A double-deck magnetic recording/reproducing apparatus includes first and second recording/reproducing portions for, during playback, receiving an FM video signal for a first (or second) format and a chrominance signal, and mixing an FM-modulated video signal and a converted-up chrominance signal to output a composite video signal, and, during recording, separating an input composite video signal into a video signal and a chrominance signal, FM-modulating the separated video signal, and converting down the separated chrominance signal to record the converted signal on the tape for the first (or second) format, an FM converter for receiving playback FM video signals from the first and second recording/reproducing portions and outputting a recording FM video signal in which the frequency band is converted from one format to the other format; a first switch which selectively supplies the recording FM video signal of the first recording/reproducing portion and the recording FM video signal of the FM converter to a recording head for the tape for the first format and a second switch which selectively supplies the recording FM video signal of the second recording/reproducing portion and the recording FM video signal of the FM converter to a recording head for the tape for the second format.

BACKGROUND OF THE INVENTION 
The present invention relates to a double-deck magnetic 
recording/reproducing apparatus, and more particularly, to a double-deck 
magnetic recording/reproducing apparatus which can use 8 mm- and 
VHS-format magnetic tapes in recording and reproducing. 
The ongoing miniaturization of camcorders has involved the use of both 
0.5-inch VHS-format tape and 8 mm tape. The 8 mm tape recorded with an 8 
mm camcorder cannot be reproduced by an ordinary VHS videocassette 
recorder for home use. Recently, a double-deck videocassette recorder, 
which can record/reproduce both tape types by mounting an 8 mm deck and 
VHS deck together in one set, has been introduced. 
Such a double-deck videocassette recorder is capable of copying or editing 
a video signal of the 8 mm tape or VHS tape onto the other type of tape. 
Since the recording frequency band for the 8 mm video signal is 4.2-5.4 
MHz while that for the VHS video signal is 3.4-4.4 MHz, the FM signal 
cannot be copied directly. In order to copy the FM signal, a reproduced FM 
signal of a first format is demodulated, a composite video signal is 
transmitted, and the transmitted composite video signal is modulated into 
an FM signal of a second format. 
Through this signal conversion procedure with respect to the composite 
video signal, noise is introduced and the image quality is deteriorated 
accordingly. 
SUMMARY OF THE INVENTION 
Therefore, in order to overcome such a problem, it is an object of the 
present invention to provide a double-deck magnetic recording/reproducing 
apparatus which is capable of directly copying a playback FM signal of a 
first format tape onto a second format tape. 
To accomplish the above object of the present invention, there is provided 
a double-deck magnetic recording/reproducing apparatus for 
recording/reproducing a tape for a first format and a tape for a second 
format, comprising: a first recording/reproducing portion for, during 
playback, receiving an FM video signal of a first frequency band picked up 
from the tape for the first format and a chrominance signal converted down 
into a first frequency, and mixing an FM-modulated video signal and a 
converted-up chrominance signal to output a composite video signal, and, 
during recording, separating an input composite video signal into a video 
signal and a chrominance signal, FM-modulating the separated video signal 
into the band of the first frequency, and converting down the separated 
video signal into the first frequency to record the converted signal on 
the tape for the first format; a second recording/reproducing portion for, 
during playback, receiving an FM video signal of a second frequency band 
picked up from the tape for the second format and a chrominance signal 
converted down into a second frequency, and mixing an FM-modulated video 
signal and a converted-up chrominance signal to output a composite video 
signal, and, during recording, separating an input composite video signal 
into a video signal and a chrominance signal, FM-modulating the separated 
video signal into the band of the second frequency, and converting down 
the separated video signal into the second frequency to record the 
converted signal on the tape for the second format; an FM converter for 
receiving playback FM video signals from the first and second 
recording/reproducing portions and outputting a recording FM video signal 
in which the frequency band is converted from one format received 
according to a given copying mode to the other format; first switching 
means for selectively supplying the recording FM video signal of the first 
recording/reproducing portion and the recording FM video signal of the FM 
converter to a recording head for the tape for the first format according 
to the given copying mode; and second switching means for selectively 
supplying the recording FM video signal of the second 
recording/reproducing portion and the recording FM video signal of the FM 
converter to a recording head for the tape for the second format according 
to the given copying mode.

DETAILED DESCRIPTION OF THE INVENTION 
Referring to FIG. 1, a recording/reproducing system 100 for 8 mm tape 
amplifies a signal picked up from a playback head by a playback (PB) 
amplifier 10, during playback. The amplified playback signal is equalized 
to a playback FM video signal of 4.2-5.4 MHz by an FM playback (PB) 
equalizer 12 and to a playback chrominance signal of 743 KHz by a playback 
(PB) color equalizer 14. The equalized playback FM video signal is 
demodulated in a modulator/demodulator 16 and output as a video signal. 
The equalized playback chrominance signal is converted up and output as a 
chrominance signal. The output video signal and chrominance signal are 
mixed in a Y/C mixer 20 and output as a composite video signal. 
In recording, an external composite video signal and a composite video 
signal supplied from a VHS recording/reproducing system 200 are 
selectively input by a first switch (SW1) 22. The input composite video 
signal is separated into a video signal and chrominance signal in a Y/C 
separator 24. The separated video signal is modulated in 
modulator/demodulator 16 and output as a recording FM video signal of the 
frequency band of 4.2-5.4 MHz. The separated chrominance signal is 
converted down to 743 KHz in a chrominance down/up converter 18. The 
recording FM video signal and converted-down chrominance signal are mixed 
in mixer 26, amplified in a recording (REC) amplifier 28, and recorded on 
the 8 mm tape by a recording head. 
The recording/reproducing system 200 for the VHS tape, amplifies a signal 
picked up from a playback head by a playback amplifier 30, during 
playback. The amplified playback signal is equalized to a playback FM 
video signal of 3.4-4.4 MHz by an FM equalizer 32 and to a playback 
chrominance signal of 629 KHz by a color equalizer 34. The equalized 
playback FM video signal is demodulated in a modulator/demodulator 36 and 
output as a video signal. The equalized playback chrominance signal is 
converted up in chrominance up/down converter 38 and output as a 
chrominance signal. The output video signal and chrominance signal are 
mixed in a mixer 40 and output as a composite video signal. 
In recording, an external composite video signal and a composite video 
signal supplied from 8 mm recording/reproducing system 100 are selectively 
input by a second switch (SW2) 42. The input composite video signal is 
separated into a video signal and chrominance signal in a separator 44. 
The separated video signal is modulated in modulator/demodulator 36 and 
output as a recording FM video signal of the frequency band of 3.4-4.4 
MHz. The separated chrominance signal is converted down to 629 KHz in a 
chrominance down/up converter 38. The recording FM video signal and 
converted-down chrominance signal are mixed in mixer 46, amplified in a 
recording amplifier 48, and recorded on the VHS tape by a recording head. 
In such a conventional method, the frequency characteristic of an original 
signal is deteriorated through the modulation/demodulation of the video 
signal. After being copied three or four times, the shape and edges of an 
image contour are collapsed to create white stains, resulting in a poor 
quality image. 
In order to overcome the problem, the purpose of the present invention is 
to present an apparatus for directly copying the FM signal without the 
intervening modulation or demodulation operation. 
In FIG. 2, the same components as those of FIG. 1 are numbered with the 
same numerals and the detailed description thereof will be omitted. The 
apparatus of the present invention further comprises an FM converter 300 
for receiving the playback FM video signals of a first 
recording/reproducing portion (or 8 mm recording/reproducing system) 100 
and of a second recording/reproducing portion (or VHS 
recording/reproducing system) 200 and supplying the recording FM video 
signal to first and second recording/reproducing portions 100 and 200, 
first switching means 400 for selectively supplying the recording FM video 
signal supplied from modulator/demodulator 16 of the first 
recording/reproducing portion 100 and the recording FM video signal 
supplied from the FM converter 300 to mixer 26 according to a given 
copying mode, and second switching means 500 for selectively supplying the 
recording FM video signal supplied from modulator/demodulator 36 of second 
recording/reproducing portion 200 and the recording FM video signal 
supplied from the FM converter to mixer 46. 
Referring to FIG. 3, the operating mode of FM converter 300 is determined 
in response to a control signal generated from a controller 310. The FM 
converter 300 comprises an input selection switch 312 for selectively 
receiving the playback FM video signals supplied from first and second 
recording/reproducing portions 100 and 200 according to a copying 
operation mode given from controller 310, wave-shaping means for receiving 
the selected playback FM video signal, amplifying the received signal in 
an amplifier 314, limiting the amplified signal in a limiter 316 and 
wave-shaping the limited signal in a pulse-width modulating encoder 318, 
to output a square-wave signal, a frequency detector 320 for comparing the 
frequency of the wave-shaped square wave signal with the frequency of a 
given first reference signal and detecting the frequency difference, a 
control voltage generator composed of an integrator 324, an inverter 326 
and a switch 328, for integrating the square-wave signal and thereby 
selectively generating a direct-current signal proportional to the 
frequency and a signal in which the direct-current signal is inverted 
according to the given copying mode, a frequency generator 322 for 
generating an FM video signal of a predetermined band as a second 
reference signal in response to the output signal of the frequency 
detector 320 and the control voltage signal, a reference signal generator 
composed of a first oscillator 330, a second oscillator 332 and a carrier 
generator 334, for generating a first reference signal (f0) of 3.4 MHz for 
VHS and a second reference signal (f1) of 4.2 MHz for 8 mm and alternately 
supplying the signals to the frequency detector 320 and frequency 
generator 322, according to the given copying operation mode, and an 
output circuit composed of a high-pass filter (HPF) 336, a low-pass filter 
(LPF) 338 and a buffer amplifier 340, for buffering the output of the 
frequency generator 322. 
The operation and effect of the apparatus of the present invention 
constructed as above will be explained below. 
First, in copying an 8 mm format onto a VHS tape, first 
recording/reproducing portion 100 operates in the playback mode, and 
second recording/reproducing portion 200 operates in the recording mode. 
The playback FM video signal reproduced in the first recording/reproducing 
system is supplied to FM converter 300. The chrominance signal is 
converted up through chrominance up/down converter 18 and supplied to 
second recording/reproducing portion 200 through Y/C mixer 20. The 
chrominance signal is input to separator 44 through second switch 42 of 
second recording/reproducing system 200, converted down into 629 KHz in 
chrominance up/down converter 38, and supplied to mixer 46. The playback 
FM video signal is selected through input selection switch 312 of FM 
converter 300 and wave-shaped into a square-wave signal by the 
wave-shaping means (314, 316 and 318). The square-wave signal is supplied 
to frequency detector 320 and the control voltage generating means (324, 
326 and 328). The reference signal generating means (330, 332 and 334) is 
switching-controlled to supply the 4.2 MHz reference signal to frequency 
detector 320 and the 3.4 MHz reference signal to the frequency generator 
322. Frequency detector 320 compares the input squarewave signal with the 
reference signal and generates a detection signal for activating the 
frequency generator if the frequency of the square-wave signal is greater 
than or equal to 4.2 MHz of the reference as it falls within 4.2-5.4 MHz. 
The control voltage generating means (324, 326 and 328) generates a 
control voltage proportional to the frequency of the square-wave signal. 
The frequency generator 322 generates an FM signal of 3.4-4.4 MHz which 
varies in proportion to the control voltage referenced to the 3.4 MHz 
reference signal. The generated FM signal, a recording FM video signal 
which is converted into the VHS frequency band, is high-pass-filtered and 
then low-pass-filtered, through the output means (336, 338 and 340), 
amplified to an appropriate level suitable for mixing with the chrominance 
signal, and supplied to mixer 46. 
Accordingly, the recording is performed so that the chrominance signal is 
transmitted after frequency conversion and the video signal is directly 
transmitted as an FM signal, thereby preventing the characteristic 
deterioration of a video signal. 
The case in which a VHS format is copied onto an 8 mm tape is carried out 
in a manner similar to the above. Here, the first reference signal is 3.4 
MHz and the second reference signal is 4.2 MHz. Therefore, the VHS FM 
signal is detected and then converted into an 8 mm FM signal. 
As described above, in copying both the 8 mm tape and VHS tape, the present 
invention copies a video signal directly as an FM signal without FM 
modulation/demodulation of a video signal, thereby maintaining high 
picture quality.