JPS5947375B2 - Tape remaining amount display device for magnetic recording/reproducing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape remaining amount display device for a magnetic recording/reproducing machine.
The purpose is to make it possible to know the remaining tape running time at a glance.

Conventional magnetic recording and reproducing machines are equipped with a mechanical tape counter so that any position on the tape and the amount of tape travel can be determined.

This tape counter is simply constructed so that multiple number plates rotate with the rotation of the reel stand, so if you want to know the remaining amount of tape, it is necessary to run all the tapes beforehand. You cannot know the remaining amount of tape unless you check the number indicated on the tape counter, memorize this number, and organize the number while the tape is running and the number memorized above in your head. It was hot.
Moreover, in this case, it is extremely difficult to grasp the remaining amount of tape in terms of time; for example, the remaining amount of tape is about half of the total amount of tape, considering that the tape being used is for 30 minutes on one side. All I knew was that there were probably about 15 minutes left. Furthermore, the total distance traveled by the tape varies depending on the thickness of the tape used and the reel diameter, so when replacing the tape, it is first necessary to check the number on the counter for the total distance traveled by the tape. It was extremely troublesome. Therefore, in recent years, devices have been provided that can indicate the amount of tape travel by the deflection of a meter pointer, but this type of device transmits the rotation of the take-up reel stand to a rotating body via a belt. By using a magnet installed around the outer circumference of this rotary body, a reed switch placed near it is opened and closed, and by focusing on the fact that the opening and closing time of this reed switch slows down as the tape runs, this opening and closing operation is performed. In this system, a meter is driven by replacing the change in time with a change in current, and the amount of tape travel is determined by the percentage scale provided on the meter.

However, this type of device has the disadvantage that, like cassette tapes, if the tapes have different thicknesses, lengths, reel hub diameters, etc., the amount of tape travel cannot be accurately determined. For example, if you use a 90-minute cassette tape,
If you adjust so that the meter pointer indicates 0% at the start of tape running and 100% at the end of tape running, it will be 75% when using a 45-minute force setting tape, and 30 minutes. In the case of using a force setting tape, the tape running ends at the 50% position. Therefore, it goes without saying that it is not possible to know the remaining amount of tape in terms of time at a glance, and if the type of tape used changes, the maximum deflection position of the meter pointer must be checked in advance. It was no longer possible to know the remaining amount of tape, and it had the same drawbacks as the mechanical tape counter mentioned above. In view of these conventional drawbacks, the present invention is designed to enable the remaining amount of tape to be known in terms of time at a glance.One embodiment of the present invention will be described below with reference to the drawings.

In the figure, reference numeral 1 denotes a tape cassette in which a magnetic tape 2 is wound and stored around two reel hubs 3 and 4 with both ends thereof fixed to the two reel hubs 3 and 4, and a supply reel stand 3''.
, is attached to the take-up reel stand 4''. Reference numerals 5 and 6 indicate a capstan and a pin 5 that sandwich and drive the magnetic tape 2.
The pinch roller 6 is configured to be pressed against the capstan 5 only during recording and reproduction.

7 is a supply side motor that rotates the supply reel stand 3'' of force set 1 clockwise to perform high-speed winding of the tape during the winding operation; 8 is a motor that rotates the take-up reel stand 4'' of force set 1; This is the winding side motor that rotates clockwise to wind the tape during recording/playback operations or high-speed winding of the tape during fast forwarding operations, and is the supply side motor 7.
is connected to a motor drive power source 10 via switches 9a and 9b, and the winding side motor 8 is connected to a power source 1 via a switch 11.
Connected to 0.

The switches 9a, 9b and 11 are switched to the fixed contact a side to rotate only the winding side motor 8 during recording/reproducing operation or fast forward operation, and are switched to the fixed contact b side to rotate the supply side motor during the winding operation. Rotate only 7. It should be noted that the voltage applied to the take-up motor 8 differs during recording and reproducing operations and during fast-forwarding operations, and its rotational speed changes to a value suitable for both of the above operations, but this configuration is not directly related to the present invention and will therefore be omitted. ing.

12a and 12b are switches that are switched to the fixed contact d side only during recording and reproducing operations, and are switched to the fixed contact c side during operations other than recording and reproducing, and are electrically supplied from the motor drive power source 10 during recording and reproducing operations. The side motor 7 is connected to the differential amplifier 13.

The differential amplifier 13 includes a transistor 15 whose base is connected to the movable contact of the switch 12a via a resistor 14;
This collector resistor 16, a transistor 17 whose emitter is commonly connected to the emitter of the transistor 15, this collector resistor 18, a common emitter resistor 19 of the transistors 15 and 17, the base of the transistor 17, and the positive and negative sides of the power supply 20. A resistor 21 and a semi-fixed resistor 22 are connected between the resistor 21 and the semi-fixed resistor 22, respectively, and a power supply 23 is connected in series to the power supply 20 and has its negative terminal connected to the common emitter resistor 19. A series circuit of a semi-fixed resistor 24 and a tape remaining amount display meter 25 is connected between the collectors of the two transistors 15 and 17 constituting the differential amplifier 13. The tape remaining amount display meter 25 has a pointer 26 and three time scales 28 and 29 as shown in FIG.
have. The time scale 27 is a scale for a tape young set that can run for 90 minutes in a round trip, that is, a scale for a C-90 force set, the time scale 28 is a scale for a C-60 and C-45 force set, and the time scale 29 is a scale for a tape with a normal reel hub diameter. This is a scale for large hub cassettes. For example, considering the scale 27 for the C-90, the time scale is only set from O to 24 minutes, whereas the one-way running time for force setting is 45 minutes, which indicates the remaining tape time. Since it is thought that it is necessary to know this only when the tape running is nearing the end, it is of course possible to provide a total running time scale. In the embodiment described above, during the recording/reproducing operation, the magnetic tape 2 is made to travel at a constant speed in the direction of the arrow by the capstan 5 and the pinch roller 6, and is wound onto the take-up reel hub 4 side. At this time, the supply reel hub 3 and the reel stand 3'' are rotated in the direction of the arrow as the tape runs, and the number of rotations is determined by the fact that the tape winding diameter of the supply reel hub 3 gradually decreases as the tape runs. It gradually rises.Therefore, the above reel hub 3
The supply motor 7 that drives the tape operates as a generator, and its generated voltage gradually increases as the tape progresses. The voltage generated by the supply motor 7 is applied via a resistor 14 to the base of one transistor 15 constituting a differential amplifier, changing the conduction state of the transistor 15 and changing its collector voltage.

This change in collector voltage decreases in inverse proportion to the rotational speed of the motor 7 because the voltage applied to the base of the transistor 15 increases as the rotational speed of the motor 7 increases. Therefore, when the running of the magnetic tape 2 progresses and is just before reaching the end, that is, when the collector voltage of the transistor 15 is the lowest, the semi-fixed resistor 10 is adjusted to change the base voltage of the transistor 17, and the collector voltage of the transistor 17 is adjusted. The voltage is made equal to the collector voltage of the transistor 15, and the current flowing through the meter 25 is made zero.

At this time, the pointer 26 of the meter 25 points to the left end of the scale 27J. Also, immediately after the magnetic tape 2 starts running, the collector voltage of the transistor 15 is at its highest, so at this time, the semi-fixed resistor 24 is adjusted to adjust the current flowing to the meter 25, and the pointer 26 of the meter 25 is adjusted. Adjust so that the right end of the scale 27 is indicated, that is, the full scale position. By making the above adjustments at the manufacturing stage,
As a result, the pointer 26 of the meter 25 gradually swings from the full scale position of the scale toward the O minute position from the start of the tape run to the end of the run, and in the swing process. If you use the c-90 scale, you can directly read the remaining tape time from 24 minutes to O minutes. By the way, tape cassettes commonly used include the C-60 force set with a tape thickness of 18μ and the C-90 force set with a tape thickness of 12μ, and the total length of the tape in each cassette is different. .

Also, in recent years, large hub force sets, such as the above-mentioned C-60 force set or C-90 force set, have appeared, which have a reel hub larger in diameter than the reel hub. In this embodiment, three types of time scales 27 to 29 are provided for these various force setting tapes so that the remaining amount of tape can be directly read. meter 2
Adjustment of the deflection range of the pointer 26 of No. 5 is as explained earlier.
Since this is done using the -90 scale 27, c -
When using the 60 force set, the pointer 26 of the meter 25 does not swing to the full scale position, but the c-90, c. -60
Since the diameter of the reel hub is the same for both force sets, the 0 minute position is the same, and the remaining tape time is 24 minutes to 0 minutes for the C-90 force set, and for the C-60 and C-45 force sets. It can be read directly from 15 minutes to 0 minutes. Ru. For large hub cassettes, since the diameter of the reel hub is larger than the normal force setting, the position slightly to the left of the middle position between the scales 27 and 28 is the O minute position, and the remaining tape time from 12 minutes to 0 minutes can be directly read. As is clear from FIG. 2, as the remaining time on the tape approaches 0 minutes, the intervals between the time scales become wider, making it easier to read. Parts 27a to 2 of the above time scales 27 to 29 from 0 minutes to 3 minutes
By making 9a a different color from the other parts, you can alert the user when the remaining amount of tape is running low. This prevents you from missing a recording. As described above, the present invention utilizes the fact that the electromotive force generated in the supply motor is approximately proportional to the rotation speed of the supply reel base, and uses this voltage as one input of the differential amplifier to increase the differential voltage. The pointer of the meter connected between the collectors of the two transistors of the amplifier was swung from the maximum deflection position to the minimum deflection position, and a time scale was provided on the motor to enable continuous running of the remaining amount of tape. It is something.

With this configuration, the remaining amount of tape can be seen to be continuous in time, which is extremely convenient for use. Furthermore, by using the supply side motor, not only is there no need to provide a special rotation speed detection device for the reel stand, but the supply side motor is also used to apply back tension, which has a significant effect on space saving and cost reduction. It is something that plays. In addition, if the meter is equipped with multiple time scales that correspond to multiple types of tapes with different tape thicknesses and lengths, there is an advantage that the remaining amount of tape can be read directly in terms of time for each type of tape. be.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a front view of a tape remaining amount display meter. 1... Tape cassette, 3, 4...
Reel hub, 3', 4'...Reel stand,
7... Supply side motor, 8... Winding side motor, 13... Differential amplifier, 15, 17...
...Transistor, 25...Tape remaining amount display meter.

Claims (1)

[Claims] 1. A take-up side motor that drives the take-up reel stand when the tape is running at a constant speed and during high-speed fast forwarding, and a supply side motor that is separate from this take-up motor and that drives the supply reel stand when the tape is rewinded; A supply reel that is taken out from the winding terminal of the supply side motor, and includes a differential amplifier having two transistors, and a tape remaining amount display meter connected between the collectors of each of the two transistors constituting the differential amplifier. Applying a voltage approximately proportional to the rotation speed of the stand to the base of one transistor constituting the differential amplifier,
A magnetic recording/reproducing device in which the pointer of the meter swings from the maximum position at the start of tape running and swings toward the minimum position as the tape runs, and the meter is provided with a time scale for displaying the remaining amount of tape. The machine's tape remaining amount display device.