Changer-type disc playback device

A disc player moves a selected disc between a playback position and a stocker. Carriages, for holding discs, are stacked concentrically and pivotally supported tightly together within the stocker. The carriages are extracted from the stocker by lifting a front end of an adjacent carriage above the selected carriage. A shuttle then moves the selected carriage from the stocker to the playback position. When the disc player is turned on, the device goes through an initialization sequence to determine whether the carriage, aligned with the playback position, is in the store position within the stocker. If not, the shuttle moves the carriage to the store position. If the carriage and shuttle do not return to the store position within a predetermined period of time, then the disc player attempts to re-engage the shuttle with the carriage by shifting the stocker slightly to clear the shuttle path, while attempting to drive the shuttle to its home position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 1, a disc playback device, shown generally at 1000, 
includes a stocker 50 which holds seven carriages 51-57. Each carriage 
51-57 has a 12 cm diameter first recess 162 for receiving individual 
standard size compact discs 1. Each of the fifth, sixth and seventh 
carriages 55-57 of stocker 50 also have a centered 8 cm diameter second 
recess 166 for smaller single-play discs. 
Referring now also to FIGS. 2 and 7, a comb-type spring 59 attached at the 
rear of stocker 50 includes fingers which engage V-shaped notches 169 in 
each carriage 51-57, concentrically aligning carriages 51-57. Each of 
carriages 51-57 has two protrusions 170 which engage slits 500 in the rear 
of stocker 50, permitting the front of each carriage 51-57 to pivot 
upwards about its protrusions 170. An upper plate 585 reinforces the top 
of stocker 50 and limits the pivotal range of carriage 57. 
Stocker displacement mechanism 318 moves stocker 50 vertically to align one 
of seven store positions Pos(1)-Pos(7), corresponding to the locations of 
the seven carriages 51-57, with a vertical level of a playback position. 
The store position is a position of a disc, or carriage, of stocker 50 
which is in planar alignment with the playback position. 
Displacement of stocker 50 is accomplished as follows. A left chassis 12 
and 9 right chassis (not shown) guide stocker 50 along an axis defined by 
the arrow Z. A cam groove 521 of a sliding panel 520 engages a projection 
520A of stocker 50. As sliding panel 520 moves along an X axis, projection 
520A raises or lowers stocker 50 into one of positions POS(1)-POS(7). 
Once a selected carriage is aligned with the store position, a shuttle 28 
of a tray/carriage transport mechanism 309 engages a cutout 168 in the 
selected carriage (the selected carriage is shown as carriage 51 in FIG. 
5). Shuttle 28 transports the selected carriage from the store position to 
a load position, in which it inserts the selected carriage into a tray 20. 
Tray 20, in turn, moves between a close position, where it is stored 
within the disc player, and an eject position, accessible from outside the 
disc player (See FIG. 6). 
Referring now to FIGS. 2, 5 and 7, the right chassis (not shown) also 
supports and guides a control panel 43. As a shuttle 28 moves the selected 
carriage from the store position to the load position, control panel 43 
moves rearward. A lifter pin 36, which projects from control panel 43, 
engages an inclined engagement piece 167R of an adjacent carriage located 
immediately above the selected carriage. When the selected carriage moves 
to the load position, lifter pin 36 pushes the right side of the adjacent 
carriage upward. The adjacent carriage in turn pushes upward all carriages 
located above the adjacent carriage. 
Referring now also to FIG. 8, upward force on the left side of the adjacent 
carriage is provided by a tandem-motion member 58. The disc player chassis 
(not shown) rotatably supports tandem-motion member 58 through shafts 580L 
and 580R. A groove 582 of tandem-motion member 58 engages a bend 430. 
Tandem motion member 58 rotates with the movement of control panel 43. 
When control panel 43 moves rearward, a lifter piece 583 on a left side 
581L of tandem-motion member 58 engages an engagement piece 167L of the 
carriage next above the selected carriage, providing upward force on the 
left side of the adjacent carriage. 
The combined force of lifter pin 36 and lifter piece 583 lifts each of 
carriages 51-57 which are disposed above the selected carriage, permitting 
the selected carriage to be dismounted smoothly from stocker 50. This also 
creates a space between the selected disc and the next higher overlapping 
disc on an adjacent carriage, thereby providing sufficient clearance for a 
magnetic damper 190 to clamp a disc. 
Referring now to FIGS. 2 and 8, engagement pieces 584L and 584R of 
tandem-motion member 58 engage the upper surface of carriage 57 when 
stocker 50 is in the Pos(1) position, stabilizing carriages 51-57 from 
external vibrations. 
A top panel 30, which is fixed on the chassis, covers stocker 50 and shafts 
580L and 580R. A tongue at a front of top panel 30 supports magnetic 
damper 190, which fixes the disc onto a turntable 202. 
Referring now to FIGS. 1, 3, 4 and 6, an upper disc-lock shaft 250 extends 
from a lower surface of top panel 30, projecting through spindle holes 163 
of discs 1-7 stored within stocker 50. A lower end of upper disc-lock 
shaft 250 projects through spindle hole 163 of the n+1 carriage when 
stocker 50 is in Pos(n), preventing discs 1-7 from moving due to shock or 
tilting. 
A support base 252 movably supports a lower disc-lock shaft 251 which 
coaxially opposes upper disc-lock shaft 250. Support base 252 permits 
lower disc-lock shaft 251 to move vertically to mate with upper disc-lock 
shaft 250 as follows. A spring 253 (shown in FIGS. 4 and 6), disposed 
within lower disc-lock shaft 251, applies an upward bias to lower 
disc-lock shaft 251. A control arm 254 is pivotally mounted on support 
base 252 by a shaft 255. A follower pin 256 extends from an end of control 
arm 254 to engage a cam groove 101 in an outer surface of a cam member 
110. A cam member drive mechanism 319 drives cam member 110. 
Cam groove 101 wraps around cam member 110 in a spiral fashion (only part 
of cam groove 101 is visible in the figures). A yoke 257, extending from 
another end of control arm 254, engages an upper surface of a pin 258 
projecting from lower disc-lock shaft 251. Rotation of cam member 110 
pivots control arm 254, thereby raising and lowering lower disc-lock shaft 
251 between a lock position, in which it abuts upper disc-lock shaft 250 
(FIG. 4), and an unlock position, in which its upper end retracts below 
the selected carriage (FIG. 3). Thus, lower disc-lock shaft 251 
alternately passes through, and is withdrawn from, spindle hole 163 of the 
disc on the selected carriage as lower disc-lock shaft 251 moves up and 
down, respectively. 
An optical mechanism 200, which includes an optical head 203 and a spindle 
motor 327, is disposed below tray 20. A horizontally mounted pin 204 
pivotally supports a damper base 180, which in turn supports optical 
mechanism 200 through a damper 205. A second pin (not shown) engages cam 
groove 101, permitting optical mechanism 200 to move vertically responsive 
to rotation of cam member 110. 
Optical mechanism 200 moves between an upper position and a lower position. 
In the upper position, optical mechanism 200 aligns with a disc in the 
playback position. In the lower position, optical mechanism 200 moves 
below the plane defined by the disc, thereby freeing the path for 
transferring a selected carriage into and out of tray 20. A cam 260, 
integrally formed on a lower portion of cam member 110, engages switches 
312-314 that indicate different states of the disc playback device as 
described below. 
Referring now to FIGS. 9-11, cam 260 rotates with cam member 110 to 
sequentially actuate switches 312-314, positioned at separate locations on 
a lower surface of a main chassis of the disc playback device 1000. 
Actuation of switches 312-314 generate signals POS 1-3 (shown in FIG. 12), 
respectively, which are sent to a system controller ("syscon") 300. 
Referring now also to FIG. 12, a rotational angle of zero for cam 260 is 
defined as the angle at which rotation of cam 260 lifts optical mechanism 
200 into its upper position. Cam groove 101 has a spiral shape so that 
optical mechanism 200 is advanced when cam member 110 rotates through 
angles of 0.degree. to -90.degree.. However, there are also non-advancing 
portions of cam groove 101 where the optical mechanism remains stationary 
while cam member 101 rotates through angle ranges of +22.5.degree. to 
0.degree., and -90.degree. to -202.5.degree.. 
Referring now to FIGS. 9 and 12, angles of rotation of cam 260 between zero 
and +22.5.degree., otherwise known as the UP range, maintains optical 
mechanism 200 in the upper position and lower disc-lock shaft 251 in the 
lock position. Switches 312-314 are all turned on, rendering signals POS 
1-3 all at a state identified in FIG. 9 as "L" (hereinafter "H" and "L" 
represent high and low signal level states respectively). 
When cam 260 rotates from a cam angle of zero to -90.degree., optical 
mechanism 200 moves from its upper to its lower position, while lower 
disc-lock shaft 251 similarly descends from its lock position to an unlock 
position. During this time, switch 312 is off, and POS 1 signal is "H". 
Referring now to FIGS. 10 and 12, at rotational angles between -90.degree. 
and -135.degree., otherwise known as the DOWN range, cam 260 turns 
switches 312 and 313 off, and POS 1 and POS 2 signals are "H". Optical 
mechanism 200 stays in its lower position while lower disc-lock shaft 251 
stays in the unlock position. 
Referring now to FIGS. 11 and 12, rotation of cam 260 negatively past 
-135.degree. turns switch 314 off, rendering all of POS signals 1-3 
signals "H". During this interval, lower disc-lock shaft 251 rises, 
returning to the lock position when cam member 110 reaches the 
-180.degree. position. When cam 260 rotates negatively past the 
-180.degree. point, switch 312 turns on, and signal POS 1 changes to "L". 
While cam 260 is within the range -180.degree. to -202.5.degree., 
otherwise known as the LOCK range, optical mechanism 200 remains in the 
down position while lower disc-lock shaft 251 remains in the lock 
position. 
Referring now to FIG. 13, a control circuit 1010 includes syscon 300. 
Syscon 300 contains conventional elements such as, for example, a 
read-only memory, a random-access memory, and interface circuitry. Syscon 
300 may also incorporate one or more microprocessors. 
Syscon 300 controls disc playback device 1000 according to an operating 
mode set by user input through a mode control panel 301. A backup power 
supply 302 connected to syscon 300, allows its random-access memory to 
retain data when the normal power supply is turned off or otherwise 
interrupted. 
Limit switches 303-305 apply high "H" and low "L" signal levels to STORE, 
T.CLOSE, and EJECT (although these inputs are shown in the drawings as 
active upon receipt of a "0", they are referred to in the specification by 
the proper name) inputs of syscon 300, respectively. An "L" signal level 
at these inputs indicates that tray/carriage transport mechanism 309 has 
moved the selected carriage to the store, close, and eject positions, 
respectively. A photo-interrupter 306 detects that tray/carriage transport 
mechanism 309 has moved the selected carriage to the playback position by 
applying a signal at a CENTER input of syscon 300. 
The STORE signal is responsive to the location of shuttle 28, such that 
STORE is "H" if shuttle 28 is prevented from returning to the rear of the 
device. 
Syscon 300 applies control signals to a motor drive circuit 307 via FRONT 
and REAR outputs. A tray motor 308 rotates in forward and reverse 
directions according to output from motor drive circuit 307. Tray motor 
308 drives tray/carriage transport mechanism 309. 
According to the preferred embodiment of the invention, tray 20 moves 
toward the front (toward the eject position) of disc playback device 1000 
when an "H" signal level is applied by the FRONT output. Tray 20 moves to 
the rear (toward the store position) of disc playback device 1000 when an 
"H" signal level is applied by the REAR output. An "H" level applied 
simultaneously by both FRONT and REAR outputs shorts the outputs of motor 
drive circuit 307, causing a magnetic braking effect in tray motor 308 
(hereinafter referred to as "electromagnetic braking"). When both outputs 
are held at the "L" level, the outputs of motor drive circuit 307 are 
open. 
Syscon 300 has several additional inputs for receiving input signals. A 
D.CNT input, connected to a photo-interrupter 310, receives an input 
signal indicating the position of stocker 50. An H.POS input, connected to 
a limit switch 311, receives an input signal that detects a reference 
position of stocker 50. Inputs POS 1-3 are connected to switches 312-314, 
which indicate the position of cam 260, described above. 
FIG. 14 shows the changes in D.CNT signal and H.POS signal corresponding to 
the position of stocker 50. The D.CNT signal outputs a brief "L" each time 
stocker 50 brings a disc into its respective position Pos(n) (where n is 
the disc number). The H.POS input normally remains at "H", except when 
stocker 50 is roughly midway between Pos(1) and Pos(2), at which point 
H-POS becomes an "L". 
Simultaneous reception of an "L" at both the H.POS and D.CNT inputs 
indicates to syscon 300 that stocker 50 is at Pos(1). This condition acts 
as a home-position signal. The remaining positions are detected by 
counting the D.CNT signal as stocker 50 moves in a given direction. 
Returning now to FIG. 13, syscon 300 applies a signal level to an ST.UP 
output and an ST.DWN output. The ST.UP and ST.DWN outputs are connected to 
a motor drive circuit 315. Motor drive circuit 315 controls a stocker 
motor 316, which rotates in a reverse direction in response to the output 
from motor drive circuit 315. The rotary output of stocker motor 316 is 
transmitted, via a selection mechanism 317, to either sliding plate 520 or 
cam 110. Selection mechanism 317 is responsive to tray/carriage transport 
mechanism 309 based on the position of the selected carriage. 
When a selected carriage 51-57 is in the store position, sliding panel 520 
is selected. Stocker 50 moves upward when the ST.UP signal is "H" and 
moves downward when the ST.DOWN signal is "H". When both signals are "H," 
motor drive circuit 315 outputs are shorted, thereby applying a magnetic 
brake to stocker motor 316. When both signals are "L," motor drive circuit 
315 outputs are disconnected, releasing the magnetic braking action. 
Selection mechanism 317 transfers rotary input to cam 110 when a selected 
carriage is in a position other than the store position (e.g., the 
playback or eject positions). If the ST.UP signal is "H", cam 110 turns 
clockwise, moving optical mechanism 200 downward. If the ST.UP signal is 
"H," cam 110 turns counter-clockwise, moving optical mechanism 200 upward. 
Syscon 300 also has a D.DET input to which signals are applied by a disc 
sensor 328 to register in memory the presence of a disc 1 in a selected 
carriages. 
Optical head 203 is movably connected to optical mechanism 200. Optical 
head 203 uses a laser to read recorded information from a disc, generating 
a playback signal responsively to information recorded therein. The 
playback signal is applied to signal processor circuit 320 via a RF 
amplifier 322. Signal processor circuit 320 generates left and right 
channel audio data, Lch and Rch, respectively, following EFM demodulation, 
de-interleaving and error correction to the raw signal. Audio data are 
sent to digital-to-analog converters 323 and 324, respectively, for 
digital-to-analog conversion. The analog output signals are applied to low 
pass filters 325 and 326, respectively. 
Syscon 300 connects to a servo signal processor circuit 321, which controls 
a focus servo, a tracking servo and a feed servo on optical head 203. 
Servo signal processor circuit 321 also controls a CLV servo of a spindle 
motor 307. 
The operation of syscon 300 in conjunction with the remaining elements of 
the disc playback device are shown in the flowcharts of FIGS. 15-26, and 
the corresponding time charts shown in FIGS. 27-33. In the flowcharts, "n" 
refers to the selected disc number (carriage number) set responsive to a 
disc selection key, while "m" refers to the current position of stocker 
50. Flag(m) indicates the presence of a disc on the m.sup.th storage 
position of stocker 50, where m is an index indicating the storage 
position number (e.g. Flag(3)=1 indicates that a disc is present in third 
carriage 53). 
Referring now to FIG. 15, syscon 300 initialize the disc player when the 
power turns on. At a step S200, syscon 300 checks switches S1-S3 to check 
whether cam 110 is in the DOWN range. If not, cam 110 rotates into the cam 
range at a step S201 before proceeding to step S202. 
Once in the DOWN range, syscon 300 checks the STORE signal to see if the 
carriage is in the store position (STORE="L") at step S202. If a carriage 
is present, then at step 203 signal REAR pulses for 100 msec with 10 msec 
periods at a 40 percent duty cycle (this process ensures that the carriage 
is completely withdrawn into the store position). Once complete, FRONT and 
REAR are set to "H" at step S204 for 50 msec to apply an electromagnetic 
brake to tray motor 308, preventing a belt portion of tray/carriage 309 
from stretching. 
Once the selected carriage is placed stably within stocker 50, syscon 
checks the value of m at step S205 to determine whether stocker 50 is in 
Pos(1). If m.noteq.1, then stocker 50 moves to Pos(1) at step S206 before 
proceeding to the MAIN flowchart. Once in Pos(1), stability is provided by 
engagement pieces 584L and 584R of tandem-motion member 58 with carriage 
57, as well as upper disc lock shaft 250, which passes through spindle 
holes 163 of any discs located on carriages 52-57. 
If the selected carriage is not in the store position at step S202 
(STORE="H"), then REAR is set to "H" at step S207, causing tray 20 to 
retract from the eject position and shuttle 28 to return the selected 
carriage to the store position. A marker C is set to 5 at step S208, and a 
five second timer is activated at a step S209. 
When the selected carriage passes the playback position (FIG. 3), signal 
CENTER falls at step S212 and syscon 300 checks signal D.DET at step S213 
to determine whether a disk is present. If a disc is present on the 
carriage (D.DET="L"), then FLAG(m) is set to "1" and control returns to 
proceeds step S210. When the selected carriage returns to the store 
position and signal STORE becomes "L", then syscon 300 proceeds to step 
S203 described above. 
If, however, shuttle 28 does not return to the store position (STORE="H") 
with in the allotted 5 seconds, then control proceeds to step S215 to 
determine whether the tray is in the close position. If not (T.CLOSE="H"), 
then syscon 300 assumes that tray 20 is jammed and cannot return to the 
close position. Signal REAR is returned to "L" at step S230, an error 
message is indicated on the display, and action is halted. 
If, however, the tray is in the close position (T.CLOSE="L"), then it is 
assumed that shuttle 28 is disengaged from carriage cutout 168 and, 
instead, is engaged with carriage front surface 168' (FIG. 7). Thus, 
although the engagement of shuttle 28 with front surface 168' returns the 
selected carriage to stocker 50, front surface 168' similarly prevents 
shuttle 28 from returning to the rear of the device. In this state, 
shuttle 28 is unable to move carriages out of stocker 50. 
In order to reconnect shuttle 28 in cutout 168, an electromagnetic brake is 
applied to tray motor 308 at step S216 to avoid possible motor overload. 
At step S217, syscon 300 applies a "H" FRONT signal for 30 msec, 
separating shuttle 28 from carriage front surface 168'. An electromagnetic 
brake is applied to tray motor 308 at step S218 for 50 msec to stop 
further motion of shuttle 28. 
At step S219, syscon 300 checks count value C, initially set at C=5 at step 
S208. If C.noteq."0", then stocker moves to a position between Pos(1) and 
Pos (2), where syscon will attempt to re-engage shuttle 28 with cutout 168 
as follows. 
Syscon 300 checks H.POS at step 220. If "L", stocker 50 lowers (ST.DWN="H") 
at step S221 until it is disposed between Pos (1) and Pos (2) (H.POS 
changes to "H" at step S222). Electronic braking is applied to the stocker 
at step S223. At step S224, stocker 50 raises (ST.UP="H") until, at step 
S226, H.POS becomes "L". If signal H.POS is "H" at step S220, then syscon 
300 raises stocker 50 in steps S224-S226 as described above. 
Syscon 300 sets signal REAR to "H". moving shuttle 28 toward the rear of 
the device at step S227. A one-second timer is initiated at step S229, and 
count value C is decreased by one at step 229. Syscon 300 returns control 
to step S211 described above. 
By moving toward the rear of the device, shuttle 28 is interposed between 
carriage 51 and carriage 52. When it reaches cutout 168, store position 
detection switch 303 (FIG. 13) turns on (STORE="L") and syscon 300 
proceeds to step S203 described above. If shuttle 28 cannot engage cutout 
168 when the one second timer elapses, syscon 300 repeats steps S215-S229. 
Each repeated stocker positioning creates a slight difference in the 
relative positioning of shuttle 28 and carriages 51, 52, increasing the 
probability that shuttle 28 will engage cutout 168. If shuttle 28 fails to 
engage after five tries, syscon 300 detects count value C=0 at step S219, 
displays an error message and halts operation. 
Referring to FIG. 16, if the initialization sequence completes 
successfully, control passes to the MAIN flowchart. The following is a 
description of the operations corresponding to key entry in each of the 
modes. 
Referring now to FIG. 16, syscon 300 follows the operation in the MAIN 
flowchart, in which syscon 300 awaits depression of a command key, or the 
completion of the playback mode for a disc. Each of the functions shown in 
FIG. 16 is referred to in the detailed flow descriptions of later figures. 
Thus, further description of FIG. 16 is unnecessary, and is omitted. 
Referring now to FIGS. 17-19, when an eject key is pressed while tray 20 is 
in the eject position, control by syscon 300 passes from step S1 of FIG. 
16 to steps S10 and S11 of FIG. 17. Step S10 is the first step in a JOB 
EJECT routine. Beginning with step S11, The JOB EJECT routine proceeds 
through operation TC2 of FIG. 27. Operation TC2 details how the device 
goes from the eject mode to the stop mode by returning the tray to the 
close position and the selected carriage to the store position. 
In step S11, syscon 300 applies the "H" level is to the REAR output to 
retract tray 20 toward the close position. Simultaneously, cam member 110 
rotates counterclockwise responsive to a "H" level to the ST.DWN output 
toward the DOWN range. This also moves lower disc-lock shaft 251 toward 
the unlock position (indicated in FIG. 1). When lower disc-lock shaft 251 
arrives at the unlock position and POS 3 signal is set to "L" as a result 
of the rotation of cam 260, syscon 300 activates the electromagnetic brake 
for motor 316 by applying the "H" level to the ST.UP output to short motor 
drive circuit 315 for 50 msec. Following the first application of the 
brake, syscon 300 proceeds to step S12 unless cam member 110 over-rotates 
past the DOWN range. 
If cam member 110 over-rotates beyond the desired range, syscon 300 applies 
the "L" level to the ST.DWN output, driving cam member 110 clockwise. When 
the POS 2 signal changes to "H," syscon 300 sets the ST.DWN signal to "H", 
magnetically braking stocker motor 316 for 50 msec. 
At step S12, syscon 300 waits for the CENTER input signal to change to "L" 
in response to photo-interrupter 306. The CENTER input changes upon 
arrival of the selected carriage at the playback position. Once tray 20 is 
in the close position and the selected carriage disengages tray 20, switch 
313 applies "L" to the CENTER output. Control passes to step S13 where 
syscon 300 determines if a disc is present in the selected carriage. 
The presence (or lack thereof) of a disc in the selected carriage is 
indicated by the D.DET signal. If a disc is present (D.DET signal is "L"), 
FLAG(m) is set to "1" at step S15 before proceeding to step S16. At step 
S16, syscon 300 waits for the STORE signal to change to "L", which 
indicates that shuttle 28 and the selected carriage have returned to 
stocker 50. 
On occasion, two discs may be placed accidentally into tray 20 while in the 
eject position. For example, if two discs were set in selected first 
carriage 51, the top disc would hit a rim 21 of the tray opening when the 
selected carriage moves from the playback position to the store position. 
Once selected carriage 51 withdraws to its store position, the top disc 
would fall into tray 20, jamming the device and damaging the disc when 
stocker 50 moves. 
In order to prevent such damage, the present invention checks to ensure 
that tray 20 is clear before moving stocker 50. Following an "L" STORE 
signal, syscon 300 again checks the D.DET signal at step S17. 
If the D.DET signal is "H" (no disc present in tray 20), signal REAR is 
pulsed for 10 msec at a 40% duty cycle at step S150. Control passes to 
step 18 (the last step of Operation TC2), where syscon 300 activates the 
electromagnetic brake for motor 316 by setting FRONT output signal to "H", 
shorting the input leads to stocker motor 316 for 50 msec. 
At step S151, stocker 50 defaults to position Pos(1). First, the value of 
"m" is checked at step 151 to see if stocker 50 is already in Pos(1). If 
not, stocker 50 moves to Pos(1) at step 152 before proceeding to step S19, 
where a MODE variable is set to indicate a "STOP" mode and control returns 
to the MAIN routine of FIG. 16. 
If D.DET signal is "L" at step S17, indicating the presence of a disc, 
syscon 300 sets REAR to "L" at step S20 and control passes to step S21 of 
FIG. 18. Beginning with step S21, the JOB EJECT routine proceeds through 
operation TC4 of FIG. 24. Operation TC4 details how the device secures the 
stocker prior to entering into the eject mode. 
Referring now also to FIG. 18, at step S21, syscon 300 sets the FRONT 
signal to "H", moving selected first carriage 51 toward the playback 
position. CENTER input signal changes to "L", indicating arrival of 
selected first carriage 51 at the playback position, at a step S22. Once 
CENTER input signal changes to "L", syscon 300 resets FLAG(m) to "0" at a 
step S23. 
At a step S24, syscon 300 moves cam member 110 to the LOCK range. ST.UP is 
set to "H," rotating cam member 110 clockwise to move lower disc-lock 
shaft 251 toward the lock position. Once lower disc-lock shaft 251 moves 
to the lock position and the POS 1 signal is "L", the ST.DWN output signal 
is set to "H" to brake stocker motor 316. In this state, the remaining 
discs in stocker 50 are secure, and will not shift due to shock or 
inclination of playback device 1000. 
At step S25, syscon 300 waits for tray 20 to arrive at the eject position 
(EJECT="L"), at which time syscon 300 applies the "H" level to the REAR 
output and magnetically brakes tray motor 308 for 50 msec at step S26. At 
step S27, the MODE variable is set to indicate an "EJECT" mode and control 
returns to the MAIN routine. 
Referring now to FIGS. 19 and 29, when the eject key is pressed during a 
"PLAYBACK" mode, syscon 300 proceeds from step S1 of FIG. 16 through step 
S10 of FIG. 17 to steps S28 and S29 of FIG. 19. Disc playback halts at 
step S29 before the JOB EJECT routine proceeds through operation TC3 of 
FIG. 29. Operation TC3 details how the device secures the stocker prior to 
ejecting a disc from the playback position. 
At step S30, syscon 300 applies an "H" level to the ST.UP output. Syscon 
300 then rotates cam member 110 clockwise to bring optical mechanism 200 
into the lower position and lower-disc-lock shaft 251 to the lock 
position. Once lower disc-lock shaft 251 arrives at the lock position and 
the POS 1 signal becomes "L", motor 316 magnetically brakes for 50 msec by 
a "H" ST.DWN signal. 
Following braking, an "H" level signal is applied to the FRONT output at a 
step S31, moving tray 20 to the eject position. At step S32, FLAG(m) is 
reset to "0". After tray 20 arrives at the eject position (EJECT="L") at 
step S33, an "H" level at the REAR output magnetically brakes tray motor 
308 for 50 msec at step 34. Finally, the MODE variable is set to indicate 
the "EJECT" mode and control returns to the MAIN routine of FIG. 16 in a 
step S35. 
When the eject key is pressed during the STOP mode (all carriages 51-57 are 
in stocker 50), syscon 300 proceeds from step S1, through steps S10, S28, 
S36 to step S37, at which the selected disc number "n" is compared with 
the present disk number "m". If m=n, control proceeds to the flowchart of 
FIG. 18, described previously. If not, stocker 50 moves to Pos(n) prior to 
control proceeding to the flowchart of FIG. 18. 
Referring now to FIGS. 20 and 30, when a play key is pressed during the 
"EJECT" mode, syscon 300 proceeds from step S2 of FIG. 16 to steps S40 and 
S41 of FIG. 20. At step S41, an "H" level to the REAR output moves tray 20 
toward its close position. At the same time, cam member 110 rotates 
counterclockwise to the DOWN range, moving lower disc-lock shaft 251 
downward from the lock position. When lower disc-lock shaft 251 arrives at 
the unlock position and the POS 3 signal is set to "L" as a result of the 
rotation of cam 260, syscon 300 activates the electromagnetic brake for 
motor 316 by applying the "H" level to the ST.UP output to short motor 
drive circuit 315 for 50 msec. Following the first application of the 
brake, syscon 300 proceeds to step S42 (unless cam member 110 
over-rotates, thereby requiring restoration in the manner described 
previously). 
At step S42, syscon 300 waits for the CENTER input signal to change to "L," 
in response to photo-interrupter 306. When the CENTER output signal 
changes to "L," control passes to step S43 where syscon 300 determines if 
a disc is present in the selected carriage. If a disc is present (D.DET 
signal="L") the corresponding FLAG(m) is set to "1" at step S44. Tray 20 
moves to the playback position at step S45. When the CENTER input signal 
terminal state changes to "L," syscon 300 outputs an "H" signal level from 
the FRONT output braking tray motor 308 for 50 msec. 
After braking, if tray motor 308 rotated past the playback position, an "L" 
level is output from the REAR output, and the FRONT output is cycled 
between "H" and "L" with a 50% duty cycle and a cycle period of 10 msec. 
Selected first carriage 591 thus moves in the eject direction at a low 
speed. Once the CENTER input signal changes to "L," an "H" level is output 
from both the FRONT and the REAR output terminals braking tray motor 308 
for 50 msec. 
At step S46, syscon 300 brings cam member 110 to the UP range, shown in 
FIG. 9. An "H" signal level is applied by the ST.DWN output, rotating cam 
member 110 counterclockwise. Optical mechanism 200 moves toward its upper 
position, whereupon the POS 1 signal changes to "L". Magnetic braking is 
activated by an "H" level signal is output from the ST.UP. After the 
braking, signal processor circuit 320 and servo signal processor 321 are 
controlled to begin the playback procedure at step S47. Once disc playback 
begins, the MODE variable is set to indicate the "PLAY" mode and control 
returns to the MAIN routine at step S48. 
If no disc is present in the selected carriage (D.DET is "H") at step S43, 
control proceeds to step S50, where syscon 300 waits for the selected 
carriage to arrive at the store position (STORE changes to "L"). When the 
selected carriage arrives at the store position, REAR signal pulses for 
100 msecs at a 40% duty cycle at step S153. Control passes to step S51, 
where syscon 300 outputs an "H" level at the FRONT output to brake tray 
motor 308. At step S154, m is checked to see if stocker 50 is in Pos(1). 
If m=1, a MODE variable is set to indicate a "STOP" mode at step S52 and 
control returns to the MAIN routine of FIG. 16. If m.noteq.1, stocker 50 
moves to Pos(1) at step 155 before control passes to step S52. 
Referring now to FIGS. 21, if the play key is pressed during the "STOP" 
mode, syscon 300 proceeds to a JOB PLAY routine, through steps S40 and 
S53, to step S54 at which the selected carriage is checked for the 
presence of a disc (Flag(m)=1). 
If FLAG(m) was "0" at step S54, syscon 300 searches all flags sequentially 
from FLAG(1) to FLAG(7) at step S62. If a flag set to "1" is found, 
control proceeds to step S63, wherein stocker 50 moves to the position 
corresponding to the flag which was set to "1". Control then passes to 
step S55. If all of the flags are set to "0" in step S62, stocker 50 
return to Pos(1) at steps S156 and S157, and control passes to the MAIN 
routine of FIG. 16. Pressing of the play key is, in effect, ignored. 
If a disc is detected in the selected carriage at step S54, control passes 
to step S154 at which the selected disc number "n" is compared with "m". 
If they are identical, control proceeds to step S55. If not, stocker 50 
moves to POS(n) prior to control proceeding with step S55. 
At a step 55, operations TC6 and TC7 commence as shown in FIGS. 31 and 32, 
respectively. Operation TC6 involves transferring a disc from a selected 
carriage in stocker 50 to the playback position, from which playback 
commences. Operation TC7 is a branch of TC6, responsive to the absence of 
a disc in the playback position, for returning the selected carriage to 
stocker 50. 
Syscon 300 outputs an "H" level signal at the FRONT output at step S55. The 
selected carriage moves out of stocker 50 toward the playback position 
until the CENTER input signal changes to "L" in step S56. Once the 
selected carriage arrives at the playback position, syscon 300 checks the 
D.DET input at step 57 to check if a disc 1 is present in the selected 
carriage. Step S57 thereby corrects data errors in FLAG(m) (possibly due 
to a power loss) to prevent unnecessary operation of the device. 
If a disk is absent from the selected carriage (D.DET is "H"), syscon 300 
sets FLAG(m) to "0" at step S64. At step S65, an "L" signal level is 
applied to the FRONT output and an "H" signal level is applied to the REAR 
output, returning the selected carriage to its store position. Once the 
selected carriage returns to the store position in step S66, REAR is set 
to "H" for 100 msec at 40% duty cycle. At step S68, syscon 300 applies an 
"H" level to the FRONT output terminal and brakes tray motor 308 for 50 
msec. This step completes operation TC7, after which control returns to 
step S62. 
If a disk is present in the selected carriage at step S57 (D.DET is "L") 
control proceeds to step S58, where syscon 300 moves the selected carriage 
to the playback position. At step S59 cam member 110 rotates until it is 
in the UP range. After the CENTER input signal changes to "L," syscon 300 
outputs an "H" level at the REAR signal terminal, braking tray motor 308. 
If, the carriage overshoots the playback position, an "L" signal level is 
output from the FRONT output terminal and the REAR output is cycled, at a 
50% duty cycle with a 10 msec cycle period, slowly bringing the selected 
carriage to the playback position. Once the CENTER input signal changes to 
"L," "H" levels are output at both the FRONT signal terminal and the REAR 
signal terminal for 50 msec to magnetically brake tray motor 308. 
Next, syscon 300 outputs an "H" signal level at the ST.DWN output terminal. 
Cam member 110 rotates counterclockwise, moving optical mechanism 200 
toward its upper position. When optical mechanism 200 arrives at the up 
position and the POS 1 signal changes to "L," braking is induced by an "H" 
level ST.UP. This step completes operation TC6, after which disk playback 
initiates at step S60. At step S61, the MODE variable is set to indicate 
the "PLAY" mode. Control then returns to the MAIN routine. 
Referring now also to FIGS. 22 and 29, when the STOP key is pressed during 
the "PLAY" mode, syscon 300 proceeds from step S3 of FIG. 16 through steps 
S70 and S71 of FIG. 22. Disc playback halts at step S71. At a step S72, 
operation TC8 begins, in which the selected carriage returns to the store 
position from the playback position. 
At step S72, cam member 110 rotates toward the DOWN range. Syscon 300 sets 
the ST.UP signal to "H". Cam member 110 rotates clockwise to move optical 
head 203 and lower disc-lock shaft 251 downward. Syscon 300 compensates 
for any overshoot as described previously. 
When optical head 203 reaches the down position and the POS 2 signal 
changes to "H," syscon activates the electromagnetic brake. Then, at step 
S73, syscon 300 outputs an "H" signal level from the REAR output. Control 
passes to step S75 when the selected carriage arrives at the store 
position and the STORE input signal changes to "L" at step S74. At step 
S75, syscon 300 determines if a disc is present by the D.DET input signal. 
If no disc is present (D.DET signal is "L") at step S78, syscon 300 sets 
the REAR output signal to "L", whereby control proceeds to the flowchart 
of FIG. 18 as above. 
If a disc is present (D.DET is "H") at step S75, control proceeds to step 
S158, at which REAR is set to "H" for 100 msec at a 40% duty cycle. At 
step S76, tray motor 308 magnetically brakes as described previously. This 
concludes operation TC8, and control proceeds to step S159. 
At step S159, m is checked to determine if stocker 50 is at position 
Pos(1). If so, control passes to step S77, where the MODE variable is set 
to indicate the "STOP" mode and control returns to the MAIN routine. If 
stocker 50 is not in Pos(1) at step S159, syscon 300 moves stocker 50 to 
that position at step S160 prior to proceeding with step 77. 
Referring now to FIG. 16, mode control panel 301 includes a plurality of 
DISC selection keys (not shown), one for each of the seven carriages 51-57 
in stocker 50. When one of the DISC selection keys is pressed, syscon 300 
branches from a corresponding one of steps S4 through S7 of FIG. 16 to a 
corresponding JOB DISC-N routine (steps S80-S83) shown in FIG. 23, where N 
is the number of the DISC selection key that is pressed. A constant n is 
set to "1", "2", . . . "7" according to the DISC selection key pressed. 
If the disc selection key is depressed while the device is in the "EJECT" 
mode, control proceeds from step S84 to operation TC2 (movement from the 
eject position to the store position) through a series of steps S85-S88, 
S90-S92, S94, and S161. These steps are identical to steps S11-S13, 
S15-S18, S20 and S150, described with respect to FIG. 17, and need not be 
repeated here. After step S92 in which the tray motor 308 stops, stocker 
50 moves to POS(n) at step S93. Control then proceeds to step S21 in FIG. 
18, discussed above. 
Referring now to FIG. 24, when a DISC key is pressed during "PLAY" mode, 
syscon 300 proceeds from the corresponding JOB DISC routine (the one of 
S81-S83 corresponding to the key pressed) to steps S84, S95 and S96, 
wherein FLAG(n) is checked for the presence of a disc (n is the DISC key 
number that was pressed). If no disc is present (FLAG(n) is "0") control 
immediately returns to the MAIN routine and the pressing of a DISC key is, 
in effect, ignored. If a disc is present (FLAG(n) is "1"), control 
proceeds to step S97 where syscon 300 halts disc playback. 
Beginning with step S98, the routine proceeds through operation TC8 
(movement from the playback position to the store position) through a 
series of steps S98-S103 and S162. These steps are identical to steps 
S72-S76, S78, and S158, described with reference to FIG. 22, and need not 
be repeated here. After step S103 in which the tray motor 308 stops, 
stocker 50 moves to POS(n). Control then proceeds to step S105 in FIG. 25. 
Referring now also to FIG. 25, both operations TC6 and TC7 commence at step 
105-S115, which are identical to steps S55-S61 and S64-S68 of FIG. 21 
(store position to playback position; if a disc is not in the selected 
carriage, return to store position), described above. If a disc is present 
in the selected carriage, control passes through path TC6 to steps S110 
and S111, where the disc is played and the MODE variable is set to PLAY. 
If a disc is not present in the selected carriage, control proceeds through 
TC7 to step 115, in which motor 308 is braked electromagnetically. If 
stocker 50 is not in Pos(1) at step S164, syscon 300 moves stocker 50 to 
that position at step S165 prior to proceeding with step 116. At step S116 
the MODE variable is set to indicate the "STOP" mode and control returns 
to the MAIN routine. 
Referring now to FIG. 26, the operation of continuous playback in play mode 
is described. Syscon 300 detects completion of disk playback from signal 
processor circuit 320. Control proceeds from step S8 of FIG. 16 to step 
S120 in FIG. 26, where the disc is halted. Commencing with step S121, the 
routine proceeds through operation TC8 (movement from the playback 
position to the store position) through a series of steps S121-S126 and 
S166. These steps are identical to steps S72-S76, S78, and S158 of FIG. 
22, discussed above. 
At a step S127, the flags are checked sequentially beginning with FLAG(m+1) 
through Flag(7) to locate the next disc in stocker 50. If no disc is 
found, control passes to step S167 to determine if stocker 50 is at 
position Pos(1) (m=1). If so, control passes to step S128, where the MODE 
variable is set to indicate the "STOP" mode and control returns to the 
MAIN routine. If stocker 50 is not in Pos(1) at step S167, syscon 300 
moves stocker 50 to that position at step S168 prior to proceedings with 
step S128. 
If a Flag is detected in Flag(m+1) through Flag(7), then stocker 50 moves 
to POS(n) at step S129, where n is the first sequential carriage in which 
the flag was detected. 
Step 130 commences both operations TC6 and TC7. Steps S130-S140 and S169 
are identical to steps S55-S61 and S64-S67 of FIG. 21 (store position to 
playback position; if a disc is not in the selected carriage, return to 
store position), described above. If no disc is present, control proceeds 
from S140 to S127. If a disc is present, disc playback resumes, MODE is 
set to play, and control returns to the main routine. 
Referring now to FIGS. 34-36, a display 329 indicates various modes of 
operation and the presence of discs as the foregoing operations occur. 
Various alterations of the embodiment described above may be effected by 
those of ordinary skill in the art, having the benefit of this 
description, without departing from the scope and spirit of the present 
invention. For example, during the initialization phase, stocker 50 may be 
raised above Pos (1) such that shuttle 28 passes below first carriage 51. 
Another possible alteration would be to check for shuttle disengagement 
during normal operations. 
Although the preferred embodiment shuttle 28 engages cutout 168, the 
present invention is not limited to that specific structure. Several 
methods may be employed to engage shuttle 28 with the selected carriage. 
For example, the selected carriage could have a protrusion which engages a 
cutout in the shuttle. 
In still another embodiment of the invention, stocker 50 could be fixed, 
and tray 20 could move vertically along stocker 50 to align with selected 
carriages 51-57. In such an embodiment, if shuttle 28 disengages from the 
selected carriage, then tray 20 and shuttle 28 move vertically to align 
below or above any desired carriage. Tray 20 is subsequently raised or 
lowered to engage shuttle 28 with the selected carriage. 
Having described preferred embodiments of the invention with reference to 
the accompanying drawings, it is to be understood that the invention is 
not limited to those precise embodiments, and that various changes and 
modifications may be effected therein by one skilled in the art without 
departing from the scope or spirit of the invention as defined in the 
appended claims.