JPH06302134A - Method for detecting encoded servo stored in disk drive assembly and disk - Google Patents

Abstract

PURPOSE: To provide a reinforced magnetic disk drive assembly to be used on extreme conditions and a method for detecting a coded servo stored on a disk. CONSTITUTION: A high-capacity high-speed memory system is provided with a disk drive cartridge 52 and an electronics unit 54. The former is provided with fine magnetic hard disks having the usable capacity of 300 megabytes stored in an airtight cut-off sealed self-supply type unit suitable for use on the external conditions of vibrations, shock and temperature or the like. The latter is provided with metal structure housing electronics for system. The electronics unit has a new peak detection circuit. When using a single peak detector, high-speed operation is required and through a single circuit, a temperature induction change is fixed for each servo. This circuit is provided with an accuracy rectifier for servo burst rectification.

Description

Detailed Description of the Invention

CROSS REFERENCE TO RELATED APPLICATIONS David W. A magnetic disk drive unit (Magnetic D) according to the invention of Richard (David W. Richard) and others.
US Application entitled Atkney Drive Unit (Attorney Docket No. 92-1170} and David W.W. A magnetic disk drive unit (Magnetic D) according to the invention of Richard (David W. Richard) and others.
A related US application entitled Atkone Docket No. 92-1445 entitled "isk Drive Unit" was filed at the same time as this application.

[0002]

FIELD OF THE INVENTION The present invention relates to the field of magnetic disk memory units. More specifically, the present invention is suitable for use in unfavorable or harsh environments, is capable of withstanding loads or stresses such as extreme shock, vibration and temperature and is operable in any position. The present invention relates to a magnetic disk memory unit. The unit of the present invention is particularly suitable for military applications, but can also be used in other difficult environments such as oil and gas wells and seismic prospecting.

[0003]

BACKGROUND OF THE INVENTION Both magnetic tape recorder units and magnetic disk memory units have long been known in the art. While it is possible to use tape units suitable for use in difficult applications, improvements in disk units are needed. An example of such a conventional disc unit is US Pat. No. 4,791,508.
No. 4,870,703 and 4,965,686, both of which are assigned to the assignee and incorporated herein by reference.

[0004]

The above and other problems and deficiencies of the prior art are overcome or alleviated by the high capacity, high speed memory system of the present invention. According to the invention, the system includes a disk drive cartridge and an electronics unit. The disk drive cartridge contains five magnetic hard disks with a usable capacity of 300 MB housed in a hermetically sealed enclosure self-contained unit suitable for use in extreme conditions such as vibration, shock and temperature. The electronics unit includes a metal structure that contains the electronics for the system.

The disk drive cartridge has a stationary spindle to which a motor stator assembly is mounted, the motor stator assembly being constituted by a rotary hub mounted around the stator, which hub is internally located. It has a drive electromagnet attached. Upper and lower bearing assemblies are located between the stator and rotor. The bearing assembly is preloaded by a pair of angled springs located around the spindle and supported by the floating races of the upper bearing assembly. By preloading the assembly in this manner, staircase contact between the vibrating bearing and the spindle shaft is avoided. It has been found that such staircase contact produces a head position error during vibration. These head position errors exceed the bandwidth of typical conventional closed loop servos. However, due to the increased capacity of the present invention, higher bandwidth is used. Therefore, the angled spring of the present invention prevents stair contact, thereby avoiding possible head errors.

The disk drive cartridge further includes a temperature sensor mounted on the circuit board of the spindle assembly. The temperature sensor measures the internal temperature of the disk drive cartridge. This temperature information is used to modify the seek algorithm. More specifically, the information includes modification of the drive current level for the voice coil (since the voice coil resistance changes with temperature), modification of the load / unload operation of the head, Hall effect devices.
Used to correct temperature drift for reading and to obtain good bending bias of capton flex circuits.

The disk drive cartridge further includes a head loading sensor assembly. A magnetic flux sensor is located on a circuit board that extends over a portion of the arm assembly. The arm assembly has a permanent magnet disposed therein that passes under the magnetic flux sensor (eg, Hall effect sensor, etc.). Therefore, as the arm assembly moves, the magnetic flux from the permanent magnets detected by the flux sensor changes. This has been confirmed to be a linear relationship overall. Thus, the position of the arm assembly (and more particularly the permanent magnet in the arm assembly) is tracked by the flux sensor. In addition, the arm assembly has a park or stop position like a conventional arm assembly. However, unlike conventional arm assemblies, the arm assembly of the present invention is fully displaced (fully retracted) from the disc in the park position. In this fully retracted position, the head and disk are immune to induced shock and vibration.

The electronics unit has a novel peak detection circuit. Prior art individual peak detectors have been used to recover each servo burst (to determine head position, or track position and center).
Fast operation is required to use a single peak detector as in the present invention. Using a single circuit, the temperature induced change is constant for each servo.
The circuit includes a precision rectifier for rectifying the servo burst. The rectified signal is integrated by the integrator.
The integrated signal passes through the multiplexer and the high speed A / D
It is converted into an 8-bit word by the conversion device.

The above as well as other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description and drawings.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 and 2, a disk memory system is shown generally at 50. Disk memory systems are high capacity, high speed memory systems designed to operate in harsh environments such as military aircraft. Disk memory system 50
Includes a disk drive cartridge 52 and an electronics unit 54. The disk drive cartridge 52 contains five magnetic hard disks that provide a usable capacity of 300 megabytes. The disc is Winchester disc technology
ster disk technology) and is housed in a self-contained unit of hermetically sealed and sealed type configured as a plug-in-module. Thus, the disk drive cartridge 52 is fully replaceable and capable of rough handling, shipping and operation in extreme vibration, shock and temperature environments.

The disk drive cartridge 52 includes a housing 58 having a main housing portion 60, with a removable cover plate 62 secured to the main housing portion 60 by a plurality of screw fasteners 64. The housing portion 60 and the cover plate 62 are made of metal, preferably aluminum. The front cover 66 is a vibrating cradle (vibr
release latch mechanism 6 for locking in or removing from the cradle (not shown).
Have eight. The housing portion 60 has mounting slots 70 along the length of its two opposing sides, these grooves engaging corresponding runners or guides in the cradle. To ensure that the unit fits properly in the cradle (and to ensure proper alignment with the electrical connectors on the rear end of the unit), the grooves are offset on the two sides of the unit. (Similar to the cradle engagement guide). Due to the asymmetry of the groove and the mating guide, the unit can only be mounted in one position in the cradle (i.e. the proper position).

The electronics unit 54 is a sealed metal structure 7 that contains the system electronics.
Includes 2. The structure 72 includes a main housing portion 74 having a removable cover plate 76 secured to the housing portion 74 by a plurality of screw fasteners 73. The housing portion 74 and the cover plate 76 are made of metal, preferably aluminum. A plurality of connectors 78 are attached to the front end of housing portion 74 to provide a means for interfacing electronics unit 54 to disk drive cartridge 52, host computer 85 (FIG. 2) and a power source. The electronics unit 54 further includes an elapsed time indicator 75, a bit start switch 77.
And a bit indicator 79.

The disk drive cartridge 52 is interconnected by a signal line 82 (ie, a cable) to an electronics unit 54, and more specifically to disk drive control electronics 80. The disk drive control electronics 80 is in communication with the interface electronics 84 (described below) within the electronics unit 54 by signal line 86. The electronics unit 54, and more specifically the interface electronics 84, includes a small computer system interface (SCSI) bus 88.
(Ie, a cable) to communicate with the host computer 85.

Referring to FIGS. 3 and 4A-4E,
Disk drive cartridge 52 includes a spindle assembly 90 (discussed below). The spindle assembly 90 includes a circuit board 96 at its lower end.
The actuator plate 100 is mounted within the housing portion 60 adjacent the spindle assembly 90. An arm pivot shaft 102 extends upward from the actuator plate 100. The field assembly 104 with the head loading assembly 106 mounted thereon is mounted on the actuator plate 100.
Is mounted on. The field assembly includes a core 104a, a top field 104b and a bottom field 104c. An adjustable pair of arm stroke limiters 108 are attached to opposite ends of the field assembly 104 by fasteners 109.

A first bearing assembly 110 is disposed on shaft 102 and is supported by plate 100. The arm assembly 111 includes a central arm 112 having upper and lower arms 114, 116 attached to the arm by fasteners 117. The arm assembly 111 is disposed on the shaft 102 and is supported by the bearing 110 to support the shaft 102.
It is rotatable with respect to. Central arm assembly 112
Includes a housing portion 118 in which the voice coil unit 120 is housed. The voice coil 120 includes a central opening 120a in which the motor core 104a is located. The current passing through the voice coil unit 120 cooperates with the field assembly 104 to linearly drive the arm assembly. An landing zone flag 117 and an landing position flag 119 are attached to the housing 118. Flags 117 and 119 are detected by optical assembly 115. Each arm 112, 11
4, 116 include a plurality of flexible members 121. The flexible member 121 has at least one raised or button-shaped portion 122 on its surface and a head assembly 124 located at one end thereof. The second bearing assembly 126 is located on the shaft 102 above the arm assembly. The nut and preloading washer 128 attaches to the shaft 10.
It is fixed at 2 to hold and supply a preload force on the arm assembly. A clock plate 130, preferably made of metal, is secured to the housing portion 60, spindle assembly 90 and shaft 102 by a plurality of screw fasteners 132.

A landing pad 134 with a lamp bracket is attached to the actuator plate 100.
Landing pad 136 with ramp slide is fastener 137
It is attached to the bracket 134 by. The landing pad 136 with ramp slides is used for multiple landing ramps 1.
38 and landing pad 142. The landing ramp 138 includes a recess 140 configured to receive the button 122 on the flexible member 120.

Voice coil flex circuit 144 is attached to flex mount bracket 14 by a pair of fasteners 148.
It is fixed at 6. The bracket 146 is a fastener 15
It is attached to the plate 100 by 0. The circuit 144 is connected to the voice coil 120.

The mounting bracket 1 in which the hybrid circuit board 152 is fixed to the inner surface of the housing portion 60.
Mounted on 54. Head flex circuit 1
51 is connected to the substrate 152 and the fastener 1
It is held by a flex holder 154 attached to the substrate 152 by 56. The circuit 151 is connected to the arm assembly at the other end. One end of the substrate 152 is fixed to the bracket 154 by the fastener 156. The other end of the board 152 is fixed to the bracket 154 by a fastener 158. The flex circuit 151 is a stiffner 1
Includes 60. Another flex circuit 162
However, the board 152 and the connector 164 are connected via the rear end of the housing portion 60. A spindle motor flex circuit assembly 166 connects between the substrate 96 and the connector 164.

Spindle assembly 90 includes a plurality of magnetic recording disks 168 (eg, five disks) disposed around spindle motor assembly 170. The disks 168 are installed at intervals by a plurality of disk spacers 172. The disk 168 and spacer 172 are held on the assembly 170 by a disk holder 174.

Spindle motor assembly 170 spins disk 168 in a precision rotation path so that the magnetic tracks on the disk maintain their set concentric position even in extreme temperature and vibration operating environments. With this accuracy,
Ultimately, the minimum track width available and the associated maximum track per inch (described below) that is directly related to data capacity are limited.

Conventional commercially available disk drive devices are susceptible to vibration and temperature. For example, while undergoing low levels of vibration, the spindle pattern may become overloaded by g-stress, or in some cases the shaft itself may bend, contributing to this effect, causing the disk pattern to begin to wobble. . Even a small movement of about 300 micro inches will cause misalignment of the track, resulting in a data error. Furthermore, at temperatures in the range of −155 ° C. to + 71 ° C., significant track misalignment occurs due to the disc clamp design and the disc media itself. In the case of disc clamps, the temperature coefficient mismatch due to the steel spindle shaft (needed for bearing loads) and the alumina platter causes
The platter expands and contracts around one of the clamp screws, rather than the centerline of the spindle.
As a result, the platter's "one round"
d) Fluctuations occur resulting in track misalignment and data errors. In addition, a second temperature-inducing effect is caused by the non-uniform coefficient of thermal expansion around the platter's circumference. This lack of concentric expansion and contraction due to anisotropic temperature also caused track misalignment and data errors. The spindle assembly 90 of the present invention solves these vibration problems.

Referring to FIG. 5, the spindle motor assembly 170 includes a hub 176 having a shaft 178 around its center. The shaft 178 (preferably a steel shaft) is mounted on the support plate 180. The spindle shaft 178 is attached to the support plate 180 by threads 182 and has a hollow interior defining a central passage 185.
The support plate 180 is fixed to the bottom of the outer case 60 by a plurality of screws (not shown). The upper end of the spindle shaft 178 is held by the plate 130 via the screw 132 (FIG. 4B).
In this way, the upper and lower ends of the spindle shaft 178 are fixedly held.

Annular motor windings 184 that form the stator of the electric motor have upper and lower sleeves 186, 188.
Mounted on the shaft 178 via. Sleeves 186 and 188 are fixed around shaft 178. The sleeve 186 is fixed to the shaft 178 by a locking bar 189 and a set screw 190. The washer 191 is the shoulder 1 of the shaft 178.
It is mounted on 92. The washer 191 and the shoulder 192 support the sleeve 188 and prevent the sleeve from moving downward along the axis of the spindle shaft 178.

The rotor structure of the motor has a steel sleeve 19
6 has an annular magnet 194 adhesively fixed to
The sleeve 196 is locked to the steel outer rotary hub 176. The upper end of the annular cap 198 is the hub 176.
It is fitted inside the inner diameter of.

Magnet 194, sleeve 196, hub 176
And the cap 198 constitutes a rotor structure that rotates around a stator structure mounted on a spindle shaft 178, and therefore this rotor structure needs to be mounted on bearings. Therefore, the rotor structure is mounted on the lower and upper bearings 200 and 202. The inner race of the lower bearing 200 has a shoulder 204 on the spindle shaft 178.
And is trapped and locked against rotation between and the shoulder 206 on the base plate 180. A flange 208 extending radially inward from the hub 176 engages the rotating outer race of the bearing 200.

Floating inner race 2 of upper bearing 202
09 is a pair of angled springs 2 arranged in a recess or groove 211 around the spindle shaft 178.
It is fixed to the shaft 178 by 10. Inclination spring 210 is 30 according to ASTM-A580
It is preferably composed of two stainless steel wires. The angled spring 210 eliminates metal-to-metal step contact between the race 209 of the bearing 202 and the spindle shaft 178 (due to external vibration / shock environment). The staircase contact produces a head position error that exceeds the bandwidth of a typical closed loop servo (eg, the normal bandwidth of a closed loop servo is 250 Hz). However, the present invention has a track density of about 2075 tracks per inch with a center spacing of about 476 microinches. This is a much higher capacity than taught by the prior art (eg, about 875 tracks per inch). Staircase contact causes a head error within the bandwidth of the closed loop servo of the present invention. Therefore, the angled spring 210 prevents stair contact, and thus eliminates the head position error caused by such contact. The angled spring 210 provides high axial and radial stiffness in the spindle motor assembly,
Spring 210 is an important feature of the present invention because high rigidity provides high resistance to vibration / shock / temperature. The angled spring 210 also allows bearing preloading with proper axial movement. This movement is necessary to apply a constant bearing preload as the material expands and contracts due to temperature changes. One of two identical beveled springs 210 is shown in FIGS. 6A and 6B. Spring 210
Includes a plurality of continuous coils 212 configured to form an annulus having an inner diameter suitable for engaging a recess in shaft 178. Inner race 2 of bearing 202
09 is also held by the washer 213.

The washer 213 is a spring washer 2
14, washer 215 and spindle shaft 178
It is held in place by a nut 216 that is screwed onto the top of the. The rotary outer race of the bearing 202 engages a radially inwardly projecting flange 218 on the cap 198. Thus, the rotor structure of magnet 194, sleeve 196, hub 176 and cap 198 are rotatably supported by bearings 200 and 202.

In addition, a preload force is exerted on the bearing 202 by a nut 216 acting through a washer 210, a spring washer 214 and a washer 213 to impose a load on the inner race, the load on the balls of the bearing 202. It is transmitted and loads the outer race against the flange 218 on the cap 198. By transmitting a preload from the cap 198 via the sleeve 196 and the outer hub 176 to impose a load on the outer race of the bearing 200 and then also via the balls of the bearing 200 to repel the plate 180. A preload is also applied on the bearing 200. The preload acts to maintain contact throughout the bearing pack, reducing shock loading and vibration effects.

The wire 22 coming from the winding of the stator 184
0 is a pair of opposed openings 2 in the spindle shaft 178.
22 through the central passage 18 of the spindle shaft 178
Go to 5 Wires 220 pass through passages 224 in plate 180 and are connected to printed circuit board 96. Circuit board 96 includes screws 22 that are screwed into spacers 226 and plate 180.
It is attached to the plate 180 at a distance from the plate 180. Current is supplied to the windings of stator 184 via wires 220 to drive rotor and disk 168.

Referring to FIGS. 7A and 7B, the spindle motor circuit board 96 includes Hall effect sensor 236, resistors 238, 240 and concentrator 241 respectively.
A plurality of Hall effect circuits 230, 232 and 23 including
Includes 4. Circuit 234 also includes capacitor 242.
Is included. Sensor 236 and capacitor 242 are secured to substrate 96 by a suitable adhesive. The circuit board 96 is generally circular and has approximately the same outer diameter as the disk 168. Substrate 96 also has shaft 178
Has an opening 244 around its center. The Hall effect sensor 236 is used to supply the rotary magnet position information supplied to the spindle servo circuit 245 (FIG. 8). The disk spindle rotation speed is controlled by a closed loop speed servo circuit 245 and a motor (described below). The phase locked loop 246 on the spindle servo circuit uses the Hall signal to lock the spindle speed. The spindle servo circuit 245 includes a pre-driver 247 that adjusts the set drive current amount regardless of the temperature-induced gain change. This results in a predictable and repeatable spindle start time under critical operating temperatures.

A temperature sensor 247 is mounted on the circuit board 96. Mounting pad 248 is located between sensor 247 and substrate 96. Temperature sensor 247 is an important feature of the present invention. The output of the temperature sensor 247 is used to modify the seek algorithm. More specifically, the drive current level to the voice coil 120 is adjusted for temperature changes (since the voice coil resistance changes with temperature) to adjust the load / unload operation of the head and read the Hall effect device. To correct the temperature drift and increase the bending bias acquisition rate of the Capton flex circuit.

The output of the temperature sensor 247 is used to modify servo parameters during head load / unload and seek operations. The output of the temperature sensor 247 is controlled by the drive control device 350 A
A / D converter 456 (FIG. 13—described below with the novel peak detection circuit). Corresponding temperature dependent servo parameters are stored in the ROM lookup table. The following servo parameters are temperature dependent parameters for head load / unload operations. (1) Hall effect position sensor gain, and (2) constant acceleration, drive current required to drive the actuator arm in an open loop manner.

The following servo parameters are temperature dependent parameters for seek operations.

(1) Flexible head cable compliance, and (2) drive current required to accelerate the actuator arm with constant acceleration.

A typical commercially available disk drive device is
It is susceptible to what is commonly known as a "head crash" when subjected to vibrations. The floating head is supported by an air bearing that is sufficiently stable and rigid to resist contact with the disk surface due to the exponential content of the air bearing force relative to the travel curve. It has been determined that head crashes and media damage generally occur when the disk drive device undergoes vibration during the following operations. That is, especially when the head is rapidly positioned between tracks in the lateral direction which tends to destabilize the air bearing by tilting or rotating the head during vibration. By optimizing the mounting point of the head flexible member with respect to the center of gravity of the head, the tilt or rotation tendency of the head during rapid positioning is eliminated, which increases air bearing stability and resistance to operating vibrations. To be done. Crashes also occur when the disk spins up and down, which weakens the air bearing of the head and can cause the head to contact the disk during vibration. Also, when the head stops, it will ride on the disk surface. Normally, while spinning down, most commercial disks keep the head in contact with the disk surface head until the disk spins up again and air bearing is reestablished. This condition is not suitable for military type products that are subject to shock, vibration and rough handling during operation.

Therefore, the head must be removed from the disk surface at the beginning of spin down. With the arm assembly 111 of the present invention, the head is completely removed from the disk.

Referring to FIGS. 9A and 9B, the actuator arm assembly is shown generally at 111. The arm assembly is the central arm assembly 11
2, including an upper arm 114 and a lower arm 116. The central arm assembly includes a housing portion 118. The arm assembly 111 is dynamically balanced about its axis of rotation so that shock, vibration and load elements on the cartridge are not input and induce a twisting effect on the arm. As a result, the head remains on the track during high acceleration input jamming. Housing 1
18 has a through cylindrical opening 250 having a diameter sufficient to receive the bearings 110 and 126. The housing 118 further has opposed pairs of rectangular openings 252, 254 that define a cavity within the housing 118 in which the voice coil 120 is mounted. The housing 118 further includes another opening 256 within which the magnet assembly 258 is attached to the housing 118 by fasteners 260. Furthermore, FIG. 10A
And with reference to FIG. 10B, a magnet assembly 258.
Is a precision front surface 264, opposing surfaces 266, 268, and a rear surface 270 including extensions 272 on each side 266, 268.
And a block assembly 262 having opposed top and bottom surfaces 274 and 276. A mounting hole 278 is provided in each expansion portion 272. Fastener 26
0 passes through the mounting hole 278. Surface 274 includes a pedestal 280 having channels or slots 282 therein. A permanent magnet 284 is secured within channel 282 by a suitable adhesive. The magnet 284 has opposing precision front and back surfaces 286, 287, side surfaces 288,
290 and includes a top surface 292 and a bottom surface 294. The magnet 284 has a north pole 296 labeled (N) at end 288 and an opposing south pole 298 labeled (S) at end 290.

Referring to FIGS. 4A and 11A-11D, the head loading sensor assembly is shown at 106. Assembly 106 has opposite bottom surface 3
02 and printed wiring board 30 having a top surface 304
Contains 0. Magnetic flux sensor 3 having lead wire 308
06 (ie, Hall effect sensor) is attached to surface 302 by a suitable adhesive. The sensor 306 is
It is located above the Hall effect concentrator 310, which is located within an opening 312 that extends through the substrate 300. A plurality of contact pins 314 extend through the substrate 300.
Pin 314 provides a means of connection with spindle motor flex circuit assembly 166. Resistor 316,
318 and capacitor 320 are on the surface 30 of the substrate 300.
It is attached to 4. The sensor 306 is preferably a Hall effect type magnetic flux sensor having a ceramic substrate with a hermetically shielded sealing element. The sensor 306 senses the magnetic flux from the magnet 284 of the actuator arm assembly 111. The assembly 111 is shown in the parked or fully retracted position in FIG. 4A, with the button 122 on the flexible member 121 within the recess 140 of the landing ramp 138 where the head 124 is located between the corresponding landing pads 142. It is located in. In this position, the head and disk are immune to induced shock and vibration. This fully retracted position of the arm / head assembly is an important feature of the present invention. The magnetic flux from magnet 284 sensed by sensor 306 is maximum in this fully retracted position. Arm assembly 11
As one rotates to position head 124 over corresponding disc 168, magnet 284 moves away from sensor 306 and the magnetic flux from magnet 284 sensed by sensor 306 decreases. It has been found that the output of sensor 306 is related to the position of linear arm assembly 111 (ie, head position). Therefore, the sensor 306 senses the magnetic flux from the magnet 284 to determine the head position.

Further, automatic head retraction is achieved in both normal and abnormal operating conditions. For normal operation, the head is retracted from the media each time the spindle is turned off. Withdrawal is accomplished within 100 milliseconds, so a graceful shutdown does not take much time. Abnormal operation occurs when initial system power is lost or the operator inadvertently removes the cartridge while the spindle is still spinning. In response to the initial power failure that causes the disk to stop spinning, the electronics sense the power failure and use the spinning spindle motor's back EMF to remove the head from the disk and place it on the pad. Generates the necessary power to place it. Thus, the rotational inertia energy of the motor / disk assembly is translated into a retracting motion that unloads the head and protects the head and media from shock and vibration. The second abnormal sequence occurs when the operator removes the cartridge while it is spinning. In this case, the sensor on the cartridge handle senses that handle release has been activated. The electronics responds to this signal by quickly returning the head to the stationary pad. Again, this is accomplished within 100 ms, after which the connector is removed from the cartridge.

The use of magnetic flux sensor 308 and magnet 284 as position sensors is an important feature of the present invention. This position information can be used to correct position errors.

Referring to FIG. 12, an example of such a closed loop system is shown generally at 322. The commanded position signal is provided to summing junction 326 on line 324. The output of junction 326 on line 328 is a position error and actuator arm dynamics are used to position the head. Head position is sensed at 332 by a position sensor (ie, sensor 308 and magnet 284). A head position indication signal is provided to junction 326 on line 334. The actuator arm position 322 measured by the Hall effect sensor 332 (eg, sensor 306) is 33
Feedback at 4 and subtraction from the commanded position at 324 provides a position error signal on line 328.

Referring to FIG. 13, controller interface electronics 84 may be, for example, an Intel 80C.
186 microprocessor (Intel 80C186 microproces
an input / output controller such as a sor) (operating at 12.5 MHz) is included as the main control element. Intel 80
C186 is a chip selection logic, two channel DMA
It is a highly integrated 16-bit microprocessor with a controller, three timers and an on-board interrupt controller.
The control program is, for example, 64K × 16-bit EPR
It is stored in an electronic memory 338 such as an OM or E ² PROM. In addition, two 32Kx8 static RAMs for scratchpad and variable storage
There is also a (SRAM) 340. In addition, 12 discrete system input signals and 16 discrete output signals are used for various functions from controlling the ready lights to the input / output controller to drive controller communication. An I / O / disk data combination controller 342 {e.g., 8496 from National Semiconductor, etc.} is within electronics 84. The input / output unit 344 of the device is a state machine sequencer that receives commands from the processor.
r) is executed. These commands perform various functions such as phase and state phase data. When the operation is complete, an interrupt to the I / O controller is triggered. Various control status registers are used to store error condition conditions. The disk data controller 346 is also a state machine sequencer that executes commands issued by the I / O controller. The commands control reading and writing to disk. Again, various controls, status and error registers provide the ability to correct the error or determine if a retry is required. The I / O / disk data combination controller uses its own dedicated data buffer composed of two high speed 32Kx8 SRAMs. The three disk channels to the data buffer are controlled by the I / O / disk data controller. The three channels are I / O, disk and processor. Disk channels have the highest priority, and processor channels have the last priority. This configuration allows simultaneous data transfer between the I / O and the disk interface. 31 analog voltage channels monitor various system functions for self-test. 8-bit A
A / D converter 348 measures these channels and
The IT software determines if there is a system failure.

The disk drive cartridge 52 uses both a dedicated surface and an embedded servo system. This means that one of the five media patterns is completely dedicated to track servo information. Servo information is also embedded on every other surface at the beginning of every sector on every track. This servo system provides the best combination of coarse and fine positioning required for high speed operation in extreme environments.

Disk drive circuit 80 performs the critical drive level functions required for high speed disk drive operation. The disk drive circuit positions the read / write head (rotary actuator motor or voice coil 12 in the field assembly 104).
0 movement control), read / write head selection, spindle motor start / stop, BIT function and power interruption and temporary recovery control.

The drive controller 350 is the main control element of the disk drive circuit 80. The drive controller is a high speed digital signal processor {eg Texas Instruments TMS320C30 state-of-the-art 32-bit digital signal processor (Texas Instrumennts TMS320C30
state-of-the-art 32 bit digital signal processo
r) is used to control the position of the head by executing a closed loop digital control algorithm.

The disk drive control scheme uses a complementary system of dedicated and embedded servo information to ensure optimal control of read / write head position during track seek, read and write operations.

Track acquisition is accomplished via the rotary actuator closed loop control 352. Coarse position information is written on a dedicated surface (ie, one of the five disks 168). The information is 0.70MHz
And a 1.00 MHz alternate track signal. The midpoint between each of these tracks defines the center of each cylinder so that the data tracks rest on the remaining disk surface. When a seek command is received, the drive controller uses the coarse position information to control the speed of the head actuator during acceleration and seek operations.

Once the track is acquired, the embedded servo 354 information on the acquired track is used to perform track centering and tracking. 14
15, and a novel peak detector (discussed below) is used to recover amplitude information for each of the four servo bursts labeled A, B, C, and D, respectively. This information is processed by the drive controller 350 to determine the exact head position and the amount of current applied to the rotary actuator (ie, voice coil 120) to correct and maintain head position.

Tracks A ₁ , B ₁ , A ₂ , B ₂ , A ₃ and B ₃ are shown in FIG. The embedded servo information is indicated by A, B, C and D, respectively. The amplitude peak information, shown at 356, is detected by the novel peak detector circuit described below. This servo information is a quad burst of the time displacement pulse.
st) {For example, burst is 2.5M per 4 microseconds
It is possible to simply compromise a sine wave of Hz}. The head can be maintained at the center of the track by equalizing the amplitude between overlapping servo bursts. For example, burst 358, labeled A, and burst 360, labeled B, overlap track centerline 362 of track A ₁ . Line 362 corresponds to equal amplitudes for A and B as indicated by V _A and V _B (ie, V _A = V _B ). Thus, the head can be maintained on the center of the track by adjusting the head position so that the amplitudes between overlapping servo bursts are equal (eg, V _A = V _B ). The quadburst is given a +/- 1 track tolerance for positioning between straight tracks. In addition, these embedded servo bursts are used for track-to-track positioning and fine positioning as described below.

Each sector (0-54, FIG. 15) contains a data segment 364 following the embedded servo bursts A, B, C and D. The embedded servo / sector timing sequence is shown in FIG. This includes timing or zero, dedicated surface index, sector mark detection window, read signal, data head, detected sector mark, multiplexer A.
_O , A ₁ and A ₂ , servo CS, WR, INT and R
D, as well as operations such as embedded servo reset.

Rotary actuator drive circuit 36
5 is a 12-bit D / A converter 366 and an amplifier 3
Includes 68. The actuator drive 365 is
Positioning data is received from the drive controller 350 that has been converted to an analog voltage for a rotary actuator motor drive. The velocity profile and rotary actuator drive current are held constant regardless of resistance changes to provide optimum performance under harsh environments.

The drive control device 350 has a RAM 370.
And a PROM 372 are both supported by the drive controller memory. RAM370
Is a 64K-bit CMO organized as 2Kx32.
It is an S static RAM and an on-board drive controller. The device temporarily stores and manipulates program data elements. The PROM 372 stores the drive control device operation program, and at the same time, 32
1Mbit CMOS organized to be Kx32
EPROM.

The drive controller 350 is in communication with the disk data processor via a parallel communication port. An input / output port for discrete signals is also provided. The discrete signal is
Disk electronics 80 and cartridge 52
Originating from other parts of the system, including "retracted head", "closed handle", communication port flags, A / D converter status and power status. Further incorporated is an output signal, which includes spindle motor enable, rotary actuator enable, head select, A / D converter and D / A converter.

The closed loop spindle control circuit 374 described above uses Hall signal feedback 376 to control the spindle speed.

The read / write analog signal processing circuit 378 enables high density encoding / decoding for disk data read / write operations. The data is encoded from the NRZ and clock to perform the limited run length by the encoder 380.

During the write process, the NRZ formatted data and clock information are encoded and provided to the write driver. During the read operation, the encoded data stored on the disk is phase-locked loop (PLL) 381 and limited run-length (PLL) 381 to the NRZ decoder 382 via analog amplification and detection, subsequent clock recovery and data synchronizer. R
LL) is decrypted to recover.

The first stage of the analog circuit includes an automatic gain control amplifier, which maintains a constant signal amplitude at the output of the Bessel filter in the read train. The Bessel filter band limits the read signal provided to the equalizer and detector. The equalizer restores the critical amplitude and phase information for detection of data transitions by the detector circuit.

The output of the data detector is supplied to the phase-locked loop phase comparator via the data synchronizer. The synchronizer executes a PLL on the reference clock when the system is not in read mode,
Used to ensure quick phase lock acquisition. The synchronized run length limited data and the phase locked clock are provided to the decoder 382 for conversion to NRZ data and clock.

Write interlock and cartridge file protection features are incorporated into the circuit at 384 to allow user selectable protection against loss of stored information due to inadvertent overwriting.

Referring to FIGS. 16A-16C, the novel peak detection circuit is shown generally at 386. 16A-16C are schematic diagrams of track tracking servo electronics 354 and course position servo 352. Therefore, the figure further shows a dedicated servo detection circuit 388,
The index detection circuit 390 and the sector mark detection circuit 392 are also shown. Peak detect circuit 386 includes a precision rectifier 394 having an input on line 396 to amplifier 398. The amplifier 398 is a resistor 40.
It has a feedback loop including 0, 402 and diode 404. The output of amplifier 398 is connected to diode 406. Capacitor 410 and inductor 412 are also connected to amplifier 398.
The output of rectifier 394 is provided on line 408. This output is the precision rectified signal of the input signal (ie, servo burst) provided on line 396. Integrator 414
Receives the signal provided on line 408. This signal is provided to the input of amplifier 418 via resistor 416. Resistor 420 is connected between ground and the other input of amplifier 418. Capacitor 422 and inductor 424 are also connected to amplifier 418. The output of amplifier 418 is provided on line 426. This output is the integrated signal of the signal input on line 408.

Integrated dump 428 receives the signal provided on line 426. Dump 428 includes a pair of high speed analog switches 430, 432 and a resistor 434. The integrated signal is then provided to amplifier 438 which has a feedback resistor 440 on line 436. The other input of amplifier 438 is connected to ground by resistor 442. The output of amplifier 438 on line 444 is provided to multiplexer 446. Capacitor 44
8 and inductor 450 are also multiplexers 446.
It is connected to the. The selected input of multiplexer 446 is provided on line 452 at its output. The signal on line 452 is provided to amplifier 454. Amplifier 45
The output of 4 is converted from an analog signal to a digital signal (that is, an 8-bit word) by the A / D converter 456. The voltage regulator 458 converts the reference voltage into the conversion device 4
Supply to 56. Capacitors 460, 462 and resistor 464 are connected to regulator 458. Capacitors 466, 468 and inductor 470 are connected to converter 456.

This single high speed peak detect circuit 386 is used with a high speed A / D converter 456 to recover magnetically recorded, time division multiplexed and spatially moved servo information bursts. This recovery method is in contrast to conventional commercial methods where individual detectors are used for recovery of each servo burst. The advantage of a single recovery circuit lies in its operation under the extreme temperatures at which the parameter drift of the individual circuits has to be compensated. The single recovery circuit parameter change with temperature is the same for each servo burst, thus canceling out any negative effects.

Referring to FIG. 17, a chart of the most important level structure of the software is shown. I / O control 3
The software for 36 performs the following functions.

-Receive a command from the input / output bus, generate a necessary signal, and execute the command.

Control the data flow between the I / O bus and the disk drive.

Monitor the drive status and report any anomalies on the I / O bus.

Receiving the command, generating and transmitting the disk status.

The software for drive control 350 performs the following functions.

-Positioning the read / write head-Starting and stopping the spindle motor-Retracting the head during power loss or cartridge removal-Selecting the read / write head-Power interruption and recovery control for both controllers-Incorporation Test function-Monitor drive status and report to I / O controller.

The functions performed by the software are:
Read operations, write operations, and built-in tests (Built-In-Test)
It is shown by listing the (BIT) function.

The command is received on the I / O bus and is decoded by the I / O control as a read command. The condition of the drive is checked for installed cartridges and spinning disks. If these conditions are met, the command is determined to be valid and a read operation is initiated. The address information received by the read command is translated into head and cylinder numbers. This information is a seek command which is transmitted to the drive control which decodes the seek command and selects the required head. The drive controller 350 then drives the rotary actuator to position the head on the required cylinder. This operation includes acceleration and deceleration based on the number of cylinders that require head movement. After this open loop move is complete, the servo error voltage is read and used by the closed loop digital control algorithm to center the head on the track. After the head is centered,
A command completion response is sent back to the I / O control.

The input / output control is performed by the disk data control device 3
Perform the read operation by loading 46 registers with the appropriate information. This information includes the starting sector number on the track and the number of sectors to be read. As part of the read operation, the I / O control checks the header information to see if the head was centered on the correct track by the open loop move. If the head is on the wrong track, the I / O control calculates the correction needed to position the head. The I / O control sends another seek command to the drive control to put the head in the correct position. Immediately after this operation is completed, the command completion is transmitted from the drive control to the input / output control again. Another read operation is performed by the I / O control.
During data transfer from disk to RAM, error detection is performed under the control of disk data controller 346. When a data error occurs, the disk data controller 346 supplies the syndrome bytes to the I / O control to cause the device to correct the error. I / O control performs an "exclusive OR" on the data with these syndrome bytes to correct the data error. After the data sector is loaded into RAM, the I / O control signals the drive control to enable the disk controller to transfer data from RAM to the I / O bus. Therefore data transmission is from disk to RAM and RA
It occurs simultaneously from M to the input / output bus.

It should be noted that it is impossible to determine the actual head position by drive control.
Immediately after receiving a seek command, drive control loads the cylinder address register with the number of cylinders and moves it open loop. If the I / O control makes an incorrect positioning, then the I / O control must send a special command to the drive control to reposition the head without changing the contents of its cylinder address register. This maintains synchronization between the two controllers.

In a write operation, the same head positioning operation is performed as during a read operation. Data transfer from the I / O bus to RAM is performed concurrently with the initial head positioning operation.

Some visual display is provided to display the progress under test during the execution of the BIT. Immediately after entering the test, both BIT indicators are set. The disk drive cartridge ready LED is then illuminated to indicate that both processors are operational. As soon as the ROM checksum test is completed, LE
D turns off. Immediately upon completion of the test, the I / O control processor clears only the BIT indicator, which represents a complete functional line replaceable unit (LRU).

The system incorporates a BIT function to provide fault detection and location functions for on-board and off-aircraft level maintenance. B
The IT function can be activated by a combination of manual, automatic or remote commands and also includes self-monitoring for normal operating mode. An indication of the fault condition may be provided remotely via the bus or locally via the fault indicator.

The BIT power controller is used to control the BIT indicator. The controller powers the BIT indicator driver directly from the + 28V DC input and provides a power boost pulse to set both BIT indicators as soon as power is boosted despite a power failure. . The power control device is provided with a power supply sequential opening / closing mechanism to prevent generation of a BIT error display in a normal power increase / decrease routine.

Two BIT indicators 79 are provided to provide a visual indication of the functional conditions of the LRU they represent.
One indicator represents the electronics unit 54,
The other display shows the disk drive cartridge 52. Both indicators are magnetically latched so that the last tested functional condition remains in the display state even after the power is reduced. Once the display is set,
It remains set until the indicated LRU successfully passes the execution of the BIT program.

A BIT switch 77 is provided, and B
The IT routine can be started manually. This switch only activates the BIT when the system is not performing the commanded function.

Wrap functions are provided to test the data path in the extended loop.
These folding tests loop data locally at the controller, encoder / decoder and finally the disc itself.

The system includes the ability to monitor test points during the BIT routine. Built-in test circuits consisting of analog-to-digital converters with multiplexed inputs perform individual measurements of key circuit test points located on read / write data channels, spindle drive circuits, rotary actuator drives and power supplies and the like. The measured value is compared with the ROM stored value to determine the validity of the signal.

While the preferred embodiment has been illustrated and described, various modifications and substitutions of the above embodiment are possible without departing from the spirit and scope of the invention. Therefore, it should be understood that the present invention has been described by way of illustration and not limitation.

[Brief description of drawings]

FIG. 1 is a perspective view of a disk drive cartridge and associated electronics unit according to the present invention.

2 is a block diagram showing the interconnection of the disk drive cartridge and electronics unit of FIG. 1. FIG.

FIG. 3 is an enlarged perspective view of the disc drive cartridge of FIG. 1 with a cover removed.

FIG. 4A is a plan view of the disk drive cartridge of FIG. 1 with the cover removed.

4B is a side view with a part of the disk drive cartridge of FIG. 1 cut away.

FIG. 4C is a rear view of the disk drive cartridge of FIG. 1 with a part cut away.

4D is a cross-sectional view taken along line 4D-4D of FIG. 4A with arms and sensors removed for clarity.

4E is a plan view diagram of a flexible circuit used in the disk drive cartridge of FIG. 1. FIG.

5 is a partial side view of a cross section of a spindle motor assembly used in the disk drive of FIG.

6A is a plan view of a canted spring used in the spindle motor assembly of FIG. 5. FIG.

6B is a cross-sectional view taken along line 6B-6B of FIG. 6A.

7A is a plan view of a circuit board assembly used in the spindle assembly of the disk drive cartridge of FIG. 1. FIG.

7B is a cross-sectional view taken along line 7B-7B of FIG. 7A.

8 is a block diagram of a spindle servo circuit used in the electronics unit of FIG.

9A is a plan view of an arm assembly used in the disk drive cartridge of FIG. 1. FIG.

9B is a side view of the arm assembly of FIG. 9A.

FIG. 10A is a plan view of a magnet assembly in the arm assembly of FIGS. 9A and 9B.

FIG. 10B is an elevation view of the magnet assembly in the arm assembly of FIGS. 9A and 9B.

11A is a bottom view of the sensor assembly used in the disk drive cartridge of FIG. 1. FIG.

1. FIG. 11B is an end view of the sensor assembly used in the disk drive cartridge of FIG.

FIG. 11C is a plan view of the sensor assembly used in the disk drive cartridge of FIG. 1.

11D is a cross-sectional view taken along line 11D-11D of FIG. 11A.

FIG. 12 is a block diagram of a closed loop system used in the electronics unit of FIG.

13 is a block diagram of a circuit of the electronics unit of FIG.

FIG. 14 is a diagram of embedded servo burst information used for centering and positioning tracks according to the present invention.

FIG. 15 is a timing diagram for the embedded servo burst information of FIG.

FIG. 16A is a schematic diagram of a servo recovery circuit according to the present invention.

FIG. 16B is a schematic diagram of a servo recovery circuit according to the present invention.

FIG. 16C is a schematic diagram of a servo recovery circuit according to the present invention.

FIG. 17 is a chart of the most important level structure of software according to the present invention. In some of the drawings above,
Similar elements have similar reference numerals.

[Explanation of Codes] 52 Disk Drive Cartridge 54 Electronics Unit 68 Latch Mechanism 79 BIT Display 90 Spindle Assembly 96 Circuit Board 111 Arm Assembly 176 Hub 210 Inclined Spring

Claims (13)

[Claims] 1. At least one disk having a plurality of stored encoded servos.
A plurality of tracks, at least one head arranged for the disk for reading the servo, and means for supplying a corresponding servo signal from the read servo, wherein the servo signal is the head And a single peak detector means for detecting each of the plurality of servo signals, the disc drive assembly being used to position the disc on a selected track of the disc. 2. The peak detecting device means, rectifier means for rectifying a servo signal to supply a rectified signal, and integrator means for integrating the rectified signal and supplying an integrated signal. An analog-to-digital converter for converting the integrated signal into a digital signal.
Disc drive assembly as described in. 3. The disk drive assembly of claim 1, wherein each of the servos includes a plurality of time displacement pulses. 4. The disk drive assembly of claim 2, wherein the digital signal comprises a digital word. 5. A method for detecting a plurality of coded servos stored on a disk having a plurality of tracks, the method comprising: (1) using the head positioned with respect to the disk; Reading one of the following, (2) supplying a servo signal from the read servo, (3) detecting the servo signal using only a single peak detector, and (4) the Reading another of the servos using a head;
(5) supplying another servo signal from the other read servo, and (6) detecting the other servo signal using the single peak detector.
(7) Repeating the above steps (4) to (6) for each of the servos, and detecting a coded servo. 6. The method of claim 5, further comprising positioning the head on a selected track of the disk using the detected servo signal. 7. Each of the detecting steps rectifies the servo signal to provide a rectified signal, integrates the rectified signal to provide an integrated signal, and outputs the integrated signal to a digital signal. The method of claim 5, further comprising: 8. The disk drive assembly of claim 5, wherein each of the servos includes a plurality of time displacement pulses. 9. The disk drive assembly of claim 7, wherein the digital signal comprises a digital word. 10. At least one disk having a plurality of stored encoded servos.
A plurality of tracks, at least one head arranged for the disk for reading the servo, and means for supplying a corresponding servo signal from the read servo, wherein the servo signal is the head Disk drive assembly for positioning each of the plurality of servos on a selected track of the disk and comprising a single peak detector means for detecting each of the plurality of servos. 11. The single peak detector means includes rectifier means for rectifying a servo signal to supply a rectified signal, and an integrator for integrating the rectified signal and supplying an integrated signal. Means for converting the integrated signal into a digital signal; and an analog / digital converter for converting the integrated signal into a digital signal.
0 disk drive assembly. 12. The disk drive assembly of claim 10, wherein each of the servos includes a plurality of time displacement pulses. 13. The disk drive assembly of claim 11, wherein the digital signal comprises a digital word.