Cassette loading device

Disclosed is a magnetic recording/reproducing apparatus including a cassette door openably provided at a cassette port, and a cassette loading mechanism for conveying a cassette between a cassette inserted position and a cassette loaded position. This apparatus further includes a means for detecting the opening of the door of the cassette port; and a control means for starting a cassette unloading operation only if it has been detected by the means for detecting the opening of the door that the door is closed when a cassette unloading trigger button for starting the cassette unloading operation is operated after the cassette has been inserted or loaded.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a cassette loading device for a magnetic 
recording and/or reproducing apparatus having recording or reproducing 
function, such as a video tape recorder for domestic use. More 
specifically, the present invention pertains to a cassette loading device 
of a motor driving type, i.e., a cassette loading device of a front 
loading type, in which a cassette holder for holding a cassette is moved 
in horizontal and vertical directions by utilizing the driving force of a 
motor, i.e., the cassette holder is first moved in the horizontal 
direction and then in the vertical direction. 
2. Description of the Prior Art 
In such a cassette loading device of a front loading type, after the 
cassette has been loaded in the cassette loading device, a cassette 
unloading trigger button for unloading the cassette from the cassette 
loading device may be erroneously pressed by a user in a state wherein his 
or her fingers are being inserted through a cassette port of the cassette 
loading device. In that case, the fingers are caught between the cassette 
and a cassette door. 
Accordingly, it has been proposed not to open the cassette door provided at 
the front portion of the cassette port when a foreign matter other than 
the cassette is inserted. However, such a device is effective only when 
the cassette door is closed, and is ineffective for a case wherein the 
cassette door has been opened by inserting the cassette and then the 
fingers into the cassette port. The device of this type is disclosed in, 
for example, in the specification of Japanese Patent Laid-Open No. 
61-206992. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a cassette loading device 
which can obviate the above-described problem of the prior art and which 
is safe to a user. 
To this end, the present invention provides a cassette loading device which 
includes a means for starting a cassette unloading operation only if the 
door of a cassette port is closed when a cassette unloading trigger button 
is pressed after a cassette has been inserted or loaded. More 
specifically, the cassette loading device of this invention includes a 
means for detecting the opening/closing of the door of the cassette port. 
Therefore, when the cassette unloading trigger button is pressed after the 
cassette has been inserted or loaded, the cassette unloading operation is 
started only if it has been detected that the door of the cassette port is 
closed. 
Thus, when the cassette unloading trigger button is pressed after the 
cassette has been inserted or loaded, a cassette unloading operation is 
started, according to the present invention, only if the door of the 
cassette port has been closed. In consequence, even if the cassette 
unloading trigger button is pressed with a hand being inserted through the 
cassette port, the hand is not caught by a cassette which is to be 
unloaded.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Embodiments of the present invention will be hereinunder described in 
detail with reference to the accompanying drawings. Referring first to 
FIG. 1 which is a perspective view showing a state wherein a cassette is 
inserted into a cassette port of a video tape recorder, FIG. 2 which is a 
perspective view of a cassette loading device including a cassette loading 
mechanism, and FIGS. 3, 4, 5 and 6 which are cross-sectional views 
illustrating the operation of the cassette loading mechanism of FIG. 2, a 
cassette loading mechanism 5 includes a cassette holder 6 which is 
disposed between a right side bracket 21 and a left side bracket 31 and 
which is supported through guide slots 21a and 21b formed in the right 
side bracket 21 and guide slots 31a and 31b formed in the left side 
bracket 31. The cassette loading mechanism 5 also includes a motor 7 
specifically used to front-load a cassette. Power of the motor 7 is 
transmitted to a gear 42 through a worm 41 rotated together with the motor 
7, then to a gear 43. A plate-like projecting member 44 with an elongated 
slot 44a formed therein is fixed to the rotary shaft of the gear 43, and a 
cassette holder supporter 45a is caused to pass through the elongated slot 
44a after it has passed through the guide slot 21a formed in the right 
side bracket 21. A cassette holder supporter 45b is passed through the 
guide slot 21b. A cassette guide frame 8 (front holder) is mounted on the 
right and left brackets 21 and 31. 
When a cassette 1 is loaded into the cassette holder 6 through a cassette 
port 4 from a direction indicated by the arrow in FIG. 2, the gear 43 is 
rotated clockwise through the plate-like projecting member 44 by the 
supporter 45a of a moving cassette holder 6, as shown in FIG. 4. This 
causes an arm 47 to be turned counterclockwise about a shaft 49 provided 
on the right side bracket 21 along a cam 43a provided on the gear 43 so as 
to turn on a detecting switch 15 by a forward end 47a of the arm 47. The 
detecting switch 15 serves to detect that the cassette 1 has been loaded 
at a predetermined position. This in turns causes the motor 7 of the 
cassette loading mechanism 5 to be actuated The driving force of the motor 
7 is transmitted to the gear 43 through the worm 41 and the gear 42, 42'. 
As the gear 43 is rotated clockwise, the plate-like projecting member 44 
pivots in the same direction. As a result the cassette holder 6 receives 
the rightward force from the plate-like projecting member 44, and is 
carried inward horizontally while being guided by the guide slots 21a, 
21b, 31a, and 31b in a state wherein it is loading the cassette 1. After 
it has moved through a predetermined distance in the horizontal direction, 
the cassette holder 6 is conveyed downward in the vertical direction while 
being guided by the vertical portions of the guide slots 21a, 21b, 31a, 
and 31b. During this time, an arm 48 is turned counterclockwise about the 
shaft 49 along a cam 43b provided on the gear 43 so as to turn on a 
detection switch 16 by a forward end 48a thereto. This stops the operation 
of the cassette loading mechanism 5 which has moved the cassette 1 through 
positions shown in FIGS. 3 and 4 to a position shown in FIG. 5. 
When the cassette 1 has been loaded at a predetermined position in the 
manner described above a tape loading mechanism (not shown) of a video 
tape recorder is actuated in the known manner so as to draw a magnetic 
tape (not shown) from the cassette 1 and wind it around a cylinder (not 
shown) on which a recording and reproducing head is loaded before 
recording is performed on the magnetic tape or reproduction is performed 
therefrom. 
In such a cassette loading device, if a cassette unloading button 3 shown 
in FIG. 1 is pressed by mistake in a state wherein fingers 14 have been 
inserted through a door 9 of the cassette port while the cassette has been 
loaded, as shown in FIG. 6, the cassette 1 is moved from the state shown 
in FIG. 6 to the state shown in FIG. 3 by the reverse rotation of the 
motor 7. In consequence, the fingers 14 may be caught between the cassette 
1 and the cassette door 9 and be injured. 
The present invention is directed to obviating this problem, and its detail 
will be described below with reference to FIGS. 7 to 10. 
Referring first to FIG. 7 which is a perspective view of the essential part 
of a first embodiment of the present invention, a cassette holder 8 has a 
rotatable cassette door 9. A light-receiving element 10 is mounted on one 
side of the cassette door 9 in a manner that it is buried therein. A 
light-emitting element 11 is mounted on a cassette inserting portion of 
the cassette holder 8 in such a manner as to face the light-receiving 
element 10. The light-receiving element 10 and the light-emitting element 
11 constitute a cassette door opening state detecting means. They may be 
mounted on opposite positions from those described above. 
In the structure shown in FIG. 7, the opening state of the door 9 is 
detected by the light-emitting element 11 provided on the cassette holder 
8 and the light-receiving element 10 provided on the door 9. More 
specifically, while the door 9 is being opened, light emitted from the 
light-emitting element 11 does not enter the light-receiving element 10. 
Reversely, the light-receiving element 10 produces an output while the 
door is being closed so as to enable opening of the door 9 to be detected. 
FIG. 8 is a perspective view of the essential part of another embodiment 
according to the present invention. In this embodiment, switch contacts 12 
and 13 are respectively mounted on the cassette holder 8 and the cassette 
door 9 as a cassette door opening state detecting means. 
In the structure shown in FIG. 8, the switch contacts 12 and 13 are in 
contact with each other while the door 9 is being closed. They are 
separated from each other while the door is being opened. This enables the 
opening of the door 9 to be detected. 
FIG. 9 is a block diagram of a control circuit for controlling the cassette 
unloading operation, and FIG. 10 is a flowchart illustrating the operation 
of the control circuit. 
The control circuit includes a cassette insertion operation completion 
detecting means 15, a cassette loading operation completion detection 
means 16, a door opening state detecting means 17 for detecting the 
opening/closing of the door 9 by the light receiving state of the 
light-receiving element or by the state of the switch contacts, a cassette 
loading mechanism driving circuit 19, a cassette unloading means 20 
including a cassette unloading trigger button 3, and a microcomputer 18 
connected to each of these units as a control device. 
The operation of the control circuit shown in FIG. 9 will now be described 
with reference to the flowchart of FIG. 10. 
If the cassette unloading trigger button 3 is pressed in the state wherein 
the cassette is being loaded, an input from the means 17 for detecting the 
opening of the door 9 which consists of the light-receiving element and 
the light-emitting element shown in FIG. 7 or of the switch contacts 12 
and 13 shown in FIG. 8 is examined in addition to those from the cassette 
insertion operation completion detecting means 15 and the cassette loading 
operation completion detecting means 16. If it has been detected by the 
door opening state detecting means 17 that the door 9 is closed, a trigger 
signal from the cassette unloading means 20 is supplied through the 
microcomputer 18 to the cassette loading mechanism driving circuit 19, by 
which the cassette loading mechanism driving circuit starts the cassette 
unloading operation in the known manner in accordance with the flowchart 
of FIG. 10 (steps (1) to (6)). If it has been detected by the door opening 
state detecting means 17 that the door 9 is opened by the fingers 14 or 
the like, as shown in FIG. 6, no signal is output to the cassette loading 
mechanism driving circuit 19 in accordance with the flowchart, and the 
cassette unloading operation is not performed (steps (1) to (3)). 
Any suitable means may be used as a means for detecting the opening of the 
door 9 in place of those shown in FIG. 7 and 8. 
The cassette insertion is detected by the switching-on of the detection 
switch 15, and the cassette loading is detected by the switching-on of the 
detection switch 16. However, the insertion and loading may be detected by 
the switching-on and off of one detection switch, respectively. 
As will be understood from foregoing description, when the cassette is to 
be discharged, the cassette discharge operation is started only when the 
door is closed according to the present invention. In consequence, the 
cassette unloading operation is not started if the fingers have been 
inserted, and an accident can be prevented in which the fingers are caught 
by an unloaded cassette.