Signal reproducing apparatus having means for modifying a pre-recorded control signal

A signal recording and/or reproducing system is provided in a recording and/or reproducing apparatus having a control head for performing recording and/or reproduction of a control signal with respect to a control track on a tape, and a control circuit supplied and controlled by a reproduced control signal. The signal recording and/or reproducing system comprises a switching circuit for only passing signal parts in a signal reproduced by the control head which are required in the control circuit for control, a circuit for obtaining a signal which has passed through the switching circuit as a reproduced control signal and supplying this reproduced control signal to the control head, a modifying circuit for modifying signal parts recorded on the control track other than the signal parts required in the control circuit for control, and a discriminating circuit for discriminating signal parts within a reproduced signal obtained by reproducing the control track by the control head which are modified by the modifying circuit, to produce a discrimination signal.

BACKGROUND OF THE INVENTION 
The present invention generally relates to signal recording and/or 
reproducing systems, and more particularly to a signal recording and/or 
reproducing system in which a signal within a signal part recorded on a 
control track on a tape and reproduced to be used as a control signal is 
modified or a new signal is added within the above signal part in order to 
add another signal information, so that this other signal information can 
be utilized upon reproduction. 
Generally, a broadcasted television program such as a movie, drama, and 
concert is recorded onto a cassette tape by use of a video signal magnetic 
recording and reproducing apparatus for home use (so-called video tape 
recorder, and hereinafter simply referred to as a VTR). These recorded 
television programs are collected to form a library of programs. When 
recording or reproducing the above television programs, the operator 
usually does not want to record or reproduce unwanted parts such as 
commercials which are broadcasted during these television programs. 
If the operator of the VTR decides not to record the above unwanted part 
within the television program, the operator must monitor the picture 
screen of a television receiver and manipulate a pause-switch during an 
interval in which the unwanted part exists. When the pause-switch is 
manipulated, the tape travel is temporarily stopped to discontinue the 
recording. Accordingly, the unwanted part of the program is prevented from 
being recorded. When the desired program starts, the operator performs an 
operation to resume the recording operation. However, the above described 
operations are troublesome to perform. In addition, there was a 
disadvantage in that the operator must stay with the VTR and monitor the 
program during the recording. 
When the above described operation to discontinue the recording operation 
selectively is not performed, or when a so-called timer recording is 
performed to record a desired program between two preset times, the above 
unwanted parts are unavoidably recorded onto the tape. Hence, if the above 
unwanted parts are to be eliminated after the recording, it is necessary 
to perform dubbing in order to edit the recorded program. Furthermore, the 
above unwanted parts are not solely introduced with respect to the 
broadcasted television programs. Even when a signal picked up by a 
television camera is recorded onto the tape by the VTR, the unwanted parts 
often appear when the signal is reproduced. In this case, the above 
dubbing must be performed to similarly edit the signal and eliminate the 
unwanted parts. However, it is troublesome and time consuming to perform 
dubbing in order to edit the program and the like. Moreover, there was a 
disadvantage in that expensive editing devices were required to perform 
the above editing. 
In each of the above described conventional examples, the above unwanted 
program parts are not recorded on the magnetic tape which is finally 
obtained. Therefore, there was another disadvantage in that it was 
impossible to reproduce these unwanted program parts even when the need 
arises. 
SUMMARY OF THE INVENTION 
Accordingly, it is a general object of the present invention to provide a 
novel and useful signal recording and/or reproducing system in which the 
above described disadvantages have been overcome. 
Another and more specific object of the present invention is to provide a 
signal recording and/or reproducing system in which a signal within a 
signal part recorded on a control track on a tape and reproduced to be 
used as a control signal is modified or a new signal is added within the 
above signal part in order to add another signal information, so that this 
other signal information can be utilized upon reproduction. According to 
the system of the present invention, the signal information is added by 
use of the control track which is conventionally used for the recording 
and reproduction of the control signal. Hence, it is unnecessary to 
provide an additional track and an additional head for recording and 
reproducing this additional track. Therefore, the tape utilization 
efficiency is high, and the construction of the recording and/or 
reproducing apparatus does not become complex. 
Still another object of the present invention is to provide a signal 
recording and/or reproducing system in which parts other than signal parts 
within the normal control signal recorded upon recording of the video 
signal and used for control are modified, and the modified parts are used 
for performing an operation other than normal reproduction such as a 
fast-forward operation when the modified parts are reproduced. 
Another object of the present invention is to provide a signal recording 
and/or reproducing system in which a fast-forward operation is performed 
with respect to the unwanted parts within the program recorded on the 
magnetic tape, to automatically perform an operation in which the unwanted 
parts are essentially not reproduced and only the desired parts of the 
program are reproduced, by reproducing the above modified signal parts. 
According to the system of the present invention, it is unnecessary to 
perform an operation to discontinue the recording upon recording or 
perform a dubbing operation to edit the program containing unwanted parts 
after the recording, as in the conventional case. In the system according 
to the present invention, the whole program is recorded, and a simple 
signal processing is performed after the recording to add a second control 
signal. Hence, the unwanted parts can essentially be skipped during 
reproduction. 
Other objects and further features of the present invention will be 
apparent from the following detailed description when read in conjunction 
with the accompanying drawings.

DETAILED DESCRIPTION 
In FIG. 1, an output terminal of a 1/2 power source voltage supplying 
circuit 11 is connected to one terminal of a control head 12 and also to a 
non-inverting input terminal of a differential amplifier 13. The control 
head 12 performs recording and reproduction of a control signal with 
respect to a control track on a magnetic tape 10. Another terminal of the 
control head 12 is connected to an input side of an electronic switch 14 
and to output sides of electronic switches 26 and 27. The output side of 
the electronic switch 14 is connected to an inverting input terminal of 
the above differential amplifier 13. An output terminal of the 
differential amplifier 13 is connected to input terminals of an inverting 
amplifier 15 and a non-inverting amplifier 16. Output terminals of the 
inverting amplifier 15 and the non-inverting amplifier 16 are respectively 
connected to an input terminal of a peak detecting and comparing circuit 
17. An output terminal of this peak detecting and comparing circuit 17 is 
connected to an input side of an electronic switch 18. The output terminal 
of the inverting amplifier 15 is also connected to a reproduced control 
signal output terminal 30 and to an input terminal of a positive pulse 
detector 19. 
On the other hand, a logic circuit 25 has four electronic switch control 
signal output terminals. These output terminals are respectively connected 
to control signal input terminals of the electronic switches 14, 18, 26, 
and 27. An output terminal of the positive pulse detector 19 is connected 
to input terminals of a monostable multivibrator 20 for gating and a 
monostable multivibrator 21 for waveform generation. An output terminal of 
the monostable multivibrator 20 is connected to one input terminal of the 
above logic circuit 25. An output terminal of the monostable multivibrator 
21 is connected to input terminals of a triangular wave generator 23 and a 
sawtooth wave generator 24, respectively, through an inverter 22. Output 
terminals of the triangular wave generator 23 and the sawtooth wave 
generator 24 are respectively connected to the input sides of the 
electronic switches 26 and 27. The above logic circuit 25 is connected to 
a indicator and switch part 28. 
A recording control signal input terminal 29 is connected to the above 
other terminal of the control head 12. An output side of the electronic 
switch 18 is connected to a fast-forward control signal output terminal 
31. 
An embodiment of a concrete circuit of the above block system is shown in 
FIG. 2. In FIG. 2, those parts which are the same as those corresponding 
parts in FIG. 1 are designated by the same reference numerals, and their 
description will be omitted. The 1/2 power source voltage supplying 
circuit 11 comprises a resistor R3 connected to a terminal 41 which is 
applied with a voltage of 12 volts, a resistor R4 connected to a ground 
terminal 42, capacitors C2 and C3, and an operational amplifier 43. The 
differential amplifier 13 comprises resistors R5 through R7, and R42, 
capacitors C4 and C15, and an operational amplifier 44. The inverting 
amplifier 15 comprises resistors R8 through R10, and an operational 
amplifier 45. The non-inverting amplifier 16 comprises resistors R11 
through R13, and an operational amplifier 46. The peak detecting and 
comparing circuit 17 comprises resistors R14, R15, and R41, capacitors C5 
through C7, diodes D1 and D2, and an operational amplifier 47. The 
positive pulse detector 19 comprises resistors R16 through R18, a 
capacitor C8, and a transistor X1. The triangular wave generator 23 
comprises resistors R21 through R23, a capacitor C11, a diode D3, a 
transistor X2, and an electronic switch 48. The sawtooth wave generator 24 
comprises resistors R26 through R29, a capacitor C12, and a transistor X3. 
The logic circuit 25 comprises resistors R31 through R40, diodes D6 
through D11, and inverters 49 through 52. 
During a normal recording mode, a video signal recorded onto the magnetic 
tape 10 by rotary heads (not shown), and the circuits in FIGS. 1 and 2 are 
put into a control signal recording mode. A recording control signal 
indicated in FIG. 3(A) which is obtained from the terminal 29, is applied 
to the control head 12 through the capacitor C1 and the resistor R1, to 
record the control signal on a control track on the magnetic tape 10. The 
waveform of the above recording control signal is the same as that used 
conventionally. Since the other circuit system parts in FIGS. 1 and 2 are 
cut off from the power source except during a reproducing mode, the 
circuit system parts do not operate during the recording mode. 
Accordingly, an output signal from the terminal 30 remains at low level as 
indicated in FIG. 3(B). 
Next, during a normal reproduction mode, the circuit system parts in FIGS. 
1 and 2 are also put into a control signal reproducing mode. In this mode, 
switches 32, 33, and 34 in the indicator and switch part 28 are all in the 
OFF state, and indicator elements 32a, 33a, and 34a are not lit. The 
circuit operation is the same as in the conventional servo circuit during 
this mode. 
The .kappa. power source voltage supplying circuit 11 supplies a voltage of 
relatively low impedance, namely Vcc/2 which is 1/2 the power source 
voltage Vcc, to the terminal of the control head 12 which was 
conventionally grounded. Hence, the voltage applied to terminals of the 
capacitor C4 does not vary when the electronic switch 14 is turned ON or 
OFF. Thus, the switching noise can be reduced to a minimum. 
The control signal is reproduced from the control on the magnetic tape 10, 
by the control head 12. This reproduced control signal has a waveform 
indicated in FIG. 4(A), which can be obtained by differentiating the 
recording control signal indicated in FIG. 3(A). The reproduced control 
signal comprises positive (positive polarity) and negative (negative 
polarity) pulses respectively corresponding to the rise and fall in the 
waveform of the recording control signal. The electronic switch 14 is 
supplied with a switch control signal of high level indicated in FIG. 4(B) 
from the logic circuit 25, and is turned ON, that is, the electronic 
switch 14 is closed. The electronic switches 18, 26, and 27 are turned 
OFF. The above reproduced control signal is supplied to the differential 
amplifier 13 through the electronic switch 14. An output signal of the 
differential amplifier 13 having a waveform indicated in FIG. 4(C) is 
supplied to the inverting amplifier 15 wherein the phase of this output 
signal is inverted and the signal is amplified. Thus, a signal having a 
waveform indicated in FIG. 4(D) is obtained from the inverting amplifier 
15. On the other hand, the output signal of the differential amplifier 13 
is amplified without its phase being inverted, at the non-inverting 
amplifier 16. The above output signal of the inverting amplifier 15 is 
obtained as a reproduced control signal through the terminal 30. This 
reproduced control signal is supplied to a capstan servo circuit 100 which 
controls a capstan motor 101 and used as a control signal. In this case, 
positive and negative pulses such as those indicated in FIG. 4(D) are 
supplied to the servo circuit, however, only the positive pulses are 
actually used in the servo circuit in order to perform the control 
operation. 
Because the electronic switches 18, 26, and 27 are turned OFF (opened) by 
the logic circuit 25, a signal is not obtained from the terminal 31. Thus, 
a signal is not supplied to the control head 12 through the electronic 
switches 26 and 27. 
Next, description will be given with respect to a modifying mode in which a 
part of the control signal recorded on the control track on the magnetic 
tape 10 is modified in accordance with an unwanted program signal part 
which essentially does not need to be reproduced. 
During this mode, the switches 32 and 34 in the indicator and switch part 
28 remain in the OFF state, and the switch 33 is turned ON. This switch 33 
is maintained in the ON state for the duration of the above unwanted 
program signal part. Hence, among the indicator elements 32a through 34a 
comprising light-emitting diodes, only the indicator element 33a is lit to 
indicate that the system is in a control signal modifying mode. A switch 
control signal indicated in FIG. 5(A) is applied to the electronic switch 
14 from the logic circuit 25, and the electronic switch 14 is turned ON 
during the high-level period of the switch control signal and turned OFF 
during the low-level period of the switch control signal. Accordingly, if 
the time interval of the control signal is designated by T, the electronic 
switch 14 is turned ON during the interval of 0.1T in which the positive 
pulse exists, and turned OFF during an interval of approximately 0.9T 
thereafter. Therefore, only the positive pulses in the control signal 
reproduced by the control head 12 passes through the electronic switch 14. 
Hence, an output indicated in FIG. 5(B) is obtained from the differential 
amplifier 13, and an output indicated in FIG. 5(C) is obtained from the 
inverting amplifier 15. 
The output reproduced control signal of the inverting amplifier 15 is 
obtained through the terminal 30, and supplied to the capstan servo 
circuit 100 to control the operation of the capstan servo circuit 100. In 
this case, the negative pulses such as those in the reproduced control 
signal indicated in FIG. 4(D) is not supplied to the capstan servo circuit 
100. However, no problems are introduced, since only the positive pulses 
in the reproduced control signal contribute to the servo control 
operation, and the negative pulses do not contribute to the servo control 
operation. 
In the differential amplifier 13 shown in FIG. 2, the resistor R7 and the 
capacitor C15 construct a lowpass filter. This lowpass filter acts to 
reduce the pulse noise such as switching noise which is generated when the 
electronic switch 14 is opened and closed. 
The reproduced control signal from the inverting amplifier 15 which has the 
waveform indicated in FIG. 5(C), is also supplied to the positive pulse 
detector 19. Because this reproduced control signal solely consists of 
positive pulses, detection is accordingly performed. A detected outut 
indicated in FIG. 5(D) is obtained from the positive pulse detector 19. 
The output signal of the detector 19 is supplied to the monostable 
multivibrator 20 for gating. A gating signal obtained from the monostable 
multivibrator 20 having a waveform indicated in FIG. 5(E), is supplied to 
the logic circuit 25. As indicated in FIG. 5(E), the output signal of the 
monostable multivibrator 20 becomes of low level in response to a rise in 
the output signal of the detector 19, and this low level is maintained for 
an interval (0.9T) determined by a time constant obtained from the 
capacitor C9 and the resistor R19. Because the output of the monostable 
multivibrator 20 is supplied to the logic circuit 25 as a gating signal, 
the above switch control signal indicated in FIG. 5(A) is supplied to the 
electronic switch 14 from the logic circuit 25. 
On the other hand, the output signal of the detector 19 is also supplied to 
the monostable multivibrator 21 for waveform generation. An output having 
a waveform indicated in FIG. 5(F) is accordingly obtained from the 
monostable multivibrator 21. The time constant of the interval during 
which the above output signal is of low level, is approximately 0.6T. This 
output is inverted at the inverter 22, and supplied to the triangular wave 
generator 23 and the sawtooth wave generator 24, as a signal having a 
waveform indicated in FIG. 5(G). A triangular wave having a waveform 
indicated in FIG. 5(H) in which the lower end of the waveform is 1/2 the 
power source voltage, is generated by operations of a 1/2 power source 
voltage generating part constructed from the resistors R24 and R25 and the 
capacitor 13, and an integrating circuit constructed from the resistors 
R21 and R22 and the capacitor C11 within the triangular wave generator 23. 
This triangular wave is obtained after being subjected to impedance 
conversion at the transistor X2. In the triangular wave generator 23, a 
circuit comprising the diode D3 and the electronic switch 48 forcibly 
restricts the voltage so that a voltage over 1/2 the power source voltage 
is not supplied to the electronic switch 26 when the electronic switch 14 
is in the ON state, due to errors in the circuit time constant, 
temperature variation, variation with respect to time, and the like. This 
circuit may be omitted. 
During this signal modifying mode, the electronic switch 26 is turned ON 
while the electronic switches 27 and 18 are turned OFF, by the switch 
control signals from the logic circuit 25. Accordingly, the triangular 
wave indicated in FIG. 5(H) which is obtained from the triangular wave 
generator 23, is applied to the control head 12 through the electronic 
switch 26. Because the electronic switch 27 is turned OFF, a signal 
applied to the control head 12 has a triangular waveform as the signal 
indicated in FIG. 5(H), as indicated in FIG. 5(J). When this signal 
indicated in FIG. 5(J) is applied to the control head 12, parts in the 
control signal recorded on the control track on the tape 10 corresponding 
to parts other than the positive pulses are subjected to DC-erasure. 
Hence, the negative pulses are erased, and as a result, the control signal 
is modified. When the interval in which the signal having the waveform 
indicated in FIG. 5(J) is applied to the control head 12 to erase the 
negative pulses and modify the control signal as described above is 
reproduced again in a latter mode, a signal having a waveform indicated in 
FIG. 5(L) is accordingly reproduced. The negative pulses do not exist 
during this interval. The triangular wave is used to erase the negative 
pulses, so that the pulse noise do not remain due to the rapid change in 
the waveform. The triangular wave is suited for the erasing of the 
negative pulses, since the level of the triangular wave gradually changes 
and does not comprise rapidly changing parts. 
The above described operation is performed during an interval in which an 
unwanted part (a commercial, for example) which essentially do not need to 
be reproduced exists within the program recorded onto the tape 10. During 
this interval, a part of the control signal recorded on the control track 
on the tape corresponding to the part which essentially do not need to be 
reproduced is modified, and the negative pulses are accordingly erased and 
eliminated. 
The logic circuit 25 shown in FIG. 2 is constructed so that, when the 
switch 34 is erroneously turned ON together with the switch 33, the switch 
33 has priority over the switch 34 and only the switch 33 is turned ON. 
Next, description will be given with respect to the operation during a 
reproducing mode in which the above processed signal is reproduced from 
the tape 10. During this mode, the switch 32 in the indicator and switch 
part 28 is turned ON, and the switches 33 and 34 are turned OFF. In this 
state, the indicator element 32a is lit to indicate that the system is in 
a partially omitting reproducing mode. Furthermore, the electronic 
switches 14 and 18 are turned ON and the electronic switches 26 and 27 are 
turned OFF, by the switch control signals from the logic circuit 25. The 
signal reproduced by the control head 12 is supplied to the differential 
amplifier 13 through the electronic switch 14. 
When reproduction is performed with respect to the part which is not 
subjected to the above signal modification, a control signal indicated in 
FIG. 6(A) comprising positive and negative pulses is reproduced by the 
control head 12. The signal indicated in FIG. 6(A) is the same as the 
signal indicated in FIG. 4(A). Signals having waveforms respectively 
indicated in FIGS. 6(B) and 6(C), are respectively obtained from the 
inverting amplifier 15 and the non-inverting amplifier 16. The gain 
(amplification) of the non-inverting amplifier 16 is set to a value larger 
than the gain (amplification) of the inverting amplifier 15. Thus, an 
amplitude P1 of the output signal of the inverting amplifier 15 is smaller 
than an amplitude P2 of the output signal of the non-inverting amplifier 
16. Accordingly, the output of the peak detecting and comparing circuit 17 
which detects and compares the peaks of the output signals supplied from 
the amplifiers 15 and 16, remains at low level as indicated in FIG. 6(D). 
The signal at the terminal 31 thus remains at low level as indicated in 
FIG. 6(E). Therefore, the VTR continues to be in the normal reproduction 
mode. 
Next, when the signal part which is modified in the above described manner 
is reproduced, the signal reproduced by the control head 12 has a waveform 
indicated in FIG. 7(A). As seen in FIG. 7(A), the negative pulses are 
eliminated and only the positive pulses exist in this signal. Accordingly, 
the output signal of the inverting amplifier 15 becomes as indicated in 
FIG. 7(B), comprising only the positive pulses and having an amplitude P3. 
On the other hand, the output signal of the non-inverting amplifier 16 
becomes as indicated in FIG. 7(C). This output signal of the non-inverting 
amplifier 16 does not have any positive pulses, except for parts which 
correspond to traces of the above eliminated negative pulses and having an 
amplitude P4. Hence, between the signals supplied to the peak detecting 
and comparing circuit 17, the amplitude P3 of the output signal of the 
inverting amplifier 15 is larger than the amplitude P4 of the output 
signal of the non-inverting amplifier 16. The output signal of the peak 
detecting and comparing circuit 17 thus becomes of high level as indicated 
in FIG. 7(D). Therefore, the high-level signal indicated in FIG. 7(E) is 
supplied to the terminal 31 through the electronic switch 18 which is in 
the ON state, and this high-level signal is then supplied to a circuit in 
a succeeding stage of the VTR as a fast-forward control signal. 
By the known construction of the VTR, the VTR is put into the fast-forward 
mode, and the speed of the tape travel is increased to twenty times the 
tape speed upon normal reproduction, for example. During this fast-forward 
mode, it only takes about ten seconds to forward the tape which usually 
takes three minutes to reproduce upon normal reproduction. Hence, the 
modified signal part corresponding to the unwanted signal part which does 
not need to be reproduced is essentially not reproduced, and this part is 
passed within an exceedingly short period of time. When a part which is 
not subjected to the signal modification is reached, that is, when the 
control signal indicated in FIG. 6(A) is reproduced, the VTR again returns 
to the normal reproduction mode. 
During the above fast-forward mode, a time interval t of the reproduced 
positive pulses becomes small and the frequency of the reproduced positive 
pulses becomes high, since the tape speed is increased. The amplitudes P3 
and P4 accordingly increase, however, the above fast-forward mode is 
maintained until a negative pulse is reproduced, because the relation 
P3&gt;P4 does not change. Muting may be performed with respect to the 
reproducing systems for the video signal and the audio signal by using the 
signal obtained from the terminal 31, during the above fast-forward mode. 
In a state where the above mode is obtained by turning the switch 32 ON, 
the logic circuit 25 shown in FIG. 2 is constructed so that this state is 
maintained regardless of whether one or both the other switches 33 and 34 
are erroneously turned ON. 
There are cases where the above described signal modification is performed 
with respect to the part of the control signal corresponding to the part 
which was originally considered as having no need to be reproduced, and 
the operator of the VTR later decides to reproduce this part. In such a 
case, the modified signal part is restored to its original state by 
performing the following operations. For this mode, the switches 32 and 33 
are turned OFF and the switch 34 is turned ON. By these operations, the 
indicator element 34a is lit to indicate that the system is in a signal 
restoring mode. Moreover, the electronic switches 18 and 26 are turned OFF 
and the electronic switch 27 is turned ON by the switch control signals 
from the logic circuit 25. The electronic switch 14 is applied with the 
same gate control signal indicated in FIG. 5(A) as in the above described 
signal modifying mode. Thus, the electronic switch 14 is turned ON during 
a short interval including the positive pulse, and is turned OFF during 
other intervals. The relationship between the ON and OFF states of the 
electronic switches 26 and 27, is reversed during the above signal 
modifying mode and the signal restoring mode. 
Similarly as in the above signal modifying mode, the output of the 
monostable multivibrator 21 having the waveform indicated in FIG. 5(F), is 
supplied to the triangular wave generator 23 and the sawtooth wave 
generator 24 through the inverter 22, as a signal having the waveform 
indicated in FIG. 5(G). Because the electronic switch 26 is in the OFF 
state, the output of the triangular wave generator 23 is not supplied to 
the control head 12. 
On the other hand, a sawtooth wave indicated in FIG. 5(I) is obtained from 
the sawtooth wave generator 24, and this sawtooth wave is applied to the 
control head 12 through the electronic switch 27, as a signal having a 
waveform indicated in FIG. 5(K). As clearly seen from FIG. 2, this 
sawtooth wave generator 24 is basically a differential circuit. By the 
function of the diode D5 connected between the sawtooth wave generator 24 
and the electronic switch 27 in the reverse direction, the negative pulse 
parts lower than 1/2 the power source voltage are accordingly obtained. 
Because the rise in the above sawtooth wave is sharp, the negative pulses 
are generated and then recorded onto the control track on the tape 10 by 
the control head 12. Hence, negative pulses indicated in FIG. 5(M) are 
additionally recorded onto a signal indicated in FIG. 5(L) which is 
subjected to signal modification and the negative pulses are eliminated, 
to restore and obtain the original control signal. In the present 
embodiment of the invention, the negative pulses are restored at positions 
avoiding the positions where the negative pulses originally existed and 
traces of the eliminated negative pulses exist. Accordingly, when normal 
reproduction is afterwards performed with respect to such restored part, 
normal reproduction is correctly performed without putting the system into 
a fast-forward mode. Hence, unlike in the case where unwanted part is cut 
and edited, it is possible to again reproduce the part which was 
originally considered as having no need to be reproduced. By performing 
the above described signal modification process and the signal restoring 
process, it becomes possible to arbitrarily and essentially not reproduce 
the unwanted signal part and reproduce the unwanted part when the need 
arises. 
A circuit such as the circuit comprising the diode D3 and the electronic 
switch 48, can similarly be provided in the sawtooth wave generator 24 as 
in the case of the triangular wave generator 23. However, in the present 
embodiment of the invention, such a circuit has been omitted in the 
sawtooth wave generator 24. 
In the above described embodiment, discrimination between normally 
reproducing part and fast-forwarding part is performed by the existence or 
non-existence of the negative pulses. However, the method of 
discrimination is not limited to this method. For example, the above 
discrimination may be performed according to the number of existing 
negative pulses, or by varying the position of the negative pulses. 
Furthermore, instead of inserting a fast-forward mode information signal 
in the signal parts other than the signal parts where the positive pulses 
exist, a cue signal may be inserted to put the system into other 
operational modes. Other information signal such as a signal indicating 
the date may be inserted. The principle concept of the present invention 
is to utilize signal parts other than the signal parts originally used for 
control within the control track, for recording and reproduction of other 
information signals. 
Further, the present invention is not limited to these embodiments, but 
various variations and modifications may be made without departing from 
the scope of the present invention.