JPH01176349A - Device for detecting tape end - Google Patents

Abstract

PURPOSE:To facilitate the attachment of a light receiving element and a light emitting element and to obtain a low cost by respectively disposing the light receiving element and the light emitting element on the light reflecting surface side of a tape on both sides of a line which is almost vertical to the surface of the tape. CONSTITUTION:The light receiving element 2 and a light emitting element 1 are set out of a cassette 3 and the two elements 1, 2 are caused to be a unit. Further, the light receiving and light emitting elements 1 and 2 caused to be the unit are disposed on a movable lever to be turnable. Since a light to be emitted from the light emitting element 1 in correspondence to a pulse signal, which is generated from a pulse signal generator 6, is reflected by an information recording part 5a or a splicing tape part 5b, the light is incident on the light receiving element 2. However, since the light from the light emitting element 1 is almost transmitted in a starting edge part or a terminal part 5c of the tape, the incident light to the light receiving element 2 is disappeared when a tape 5 to be traveled in an arrow direction comes to these end parts 5c. Then, the starting edge and termination of the tape can be detected. Thus, the attachment of the light receiving and light emitting elements is facilitated and the low cost can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for optically detecting the end of a tape-shaped magnetic recording medium housed in a cassette.

[Prior Art] FIG. 5 is a schematic explanatory diagram of a conventional video cassette tape end detection device, in which 23 is a cassette, 21 is a light emitting diode which is a light emitting element, and 22 is a phototransistor which is a light receiving element. Conventionally, this type of device optically detects the translucent leader portion of the tape using two phototransistors 22 installed near the tape start/end detection ports provided on the side wall of the cassette. Ta.

[Problems to be Solved by the Invention] The conventional detection device as described above requires the light emitting element 21 inside the cassette and the light receiving element 22 outside the cassette. In addition, there are holes for the detection light to pass through on the side wall of the cassette, which makes it difficult to install the receiving and emitting elements in positional accuracy and complicates the shape of the cassette. Attachment of the receiving and emitting elements during the process has the problem of ensuring accuracy and increasing costs due to the complexity of the cassette shape.

This invention was made to solve these problems, and aims to provide a tape end detection device that facilitates the installation of light receiving and light emitting elements during the manufacturing process, and is low cost and simple in construction. A further object of the present invention is to provide a tape end detection device that can always keep the relative positional relationship between the tape and the receiving/emitting element unit constant regardless of the tape running mode.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method in which a light receiving element and a light emitting element are installed outside the cassette, and the two elements are formed into a unit. By arranging the receiving/emitting element on a rotatable moving lever, the reflected light component from the translucent leader section provided at the beginning and end of the tape can be reduced in various tape running modes. This configuration allows the end of the tape to be detected accurately.

[Function] By configuring as described above, it is possible to have flexibility in the installation positions of the light receiving element and the light emitting element, and by unitizing the two elements, the arrangement of the light receiving element and the light emitting element can be made more flexible. The positional relationship between both elements can be defined in advance so as to reliably capture the reflection of the light irradiated onto the tape from the tape. Furthermore, by arranging the receiving/emitting element unit on the moving lever, it can be used in various tape running modes. The relative positional relationship between the unit and the tape can always be kept constant, and the end of the tape can be accurately detected in each tape running mode.

[Embodiment] FIG. 1 is a schematic diagram of a tape end detection device according to an embodiment of the present invention in recording/playback mode, FIG. 2 is a block diagram showing details of the detection section shown in FIG. 1, and FIG. Special running mode (high speed search) in the device shown in FIG. 1 of this invention
FIG. 3 is a schematic diagram of fast forward/rewind mode.

In Figures 1, 2, and 3, l is a light emitting element, 2 is a light receiving element, 3 is a cassette, and 4 is a light shielding plate that blocks light from the light emitting element or from directly leaking into the light receiving element. ,
5 is tape, 9a, 9b.

10 is a guide post.

As shown in FIG. 2, the light emitted from the light emitting element 1 in response to the pulse signal generated by the pulse signal generator 6 is reflected by the information recording portion 5a and the splicing tape portion 5b. Light enters the light-receiving element, but most of the light from the light-emitting element is transmitted through the beginning or end of the tape 5c. When the end portion 5C of the tape is reached, no light enters the light receiving element 2, and the beginning and end of the tape can be detected.

As shown in FIG. 2, since the light emitting element emits light in response to a pulse signal generated by a pulse signal generator, the light receiving element receives this light and generates an alternating current signal. Then, the AC signal generated by the light receiving element is supplied to a tape running stop circuit 8 after its DC component is removed by a DC component removal circuit 7 . When the supply of the AC signal from the DC component removal circuit 7 stops, the tape running stop circuit 8 determines that the tape 5 has reached the starting end or the ending end, and stops the tape running drive source, thereby stopping the tape 5. Stop running.

In this embodiment, the receiving/emitting elements are arranged as shown in Fig. 1, or by arranging them in this way, the positions of the receiving/emitting elements can be changed even during special driving mode or fast forward/rewind mode. There will be no need. The state shown in FIG. 3 is the tape running bus in the special running mode or the fast forward 7 rewind mode.
By wrapping the tape in the recording/reproducing mode, the positional relationship between the receiving/emitting element and the tape is made the same as in the recording/reproducing mode. Note that even in the special running mode and the like, there is no change in the detection method in which the light receiving element receives reflected light from the light emitting element on the tape surface.

FIG. 4 is a schematic diagram of a second embodiment of the invention. There are various types of tape transport devices, and in the high-speed feed mode, there are cases in which the tape is pulled out from within the cassette, and cases in which the tape is carried out while the tape is stored in the cassette. What is shown in FIG. 4 is a case where the tape is run while it is housed in a cassette.

In FIG. 4, 1 is a light emitting element, 2 is a light receiving element, 3 is a cassette, 4 is a light shielding plate that blocks light so that the light from the light emitting element does not directly leak into the light receiving element, 11, 12, 13
．． Reference numeral 16 indicates levers for moving the receiving/emitting element unit, and reference numerals 14 and 15 indicate guide cams that serve as guides when moving the receiving/emitting element unit.

In the case of this embodiment, the receiving/emitting element unit moving levers 12 and 13 are shown in FIG.
It is localized at the position of However, when running the tape with it stored in the cassette, the receiver and
When the light emitting element unit is located, it is extremely difficult for the light receiving element to receive the reflected light from the tape. Therefore, in such a case, as shown in FIG.
The light emitting element unit moving lever 12, the driving link 16, and the receiving/emitting element unit moving lever 13 are rotated in the direction of the arrow to move the receiving/emitting element unit to the guide cam 14.
It is necessary to move the receiving/emitting element unit along line 15 so that the relative positional relationship between the tape surface and the unit is in the desired state as shown in FIG. In other words, the receiving/emitting element unit moving lever 12.13 is shown in the figure (b).
Even when the unit is rotated to the position shown in FIG. It goes without saying that various means other than the fan-shaped gear lever 11 and the drive link 16 can be used as the driving means for rotating the receiving/emitting element unit moving lever 12,13.

In addition, regarding the one shown in FIG. 4, the guide cam 14.
Reference numeral 15 has a grooved cam, and the receiving/emitting element unit has a pin that fits into the groove, and a moving lever 12.
13 so as to be slidable.

[Effects of the Invention] As explained above, the present invention provides a tape end detection device that has greater flexibility in the mounting position of the receiving and emitting elements, greater freedom in the shape of the cassette, and is inexpensive to manufacture. In addition, the relative positional relationship between the tape surface and the light emitting/receiving element unit can be properly maintained in all tape running modes, and the end of the tape can be accurately detected.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a tape end detection device according to an embodiment of the present invention in recording/playback mode, FIG. 2 is a block diagram showing details of the detection section shown in FIG. 1, and FIG. Special travel mode (high-speed search) and fast forward 7 in Figure 1
FIG. 4 is a schematic diagram of a second embodiment of the present invention, and FIG. 5 is a schematic diagram of a conventional video cassette tape end detection and mounting method. In the figure. 1.21: Light emitting element 2.22: Light receiving element 3.23: Cassette 4: Light shielding plate 5: Tape 9a Ni guide post (drawn out state) 9b Ni guide post (stored state) 12, 13: Receiver/light emitting element unit movement lever 14.15: Guide cam agent for moving receiving/emitting element unit Patent attorney 1) Haru Kitatake Figure 1 Figure 2 Figure 3 (b) 4r4 Su 5 H'tsu

Claims (5)

[Claims] (1) In a tape end detection device in which the beginning and end of the tape have different optical reflectance from the information recording portion, etc., a light-receiving element and a light-emitting element are installed on both sides of a line approximately perpendicular to the tape surface. A tape end detection device, characterized in that it is installed on the light-reflecting surface side of the tape. (2) The tape end detection device according to claim (1), wherein the light receiving element and the light emitting element are integrated into a unit. (3) The tape end detection device according to claim (2), wherein the unit of the light receiving element and the light emitting element is configured to be movable depending on the tape running mode. (4) The unit of the light receiving element and the light emitting element is disposed on a rotatable moving lever, and has means for driving the moving lever.
) The tape end detection device described in item 2. (5) Claim (4) characterized in that the unit of the light receiving element and the light emitting element arranged on the rotatable moving lever is structured to be guided by a cam.
Tape end detection device as described in .