases when it expands and decreases when it contracts. Reference numeral 13 denotes a track position memory which converts input of the track number N to which the magnetic head should be positioned for writing or reading and outputs the track position M, and is used to calculate P-ROM or k+76-N. It consists of vessels, etc.

14 is the number of driving steps D of the pulse motor 7 per one track of the floppy disk 1 in the standard state.

a non-volatile reference step memory for setting and storing the
5 is the output M of the track position memory 13, the output D of the converter 12, or the stored value D of the reference 1 drive step memory 14. A multiplier that multiplies and outputs the value D stored in the reference drive step memory 14. is determined by the initialization signal 1 through the AND gate 16 and by the output D of the converter 12.
are input to the multiplier 15 by the start signal ST of the head positioning command, that is, the seek command, through the AND gate 17.
given to. Reference numeral 18 indicates a track position register in which the output of the multiplier 15 is set by the initialize signal 1 or seek start signal ST input via the OR gate 19; and 20 indicates the track position register 18 by the initialize signal 1 via the AND gate 21. This head position counter is set with the contents of , and has an up/down counting function, and receives signals φ1, φ1, and φ1, which are generated from the clock generating circuit 8 and which are inputted via an AND gate 22 gated by the seek signal SS. The value of any one of φ1, φ2, and φ2 is increased or decreased depending on the polarity of the signal b', for example, every pulse of the signal φ1.

23 is " when the value of the track position register 18 is larger than the value of the head position counter 20 + 1 - smaller.
-1'', the comparator outputs the matched value O'' as a signal b', and the signal b' is sent to the head position counter 20;
is supplied to the clock generation circuit 8 via the OR gate 24,
Head position counter 20 receives signal b! When is +1", it is an up-count operation, and when it is 1-1", it is a down-count operation, and the clock generation circuit 8 uses the signals φ1 and T φ2.
，? Let the pulse motor 7 be excited in the direction in which the magnetic head 3 moves toward the inner circumference of the floppy disk 1 when the signal v is ``+1'', and in the direction toward the outer circumference when the signal v is 61-1''.

Further, the signal b' is applied directly to the AND gates 25 and 26 gated by the seek signal SS and to the inverter 2.
7, and when the seek signal SS is present and the signal b' is "+11" or -1, their output opens the gate of the clock generating circuit 8 to generate the signals φ1, φ1, φ.
When the signal b' is "O" or when the seek signal SS is absent, the gate of the clock generating circuit 8 is closed to stop the generation of the signals .phi.1, .phi.1, .phi.2, and .phi.2. These track position memory 13, reference drive step memory 14, multiplier 15, track position register 18
, head position counter 20, comparator 23, and various gates constitute drive step number determining means.

A specific example of the operation of this drive step number determining means will be described later, but in short, the output D of the converter 12 is used to determine the position of the floppy disk 1 at the track position where the magnetic head is to be positioned.
The pulse motor at the time of positioning the magnetic head (seek time) is calculated by multiplying the distance from the non-extensible reference point (center C in Figure 4) by the value M converted into the number of tracks, and converting MXD into an integer. Determine the number of drive steps of 7.

First, when the power is turned on, initialize the magnetic head 3.
is positioned as a reference point. The center C of the floppy disk 1, which does not expand or contract, can be set as a reference point, and the magnetic head 3 can be moved from there to a predetermined track according to Table 1. However, in reality, the lead screw 5 is approximately on track 10.
Since the movement is limited to the range above, the second disk 3 is moved and positioned magnetically at a constant distance from the center C, regardless of the expansion and contraction of the floppy disk 1, by the principle of parallel movement due to so-called coordinate transformation. In order to use it as a reference point, a stopper is provided on the lead screw 15, and the magnetic head 3 is moved in one direction no matter where it is on the track 10, and is stopped near the outermost or innermost circumference of the track 10. The distance at that time may be converted into the number of drive steps of the pulse motor 7. In this case, the expansion and contraction of the lead screw 5 is ignored, and the number of driving steps D per one track on the floppy disk 1 in the standard state. shall be chosen as an integer. At this time, the static position of the magnetic head 3 is the floppy disk 1.
The magnetic head 3 expands and contracts, so it does not necessarily match the predetermined track position, but for convenience of explanation, a stopper is placed on the lead screw 5 so that the magnetic head 3 stops at the outermost track position in the reference state, that is, the position of track number 0. It is assumed that it has been installed. When the power is turned on, N-0 is input to the track position memory 13, and MO=k+76-N.
-k+76 is output and becomes one input of the multiplier 15,
Memory value D of reference drive step memory 14 supplied via AND gate 16 by initialization signal 1
.

Multiplication result M. XDO is set by initialization signal 1 supplied to track position register 18 via output gate 19, and this value is set by head position counter 2.
It is also set to 0 via the AND gate 21 by the initialize signal. Therefore, the output signal b' of the comparator 23 becomes "O" and the clock generating circuit 8 does not generate any signal. The signals φ1, T1, φ2 are supplied until the magnetic head 3 reaches the stopper of the lead screw 5 near the outermost circumference position. , T2 continues to occur. However,
During this time, the signal φ1 is not supplied to the head position counter 20 because of the AND gate 22, and the head position counter 20 is at D. It remains set to XMO. For example, k is 2
D in the reference state at 0. What if you set it to 20?
×DO−(20+76)×20−1920. Next, if a seek command to track number 75 comes, for example, the seek track number N=75, which is transferred simultaneously with the seek command, is transferred to M-k+1 by the track position memory 13.
-21, the position of the mark 28 due to the expansion and contraction of the floppy disk 1 at that time is detected by the image sensor 11, and based on the detected amount, the converter 12 determines the number of drive steps per track in that state. , for example, is converted to D-20.1 and the seek start signal ST
is supplied to the multiplier 15 via the AND gate 17, so the multiplication result MXD-20.1×21=422
．． 1, and an integer value 422 is set in the track position register 18 by the seek start signal ST supplied via the OR gate 19 by rounding down the decimal places.

Since the head position counter 20 has already been set to a value indicating the current position of the magnetic head 3, ie, 1920, the output b' of the comparator 23 becomes -1'', and the AND gate 26 is opened by the seek signal SS. Clock generation circuit 8
signal φ1,? ,,φ2,? 2 occurs. The order of generation is determined by the signal b'-1, and the magnetic head 3 moves toward the inner circumference of the floppy disk 1.

The seek signal SS is also supplied to the AND gate 22, and the signal φ1 is applied to the head position counter 20, and the signal b
' is "-1", so each pulse, in other words, each time the pulse motor 7 is driven one step, it is counted down, and eventually the value 422 of the track position register 18 is counted down.
When the output of the comparator 23 becomes O', the gate of the clock generating circuit 8 is closed and the magnetic head 3 is stopped. The position corresponds to the position of track number 75 on the floppy disk 1 at that time. When the power is turned off, the values in the track position register 18 and the head position counter 20 will disappear, and the position of the magnetic head 3 may also change, so it is necessary to initialize when the power is turned on again. Since the stopping position of the magnetic head 3 is determined by the value of the head position counter 20, this position can be used as the next reference point.

Therefore, when a new seek command comes next, the track position register is determined by the product of the track number N and the step number D, which corresponds to the amount of expansion and contraction of the floppy disk 1 detected by the image sensor 11 at that time. The value of 18 is updated and set, and the rest operates as described above.
When the magnetic head 3 is moved in either direction according to the polarity of the output signal b of the comparator 23, the value of the head position counter 20 is also increased or decreased until it becomes equal to the updated value of the track position register 18. also stops working. Of course, at this time, the magnetic head 3 is at the position of the newly specified track number, and at the same time, this position becomes the next reference point after coordinate transformation of the center C, and in the same way, the expansion and contraction by the image sensor 11 at the time of a seek command is performed. The number of driving steps D per track of the pulse motor 7 is changed in accordance with the detected amount, and the magnetic head 3 is moved to the designated track number position. Note that the embodiment shown in FIG.
This circuit is an example of a circuit in which the number of drive steps per track of the pulse motor 7 can be changed by detecting the expansion and contraction of the floppy disk 1, but is not limited to this circuit in particular.

For example, other means may be used as the expansion/contraction detector, and the number of reference steps D per track may be stored in the reference drive step memory 14. Instead of setting the number of driving steps M from the center C corresponding to the stop position of the magnetic head 3 at the time of initialization. It is also possible to set XDO and set it directly in the track position register 18 or head position counter 20 at the time of initialization without passing through the multiplier 15. Also, instead of the comparator 23, (DOXMO) one (M>
The present invention can be implemented using different circuits using known techniques, such as providing a subtracter to obtain <D) and driving the pulse motor 7 by the number of steps of the resulting value.

Furthermore, although the case of a floppy disk as the magnetic medium has been described, the present invention can also be applied to a writing/reading device using magnetic media of other shapes, such as a magnetic drum, magnetic tape, magnetic belt, etc., or a device that performs only one of them. can be applied.

As described above, according to the present invention, the expansion and contraction of the magnetic medium is detected, and the number of drive steps per track of the pulse motor is adjusted according to the slight amount of expansion and contraction of the magnetic medium. (Integer) is increased or decreased to a value that includes non-integers, and the track from the reference position to the track position where the magnetic head should be positioned is determined by multiplying the number and converting the result to an integer. Since the number of driving steps of the pulse motor is determined, the amount of track position deviation of the magnetic head due to the expansion and contraction of the magnetic medium is determined by the expansion and contraction of the lead screw, the deviation of the center position of the magnetic disk, etc., and the decimal point after multiplication. Even if errors such as truncation are taken into consideration, the positioning accuracy is approximately 1/3 that of the conventional method, which not only significantly improves positioning accuracy, but also doubles or triples the track density, dramatically increasing the amount of stored information. It becomes possible to do so.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a block diagram of an example of a conventional magnetic head feeding device using a pulse motor, Fig. 2 is a waveform diagram of a two-phase clock signal generated to step drive the pulse motor, and Fig. 3 is a diagram of the waveform of a two-phase clock signal on a magnetic medium. An explanatory diagram of track deviation,
FIG. 4 is a top view of a floppy disk, and FIG. 5 is a block diagram showing an embodiment of the invention. 1... Floppy disk, 3... Magnetic head, 5... Lead screw, 7...
... Pulse motor, 8 ... Clock generation circuit, 9 ... Drive circuit, 10 ... Track, 11 ... Image sensor (expansion/contraction detector)
, 12... Converter, 13... Track position memory, 14... Reference drive step memory, 15... Multiplier, 18...・Track position register, 20...Head position counter,
23...° comparator, 28...mark.

Claims (1)

[Claims] 1. In a magnetic head feeding device in which a magnetic head is fed by driving a pulse motor in multiple steps per track, and is moved over a magnetic medium and positioned at a predetermined track position, expansion and contraction of the magnetic medium is detected. An expansion/contraction detector, and the number of driving steps per track of the pulse motor is increased when the magnetic medium expands and decreased when it contracts from the driving step number D_0 in the reference state according to the detected value of the expansion/contraction detector. converting means for converting into a value D including a non-integer, and a value obtained by converting the distance from the non-extensible reference point of the magnetic medium of the track position at which the magnetic head should be positioned to the number of tracks in the output of the converting means. Magnetism by a pulse motor, characterized in that it is provided with drive step number determining means for determining the number of drive steps of the pulse motor at the time of magnetic head positioning based on the value obtained by multiplying M by M and converting M×D into an integer. Head feeding device.