JPH0454573Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Purpose of the Invention] (Field of Industrial Application) The present invention relates to a digital audiotape player (referred to as a DAT), and particularly relates to an improvement in its tape end detection mechanism.

(Prior Art) A transparent lead tape is provided at the end of a DAT cassette tape, and by detecting this transparent lead tape with optical means, it is detected that the tape end has been reached.

As optical means for detecting the lead tape, there are known a prism type in which a light source is provided outside the cassette and a lighthouse type in which a light source is inserted into the cassette. In the prism type, light from a light source placed outside the cassette enters the cassette, is bent by a prism installed inside the cassette, and is then guided outside the cassette through the lead tape, where it is detected by a light receiving element. In the lighthouse type, light from a light source inserted into the cassette is applied directly to the lead tape, and the transmitted light is detected by a sensing element provided outside the cassette.

In order to support these two types of detection means,
Inside the DAT cassette 10, as shown in FIGS. 2A and 2B, a prism 11 is provided which has an entrance surface 11a facing outside the cassette and an exit surface 11b facing the tape T. an entrance aperture 12 and an exit aperture 13 for the prism 11;
In order to correspond to the lighthouse type, an output port 14 facing the tape T is provided. On the tape player side, in the prism type, a light source and a light receiving element are arranged outside the cassette 10 in line with the input port 12 and the output port 13, and in the lighthouse type as shown in the figure, a light source 15 is arranged at the center inside the cassette 10. is inserted, and a light receiving element 16 is provided outside the cassette 10.

(Problem to be Solved by the Invention) By the way, when a DAT cassette compatible with both detection means is installed in a lighthouse type tape player as shown in FIG. Since the light source 15 is far away from the tape T and the exit port 14, the light from the light source 15 does not reach the cassette 1.
It will spread in various directions within 0. Of this kind of diffused light, the light directed downwards from the cassette 10
L1 is reflected by the chassis of the tape player, passes below the tape T, and reaches the light receiving element 16 from the output port 14. Similarly, the light L2 directed upward from the cassette 10 is reflected by the top plate of the cassette 10, passes above the tape T, and passes from the output port 14 to the light receiving element 16.
reach. Furthermore, the light L3 directed toward the back surface of the prism 11 enters the prism 11, is bent and reflected inside, and then reaches the exit surface 11 of the prism 11.
b to the outside of the cassette 10, and the light receiving element 1
Reach 6.

In this way, in the conventional lighthouse type tape player, the lights L1 to L3 emitted from the light source sometimes bypass the tape T and reach the light receiving element 16, and the tape T does not reach the end and the transparent lead tape light source 15
There was a risk that the light receiving element 16 would detect light and perform tape end detection even though it was not facing the tape end.

The present invention solves the problems of the prior art as described above, and provides a tape end detection mechanism for a tape player that uses a lighthouse type detection method and enables tape end detection without malfunction due to diffused light. The purpose is to

[Structure of the invention] (Means for solving the problems) The tape player detection mechanism of the invention includes a light source inserted into the cassette at approximately the center of the insertion position of the cassette in the tape player, and a light source inserted into the cassette from the outside of the cassette. A light receiving element is provided between the light source and the tape in the cassette, and a light shielding wall is provided which is inserted close to the light source side of the tape inside the cassette,
A light-transmitting window is formed on the light-shielding wall at a position opposite to the tape.

(Function) In the present invention having the above configuration, the excess diffused light from the light source is blocked by the light-shielding wall in front of the tape, and is prevented from leaking outside the cassette and being detected by the light receiving element. Since only the light transmitted through the lead tape through the light-transmitting window of the light-shielding wall is detected by the light-receiving element, erroneous detection due to diffused light is prevented.

(Example) An example of the present invention will be described below with reference to FIG. Incidentally, the same members as those of the conventional tape player shown in FIG. 2A are given the same reference numerals, and explanations thereof will be omitted.

In this embodiment, a light-shielding wall 2, which is inserted into the cassette 10, is raised at the position where the cassette 10 is installed in the chassis 1 of the tape player. This light shielding wall 2 is similarly arranged between a light source 15 raised from the chassis 1 and the tape T in the cassette, and is particularly provided close to the tape T.
The upper end of this light-shielding wall 2 extends close to the top plate of the cassette 10, and includes an entrance opening 12 for the prism 11 formed on the back side of the prism 11 disposed on both sides of the cassette 10 and on the side wall of the cassette 10.
The exit port 13 is hidden from the light source 15. Shade wall 2
A light-transmitting window 3 is opened at a position facing the lighthouse-type light exit 14.

In the tape player of this embodiment having such a configuration, the light that is diffused from the lighthouse-type light source toward the bottom or top of the cassette 10 or toward the back of the prism 11 is blocked by the light-shielding wall 2, No leakage to the outside. Only the light that has passed through the transmission window 3 of the light shielding wall 2 and hit the tape T can reach the light receiving element 16 outside the cassette 10 through the exit port 14 of the cassette 10. As a result, malfunction of the light receiving element 16 due to the diffused light from the light source is eliminated, and tape end detection is performed reliably.

It should be noted that the present invention is not limited to the illustrated embodiment, and instead of directly standing up from the chassis of the light-shielding wall, another member may be fixed on the chassis.
In addition to providing a dedicated light-shielding wall, the light source and the light receiving element can also be integrated with the light-shielding wall and fixed to the shaft. The light-shielding wall may be the same metal plate as the chassis, or may be a transparent synthetic resin plate with a light-transmitting window coated or laminated with a material that reflects or absorbs light from the light source.

[Effects of the invention] As described above, according to the invention, malfunctions when detecting the end of a tape can be eliminated by an extremely simple means of providing a tape player with a light-shielding wall that is inserted into the cassette close to the tape. It is possible to improve the accuracy of tape end detection while employing a simple lighthouse-style configuration in which a light source is provided at the center of the tape player.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the tape end detection mechanism of the present invention, Fig. 2A is a sectional view showing a conventional lighthouse type tape end detection mechanism, and Fig. 2B shows a part of a cassette. FIG. T... Tape, 1... Chassis, 2... Light blocking wall, 3... Translucent window, 10... Cassette, 11...
Prism, 12... Inlet port, 13, 14... Output port, 15... Light source, 16... Light receiving element.

Claims (1)

[Scope of utility model registration request] A light source inserted into the cassette is provided approximately at the center of the insertion position of the cassette in the tape player, and a light receiving element is provided outside the cassette sandwiching the light source and the tape inside the cassette. 1. A tape end detection mechanism comprising: a light-shielding wall that is inserted in close proximity to the tape; and a light-transmitting window formed in the light-shielding wall at a position facing the tape.