JPH0454574Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Objective of the Invention] (Field of Industrial Application) The present invention relates to a tape detection mechanism for detecting a tape start and a tape end in a digital audio tape player.

(Prior Art) With the remarkable technological advances in recent years, in the field of audio, research and development of digital audio tape players (hereinafter referred to as DAT), which record and play back digital signals by winding a tape around a rotating head, have been progressing. It is currently being developed and is attracting a lot of attention because of its advantage of providing extremely high sound quality compared to conventional analog tape players. This DAT
As with conventional tape players,
When the tape is rewound to the start using the rewind mode, the play mode or stop mode is automatically activated.When the tape is rewound to the end using the play mode or fast wind mode, the tape is automatically placed into the stop mode or reverse mode. A tape detection mechanism is provided to detect tape start and tape end.

This tape detection mechanism is an optical mechanism that detects the light-transmitting lead tape sections provided at both ends of the tape, and there are two types of mechanisms: a lighthouse type and a prism type.

Among these, the prism type is a system that includes a prism-type entrance port 2 and exit port 3 provided vertically on the side surface 1a of the cassette 1 along the tape running path, as shown in FIGS. 2A and B. When the cassette is installed, light 6 is applied to the tape 5 through the entrance port 2.
It radiates. In this prism method, when the lead tape portion of the tape 5 overlaps the optical path, the incident light 6 reaches the prism 4,
The light then makes a U-turn and is emitted from the light emitting port 3, and is sent to a light receiving section provided on the light emitting path outside the cassette.

In addition, the lighthouse method, as shown in Figure 2B,
A lighthouse-type light emitting port 7 is provided on the side surface 1a of the cassette 1 in parallel with the prism-type light emitting port 3, and when the cassette 1 is installed, it is located approximately in the center of the cassette 1, as shown in FIG. Light 9 is emitted onto the tape 5 from a light source 8 such as a light emitting diode located thereon. In this lighthouse method, when the lead tape portion of tape 5 overlaps the optical path,
Light 9 emitted from the light source 8 reaches the exit port 7, is emitted from there to the outside of the cassette 1, and is sent to a light receiving section 10 disposed on an extension connecting the light source 8 and the exit port 7.

(Problems to be Solved by the Invention) By the way, in the conventional lighthouse type tape detection mechanism, the following problems occur when detecting a tape in a DAT cassette.

That is, since the light from the lighthouse type light source 8 is emitted not only in the horizontal direction to the light receiving section 10 via the tape 5, but also in the vertical direction, a part of the light is emitted as follows.
As shown by the hatching part 11 in FIG. 1, the light enters a prism 4 provided in the cassette, passes through the prism 4, passes through the upper space of the tape 5, and exits from the prism type entrance 2. Light receiving section 10
may be sent to. Therefore, even when the recording section of the tape 5 is in the middle of running, the tape start or end may be mistakenly detected due to the light passing through the prism 4 and the space above the tape 5.

Generally, the lower surface 1b of the cassette 1 is opened when the slider that protects the lower surface of the cassette moves when the cassette is installed, so that light from the light source 8 in the lighthouse method is emitted as shown by the hatched part 12 in FIG. A part of the lower surface 1b of the cassette 1
The light may reach the sheath 13 or other reflective member through the light, be reflected there, enter the prism 4, and be sent to the light receiving unit 10 in the same way as the light 11 described above. Therefore, in this case as well, there is a risk that the tape start or tape end will be detected incorrectly.

Furthermore, a part of the light from the light source 8 in the lighthouse method is reflected on the inner surface of the cassette 1, enters the prism 4, and enters the light receiving section 10 in the same way as the light 11 described above.
Sometimes it is sent to. Therefore, in this case as well, there is a risk that the tape start or tape end will be detected incorrectly.

As mentioned above, in the conventional tape detection mechanism, the light that enters the prism directly from the light source or through reflection from the inside surface of the chassis or cassette, and leaks from the space above the tape through the prism, causes false tape starts or There was a risk that the tape end would be detected.

That is, the present invention was proposed in order to solve the problems of the prior art as described above, and its purpose is to detect light directly from the light source or from reflections from the inner surface of the chassis or cassette in a lighthouse type tape detection mechanism. By making it possible to block the light that enters the prism through the prism, passes through the prism, leaks from the upper space of the tape, and leaks from the entrance of the prism system to the light receiving section, it is an excellent tape with no risk of malfunction. The purpose of the present invention is to provide a detection mechanism.

[Structure of the invention] (Means for solving the problem) The tape detection mechanism of the invention includes prisms provided on the left and right sides of the frame, a prism-type entrance and exit ports provided on the sides of the frame, The cassette is equipped with a lighthouse-style light emitting port, and the bottom surface is open when the cassette is installed, and a reflective member is provided so as to face the bottom surface of the cassette in an open state or the light source when the cassette is installed. There is.

In addition, as an optical device, a light source is arranged so as to be located inside the cassette when the cassette is installed, and a light receiving section is arranged so as to be located on the extension line connecting the light source and the lighthouse type exit of the cassette when the cassette is installed. Place.

In addition to the above configuration, the present invention is characterized in that a light shielding member is provided on the side surface of the cassette to shield the prism-type entrance when the cassette is mounted.

(Function) With the above-described configuration, the present invention allows the light emitted from the light source to enter the prism directly or through reflection from a reflective member such as the chassis or the inner surface of the cassette, and pass through the prism to the tape. Even if the light leaks from the upper space of the tape or from the prism-type entrance, this light can be reliably blocked from the light-receiving section, thereby preventing erroneous detection of tape end or tape start.

(Example) An example of the present invention will be specifically described below with reference to FIG.

As shown in FIG.
A is provided with an opening 14b for sending the light 9 emitted from the light source 8 through the lighthouse-type output port 7 to the light receiving section 10. The upper edge of the side surface 14a facing the opening 14b is extended further downward than in the past to form an extension 14c, and this extension 14c forms a prism-type entrance opening provided on the side surface 1a of the cassette 1. Lights 11 and 12 from 2,
It functions as a light shielding member that blocks light from the light receiving section 10.

Furthermore, as already described in the explanation of the prior art, when the cassette 1 is attached,
The slider that protects the lower surface 1b of the cassette 1 is configured to move to an open state. The cassette holders 14L and 14R are configured to hold the cassette 1 with its lower surface 1b facing the chassis (reflection member) 13 in this cassette mounted state.

In this embodiment having the above-described configuration, conventionally, light enters the prism 4 directly from a light source, or enters the prism 4 through reflection from the chassis 13 or the inner surface of the cassette 1, and then passes through the prism 4. The lights 11 and 12 that have passed through the upper space of the tape 5, exited from the prism type entrance 2 provided on the side surface 1a of the cassette 1, and reached the light receiving section 10 are now emitted from the extension of the side surface 14a of the cassette holder. The optical path to the light receiving section 10 is cut off by the section 14c. Therefore, when the recording section of the tape 5 is in the middle of running, there is no possibility of erroneously detecting the tape start or tape end.

In particular, in this embodiment, the side surface 14a of the cassette holder is extended and used as a light shielding member, so the number of parts can be reduced and assembly work can be facilitated.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and for example, as the light shielding member, a separate cover or the like may be provided on the optical path outside the cassette holder from the opening 14b of the cassette holder to the light receiving section 10. It is possible.

[Effects of the Invention] As explained above, in the present invention, light can be directly or Light that enters the prism through reflection from the chassis or inner surface of the cassette, passes through the prism, and leaks to the outside of the cassette from the prism-type entrance port can always be blocked from the light receiving section, so it is a simple method with no risk of malfunction. A configuration tape detection mechanism can be provided.

[Brief explanation of drawings]

Figure 1 is a sectional view showing an embodiment of the tape detection mechanism according to the present invention, and Figures 2A and B are DAT
FIG. 3 is a cross-sectional view and a side view showing a part of a cassette for use in a computer. 1...cassette, 1a...cassette side, 2
... Prism type entrance port, 3... Prism type exit port, 4... Prism, 5... Tape, 6,
9, 11, 12...Light, 7...Lighthouse type exit, 8...Light source, 10...Light receiving section, 13... Chassis (reflection member), 14L, 14R...Cassette holder, 14a...Cassette side of holder, 14
b...opening, 14c...extension (light shielding member).

Claims (1)

[Claims for Utility Model Registration] (1) A tape detection mechanism that optically detects the tape start and tape end of a cassette includes prisms installed on the left and right sides of the frame, and a prism system installed on the sides of the frame. Equipped with an entrance, an exit, and a lighthouse-style exit,
a cassette configured such that its bottom surface is open when the cassette is installed; a light source disposed to be located within the cassette when the cassette is installed; and a light source that faces the open bottom surface of the cassette or the light source when the cassette is installed. a reflecting member disposed as shown in FIG. A tape detection mechanism comprising a light shielding member positioned on a side surface of the cassette so as to shield the prism-type entrance. (2) The tape detection mechanism according to claim 1, wherein the light shielding member is formed on the side surface of the cassette holder.