Track jump controlling unit capable of correctly jumping light beam spot of photo pickup device from one of tracks to other one of tracks

In a track jump controlling unit, a tracking error detecting circuit detects a tracking error signal in response to a light beam detecting signal from a photo detecting circuit. A zero cross detecting circuit detects a zero cross of the tracking error signal to produce a zero cross detecting signal. A level comparing circuit compares a level of the tracking error signal with a predetermined reference level to produce a comparison signal when the level of the tracking error signal is higher than the predetermined reference level. A timer times first and second predetermined time periods from occurrence of a jump command signal to produce first and second time out signals. The second predetermined time period is greater than the first predetermined time period. A jump pulse producing circuit produces a kick pulse of a jump pulse signal in response to the jump command signal and holds the kick pulse regardless of the zero cross detecting signal until the jump pulse producing circuit is supplied with the first time out signal when the jump pulse producing circuit is not supplied with the comparison signal. The jump pulse producing circuit produces a brake pulse of the jump pulse signal when the jump pulse producing circuit is supplied with at least one of the zero cross detecting signal and the second time out signal after the kick pulse turns to the zero point. At least one of the timer and the level comparing circuit may be omitted.

BACKGROUND OF THE INVENTION 
This invention relates to a track jump controlling unit which uses in a 
photo disk system. 
DESCRIPTION OF THE RELATED ART 
In the manner which will later be described more in detail, a conventional 
track jump controlling unit comprises a photo detecting circuit, a 
tracking error detecting circuit, a phase compensating circuit, a zero 
cross detecting circuit, a jump command producing circuit, a jump pulse 
producing circuit, a controlling circuit, a switching circuit, and a 
tracking actuator. 
The photo detecting circuit detects a reflected light beam from a photo 
disk which is supplied with a light beam from the photo pickup device to 
produce a light beam detecting signal. The tracking error detecting 
circuit detects a tracking error signal when the tracking error detecting 
circuit is supplied with the light beam detecting signal from the photo 
detecting circuit. The phase compensating circuit produces a phase 
compensating signal when the phase compensating circuit 3 is supplied with 
the tracking error signal from the tracking error detecting circuit. 
The zero cross detecting circuit detects a zero cross of the tracking error 
signal from the tracking error detecting circuit to produce a zero cross 
detecting signal. The controlling circuit produces a jump sequence start 
signal to supply the jump sequence start signal to the jump command 
producing circuit. The jump command producing circuit produces a jump 
command signal when the jump command producing circuit is supplied with 
the jump sequence start signal from the controlling circuit. The jump 
command producing circuit supplies the jump command signal to the jump 
pulse producing circuit. The jump pulse producing circuit produces a jump 
pulse signal which has a kick pulse and a brake pulse when the jump pulse 
producing circuit is supplied with the jump command signal from the jump 
command producing circuit. 
Also, the controlling circuit produces a switch control signal to supply 
the switch control signal to the switching circuit. The switching circuit 
connects the phase compensating circuit to the tracking actuator when the 
switching circuit is not supplied with the switch control signal from the 
controlling circuit. The switching circuit connects the jump pulse 
producing circuit to the tracking actuator when the switching circuit is 
supplied with the switch control signal from the controlling circuit. The 
tracking actuator executes an operation of tracking when the tracking 
actuator is supplied with the phase compensating signal from the phase 
compensating circuit. Also, the tracking actuator jumps an object lens, 
namely, a light beam spot, of a photo pickup device from one of tracks of 
a photo disk to other one of the tracks that is adjacent to the one of the 
tracks when the tracking actuator is supplied with the jump pulse signal 
from the jump pulse producing circuit. In this event, the tracking 
actuator jumps, in a perpendicular to the tracks, the object lens of the 
photo pickup device. 
In addition, the jump pulse producing circuit produces the kick pulse when 
the jump pulse producing circuit is supplied with the jump command signal 
from the jump command producing circuit. Thereafter, the jump pulse 
producing circuit produces the brake pulse when the jump pulse producing 
circuit is supplied with the zero cross detecting signal from the zero 
cross detecting circuit. 
The jump pulse producing circuit produces the kick pulse when the jump 
pulse producing circuit is supplied with the jump command signal from the 
jump command producing circuit. Thereby, a level of the tracking error 
signal is increased until the level of the tracking error signal reaches 
at a predetermined level. Thereafter, the level of the tracking error 
signal is decreased to pass the zero point. When the level of the tracking 
error signal passes the zero point, the zero cross detecting circuit 
produces the zero cross detecting signal to supply the zero cross 
detecting signal to the jump pulse producing circuit. The jump pulse 
producing circuit produces the brake pulse which the jump pulse producing 
circuit is supplied with the zero cross detecting signal from the zero 
cross detecting circuit. Thus, the tracking actuator jumps the object lens 
of the photo pickup device from the one of the tracks of the photo disk to 
the other one of the tracks that is adjacent to the one of the tracks when 
the tracking actuator is supplied with the jump pulse signal from the jump 
pulse producing circuit. 
Another conventional track jump controlling unit of the type described is 
disclosed in Japanese Unexamined Patent Prepublication (koukai) No. 
139131/1987. The other conventional track jump controlling unit further 
comprises a jump pulse producing circuit which stops, at a lapse time 
point of a predetermined time period, to hold the kick pulse even when the 
jump pulse producing circuit is not supplied with the zero cross detecting 
signal from the zero cross detecting circuit to produce the brake pulse. 
However, the conventional track jump controlling units are incapable of 
correctly jumping the light beam spot of the photo pickup device from the 
one of the tracks of the photo disk to the other one of the tracks that is 
adjacent to the one of the tracks when the photo disk has a flaw or a 
waste to be adhered to the photo disk. This is because occurrence of the 
zero cross detecting signal is hastened or late when the tracking error 
signal is confused by the flaw of the photo disk or the waste on the photo 
disk. Thereby, occurrence of the brake pulse is hastened or late. 
SUMMARY OF THE INVENTION 
It is therefore an object of this invention to provide a track jump 
controlling units which is capable of correctly jumping a light beam spot 
of a photo pickup device from one of tracks of a photo disk to other one 
of the tracks that is adjacent to the one of the tracks even when the 
photo disk has a flaw or a waste to be adhered to the photo disk. 
Other objects of this invention will become clear as the description 
proceeds. 
According to a first aspect of this invention, there is provided a track 
jump controlling unit comprising: 
track jumping means for jumping a light beam spot of a photo pickup device 
from one of tracks of a photo disk to other one of the tracks that is 
adjacent to the one of the tracks when the track jumping means is supplied 
with a jump pulse signal which has a kick pulse and a brake pulse 
following the kick pulse; 
reflected light beam detecting means for detecting a reflected light beam 
from the photo disk which is supplied with a light beam from the photo 
pickup device to produce a light beam detecting signal; 
tracking error detecting means connected to the reflected light beam 
detecting means for detecting a tracking error signal when the tracking 
error detecting means is supplied with the light beam detecting signal; 
zero cross detecting means conn ected to the tracking error detecting means 
for detecting a zero cross of the tracking error signal from the tracking 
error detecting means to produce a zero cross detecting signal; 
level comparing means connected to the tracking error signal detecting 
means for comparing a level of the tracking error signal with a 
predetermined reference level to produce a comparison signal when the 
level of the tracking error signal is higher than the predetermined 
reference level; 
controlling means for producing a jump command signal; and 
jump pulse producing means connected to the track jumping means, to the 
zero cross detecting means, to the level comparing means, and to the 
controlling means for producing the kick pulse when the jump pulse 
producing means is supplied with the jump command signal, for holding, in 
a predetermined time period, the kick pulse regardless of the zero cross 
detecting signal when the jump pulse producing means is not supplied with 
the comparison signal, and for producing the brake pulse when the jump 
pulse producing means is supplied with the zero cross detecting signal 
after the kick pulse turns to the zero point. 
According to a second aspect of this invention, there is provided a track 
jump controlling unit comprising: 
track jumping means for jumping a light beam spot of a photo pickup device 
from one of tracks of a photo disk to other one of the tracks that is 
adjacent to the one of the tracks when the track jumping means is supplied 
with a jump pulse signal which has a kick pulse and a brake pulse 
following the kick pulse; 
reflected light beam detecting means for detecting 
a reflected light beam from the photo disk which is supplied with a light 
beam from the photo pickup device to produce a light beam detecting 
signal; 
tracking error detecting means connected to the reflected light beam 
detecting means for detecting a tracking error signal when the tracking 
error detecting means is supplied with the light beam detecting signal; 
zero cross detecting means conn ected to the tracking error detecting means 
for detecting a zero cross of the tracking error signal from the tracking 
error detecting means to produce a zero cross detecting signal; 
controlling means for producing a jump command signal; 
timing means connected to the controlling means for timing a first 
predetermined time period from occurrence of the jump command signal to 
produce a first time out signal, and for timing a second predetermined 
time period from occurrence of the jump command signal to produce a second 
time out signal, the second predetermined time period being greater than 
the first predetermined time period; and 
jump pulse producing means conn ected to the track jumping means, to the 
zero cross detecting means, to the controlling means, and to the timing 
means for producing the kick pulse when the jump pulse producing means is 
supplied with the jump command signal, for holding the kick pulse 
regardless of the zero cross detecting signal until the jump pulse 
producing means is supplied with the first time out signal, and for 
producing the brake pulse when the jump pulse producing means is supplied 
with at least one of the zero cross detecting signal and the second time 
out signal after the kick pulse turns to the zero point. 
According to a third aspect of this invention, there is provided a track 
jump controlling unit comprising: 
track jumping means for jumping a light beam spot of a photo pickup device 
from one of tracks of a photo disk to other one of the tracks that is 
adjacent to the one of the tracks when the track jumping means is supplied 
with a jump pulse signal which has a kick pulse and a brake pulse 
following the kick pulse; 
reflected light beam detecting means for detecting a reflected light beam 
from the photo disk which is supplied with a light beam from the photo 
pickup device to produce a light beam detecting signal; 
tracking error signal detecting means connected to the reflected light beam 
detecting means for detecting a tracking error signal when the tracking 
error signal detecting means is supplied with the light beam detecting 
signal; 
zero cross detecting means connected to the tracking error signal detecting 
means for detecting zero cross of the tracking error signal from the 
tracking error signal detecting means to produce a zero cross detecting 
signal; 
level comparing means connected to the tracking error signal detecting 
means for comparing a level of the tracking error signal with a 
predetermined reference level to produce a comparison signal when the 
level of the tracking error signal is higher than the predetermined 
reference level; 
controlling means for producing a jump command signal; 
timing means connected to the controlling means for timing a first 
predetermined time period from occurrence of the jump command signal to 
produce a first time out signal, and for timing a second predetermined 
time period from occurrence of the jump command signal to produce a second 
time out signal, the second predetermined time period being greater than 
the first predetermined time period; and 
jump pulse producing means connected to the track jumping means, to the 
zero cross detecting means, to the level comparing means, to the 
controlling means, and to the timing means for producing the kick pulse 
when the jump pulse producing means is supplied with the jump command 
signal, for holding the kick pulse regardless of the zero cross detecting 
signal until the jump pulse producing means is supplied with the first 
time out signal when the jump pulse producing means is not supplied with 
the comparison signal, and for producing the brake pulse when the jump 
pulse producing means is supplied with at least one of the zero cross 
detecting signal and the second time out signal after the kick pulse turns 
to the zero point.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIGS. 1 and 2, a conventional track jump controlling unit will 
first be described for a better understanding of this invention. 
In FIG. 1, the conventional track jump controlling unit comprises a photo 
detecting circuit 1, a tracking error detecting circuit 2, a phase 
compensating circuit 3, a zero cross detecting circuit 4, a jump command 
producing circuit 5, a jump pulse producing circuit 6, a controlling 
circuit 7, a switching circuit 8, and a tracking actuator 9. 
The tracking error detecting circuit 2 is connected to the photo detecting 
circuit 1. The phase compensating circuit 3 is connected to the tracking 
error detecting circuit 2. The zero cross detecting circuit 4 is connected 
to the tracking error detecting circuit 2. The jump command producing 
circuit 5 is connected to the jump pulse producing circuit 6 and to the 
controlling circuit 7. The jump pulse producing circuit 6 is connected to 
the zero cross detecting circuit 4. The switching circuit 8 is connected 
to the phase compensating circuit 3, to the jump pulse producing circuit 
6, and to the controlling circuit 7. The tracking actuator 9 is connected 
to the phase compensating circuit 3 or the jump pulse producing circuit 6 
through the switching circuit 8. 
The photo detecting circuit 1 detects a reflected light beam from a photo 
disk which is supplied with a light beam from the photo pickup device to 
produce a light beam detecting signal. The tracking error detecting 
circuit 2 detects a tracking error signal when the tracking error 
detecting circuit 2 is supplied with the light beam detecting signal from 
the photo detecting circuit 1. The phase compensating circuit 3 produces a 
phase compensating signal when the phase compensating circuit 3 is 
supplied with the tracking error signal from the tracking error detecting 
circuit 2. 
The zero cross detecting circuit 4 detects a zero cross of the tracking 
error signal from the tracking error detecting circuit 2 to produce a zero 
cross detecting signal. The controlling circuit 7 produces a jump sequence 
start signal to supply the jump sequence start signal to the jump command 
producing circuit 5. The jump command producing circuit 5 produces a jump 
command signal when the jump command producing circuit 5 is supplied with 
the jump sequence start signal from the controlling circuit 7. The jump 
command producing circuit 5 supplies the jump command signal to the jump 
pulse producing circuit 6. The jump pulse producing circuit 6 produces a 
jump pulse signal which has a kick pulse and a brake pulse following the 
kick pulse when the jump pulse producing circuit 6 is supplied with the 
jump command signal from the jump command producing circuit 5. 
Also, the controlling circuit 7 produces a switch control signal to supply 
the switch control signal to the switching circuit 8. The switching 
circuit 8 connects the phase compensating circuit 3 to the tracking 
actuator 9 when the switching circuit 8 is not supplied with the switch 
control signal from the controlling circuit 7. The switching circuit 8 
connects the jump pulse producing circuit 6 to the tracking actuator 9 
when the switching circuit 8 is supplied with the switch control signal 
from the controlling circuit 7. The tracking actuator 9 executes an 
operation of tracking when the tracking actuator 9 is supplied with the 
phase compensating signal from the phase compensating circuit 3. Also, the 
tracking actuator 9 jumps an object lens, namely, a light beam spot, of a 
photo pickup device from one of tracks of a photo disk to other one of the 
tracks that is adjacent to the one of the tracks when the tracking 
actuator 9 is supplied with the jump pulse signal from the jump pulse 
producing circuit 6. In this event, the tracking actuator 9 jumps, in a 
perpendicular to the tracks, the object lens of the photo pickup device. 
In addition, the jump pulse producing circuit 6 produces the kick pulse 
when the jump pulse producing circuit 6 is supplied with the jump command 
signal from the jump command producing circuit 5. Thereafter, the jump 
pulse producing circuit 6 produces the brake pulse which the jump pulse 
producing circuit 6 is supplied with the zero cross detecting signal from 
the zero cross detecting cicuit 4. 
Referring to FIG. 2, the jump pulse producing circuit 6 produces the kick 
pulse when the jump pulse producing circuit 6 is supplied with the jump 
command signal from the jump command producing circuit 5. Thereby, a level 
of the tracking error signal is increased until the level of the tracking 
error signal reaches at a predetermined level. Thereafter, the level of 
the tracking error signal is decreased to pass the zero point. When the 
level of the tracking error signal passes the zero point, the zero cross 
detecting circuit 4 produces the zero cross detecting signal to supply the 
zero cross detecting signal to the jump pulse producing circuit 6. The 
jump pulse producing circuit 6 produces the brake pulse which the jump 
pulse producing circuit 6 is supplied with the zero cross detecting signal 
from the zero cross detecting circuit 4. Thus, the tracking actuator 9 
jumps the object lens of the photo pickup device from the one of the 
tracks of the photo disk to the other one of the tracks that is adjacent 
to the one of the tracks when the tracking actuator 9 is supplied with the 
jump pulse signal from the jump pulse producing circuit 6. 
Referring to FIG. 3, the description will proceed to a conventional photo 
disk system which comprises the photo disk, the photo pickup device, and 
the track jump controlling unit. 
The photo disk system comprises the photo detecting circuit 1, the jump 
pulse producing circuit 6, the tracking actuator 9, a laser diode 10, a 
laser power controlling circuit 11, an analog waveform shaping circuit 12, 
a tracking servo 13, a focus actuator 14, a focus servo 15, a low 
detecting circuit 16, a shread motor 17, a synchronization detecting 
circuit 18, a PLL (phase locked loop) circuit 19, a digital signal 
processing circuit 20, a quartz oscillator 21, a spindle servo 22, a 
spindle motor 23, a CPU controlling circuit 24, and the photo disk 25. The 
photo pickup device 26 comprises the photo detecting circuit 1, the 
tracking actuator 9, the laser diode 10, and the focus actuator 14. 
Another conventional track jump controlling unit of the type described is 
disclosed in Japanese Unexamined Patent Prepublication (koukai) No. 
139131/1987. The other conventional track jump controlling unit further 
comprises a jump pulse producing circuit which stops, at a lapse time 
point of a predetermined time period, to hold the kick pulse even when the 
jump pulse producing circuit is not supplied with the zero cross detecting 
signal from the zero cross detecting circuit to produce the brake pulse. 
However, the conventional track jump controlling units are incapable of 
correctly jumping the light beam spot of the photo pickup device from the 
one of the tracks of the photo disk to the other one of the tracks that is 
adjacent to the one of the tracks when the photo disk has a flaw or a 
waste to be adhered to the photo disk. This is because occurrence of the 
zero cross detecting signal is hastened or late when the tracking error 
signal is confused by the flaw of the photo disk or the waste on the photo 
disk. Thereby, occurrence of the brake pulse is hastened or late. 
Referring to FIGS. 4, 5, 6, and 7, the description will proceed to a track 
jump controlling unit according to a first embodiment of this invention. 
Similar parts are designated by like reference numerals. 
In FIG. 4, the track jump controlling unit comprises the photo detecting 
circuit 1, the tracking error detecting circuit 2, the phase compensating 
circuit 3, the zero cross detecting circuit 4, the jump command producing 
circuit 5, the jump pulse producing circuit 6, the controlling circuit 7, 
the switching circuit 8, the tracking actuator 9, a level comparing 
circuit 27, and a timer 28. 
The tracking error detecting circuit 2 is connected to the photo detecting 
circuit 1. The phase compensating circuit 3 is connected to the tracking 
error detecting circuit 2. The zero cross detecting circuit 4 is connected 
to the tracking error detecting circuit 2. The jump command producing 
circuit 5 is connected to the jump pulse producing circuit 6 and to the 
controlling circuit 7. The jump pulse producing circuit 6 is connected to 
the zero cross detecting circuit 4. The switching circuit 8 is connected 
to the phase compensating circuit 3, to the jump pulse producing circuit 
6, and to the controlling circuit 7. The tracking actuator 9 is connected 
to the phase compensating circuit 3 or the jump pulse producing circuit 6 
through the switching circuit 8. The level comparing circuit 27 is 
connected to the tracking error detecting circuit 2 and to the jump pulse 
producing circuit 6. The timer 28 is connected to the controlling circuit 
7 and to the jump pulse producing circuit 6. 
The photo detecting circuit 1 detects the reflected light beam from the 
photo disk which is supplied with the light beam from the photo pickup 
device to produce the light beam detecting signal. The tracking error 
detecting circuit 2 detects the tracking error signal when the tracking 
error detecting circuit 2 is supplied with the light beam detecting signal 
from the photo detecting circuit 1. The phase compensating circuit 3 
produces the phase compensating signal when the phase compensating circuit 
3 is supplied with the tracking error signal from the tracking error 
detecting circuit 2. 
The zero cross detecting circuit 4 detects the zero cross of the tracking 
error signal from the tracking error detecting circuit 2 to produce the 
zero cross detecting signal. The controlling circuit 7 produces the jump 
sequence start signal to supply the jump sequence start signal to the jump 
command producing circuit 5. The jump command producing circuit 5 produces 
the jump command signal when the jump command producing circuit 5 is 
supplied with the jump sequence start signal from the controlling circuit 
7. The jump command producing circuit 5 supplies the jump command signal 
to the jump pulse producing circuit 6. The jump pulse producing circuit 6 
produces the jump pulse signal which has the kick pulse and the brake 
pulse when the jump pulse producing circuit 6 is supplied with the jump 
command signal from the jump command producing circuit 5. 
Also, the controlling circuit 7 produces the switch control signal to 
supply the switch control signal to the switching circuit 8. The switching 
circuit 8 connects the phase compensating circuit 3 to the tracking 
actuator 9 when the switching circuit 8 is not supplied with the switch 
control signal from the controlling circuit 7. The switching circuit 8 
connects the jump pulse producing circuit 6 to the tracking actuator 9 
when the switching circuit 8 is supplied with the switch control signal 
from the controlling circuit 7. The tracking actuator 9 executes the 
operation of tracking when the tracking actuator 9 is supplied with the 
phase compensating signal from the phase compensating circuit 3. Also, the 
tracking actuator 9 jumps the object lens, namely the light beam spot, of 
the photo pickup device from the one of the tracks of the photo disk to 
the other one of the tracks that is adjacent to the one of the tracks when 
the tracking actuator 9 is supplied with the jump pulse signal from the 
jump pulse producing circuit 6. In this event, the tracking actuator 9 
jumps, in the perpendicular to the tracks, the object lens of the photo 
pickup device. 
The level comparing circuit 27 compares a level of the tracking error 
signal from the tracking error detecting circuit 2 with a predetermined 
reference level to produce a comparison signal when the level of the 
tracking error signal is higher than the predetermined reference level. 
The controlling circuit 7 produces the jump sequence start signal to 
supply the jump sequence start signal to the timer 28. The timer 28 times 
a first predetermined time period from occurrence of the jump sequence 
start signal, namely, occurrence of the jump command signal to produce a 
first time out signal. Also, the timer 28 times a second predetermined 
time period from occurrence of the jump sequence start signal, name ly, 
occurrence of the jump command signal to produce a second time out signal. 
The second predetermined time period is greater than the first 
predetermined time period. 
The jump pulse producing circuit 6 produces the kick pulse when the jump 
pulse producing circuit 6 is supplied with the jump command signal from 
the jump command producing circuit 5. The jump pulse producing circuit 6 
holds the kick pulse regardless of the zero cross detecting signal until 
the jump pulse producing circuit 6 is supplied with the first time out 
signal when the jump pulse producing circuit 6 is not supplied with the 
comparison signal. The jump pulse producing circuit 6 produces the brake 
pulse when the jump pulse producing circuit 6 is supplied with at least 
one of the zero cross detecting signal and the second time out signal 
after the kick pulse turns to the zero point. The jump pulse producing 
circuit 6 supplies the kick pulse and the brake pulse to the tracking 
actuator 9 through the switching circuit 8. 
Referring to FIG. 5, the description will proceed to an operation of 
occurrence of the kick pulse and the brake pulse in the track jump 
controlling unit. When the jump command signal occurs, the jump pulse 
producing circuit 6 produces the kick pulse of the jump pulse signal. At 
the same time, the timer 28 is started. In case that a pit and a flute of 
the photo disk have flaws, the tracking error signal frequently passes the 
zero point as shown by an arrow F. As a result, the zero cross detecting 
signals earlier and frequently occur. However, the zero cross detecting 
signals occur in the first predetermined time period A, namely, before the 
first time out signal occurs. Also, the comparison signal is not produced. 
Therefore, the kick pulse is held in the first predetermined time period 
A, namely, until the first time out signal occurs. The jump pulse 
producing circuit 6 produces the brake pulse when the jump pulse producing 
circuit 6 is supplied with the zero cross detecting signal after the kick 
pulse turns to the zero point. Thus, the kick pulse and the brake pulse 
are correctly produced. 
Referring to FIG. 6, the description will proceed to another operation of 
occurrence of the kick pulse and the brake pulse in the track jump 
controlling unit. When the jump command signal occurs, the jump pulse 
producing circuit 6 produces the kick pulse of the jump pulse signal. At 
the same time, the timer 28 is started. In case that a pit and a flute of 
the photo disk have wastes to be adhered to the pit and the flute, the 
tracking error signal lately passes the zero point. As a result, 
occurrence of the zero cross detecting signal is late. The jump pulse 
producing circuit 6 produces the brake pulse when the jump pulse producing 
circuit 6 is supplied with the second time out signal, namely, when the 
second predetermined time period B elapses, after the kick pulse turns to 
the zero point. Thus, the kick pulse and the brake pulse are correctly 
produced. 
Referring to FIG. 7, the description will proceed to an operation of the 
track jump controlling unit. At a step S1, the switching circuit 8 
disconnects the phase compensating circuit 3 from the tracking actuator 9 
and connects the jump pulse producing circuit 6 to the tracking actuator 9 
when the switching circuit 8 is supplied with the switch control signal 
from the controlling circuit 7. The step S1 proceeds to a step S2 at which 
the controlling circuit 7 starts the timer 28. The step S2 proceeds to a 
step S3 at which the jump pulse producing circuit 6 produces the kick 
pulse. 
The step S3 proceeds to a step S4 at which the jump pulse producing circuit 
6 judges whether or not the comparison signal is received. When the 
comparison signal is received, the step S4 proceeds to a step S5. 
Otherwise, the step S4 is repeated. At the step S5, the jump pulse 
producing circuit 6 judges whether or not the first predetermined time 
period A elapses, namely, whether or not the jump pulse producing circuit 
6 is supplied with the first time out signal. When the first predetermined 
time period A does not elapse, the step S5 returns to the step S4. When 
the first predetermined time period A elapses, the step S5 proceeds to a 
step S6. At the step S6, the jump pulse producing circuit 6 judges whether 
or not the second predetermined time period B elapses, namely, whether or 
not the jump pulse producing circuit 6 is supplied with the second time 
out signal. 
When the second predetermined time period B does not elapse, the step S6 
proceeds to a step S7. At the step S7, the jump pulse producing circuit 6 
judges whether or not the zero cross detecting signal is received. When 
the zero cross detecting signal is not received, the step S7 returns to 
the step S6. Otherwise, the step S7 proceeds to a step S8. Also, when the 
second predetermined time period B elapses in the step S6, the step S6 
jumps to the step S8. At the step S8, the jump pulse producing circuit 6 
produces the brake pulse. The step S8 proceeds to a step S9 at which the 
controlling circuit 7 stops the switch control signal. In this event, the 
switching circuit 8 disconnects the jump pulse producing circuit 6 from 
the tracking actuator 9 and connects the phase compensating circuit 3 to 
the tracking actuator 9 when the switching circuit 8 is not supplied with 
the switch control signal from the controlling circuit 7. 
Referring to FIG. 8, the description will proceed to a track jump 
controlling unit according to a second embodiment of this invention. 
Similar parts are designated by like reference numerals. The track jump 
controlling unit comprises the photo detecting circuit 1, the tracking 
error detecting circuit 2, the phase compensating circuit 3, the jump 
pulse producing circuit 6, the switching circuit 8, the tracking actuator 
9, a CPU controller 29, a ROM 30, a RAM 31, and an A/D converter 32. 
The tracking error detecting circuit 2 is connected to the photo detecting 
circuit 1. The phase compensating circuit 3 is connected to the tracking 
error detecting circuit 2. The jump pulse producing circuit 6 is connected 
to the switching circuit 8 and to the CPU controller 29. The switching 
circuit 8 is connected to the phase compensating circuit 3, to the jump 
pulse producing circuit 6, and to the CPU controller 29. The tracking 
actuator 9 is connected to the phase compensating circuit 3 or the jump 
pulse producing circuit 6 through the switching circuit 8. The ROM 30 and 
the RAM 31 are connected to the CPU controller 29. The A/D converter 32 is 
connected to the tracking error detecting circuit 2 and to the CPU 
controller 29. 
The photo detecting circuit 1 detects a reflected light beam from the photo 
disk which is supplied with the light beam from the photo pickup device to 
produce the light beam detecting signal. The tracking error detecting 
circuit 2 detects the tracking error signal when the tracking error 
detecting circuit 2 is supplied with the light beam detecting signal from 
the photo detecting circuit 1. The phase compensating circuit 3 produces 
the phase compensating signal when the phase compensating circuit 3 is 
supplied with the tracking error signal from the tracking error detecting 
circuit 2. 
The A/D converter 32 converts the tracking error signal from the tracking 
error detecting circuit 2 to produce a digital tracking error signal. The 
A/D converter 32 supplies the digital tracking error signal to the CPU 
controller 29. The ROM 30 stores a program. The RAM 31 holds the 
predetermined reference level. Also, the RAM 31 holds a first time out 
value which corresponds to the first time period and a second time out 
value which corresponds to the second time period. The CPU controller 29 
sets the predetermined reference level and the first and second time out 
values in the RAM 31 in response to the program from the ROM 30. 
The CPU controller 29 produces the jump command signal when the CPU is 
supplied with the jump sequence start signal of the program from the ROM 
30. At the same time, the CPU controller 29 produces the switch control 
signal to supply the switch control signal to the switching circuit 8. 
Also, the CPU controller 29 supplies the jump command signal to the jump 
pulse producing circuit 6. The jump pulse producing circuit 6 produces the 
jump pulse signal which has the kick pulse and the brake pulse when the 
jump pulse producing circuit 6 is supplied with the jump command signal 
from the CPU controller 29. The CPU controller 29 detects a zero cross of 
the digital tracking error signal from the A/D converter 32 to produce the 
zero cross detecting signal. The CPU controller 29 supplies the zero cross 
detecting signal to the jump pulse producing circuit 6. 
The CPU controller 29 starts to time a time period from occurrence of the 
jump sequence start signal, namely, occurrence of the jump command signal 
to produce a timed period value. The CPU controller 29 compares the timed 
period value with the first time out value from the RAM 31 to produce the 
first time out signal when the timed period value coincides with the first 
time out value. The CPU controller 29 compares the timed period value with 
the second time out value from the RAM 31 to produce the second time out 
signal when the timed period value coincides with the second time out 
value. The CPU controller 29 supplies the first and second time out 
signals to the jump pulse producing circuit 6. 
The CPU controller 29 compares a level of the digital tracking error signal 
with the predetermined reference level to produce the comparison signal 
when the level of the digital tracking error signal is higher than the 
predetermined reference level. The CPU controller 29 supplies the 
comparison signal to the jump pulse producing circuit 6. 
The jump pulse producing circuit 6 produces the kick pulse when the jump 
pulse producing circuit 6 is supplied with the jump command signal. The 
jump pulse producing circuit 6 holds the kick pulse regardless of the zero 
cross detecting signal until the jump pulse producing circuit 6 is 
supplied with the first time out signal when the jump pulse producing 
circuit 6 is not supplied with the comparison signal. The jump pulse 
producing circuit 6 produces the brake pulse when the jump pulse producing 
circuit 6 is supplied with at least one of the zero cross detecting signal 
and the second time out signal after the kick pulse turns to the zero 
point. 
Referring to FIG. 9, the description will proceed to a track jump 
controlling unit according to a third embodiment of this invention. 
Similar parts are designated by like reference numerals. The track jump 
controlling unit comprises the photo detecting circuit 1, the tracking 
error detecting circuit 2, the phase compensating circuit 3, the zero 
cross detecting circuit 4, the jump command producing circuit 5, the jump 
pulse producing circuit 6, the controlling circuit 7, the switching 
circuit 8, the tracking actuator 9, and the level comparing circuit 27. 
The level comparing circuit 27 compares the level of the tracking error 
signal from the tracking error detecting circuit 2 with the predetermined 
reference level to produce the comparison signal when the level of the 
tracking error signal is higher than the predetermined reference level. 
The controlling circuit 7 produces the jump sequence start signal to 
supply the jump sequence start signal to the jump command producing 
circuit 5. The jump command producing circuit 5 produces the jump command 
signal when the jump command producing circuit 5 is supplied with the jump 
sequence start signal. The jump command producing circuit 5 supplies the 
jump command signal to the jump pulse producing circuit 6. 
The jump pulse producing circuit 6 produces the kick pulse when the jump 
pulse producing circuit 6 is supplied with the jump command signal. The 
jump pulse producing circuit 6 holds, in the first predetermined time 
period, the kick pulse regardless of the zero cross detecting signal when 
the jump pulse producing circuit 6 is not supplied with the comparison 
signal. The jump pulse producing circuit 6 produces the brake pulse when 
the jump pulse producing circuit 6 is supplied with the zero cross 
detecting signal after the kick pulse turns to the zero point. 
Referring to FIG. 10, the description will proceed to a track jump 
controlling unit according to a fourth embodiment of this invention. 
Similar parts are designated by like reference numerals. The track jump 
controlling unit comprises the photo detecting circuit 1, the tracking 
error detecting circuit 2, the phase compensating circuit 3, the zero 
cross detecting circuit 4, the jump command producing circuit 5, the jump 
pulse producing circuit 6, the controlling circuit 7, the switching 
circuit 8, the tracking actuator 9, and the timer 28. 
The timer 28 times the first predetermined time period from occurrence of 
the jump sequence start signal, namely, occurrence of the jump command 
signal to produce the first time out signal. Also, the timer 28 times the 
second predetermined time period from occurrence of the jump command 
signal, namely, occurrence of the jump command signal to produce the 
second time out signal. The second predetermined time period is greater 
than the first predetermined time period. 
The controlling circuit 7 produces the jump sequence start signal to supply 
the jump sequence start signal to the jump command producing circuit 5. 
The jump command producing circuit 5 produces the jump command signal when 
the jump command producing circuit 5 is supplied with the jump sequence 
start signal. The jump command producing circuit 5 supplies the jump 
command signal to the jump pulse producing circuit 6. 
The jump pulse producing circuit 6 produces the kick pulse when the jump 
pulse producing circuit 6 is supplied with the jump command signal. The 
jump pulse producing circuit 6 holds the kick pulse regardless of the zero 
cross detecting signal until the jump pulse producing circuit 6 is 
supplied with the first time out signal. The jump pulse producing circuit 
6 produces the brake pulse when the jump pulse producing circuit 6 is 
supplied with at least one of the zero cross detecting signal and the 
second time out signal after the kick pulse turns to the zero point. 
Thus, the track jump controlling units according to the embodiments of this 
invention are capable of correctly jumping the light beam spot of the 
photo pickup device from the one of the tracks to the other one of the 
tracks that is adjacent to the one of the tracks even when the photo disk 
has the flaw or the waste to be adhered to the photo disk. This is because 
the jump pulse producing circuit 6 correctly produces the kick pulse even 
when the photo disk has the flaw or the waste to be adhered to the photo 
disk.