JPS6022417B2 - magnetic recording and reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a tape cassette in which a magnetic tape having a translucent leader tape is wound and built into the final weave part, and a combination of a light emitting element and a light receiving element allows the translucent leader tape to be A magnetic device such as a cassette tape recorder that has an optical tape end detection function that detects the end of the magnetic tape and stops the device or automatically rewinds the tape by detecting the arrival of the tape. The present invention relates to a recording/reproducing device.

Note that the term "magnetic recording and reproducing apparatus" as used herein includes those having only either a recording function or a reproducing function.
Conventionally, magnetic recording and reproducing devices that have this type of tape end detection device consume a large amount of current because current continues to flow through the light-emitting elements while the magnetic tape is running, especially portable type devices that use dry batteries as a power source. However, there was a problem in that the battery life was shortened.

The present invention provides a thin magnetic recording/reproducing bag that solves such problems with a relatively simple structure.

Hereinafter, the present invention will be explained by referring to the illustrated embodiments.

FIG. 1 is a schematic diagram of a cassette-type magnetic recording/reproducing device usually referred to as a video tape recorder (hereinafter abbreviated as "VTR").

In the figure, "The magnetic tape 8 wound around the reel hub 4 inside the cassette 2 is pulled out to the outside of the cassette 2, and
The limiter 1 full-width erasing head 12t The rotating magnetic head inside (
(not shown) is attached in a Q shape to the outer periphery of the drum head 8, which is then guided by the oblique post 28 and the guide roller 22 and comes into contact with the audio control head 2M.
Even though it is driven to run at a constant speed by the capstan 26 and the pinch roller 28, it is wound up again on the reel hub 6 in the cassette 2. On the other hand, a lamp 38, which is a light emitting element, is arranged in a deck section located in a recess (not shown) provided approximately in the center of the cassette 2, and a lamp 38, which is a light emitting element, is arranged in a deck section located in a recess (not shown) provided approximately in the center of the cassette 2. A light-receiving element 3, which together with the lamp 3Q constitutes an optical tape end detection device, is disposed on the outer fixed portion of the entrance portion 32.

Further, a transparent leader tape (not shown) is connected to both ends of the magnetic tape 8 that is run at a constant speed by the capsut saw 26 and the pinch roll 28, and the transparent leader tape portion faces the closing portion 32. When the point is pressed, the light from the lamp 3Q hits the transparent radar tape and the entrance part 32.
The signal passes through and reaches the light receiving element 34, and the output of the light receiving element 34 automatically stops the operation of the VTR.

The above is similar to the conventional VTR, but in the present invention, the supply of box current to the lamp 30 is periodically interrupted by a power supply control means.

An example of its configuration is shown in FIG. To explain this, the crab supply terminal 36 connected to the crab source is connected to the lamp 30 through the resistor 38.
The other terminal of the lamp 30 is connected to the collector of a transistor 42. The emitter 46 of the transistor 42 is grounded, and the base 48 is connected via a resistor 50 to a well-known astable - Connected to the output end of an oscillation circuit 52 consisting of a multipipulator or the like.

Further, 54 is a power supply terminal that supplies power supply voltage when the tape is running at a constant speed, and 56 is a contact point for forcibly stopping the oscillation of the oscillation circuit 52. It is designed so that it closes when pressed.

Next, the operation of the circuit shown in FIG. 2 will be explained with reference to the time chart shown in FIG.

Now, when you set the VTR to constant speed running mode, t power supply terminal means 3
A predetermined power supply voltage is applied to 6 and 54.

On the other hand, the base voltage of the transistor 42 is the oscillation circuit 5
Since the ON/OFF operation is repeated depending on the two time constants T and T2 of the lamp 3, the L lamp 3 is lit while the transistor 42 is ON (conducting).

Generally, in VTRs, transparent leader tape is used as a rotating head! If this contact occurs, the rotating head may become clogged, which could lead to a serious accident. When the running speed of the magnetic tape 8 by the roller 28 is V, the intermittent lighting period T (=T, 10T2) of the lamp 30 is expressed as T
When set to <L/V, even if lamp 3Q is turned on intermittently, lamp 3 will always be lit at least once before the transparent iJ-dar tape comes into contact with drum turtle 8', and the light receiving element 34 will be activated. to put the VTR in stop mode.For a VHS type VTR, L = 10, V = 33.
, 35 arms/S, so L/V is 3 seconds.

Now ~ the two time constants T, , T2 of the oscillation circuit 52 ~T
, = 0.9 seconds and L: 2 seconds, the current consumption of the lamp 38 can be significantly reduced to 1/5 compared to the conventional case where the lamp 30 is always turned on. In addition, “VTR
When the pause button is pressed, the contact 56 closes, the output of the oscillation circuit 52 becomes Low, and the transistor 42 turns OFF.
become.

That is, in the paused state, power supply to the lamp 30 is temporarily stopped, making it possible to further extend the battery life. FIG. 4 is a diagram showing another configuration example of the power supply control means for periodically intermittent power supply to the lamp 30.
The same parts as those explained in the figures are given the same reference numerals.

In FIG. 4, the base 48 of transistor 42 is connected through a resistor 50 to a monomultipolar plate 58. In FIG.

The input terminal 606 of the mono-multivibrator 58 is connected to a power supply terminal via a read switch 66 that is sensitive to a permanent magnet 64 attached to a part of a reel stand 62 that engages with the reel hub 4 in the cassette 2 and rotates integrally. It is connected to 54. The operation of the circuit shown in FIG. 4 will be explained with reference to the time chart shown in FIG. Now, when the VTR is placed in constant speed running mode, a predetermined power source pressure is applied to the power supply terminals 36 and 54.

Since the magnetic tape 8 is unwound from the supply V supply side reel hub 4 by the capstan 26 and the pinch roller 28,
The reel base 62 that engages with the reel hub 4 and rotates integrally also rotates, and the reed switch 66 is intermittently turned on and off in response to the permanent magnet 64. A pulse rope pressure proportional to the rotation period of the reel table 62 is applied, and as a result, the lamp 30 blinks in synchronization with the rotation period of the reel table 62. In this case, when there is a large amount of magnetic tape 8 to be wound around the V supply side reel hub 4 at the beginning of winding, the lamp 30 blinks at a long cycle, and when the end of winding approaches and the remaining amount of tape on the reel hub 4 decreases, the lamp 30 blinks at a long cycle. Since the lamp 30 is short and flashes at regular intervals, it is possible to further reduce the power consumption of the lamp 30 than in the embodiment shown in FIG. 1 with VHS system VTR
For a 20 minute tape, the radius of the supply reel at the beginning is approximately 4
3, the lighting cycle of the lamp 30 is about 8.1 seconds, and the radius of the supply reel at the end of the winding is about 13 seconds, so the lighting cycle of the lamp 30 is about 2.4 seconds, and the second The power consumption of the lamp 30 can be further reduced significantly compared to the illustrated embodiment.

As explained in detail above, the magnetic recording/reproducing device of the present invention has the following features:
The light emitting element is periodically controlled by periodically controlling the supply current to the light emitting element constituting the tape end detection device for detecting the arrival of the end of the magnetic tape and therefore the arrival of the translucent leader tape. This makes it possible to achieve significantly lower power consumption compared to the case where power is continuously supplied to the light-emitting element like a slave. In a portable magnetic recording/reproducing device, the effect is remarkable.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a biden tape recorder, FIG. 2 is a configuration diagram of main parts of an embodiment of the present invention, FIG. 3 is a time chart for explaining the operation of the embodiment of FIG. 2, and FIG. 5 is a circuit diagram of a main part of another embodiment of the present invention, and FIG. 5 is a time chart for explaining the operation of the embodiment of FIG. 4. 2... Cassette, 4, 6... Reel hub, 8... Magnetic tape, 18... Drum, 30... Lamp, 34... Light receiving element, 36, 54... Power supply terminal, 42... Transistor, 5
2... Oscillation circuit, 58... Mono multi-vibrator, 62... Reel stand, 64... Permanent magnet, 66... Reed switch. Figure 2 Figure 3 Figure 1 Figure 4 Figure 5

Claims (1)

[Scope of Claims] 1. A magnetic tape having a translucent leader tape at the end thereof is wound, the magnetic tape is pulled out from a built-in cassette, and is attached to the outer periphery of a drum containing a rotating magnetic head. The magnetic recording/reproducing device is configured to run a magnetic recording/reproducing device, the optical end detection means detecting the arrival of the leader tape by a combination of a light emitting element and a light receiving element, and a current periodically supplied to the light emitting element when the magnetic tape runs. and a power supply control means that performs intermittent control on and off, and the distance from the detection unit that detects the leader tape using the light emitting element and the light receiving element to the point where the magnetic tape contacts the drum is L, and the distance of the magnetic tape is L. When the running speed is V, the period T in which the power supply control means periodically intermittents the current to the light emitting element is set to T<L/V, and the leader tape reaches at least the drum. A magnetic recording/reproducing device characterized in that the light emitting element is turned on once. 2. In the description of claim 1, the power supply control means is configured such that the supply side reel base, which is engaged with and rotates integrally with the reel hub of the cassette around which the magnetic tape is wound, has a high rotational speed. A magnetic recording and reproducing apparatus characterized in that the power supply cycle variable means is controlled so that the power supply cycle becomes shorter when the magnetic tape reaches the end, and the blinking cycle of the light emitting body is made faster as the end of the magnetic tape approaches. .