Tape recorder head adjusting mechanism

A tape recorder head adjusting mechanism includes a small gear wheel rotatably driven; a large gear wheel interlocking with the small gear wheel; a cam fixed to and rotated with the large gear wheel; a movable pin in contact with the cam; a head base moved back and forth by the movable pin; and a head fixed to said head base.

BACKGROUND OF THE INVENTION 
1. Field of the Invention: 
The present invention relates to a tape recorder. More particularly, it 
relates to an improvement of a head moving mechanism. 
2. Description of Prior Art: 
FIG. 1 shows the conventional head moving mechanism of a cassette tape 
recorder. A head (3) is positioned facing a tape (2) held in a cassette 
casing (1). The head (3) is secured on a head base (4) on which a movable 
pin (5) is set. A fixed pin (6) is set on a main base (10) so as to enter 
into a guide hole (7) formed in the head base (4). In this state, the head 
base (4) with the head (3) is movable in the longitudinal direction of the 
guide hole (7). The head base (4), pulled by a pair of springs (8), is 
moved towards the tape (2) until the fixed pin (6) make contact with the 
extreme end of the guide hole (7), that is, the front surface of the head 
(3) is brought into contact with the tape (2). On the other hand, when the 
head (3) is moved backwards, it is necessary to carry out two manual 
operations; the first operation for moving the head base (4) backwards via 
the movable pin (5) by a component of operational force and the second 
operation for engaging a hook (9) with a movable pin (5) after the 
completion of the first operation. Therefore, if a single manual operation 
is desired instead of the two separate operations, an additional mechanism 
must be incorporated. 
In order to add the function of taking the tape out at a portion in which 
desired data is recorded, that is, a heading function, it is necessary to 
position the head (3) at a slightly rearward position (normally, in the 
range between 1 mm and 2 mm), but should not move to the rearmost 
position. It is, therefore, in this case, necessary to provide a mechanism 
which sets the position of the head (3) at three different positions. 
However, there has not been known a mechanism for performing the operation 
described above except for the structure as shown in FIG. 1 in which two 
head moving mechanisms are provided. This structure has the disadvantages 
of making it complicated and requiring larger finger pressure in the 
manual operation. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a tape recorder 
provided with an improved head moving mechanism capable of overcoming the 
disadvantages of the conventional tape recorder. 
It is another object of the present invention to provide a tape recorder 
having a simple head moving mechanism which requires only a small manual 
operation force. 
The foregoing and other objects of the present invention have been attained 
by providing a tape recorder which comprises: a small gear wheel rotatably 
driven; a large gear wheel interlocking with said small gear wheel; a cam 
rotated with said large gear wheel in one piece; a movable pin in contact 
with said cam; a head base moved back and forth by said movable pin; and a 
head fixed to said head base. 
Briefly, the present invention is to move a movable pin by a cam which 
rotates with a large gear wheel interlocking with a small gear wheel to 
move a head base through the movement of the movable pin.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The features of the present invention will become apparent from the 
following detailed description with reference to drawings. 
FIG. 2 is a plane view of an embodiment of the present invention; FIG. 3 is 
a front view of the important portion of FIG. 2 and FIG. 4 is a schematic 
plane view for illustrating an operation of the embodiment as shown in 
FIGS. 2 and 3. 
A large gear wheel (12) is fixed to a small gear wheel (20) which is 
rotatably held by a bearing (22). The movable pin (5) extends through a 
main base (10) into a movable pin-receptive groove (13). A heading 
solenoid (14) and an eject solenoid (15) are fixedly positioned and the 
plungers of both the solenoids are respectively actuated in the pulling 
direction by a heading spring (16) and an eject spring (17). Each plunger 
of the solenoids (14), (15) is respectively connected to a heading plate 
(18) and an eject plate (19). The small gear wheel (20), rotatably driven 
by a motor (21), is so constructed as to mesh with the large gear wheel 
(12) whereby, when the small gear wheel (20) is driven by the motor (21), 
the large gear wheel (12) meshed therewith and held by the bearing (22) is 
driven. A cam (23) is fixed on the large gear wheel (12) so that the cam 
is rotated together with the large gear wheel (12). 
The operation of the embodiment of the present invention will be described 
with reference to FIG. 4. In FIG. 4, position lines (24a), (24b) and (24c) 
indicate the positions of the head (3) and the movable pin (5) in each 
mode taken by the tape recorder of the present invention wherein the 
position line (24a) corresponds to the position in the play (or recording) 
mode; the position line (24b) corresponds to the position in the heading 
mode; and the position line (24c) corresponds to the position in the eject 
(or the rapid feeding) mode. The positions of the head (3) and the movable 
pin (5) in each mode are indicated by the same reference numerals but the 
addition of characters a, b and c respectively. 
The movable pin (5) passing through the movable pin receptive groove (13) 
of the main base (10) is positioned facing the cam surface of the cam (23) 
and the head base (4) is forced forwards by the springs (8) whereby the 
movable pin (5) is kept in contact with the cam surface of the cam (23). 
When the large gear wheel (12) is rotated, the cam (23) is also rotated. 
In response to this, the movable pin (5) is moved back and forth along the 
movable pin receptive groove (13) and on the cam surface of the cam (23) 
and acccordingly, the head base (4) is also moved back and forth. In this 
state, when either the heading plate (18) or the eject plate (19) is 
brought to the projecting state, it makes contact with the peripheral 
surface of the movable pin (5), to secure the movable pin (5) at the 
predetermined position. A further specified embodiment will be described 
below. The position (3a) of the head (3) and the position (5a) of the 
movable pin (5) shown by a solid line FIG. 4 correspond to the position 
line (24a) which means that they are in the play mode. In this state, the 
movable pin (5) is in contact with the cam surface of the cam (23). When 
the large gear wheel (12) is rotated in the arrow direction (25) and the 
cam is similarly rotated, the movable pin (5) is lowered in FIG. 4 and 
returned to the original position by one revolution of the cam (23). The 
operation of the head (3) when it is positioned at the heading position 
(3b) is as follows: firstly, the cam (23) is rotated to lower the movable 
pin in FIG. 4; one revolution of the cam (23) permits the movable pin (5) 
to return to the original position (5a) by the action of springs (8), 
while just before the returning, electric conduction to the heading 
solenoid (14) is interrupted so that the heading plate (18) projects by 
the pulling force of the heading spring (16). On the other hand, the eject 
solenoid (15) is kept in an electric conductive condition so that the 
eject plate (19) remains non-projected. As soon as the lowered movable pin 
(5) returns toward the original position (5a), it makes contact with the 
heading plate (18) whereby the movable pin (5) remains in the heading 
position (5b). Thus the head (3) is at the position (3b) which corresponds 
to the heading position line (24b) and the heading mode is attained. In 
this embodiment, the cam (23) is controlled to be stopped at the 
completion of one revolution. 
The eject mode can be obtained by the following operation. The cam (23) 
again makes one revolution. Just before the completion of the revolution, 
electric conduction to the eject solenoid (15) is broken whereby the eject 
plate (19) projects to hold the movable pin (5) at the eject position 
(5c). Simultaneously, the head (3) is at the position (3c) which 
corresponds to the eject position line (24c). 
In the embodiment described above, the head (3) can be stopped at two or 
more different positions in the same manner as in the conventional tape 
recorder having a heading function by moving the head (3) by the 
revolution of the cam (2) and providing the plates (18), (19) which made 
contact with the movable pin (5) in accordance with the movement of the 
head (3). 
The feature of the present invention is that the head is moved by the cam 
and this feature can be applied to other types of tape recorders without 
the heading function or other than cassette tape recorders. 
As described above, in accordance with the present invention, a head moving 
mechanism of simple structure can be obtained and the necessity of force 
required in manual operation can be reduced because a head is moved by the 
revolution of a cam. If desired, plates making contact with a movable pin 
in accordance with the movement of the head can easily be attached. Thus, 
the head moving mechanism of the present invention can be applied to tape 
recorders such as ones having the heading function.