JPH0437303Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention relates to a tape end detection device for a magnetic recording/reproducing device (hereinafter abbreviated as VTR), and in particular detects the end of a magnetic tape using a light emitting element and a light receiving element. This invention relates to a VTR tape edge detection device.

[Prior Art] FIG. 5 is a sectional view showing a conventional VTR tape start/end detection device. First, the configuration of this device will be explained. In the figure, a pair of reels 1a and 1b are provided in a cassette case 4. A light-transmitting leader tape 3 is connected to the starting end of the light-shielding magnetic tape 2, and a trailer tape (not shown), which is also transparent, is connected to the trailing end of the leader tape 3. Reel 1a, 1
b winds up or supplies these tapes.
The cassette case 4 stores these tapes and the pair of reels 1a and 1b, and the cassette case 4, these tapes, and the pair of reels 1a and 1b constitute a cassette tape. A hole 5 is provided in the center of the cassette case 4, and a hole 5 is provided in the center of the cassette case 4.
A pair of light emitting elements 8 are installed in the cassette tape mounting section.
A and a light receiving element 6a, and a pair of a light emitting element 8b and a light receiving element 6b are provided facing each other with a space therebetween. The light emitting elements 8a and 8b emit light using electric power, for example. When the cassette tape is installed in the VTR, the light receiving elements 6a and 6b are inserted into the hole 5.
The light emitting elements 8a and 8b are located outside the cassette case 4, and the tape connects the light emitting element 8a and the light receiving element 6.
a and between the light emitting element 8b and the light receiving element 6b. In order to detect the beginning and end of the magnetic tape 2, optical path holes 7a and 7b are provided in the side wall of the cassette case 4 to allow the light from the light emitting elements 8a and 8b to pass through, respectively.

Next, the operation of this device will be explained. When the magnetic tape 2 begins to be wound onto the reel 1b, the magnetic tape 2 is located between the light emitting element 8a and the light receiving element 6a, and the leader tape 3 is located between the light emitting element 8b and the light receiving element 6b. Therefore, the light emitted from the light emitting element 8a passes through the optical path hole 7a and reaches the light receiving element 6a.
However, it is blocked by the light-shielding magnetic tape 2 on the way and does not reach the light-receiving element 6a. On the other hand, the light emitted from the light emitting element 8b passes through the optical path hole 7b, transmits the leader tape 3, and reaches the light receiving element 6b.
In this way, the starting end of the magnetic tape 2 is detected in a state where the light receiving element 6a does not receive light from the light emitting element 8a and the light receiving element 6b receives light from the light emitting element 8b. Next, when the magnetic tape 2 is wound around the reel 1b to some extent, the light emitting element 8a
There is a magnetic tape 2 between the light receiving element 6a and the light emitting element 8b and the light receiving element 6b. Therefore, each light emitted from the light emitting elements 8a and 8b is blocked by the light-shielding magnetic tape 2 and reaches the light receiving element 6.
It does not reach a and 6b. In this way, it is detected that the magnetic tape 2 is not at the starting end or the ending end in a state where neither of the light receiving elements 6a and 6b receives light. Next, when the magnetic tape 2 is wound onto the reel 1b, there is a trailer tape between the light emitting element 8a and the light receiving element 6a, and there is a magnetic tape 2 between the light emitting element 8b and the light receiving element 6b. Therefore, the light emitted from the light emitting element 8a passes through the optical path hole 7a, passes through the trailer tape, and reaches the light receiving element 6a. On the other hand, the light emitted from the light emitting element 8b passes through the optical path hole 7b and travels toward the light receiving element 6b, but it is blocked by the light-shielding magnetic tape 2 on the way and does not reach the light receiving element 6b. In this manner, the end of the magnetic tape 2 is detected in a state in which the light receiving element 6a receives light from the light emitting element 8a and the light receiving element 6b does not receive light from the light emitting element 8b.

[Problems to be solved by the invention] Since the conventional VTR tape start/end detection device is configured as described above, a pair of light emitting elements 8b and a light receiving element are used to detect the start end of the magnetic tape 2. The element 6b requires a pair of light emitting element 8a and light receiving element 6a for detecting the end of the magnetic tape 2, which increases the number of parts of this device. This led to problems such as high power consumption.

This invention was made to solve the above-mentioned problems, and the purpose is to obtain a VTR tape end detection device that can reduce the power consumption of the light emitting element.

[Means for Solving the Problems] The tape edge detection device for VTR according to the present invention includes a method in which a transparent tape is connected to at least one of the starting edge and the ending edge of a magnetic tape,
In a VTR, a light emitting element is provided on one side of the magnetic tape, a light receiving element is provided on the other side of the magnetic tape facing the light emitting element at a distance, and the tape is run between these elements. The magnetic tape is turned on and off, and the light transmitted from the light-emitting element through the translucent tape is received by the light-receiving element, thereby detecting at least one of the beginning and end of the magnetic tape. It is.

[Operation] In this invention, the light-emitting element is turned on and off by the pulse signal generating means, and the light-receiving element receives light from the light-emitting element that has passed through the translucent tape.

[Example] Hereinafter, an example of this invention will be described with reference to the drawings. In the description of this embodiment, the description of parts that overlap with the description of the conventional technology will be omitted as appropriate.

FIG. 1 is a sectional view showing a tape end detection device for a VTR which is an embodiment of this invention. In the figure, the difference between the configuration in FIG. 1 and the configuration in FIG. 5 is that one light-receiving element 6 is used instead of the light-receiving elements 6a and 6b, and the conventional light-emitting element 8a, which is always on, is used. , 8b are replaced by light emitting elements 8a' and 8b' which turn on and off in different phases. That is, each of the light emitting elements 8a' and 8b' located outside the cassette case 4 faces the light receiving element 6 inserted into the hole 5 provided in the center of the cassette case 4, and has a light blocking property. A magnetic tape 2, a translucent leader tape 3, and a translucent trailer tape (not shown) are run between these elements. Optical path holes 7a, 7 provided in the side wall of the cassette case 4
b allows each light from the light emitting elements 8a' and 8b' to pass through.

FIG. 2 is a block diagram of a VTR tape edge detection device which is an embodiment of this invention. In the figure, a pulse signal generator 9 is connected to a light emitting element 8a' and to one input side of an AND circuit 12. Further, the pulse signal generator 9 is connected to the light emitting element 8b' via the delay circuit 10, and is also connected to one input side of the AND circuit 13.
The pulse signal generator 9 generates a first phase pulse signal. The delay circuit 10 delays the first phase pulse signal by a predetermined phase to generate a second phase pulse signal. The light emitting element 8a' is turned on and off in response to the first phase pulse signal, and the light emitting element 8b' is turned on and off in response to the second phase pulse signal.
The light receiving element 6 is connected to the AND circuit 1 via the amplifier 11.
2 and the other input side of AND circuit 13. The light receiving element 6 is the light emitting element 8
Each light from a' and 8b' is received and photoelectrically converted. The output side of the AND circuit 12 is the integral 14,
The output side of the AND circuit 13 is connected to an integrating circuit 15. AND circuits 12, 13 and integration circuits 14, 1
5 constitutes a discrimination circuit 16. The amplifier 11 amplifies the output of the light receiving element 6. Each of the AND circuits 12 and 13 has an output only when inputs are received on both input sides, and has no output otherwise. Integrating circuits 14 and 15 are AND circuits 12 and 1, respectively.
Integrate the 3 outputs.

FIG. 3 is a timing chart of the operation of the light-emitting element and the light-receiving element of a VTR tape end detection device which is an embodiment of this invention. In the figure, the third
Figure a shows a state in which the light emitting element 8a' repeats turning on and off in response to the first phase pulse signal, and Figure 3 b
is the light emitting element 8 in response to the second phase pulse signal.
b' indicates a state where the light is repeatedly turned on and off, and the light emitting element 8a' and the light emitting element 8b' alternately emit light. Third
Figure c shows the state in which the light from the light emitting element 8b' is received by the light receiving element 6, and Figure 3 d shows the state in which the light from the light emitting element 8b' is received by the light receiving element 6.
FIG. 3e shows a state in which the light from the light emitting element 8a' is received by the light receiving element 6, while FIG. 3e shows a state in which the light from the light emitting element 8a' is not received by the light receiving element 6.

Next, the operation of this device will be explained. When the magnetic tape 2 begins to be wound onto the reel 1b, light emitted from the light emitting element 8a' travels through the optical path hole 7a, but is blocked by the light-shielding magnetic tape 2 and does not reach the light receiving element 6. On the other hand, the light emitted from the light emitting element 8b' passes through the optical path hole 7b, passes through the transparent leader tape 3, and reaches the light receiving element 6. Therefore, the light receiving element 6 receives light only during the time when the light emitting element 8b' is emitting light, as shown in FIG. 3c.
The output of the light receiving element 6 is amplified by an amplifier 11. At this time, the second phase pulse signal and the amplifier 11 output having the same phase as this signal are input to the AND circuit 13, so the AND circuit 13 has an output, and this output is integrated by the integration circuit 15 and output. be done.
On the other hand, the AND circuit 12 receives the pulse signal of the first phase and the amplifier 1 of the same phase as the pulse signal of the second phase.
Since one output is input, the AND circuit 12 has no output. In this manner, the starting end of the magnetic tape 2 is detected with only the integrating circuit 15 outputting. Next, when the magnetic tape 2 is wound around the reel 1b to some extent, the respective lights emitted from the light emitting elements 8a' and 8b' proceed through the optical path holes 7a and 7b, but both of them are covered with light-shielding magnetic fields. The light is blocked by the tape 2 and does not reach the light receiving element 6. Therefore, the light receiving element 6 does not receive light as shown in FIG. 3d. At this time, since only the first phase pulse signal is input to the AND circuit 12, the AND circuit 12
has no output. On the other hand, since only the second phase pulse signal is input to the AND circuit 13, the AND circuit 13 also has no output. In this way, the magnetic tape 2 is
It is detected that is not the starting end or the ending end.
Next, when the magnetic tape 2 is wound onto the reel 1b, the light emitted from the light emitting element 8a' passes through the optical path hole 7a, passes through the light-transmitting trailer tape, and reaches the light receiving element 6. . On the other hand, the light emitted from the light emitting element 8a' travels through the optical path hole 7b, but does not reach the light receiving element 6 because it is blocked by the light shielding magnetic tape 2. Therefore, the light receiving element 6 is as shown in FIG.
As shown in , light is received only during the time when the light emitting element 8a' is emitting light, and the output of the light receiving element 6 is sent to the amplifier 11.
is amplified. At this time, the AND circuit 12 receives the first phase pulse signal and the amplifier 11 output having the same phase as this signal.
2 has an output, and this output is integrated by an integrating circuit 14 and output. On the other hand, since the second phase pulse signal and the output of the amplifier 11 having the same phase as the first phase pulse signal are input to the AND circuit 13,
AND circuit 12 has no output. In this manner, the end of the magnetic tape 2 is detected with only the integrating circuit 14 outputting. As described above, the discrimination circuit 16
By determining which light from the light-emitting elements 8a' and 8b' is received by the light-receiving element 6, it is possible to detect the beginning and end of the magnetic tape 2 with only one light-receiving element 6. can.

Furthermore, the light emitting elements 8a' and 8b' are repeatedly turned on and off as shown in FIG. Compared to conventional devices in which two light-emitting elements are always on,
The power consumption required for the light emitting elements 8a' and 8b' to emit light can be significantly reduced.

In the above embodiment, a case has been described in which the lighting time of the light emitting elements 8a' and 8b' is shorter than the lighting time, but the lighting time may be equal to or longer than the lighting time.

Further, in the above embodiment, the case where the starting end and the ending end of the magnetic tape 2 are detected is explained.
It may be the case that only the starting end or only the ending end of the magnetic tape 2 is detected, and the light emitting element is turned on or
By repeatedly turning off the light, power consumption can be reduced similarly to the above embodiment.

Furthermore, although the above embodiment has been described with reference to the case where the cassette case 4 is provided, the cassette case 4 may not be provided, and as shown in FIG. A light-shielding magnetic tape 2, a light-transmitting leader tape 3, and a light-transmitting trailer tape (not shown) may be run between these elements.

Furthermore, although the above embodiment describes the case where one light receiving element 6 is used, two light receiving elements may be used as in a conventional device, and the light emitting elements 8a',
By alternately turning on and off 8b', power consumption can be reduced similarly to the above embodiment.

Further, in the above embodiment, a case has been described in which the light receiving element 6 is provided between the light emitting elements 8a' and 8b', but the positional relationship between these elements may be reversed with respect to the magnetic tape 2.

[Effects of the invention] As described above, according to this invention, a light-transmitting tape is arranged on at least one of the starting end and the ending end of a magnetic tape, and a light-emitting element is placed on one side of the magnetic tape in a VTR. A light-receiving element is provided on the other side of the magnetic tape facing the light-emitting element at a distance, the tape is run between these elements, the light-emitting element is turned on and off by a pulse signal generating means, and the light-emitting element is turned on and off. The light that has passed through the translucent tape is received by the light-receiving element, and at least one of the beginning and end of the magnetic tape is detected. At least one of them can be detected, and the power consumption required for light emission of the light emitting element can be reduced.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a tape end detection device for a VTR which is an embodiment of this invention. FIG. 2 is a block diagram of a VTR tape edge detection device which is an embodiment of this invention. FIG. 3 is a timing chart of the operation of the light-emitting element and the light-receiving element of a VTR tape end detection device which is an embodiment of this invention. FIG. 4 is a sectional view showing a tape end detection device for a VCR which is another embodiment of this invention. Figure 5 shows the beginning and end of a conventional VTR tape.
FIG. 3 is a cross-sectional view showing the terminal end detection device. In the figure, 1a and 1b are reels, 2 is a magnetic tape, 3 is a leader tape, 4 is a cassette case, 5 is a hole, 6, 6a, and 6b are light receiving elements, 7a,
7b is an optical path hole, 8a, 8b, 8a', 8b' are light emitting elements, 9 is a pulse signal generator, 10 is a delay circuit, 1
1 is an amplifier, 12, 13 are AND circuits, 14, 1
5 is an integration circuit, and 16 is a discrimination circuit. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims for Utility Model Registration] A tape end detection device for a magnetic recording/reproducing device that detects the end of a magnetic tape, the magnetic tape comprising: a light-shielding recording tape; a tape supply means for supplying the magnetic tape; a tape winding means for winding the magnetic tape; and generating first and second pulse signals having mutually different phases. a first light emitting means provided on the tape supply means side and emitting light in response to the first pulse signal; and a first light emitting means provided on the tape winding means side and emitting light in response to the second pulse signal. a second light emitting means that emits light in response; a light receiving means provided at a position to receive light emitted from the first and second light emitting means via the magnetic tape; connected to the light receiving means; phase coincidence detection means for detecting which phase of the first or second pulse signal the phase of the received light matches; A tape end detecting device for a magnetic recording/reproducing device, comprising an end determining means for determining an end of the tape.