JPH0240597Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a magnetic recording and reproducing device, and in particular, a magnetic recording and reproducing device that detects the start or end of winding of a magnetic tape using a light emitting section provided in a video tape recorder (hereinafter referred to as VTR). Concerning improvements to equipment.

As is well known, in order to reduce the load on the motor that occurs when the video cassette tape (hereinafter referred to as video cassette) is completely wound, VTRs are equipped with
It was necessary to detect when the video cassette had finished winding and stop it.

FIG. 1 provides the background of this invention and shows a plan view of the interior of a video cassette to which this invention is applied.

Figure 2 provides the background for this invention and shows an illustrative view of a VTR to which this invention is applied with a video cassette attached.

As shown in FIG. 1, the video cassette 10 has a magnetic tape 11, a take-up reel 12,
and a rewind reel 13. The magnetic tape 11 has transparent leader tapes formed at the beginning and end of the magnetic tape 11. Take-up reel 12
rotates clockwise to wind up the magnetic tape 11.
The rewind reel 13 rotates counterclockwise to rewind the magnetic tape 11. Also, video cassette 1
A lamp insertion hole 14 and a light transmission hole 15 for detecting the start or end of winding of the magnetic tape 11 are formed in the magnetic tape 11 . The lamp insertion hole 14 is connected to the magnetic tape 11 running between the take-up reel 12 and the rewind reel 13.
It is formed on the side and has a diameter that allows insertion of a lamp 30, which will be described later. The light transmission hole 15 is connected to the magnetic tape 1
1 side, and are formed at positions on both sides where the light from the lamp 30 can be detected through the leader tape of the magnetic tape 11.

The VTR 20 has a magnetic tape 1 as shown in Figure 2.
A guide pin 21, a tension arm 22, an erasing head 23, an impedance roller 24, a drum 25, an audio head 26, a control head 27, a capstan shaft 28, and a pinch roller 29 are provided on the path along which the recording medium 1 travels. Further, a lamp 30 serving as a light source for optically detecting the end of the winding of the video cassette is provided between the take-up reel 12 and the rewind reel 13, and
The vehicle is placed on the side where the vehicle travels. A termination detector 32 and a termination detector 31 for detecting light from the lamp 30 are provided corresponding to the light transmission hole 15. The outputs of this start end detector 32 and end end detector 31 are transmitted to the control circuit 3.
given to 3.

The video cassette 10 configured in this way is
Attached to VTR20. Therefore, the magnetic tape 11 is guided by the guide pin 21, is sandwiched between the capstan shaft 28 and the pinch roller 29, and travels by the rotation of the capstan shaft 28. Further, the tension of the magnetic tape 11 is kept constant by a tension arm 22, and the magnetic tape 11 runs stably by an impedance roller 24. At this time, when recording and reproducing video signals, a head built into the drum 25 performs the recording, a control signal is recorded and reproduced by the control head 27, and an audio signal is recorded and reproduced by the audio head 26. It can be done. Note that erasing of recorded signals is performed by an erasing head 23.

Figure 3 shows a lighting block diagram of a lamp used in a VTR.

Next, the operation of detecting the end of a video cassette of a VTR will be explained with reference to FIGS. 1 to 3. First, when power is supplied to the VTR 20 from the power source 34, a current flows through the load resistor 35 as shown in FIG. 3, and the lamp 30 lights up. At this time,
When the video cassette 10 is attached to the VTR 20 and the magnetic tape 11 is completely wound on either the take-up reel 12 or the rewind reel 13, the magnetic tape 11 is passed through the light transmission hole 15 to the start end detector 32.
And the end detector 31 properly detects the light of the lamp 30. Accordingly, the start end detector 32 and the end end detector 31 provide a signal detecting the light of the lamp 30 to the control circuit 33. Therefore, the control circuit 33
VTR20 recording, playback mode, pause mode,
Controls so that fast forward, rewind mode, and speed search mode are not activated.

Note that the same operation is performed even when the video cassette 10 is not attached to the VTR 20.

Further, when the video cassette 10 is attached to the VTR 20 and the magnetic tape 11 is in contact with the drum 25 and the recording mode is being operated, the light from the lamp 30 is blocked by the magnetic tape 11, so that the start edge detector No light is transmitted to 32 and end detector 31. Therefore, the control circuit 33 continues the recording operation.

Note that the above-mentioned operations occur in the playback mode, in the speed search mode, when the recording, playback mode, or speed search mode is not in operation, and when the magnetic tape 11 is not in contact with the drum 25 and fast-forwarding or rewinding. A similar operation is performed for the mode.

Next, when either the leader tape at the start end or the end end of the magnetic tape 11 reaches the start end detector 32 or the end end detector 31, the start end detector 32 and the end end detector 31 detect the leader tape and the end end of the magnetic tape 11. Lamp 3 through light transmission hole 15
0 light is detected and the control circuit 33 is operated. That is, in a recording mode in which the magnetic tape 11 runs clockwise, the control circuit 33
The recording operation is stopped based on the detection of the light from the lamp 30. Similarly, the above-described operation is performed in the playback mode, fast forward mode, and speed search mode. In addition, in the rewinding mode in which the magnetic tape 11 runs counterclockwise, the control circuit 33 causes the start end detector 32 to
The rewinding operation is stopped based on the detection of the zero light.

On the other hand, when the lamp 30 becomes disconnected, no current flows through the load resistor 35, so the disconnection detection circuit 36 stops the VTR 20 from operating in each operation mode.

As described above, conventional VTRs have the disadvantage that several tens of milliamps of current flows through the lamp while power is being supplied, resulting in increased power consumption. These problems are particularly noticeable in portable battery operated VTRs, which have the disadvantage of significantly shortening the battery life.

Therefore, an object of this invention is to provide a magnetic recording/reproducing apparatus which is inexpensive and has a simple circuit configuration and can detect the start or end of winding of a magnetic tape with low power consumption.

In summary, this invention is such that the current supplied to the light emitting section is intermittently controlled based on each operating mode of the magnetic recording/reproducing device.

Embodiments of this invention will be described below with reference to the drawings.

FIG. 4 shows a block diagram of a magnetic recording/reproducing apparatus according to an embodiment of this invention. In the configuration, the magnetic recording and reproducing apparatus includes a pulse generation circuit 41 as an example of a first pulse generation means, a pulse generation circuit 42 as an example of the second pulse generation means, a switching circuit 43 as an example of the switching circuit means, and a display driving means. An example of transistor 4
4. Light emitting diode (hereinafter referred to as LED) is an example of a light emitting part.
) 45, a mode switching circuit 46 for switching the operation mode of the VTR 20, an LED blinking detection circuit 47,
and resistors 48a and 48b. The pulse generation circuit 41 includes an oscillation circuit 411 as an example of pulse generation means, a frequency division circuit 412 as an example of frequency division means, and a waveform shaping circuit 413 as an example of first waveform shaping means. The pulse generation circuit 42 includes an oscillation circuit 411 and a waveform shaping circuit 421 which is an example of a second waveform shaping means.
including. The switching circuit 43 includes three-state type buffer circuits 431-433. The mode switching circuit 46 includes an operation key 461, an operation key input acquisition circuit 462, OR circuits 463 and 465, and a three-state type buffer circuit 464 that disables the output of the OR circuit 463 during the pause mode, which will be described later. including. The LED blinking detection circuit 47 detects conduction or non-conduction of the LED 45 based on the output of the switching circuit 43 and the collector terminal output of the transistor 44, and performs the same operation as the disconnection detection circuit 36.

More specifically, an oscillation circuit 411 that oscillates at several 100 Hz is connected to a frequency dividing circuit 412 and a waveform shaping circuit 421. A frequency dividing circuit 412 divides the output of the oscillation circuit 411 into a 1 Hz cycle and is connected to a waveform shaping circuit 413. A waveform shaping circuit 413 changes the duty ratio of the output of the frequency dividing circuit 412 to a ratio of 1:9, and is connected to a buffer circuit 431. Also,
The waveform shaping circuit 421 changes the duty ratio of the oscillation circuit 411 output at a ratio of 7:3, and
32.

The operation key 461 is operated from the outside to switch between various operation modes of the VTR 20, and is connected to an operation key input receiving circuit 462. The input acquisition circuit 462 supplies a switching signal based on switching of the operation key 461 to a buffer circuit 433 connected to a power supply.
At the same time, data signals corresponding to each operation mode are output to OR circuits 463 and 465. This switching signal is output for a certain period of time so that the LED 45 emits light when the operation mode of the operation key 461 is switched. That is, the switching signal consists of the chattering time when switching the operation mode of the operation key 461 and the time for decoding the data signal corresponding to each operation mode, specifically, the number of seconds.
Output only for 10msec. OR circuit 463
A data signal corresponding to a recording or reproducing mode in which the running speed of the magnetic tape 11 is slow is inputted from an input acquisition circuit 462 and connected to a buffer circuit 464 . The buffer circuit 464 is the input acquisition circuit 462
A data signal corresponding to the pause mode is inputted and connected to the buffer circuit 431 . The OR circuit 465 receives data signals corresponding to the fast forward/rewind mode and the speed search mode in which the magnetic tape 11 runs at a high speed from the input acquisition circuit 462 and is connected to the buffer circuit 432 . Buffer circuits 431-433 are connected to the base end of transistor 44 via detection circuit 47 and resistor 48a. The collector end of the transistor 44 is connected to a detection circuit 47 and a resistor 4 connected to a power supply.
It is connected to LED45 via 8b. The emitter end of transistor 44 is grounded.

FIG. 5 is an output waveform diagram of each circuit section for explaining the operation of FIG. 4, in particular, a is the oscillation circuit output,
b shows the frequency dividing circuit output, and c and d show the waveform shaping circuit output.

Next, the operation of this embodiment will be explained with reference to FIGS. 4 and 5.

(1) Operation in recording/playback mode.

First, the operation in the recording mode will be explained. In this case, from the power supply to the buffer circuit 433
A voltage is supplied to the collector end of the transistor 44 via the resistor 48b and the LED 45. Further, the oscillation circuit 411 is configured as shown in FIG. 5a.
Oscillates at a cycle of 10msec. The output of this oscillation circuit 411 is input to a frequency dividing circuit 412 and a waveform shaping circuit 421. Accordingly, the frequency dividing circuit 412 divides and outputs the output of the oscillation circuit 411 to the waveform shaping circuit 413 at Isec cycles as shown in FIG. 5B. The output of the frequency dividing circuit 412 given to the waveform shaping circuit 413 has a duty ratio of 1:9 as shown in FIG. The waveform is shaped by The output of this waveform shaping circuit 413 is input to a buffer circuit 431. Furthermore, the output of the oscillation circuit 411 given to the waveform shaping circuit 421 has a duty ratio of 7:3 as shown in FIG.
The waveform is shaped at a rate of 3msec. The output of this waveform shaping circuit 421 is input to a buffer circuit 432. At this time, since the VTR 20 is in the recording mode, the operation key 461 is operated to the recording mode.
In response, input acquisition circuit 462 provides a switching signal to buffer circuit 433. Therefore, the buffer circuit 433 supplies the voltage from the power supply to the base end of the transistor 44 and the control circuit 47 via the resistor 48a. Further, a voltage is supplied to the collector end of the transistor 44 via a resistor 48b and an LED 45. As a result, the buffer circuit 433
The LED 45 emits light during the period in which the switching signal is applied. Accordingly, when the switching signal derivation period ends, the input acquisition circuit 462 supplies the data signal corresponding to the recording mode to the buffer circuit 464 via the OR circuit 463. Therefore, buffer circuit 464 provides a data signal to buffer circuit 431. Accordingly, the buffer circuit 431 connects the output of the waveform shaping circuit 413 shown in FIG.
Give to 7. As a result, the LED 45 emits light during a high level period of 0.1 sec as shown in FIG.

Therefore, in the VTR 20, the end detector 31 detects the end of the video cassette in the recording mode based on the blinking display of the LED 45, and stops the recording operation.

That is, the speed of the magnetic tape 11 in the recording mode is approximately 3.3 cm/sec according to the VHS standard, and the length of the transparent leader tape of the magnetic tape 11 is
Since the length is 15 to 19 cm, even if the end detector 31 detects the light from the LED 45 with a delay of about 2 to 3 seconds, it can sufficiently detect the end of winding of the video cassette and stop the recording operation.

Note that the operation in the reproduction mode is the same as the operation in the recording mode, so a description thereof will be omitted.

(2) Behavior in pause mode.

In recording mode or playback mode, when operation key 461 is operated to pause mode, input acquisition circuit 462 provides a switching signal to buffer circuit 433. Therefore, during a very short period of time when the switching signal is given to the buffer circuit 433, the LED 45
The light will be displayed. However, when the switching signal is no longer derived, input acquisition circuit 462 derives a high level pause signal to disable buffer circuit 464. Therefore, the buffer circuit 464 disables the buffer circuit 431 and stops deriving the output of the waveform shaping circuit 413. That is, the output of the buffer circuit 431 becomes low level. As a result, the transistor 44 becomes continuously non-conductive, and the LED 45 ceases to emit light.
Therefore, the current supplied to the LED 45 can be reduced.

(3) Operations in fast forward/rewind mode and speed search mode First, operations in fast forward mode will be explained. In this case, the operation key 461 is operated to fast forward mode, and the input acquisition circuit 462 provides a switching signal to the buffer circuit 433. Therefore, the period during which the switching signal is given to the buffer circuit 433 is
The LED 45 emits light. Accordingly, when the derivation period of the switching signal ends, the input acquisition circuit 462 inputs the data signal corresponding to the fast forward mode to the OR circuit 46.
5 to the buffer circuit 432. Therefore, the buffer circuit 432 supplies the output of the waveform shaping circuit 421 shown in FIG. 5d to the base end of the transistor 44 and the control circuit 47. As a result, the LED
45, as shown in FIG. 5d, displays a flashing display by emitting light during a period of 7 msec and not displaying emitting light during a period of 3 msec.

Therefore, when the VTR 20 is in the fast forward mode, the end detector 31 detects the end of the video cassette and stops the fast forward operation.

That is, although the speed of the magnetic tape 11 in the fast-forward mode is approximately 1 cm/10 msec according to the VHS standard, the end detector 31 can sufficiently detect the end of the video cassette because the light emission period of the LED 45 is fast, allowing the fast-forward operation to be performed. It can be stopped.

In the speed search mode, the outputs of the waveform shaping circuits 413 and 421 shown in FIGS.

However, since the output of the waveform shaping circuit 421 shown in FIG. 5d has a faster period than the output of the waveform shaping circuit 413 shown in FIG.
Only the output will be given.

Therefore, since the operation in the speed search mode is similar to the operation in the fast forward mode, the explanation will be omitted.

Further, the operation in the rewind mode is similar to the operation in the fast forward mode, except that the start end detector 32 detects the operation, so a description thereof will be omitted.

In addition, in the above example, an LED is used for the light emitting part in consideration of short-time luminance and lifespan, but the invention is not limited to this. If so, an incandescent light bulb would be fine. In addition, in the above embodiment, the LED light emission cycle was explained using a 1sec cycle and 10% duty ratio in recording/playback mode, and a 10msec cycle and 70% duty ratio in fast forward/rewind mode and speed search mode. However, the present invention is not limited to this, and the light emission period of the LED may be selected in consideration of the sensitivity of the detector and the operating time of a control circuit that receives and controls the output of the detector.

As described above, the magnetic recording/reproducing apparatus has the advantage that the power supplied to the light emitting section can be changed intermittently based on the operating mode when the running speed of the magnetic tape is slow or fast.

As described above, this invention has the unique feature that it is possible to significantly reduce the power consumption of the light emitting part with an inexpensive and simple circuit configuration, reduce battery consumption, and detect the beginning or end of winding of the magnetic tape. The effect is produced.

[Brief explanation of the drawing]

FIG. 1 provides the background of this invention and shows a plan view of the interior of a video cassette to which this invention is applied.
Figure 2 provides the background for this invention and shows an illustrative view of a VTR to which this invention is applied with a video cassette attached. Figure 3 shows a lighting block diagram of a lamp used in a VTR. FIG. 4 shows a block diagram of a magnetic recording/reproducing apparatus according to an embodiment of this invention. FIG. 5 shows an output waveform diagram of each circuit section for explaining the operation of FIG. 4. In the figure, 411 is an oscillation circuit, 412 is a frequency dividing circuit, 413 and 421 are waveform shaping circuits, and 43
is a switching circuit, 44 is a transistor, 45 is an LED,
46 indicates a mode switching circuit.

Claims (1)

[Claims for Utility Model Registration] (1) A magnetic recording and reproducing device that magnetically records or reproduces data using a magnetic tape in which a light-transmitting portion capable of transmitting light is formed at each of the starting end and the terminating end. , the magnetic recording and reproducing are performed in a first operation mode in which the magnetic tape runs at a low speed;
The magnetic recording/reproducing device has a second operation mode in which the magnetic tape runs at a faster speed than the first operation mode, and the magnetic tape has a light transmitting portion at a starting end or a trailing end at the beginning or end of winding. a light-emitting part provided to correspond to the position of the magnetic tape; a first light-receiving part that receives light from the light-emitting part through the light-transmitting part of the starting end at the beginning of winding the magnetic tape; and the end of winding of the magnetic tape. a second light receiving section that receives light from the light emitting section through the light transmitting section of the termination section; a first pulse signal that generates a first pulse signal having a first frequency based on the traveling speed in the first operation mode; 1 pulse generating means; a first duty ratio control means connected to the first pulse generating means and controlling the duty ratio of the first pulse signal based on the traveling speed in the first operation mode; a second pulse generating means for generating a second pulse signal based on the traveling speed in the second operating mode and having a second frequency higher than the first frequency; connected to the second pulse generating means; a second duty ratio control means for controlling the duty ratio of the second pulse signal to be higher than the first pulse signal based on the traveling speed in the second operation mode; the first and second duty ratio control means; switching means for selectively outputting a first or second pulse signal whose duty ratio is controlled based on the operation mode; and a first or second pulse signal output from the switching means. a magnetic tape that detects the start or end of winding of the magnetic tape based on the output of the first light receiver or the second light receiver; Recording and playback device. (2) The magnetic tape is a cassette tape stored in a cassette, and the cassette tape has a hole into which the light emitting part can be inserted at a position where the light emitting part is formed, and a hole is formed at the beginning of winding of the magnetic tape. A request for registration of a utility model, wherein a portion of the starting end facing the light transmitting portion and a portion facing the light transmitting portion of the trailing end at the end of winding of the magnetic tape are each formed to be able to transmit light. The magnetic recording and reproducing device according to item 1.