Tape recorder apparatus capable of playing back selected information while recording other information

Apparatus is disclosed for recording information on a tape record medium, and for playing back previously recorded information therefrom without interrupting the recording operation.

FIELD OF THE INVENTION 
The present invention relates to apparatus for recording information on a 
tape record medium and for playing back information therefrom while 
recording continues. 
DESCRIPTION RELATIVE TO THE PRIOR ART 
In a typical magnetic tape recorder, magnetic tape from a supply reel is 
transported past a recording head and wound onto a take-up reel. An 
electrical signal applied to the recording head produced a magnetic field 
in the tape that varies in field strength in a manner that is 
representative of the information contained in the electrical signal. Such 
field strength variations result in the recording of signal information on 
the magnetic tape in the form of a remanent magnetization pattern. At the 
conclusion of recording, or at such time as it is desired to play back 
previously recorded information, the magnetic tape is rewound onto the 
supply reel; thereafter it is transported past a playback head which 
senses the remanent magnetization pattern and produces an output 
electrical signal in response thereto. In some recorders, the same head is 
used for both the recording and the playing back of information. 
A recorder as described above is commonly used in applications such as 
logging incoming telephone calls to a police station. A problem arises, 
however, when it is desired to play back a previously recorded call 
because recording and playback cannot take place simultaneously. In this 
instance, one is faced with the choice of playing back a previously 
recorded call or continuing the recording of incoming calls. As a solution 
to this problem, it is common practice to use two (or more) recorders 
operating in tandem. Specifically, when it is desired to play back 
information recorded on one recorder, the second recorder takes over the 
recording function, thereby freeing the first recorder for use in playing 
back the desired information, and vice versa. 
The use of two or more recorders in such applications, however, entails 
several disadvantages. For example, because the recording function is 
switched back and forth between recorders, a chronological information 
record is not produced on the tape record medium. Instead, the resulting 
information record is comprised of two (or more) tape reels which must be 
interlaced (by mechanical splicing or electronic dubbing) to provide a 
chronological information record. A further disadvantage is the 
requirement that a plurality of recorders are required, thereby increasing 
the cost and complexity of the recording system. 
SUMMARY OF THE INVENTION 
The present invention provides apparatus for recording information on a 
tape record medium and for playing back a selected segment of previously 
recorded information without interrupting the recording of information. In 
accordance with the invention, means are provided for reversing the 
direction of tape transportation through a playback station without 
affecting the direction of tape transportation through a recording 
station. The time is then determined at which a selected segment of 
previously recorded information is in position for playback, at which time 
the direction of tape transporation through the playback station is 
returned to the forward direction. As a result, the selected segment of 
previously recorded information is played back without interrupting the 
recording of information.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIGS. 1, 2 and 3 depict recorder apparatus in accordance with a first 
embodiment of the present invention wherein previously recorded 
information can be played back without interrupting the recording 
operation. By way of overview, a tape record medium in the form of a 
magnetic tape 10 from a supply reel 12 is wound onto a take-up reel 14 
that is mounted on an arm 15 that is rotatable by means of an arm motor 44 
(see FIG. 2). The magnetic tape 10 passes through a recording station 16, 
a tape accumulator 18, a braking mechanism 20, and a playback station 22. 
Tape tension is controlled by a pair of torque motors 24 and 26 (see FIGS. 
2 and 3) connected to the supply and take-up reels 12 and 14, 
respectively. As described in more detail below, tape speed through the 
recording station 16 is controlled by a capstan drive mechanism 28, while 
a variable speed capstan drive mechanism 30 controls tape speed through 
the playback station 22 during the playback operation. 
In explaining the operation of the recorder/-playback apparatus shown in 
FIGS. 1, 2 and 3, it will be assumed, initially, that recording is to take 
place but that playback of recorded information is not desired. Magnetic 
tape 10 from the supply reel 12 is advanced by the capstan drive mechanism 
28 past a recording head 32 which records an information signal from an 
information signal source 34. At the same time a marker signal from a 
marker signal source 36 is recorded which marks the location of 
information on the magnetic tape 10. It is assumed that the information 
signal and the marker signal are recorded on the magnetic tape 10 along 
respective tracks. It will be understood, however, that these signals 
could be combined on a single track or that either or both of these 
signals could occupy a plurality of tracks. After recording, the magnetic 
tape 10 is wound onto the take-up reel 14 after passing unimpeded through 
the tape accumulator 18, the braking mechanism 20 and the playback station 
22. 
Now assume that it is desired to play back a selected segment of the 
previously recorded information signal without interrupting the recording 
operation. The playback operation is initiated by energizing a solenoid 38 
within the braking mechanism 20. Energization of the solenoid 38 causes a 
movable pad 40 to press the magnetic tape 10 against a stationary pad 42, 
thereby preventing further advancement of the tape 10 through the braking 
mechanism 20. In effect, the braking mechanism 20 serves to isolate tape 
tension between the recording station 16 and the playback station 22. The 
torque applied to the take-up reel 14 by the torque motor 26 is then 
reduced to a level just sufficient to prevent the magnetic tape 10 from 
"freely" unwinding from the take-up reel 14. Energization of the arm motor 
44 (see FIG. 2) causes the arm 15 to rotate counterclockwise (when looking 
at FIG. 1), such rotational movement being facilitated by a stationary 
guide track 46. The position of the arm 15 shortly after rotational 
movement begins is as shown in FIG. 4, wherein it is seen that the 
magnetic tape 10 is in the process of being wound around the peripheral 
wall of a drum structure 48 as the tape 10 is pulled from the take-up reel 
14. The result of winding the magnetic tape 10 around the drum structure 
48 is to reverse the direction of tape transportation through the playback 
station 22. 
As the arm 15 continues its rotational motion, a playback head 50 plays 
back (in reverse) the marker signal that was previously recorded on the 
magnetic tape 10 by the recording head 32. The played back marker signal 
is applied to a system control unit (discussed in more detail below) which 
analyzes the marker signal to determine when enough tape has been unwound 
from the take-up reel 14 to commence playback of the selected segment of 
the previously recorded information signal. To begin playback, the arm 
motor 44 is de-energized, thereby stopping rotation of the arm 15. The 
torque applied to the take-up reel 14 by the torque motor 26 is brought up 
to a level suitable to provide proper tape tension for playback, and the 
capstan drive mechanism 30 is activated by energizing a solenoid 52 which 
presses the magnetic tape 10 against a capstan drive roller 54. Finally, 
as shown in FIG. 5, playback of the desired portions of the previously 
recorded information signal commences as the arm motor 44 causes the arm 
15 to rotate in a clockwise direction, whereby magnetic tape 10 is unwound 
from the drum structure 48 and transported in the forward direction past 
the playback head 50 by the capstan drive mechanism 30. 
After the selected segment of the previously recorded information signal 
has been played back, the magnetic tape 10 which remains wound about the 
drum structure 48 is rewound onto the take-up reel 14 by speeding the rate 
at which the arm 14 rotates in the clockwise direction while concomitantly 
increasing the speed of the capstan drive mechanism 30. When the magnetic 
tape 10 wrapped around the drum structure 48 has been rewound onto the 
take-up reel 14, and the arm 15 reaches its initial position (as sensed by 
an arm position sensor 49 shown in FIG. 2), the brake mechanism 20 is 
deactivated by de-energizing the solenoid 38. As a result, magnetic tape 
10 which has accumulated in an accumulator bin 55 (see FIGS. 4 and 5) 
during the playback operation is quickly wound onto the take-up reel 14. 
To minimize the jolt experienced by the magnetic tape 10 as the last of 
the tape 10 is removed from the accumulator bin 55, the speed of the 
capstan drive mechanism 30 is gradually reduced so that at the end of the 
rewind operation the speed of the capstan drive mechanism 30 is equal to 
the speed of the capstan drive mechanism 28. The capstan drive mechanism 
30 is then deactivated by de-energizing the solenoid 52, the torque 
applied to the take-up reel 14 by the torque motor 26 being returned to 
its original level. At this point, the recorder/playback apparatus has 
been returned to the state shown in FIG. 1. 
The circuitry for controlling the various functions described above is 
shown in block schematic form in FIG. 6. A system control unit receives a 
request to play back a selected segment of the previously recorded 
information signal (as identified by the marker signal). Based on this 
request and information from the played back marker signal and the signal 
output of the arm position sensor (49), the system control unit supplied 
output signals which control the operation of the supply and take-up reel 
torque motors (24, 26), the capstan drive mechanisms (28, 30), the arm 
motor (44), the playback capstan solenoid (52), and the braking mechanism 
solenoid (38). A flow chart showing the logic flow of the system control 
unit (and which summarizes the above-discussed functions) is shown in 
FIGS. 7A and 7B. 
In accordance with a variation of the embodiment of the invention described 
above with reference to FIGS. 1 through 7B, the arm 15 is held stationary 
throughout the recording and playback operation while the drum structure 
48 (and apparatus mounted thereto) is rotated to unwind magnetic tape 10 
from the playback reel 14. In accordance with this variation, when the arm 
motor 44 is energized, its shaft, which is affixed to the arm 15, remains 
stationary while the housing of the motor 44 rotates, thereby producing 
the desired rotation of the drum structure 48. In other respects, the 
recording and playback operations are as described above. 
FIG. 8 shows another embodiment of the invention wherein a loop accumulator 
21 is provided on the arm 15 to unwind magnetic tape 10 from the take-up 
reel 14 during the playback operation. As a result, both the arm 15 and 
the drum structure 48 remain stationary throughout the recording and 
playback processes. Operation of the embodiment shown in FIG. 8 is similar 
to the operation of the embodiment shown in FIGS. 1 through 7B (compare 
FIGS. 1 and 8), with the exception that the loop accumulator 21 is 
energized instead of the arm motor 44. During recording with no playback 
requested, therefore, the path of the magnetic tape 10 is as shown in FIG. 
8 by the solid line depiction of tape 10. During the playback operation, 
however, magnetic tape 10 is unwound from the take-up reel 14 by the loop 
accumulator 21, and the magnetic tape 10 assumes the path represented by 
the broken line 10'. In all other respects, the recording and playback 
operations proceed as previously discussed in connection with FIGS. 1 
through 7B. 
The invention has been described in detail with particular reference to 
certain preferred embodiments thereof, but it will be understood that 
variations and modifications can be effected within the spirit and scope 
of the invention. For example, it will be apparent to those skilled in the 
art that the drum structure need not be cylindrical in shape as shown in 
the Figures, but may assume other shapes depending upon the specific 
application.