JPS6159679A - Tape remaining quantity detecting circuit - Google Patents

Abstract

PURPOSE:To detect a remaining quantity of a tape before recording and reproducing are started by pulling out the tape from a supply side reel only at the time of loading, then, detecting a rotating condition of the supply side reel and calculating the remaining quantity of the tape. CONSTITUTION:A brake 7 is installed to a winding side reel hub 2, a brake force is given to the winding side reel hub 2 at the time of loading, a brake releasing device 8 is operated and the brake force is released. Near a tape guide pin at the supply side, a tape end detecting circuit 9 using a photo sensor, etc., is installed, and when a tape end is detected during recording and reproducing, a travelling of the tape is automatically stopped. At the end of the tape, a transparent or reflecting-type reader tape is used. At the time of loading, by giving a brake force to the winding side reel hub 2 with the brake 7, the operation is executed only from a pulling-out supply side reel of the tape at the time of loading.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic tape recording and reproducing device that records and reproduces information by feeding a tape at a constant speed, such as a tape recorder or a video tape recorder (VTR). The present invention relates to a tape remaining amount detection device.

[Conventional technology]

Conventionally, various methods have been proposed or implemented as devices for detecting the remaining amount of tape (remaining recording/playback time) in magnetic tape recording/playback devices, and these methods are already known.
Basically, a means is provided to detect the rotational angular velocity or rotation period of the take-up reel and the supply reel, and the angular velocity and/or period of the two reels are detected when the tape is running at a constant speed, and based on that, Calculating the remaining amount of tape.

Here, an example of conventional tape remaining amount calculation using only the rotation angular velocity or rotation period of the supply reel will be given.

The winding radius of the supply reel is r, the hub diameter is ro + the length of the tape wound on the supply reel.

If the thickness of the tape is δ, δL: π(rJ-r(1')...11)
If the constant feeding speed of the tape is υ and the angular velocity of the supply reel at that time is ω, then δL=x ((v/w)'-ro'')-(2).

Here, if the remaining amount of tape is expressed by the tape supply time Ts, then L=υ·Ts.

Ts-π/δυ [(υ/ω)"ro")...(
3).

Furthermore, if the period of the supply reel, that is, the time required for one rotation is T, then 1JJ=2π/T, so T s
= 7C/δυ [(υ/27C)” T' r g
”), ・
...(4) In other words, if the tape running speed υ is constant,
If the angular velocity W of the supply reel is known, the formula (3
), and if the period T is known, the formula (
4] can be used to determine the remaining tape amount Ts.

[Problem that the invention seeks to solve]

By the way, the conventional tape remaining amount detection device using such a method uses the angular velocity Iυ or period T of the supply reel or take-up reel when the tape is running at a constant speed, so it is difficult to detect whether the tape is being used in a recording/playback device. After setting the tape to 1, the remaining amount of tape cannot be detected unless the tape is run at a constant speed.

Therefore, in order to know the remaining amount of tape, there is a problem that recording or reproducing must be performed until the angular velocity or cycle of at least one of the reels can be detected.

[Means for solving problems]

This invention was made in order to solve the above-mentioned problems in a magnetic tape recording and reproducing device having a tape loading mechanism. The tape is always pulled out only from the supply reel, except when the tape is pulled out from the supply reel, the rotational state of the supply reel at that time is detected, and the remaining amount of tape is immediately calculated based on the detection result. .

The rotation state of the supply reel is the rotation angle.

Detects rotation period or rotation angular velocity.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The remaining tape amount detection device according to the present invention detects the rotational state of the supply reel during loading and calculates the remaining amount of tape based on the detection result. It is necessary to provide a means for always drawing out the tape only from the supply reel.

First, FIG. 2 shows an example of a tape loading mechanism with such a tape pulling means.

The tape 3 wound around the supply reel hub 1 and the take-up reel hub 2 is guided by a pair of tape guide pins 4.4, and is moved in the direction of arrow A from the position shown by the broken line by a pair of loading pins 5. It is moved and wound along the outer peripheral surface of the rotary head 6.

A brake 7 is provided on the take-up reel hub 2, which applies braking force to the take-up reel hub 2 during loading, and releases the braking force when a brake angle removing device 8 operates.

Also, near the tape guide pin 4 on the supply side.

A tape end detection device hi9 using a photo sensor or the like is provided, and when the end of the tape is detected during recording or playback, the running of the tape is automatically stopped. A transparent or reflective adhesive tape is used at the end of the tape.

At the time of loading, the brake 7 applies a braking force to the take-up reel hub 2, so that the tape is pulled out only from the supply reel during loading.

If the end of the tape is detected by the tape end detection device during loading, of course there is no remaining tape, so this is displayed and the brake release device 8 is activated, and the brake 7 is activated at the reel hub on the winding side. The brake force applied to 2 is released, and the tape 3 is pulled out from the take-up reel.

At this time, since the tape winding diameter on the take-up side is larger than that on the supply side, unless the brakes are applied on both reels, the tape 3 will be pulled out from the take-up reel, which has a large moment against the reel rotation. That's why.

In this example, the end of the tape is detected optically,
Although the brake force on the take-up reel is released, simply speaking, when the supply reel is locked at the end of the tape, the brake 7 is released and the brake force is released to the extent that the tape 6 is pulled out from the take-up reel. You can just set the brake force.

Although the above embodiment is for a VTR, the present invention can also be applied to an audio tape recorder, and the tape may be brought into contact with a fixed head instead of a rotating head during loading.

FIG. 1 is a block diagram showing a first embodiment of the present invention, in which the remaining amount of tape is calculated from the rotation angle of the supply reel during loading.

The tape withdrawal amount required for loading is constant, and if this is e, and the rotation angle of the supply reel during loading is φ, then the outer circumference of the tape wound on the supply side at that time is !・(2π/φ).

If the winding radius of the tape wound on the supply reel is r, then 2π'=/·(2π/φ).
From this, we obtain r=J2/φ.

Substituting this into the above-mentioned equation (1) yields δL=π(Ci2/φ)1−ro1] (5).

If the normal tape running speed is υ, then L=υ・
Since Ts, the remaining time Ts is Ts = n
/δ”((#/φ)' r o' ] −(6
).

Therefore, if the rotation angle φ of the supply reel with respect to the length e of the drawn tape is known, the remaining amount time Ts can be calculated using the formula (6
) can be calculated.

The rotation angle detection means 10 in FIG. 1 is a means for detecting the rotation angle of the supply reel during loading, and includes a large number of slits provided in a disc that rotates coaxially with the supply reel.
A means for optically detecting the number of passages through the slit using a photo sensor, etc., and a means for magnetically detecting the rotating claw of a multi-polar disk-shaped magnet that rotates coaxially with the supply reel using a magnetic head or a Hall element. Using known means such as

The rotation angle φ detected by the rotation angle detection means 10 is sent to the calculation means 11.

The calculation means 11 includes a division circuit 12, 2 east circuit 13.subtraction circuit 14. and a multiplier circuit 15, a reference signal generating means 1S that generates a signal corresponding to the length l of the tape necessary for loading, and a reference signal generating means 17 that generates a signal corresponding to the square of the hub diameter ro2. , a reference signal generating means 18 for generating a signal corresponding to a value π/δυ determined from the tape thickness δ and the tape running speed υ.

First, in the division circuit 12, the reference signal generating means 16
The length of tape required for loading to occur! Divide by the rotation angle φ of the supply reel! /φ is obtained.

this! /φ as (β/φ)2 in the next 2 East circuit 13,
Input to the subtraction circuit 14. The subtraction circuit 14 takes in the output ro2 of the reference signal generation means 17 and calculates the difference (i!/
φ) Obtain Z r o2 .

Further, this difference signal and the output π/of the reference signal generating means 18 are
δυ is input to the multiplication circuit 15, and π/δυ×[(β/
By performing the multiplication of φ)"-ro'), the tape remaining time Ts can be determined from the above-mentioned equation (6).

All that is left to do is to display this on the display in any display format.

Next, another embodiment of the invention will be described.

In the following embodiment, the tape is pulled out from the supply reel at a constant speed during loading, and the remaining amount of tape is calculated from the rotational state (rotation period or rotational angular velocity) of the supply reel at that time.

Therefore, a means is required to keep the tape withdrawal speed υ from the supply reel constant during loading. First, an example of this means will be explained with reference to FIG.

A tape withdrawal speed detection means 30 is provided to detect the tape withdrawal speed υm from the supply reel. For example, one of the tape guide pins 4 in FIG. This can be achieved by attaching a disk with slits and optically reading the rotation of this disk using a photo sensor.

The tape draw-out speed υ detected by the tape draw-out speed detecting means 60 is compared with the tape draw-out speed reference signal υ generated by the tape draw-out speed reference signal generating means 31 in a comparison circuit 62.

A signal of polarity according to the difference between υL and υmu□ and the magnitude relationship from the comparison circuit 32 is given to the motor voltage control circuit 3B, and the voltage of the loading motor 34 is controlled to keep the tape withdrawal speed υmu constant. be done.

Further, as another means for keeping the tape drawing speed constant, the following method may be used.

If a section is provided in which the amount of movement of the loading pin 5 shown in FIG. can do. That is,
If the loading mechanism is a mechanism in which the rotational speed of the motor that drives the loading pin 5 and the amount of movement of the loading pin 5 are proportional.

All you have to do is control the rotation speed of the motor and keep it constant.

If the tape withdrawal speed hole is kept constant as described above, and the rotation angular velocity W or rotation period T of the supply reel is known, the tape remaining time Ts can be calculated using the above equation (3) or equation (4). be able to.

FIG. 4 is a block diagram showing a second embodiment of the invention, in which the same parts as in FIG. 1 are denoted by the same reference numerals, and their explanation will be omitted.

In this embodiment, the remaining amount time Ts is determined by detecting the rotation period T of the supply reel, and a rotation period detection means 40 is provided as means for detecting the rotation period T of the supply reel.

As the rotation period detection means 40, for example, a disk having a slit that can obtain one pulse in one rotation is provided on the same ψIII as the supply side reel hub 1, and one rotation is optically detected. A timer may be used to measure the time required for the rotation, or a similar disc may be provided with several slits at regular angle intervals, and the rotation period T may be determined from the time required for rotation at a given angle.

The rotation period T of the supply reel detected by the rotation period detection means 40 is sent to the calculation means 41.

In the calculation means 41, the rotation period T is first input to the multiplication circuit 42, and is multiplied by υ/2π outputted from the reference signal generation means 43 to obtain (υ/2π)·T.

Thereafter, the square path 13 in the calculating means 11 of FIG.
By performing the same processing using the same circuit as described below, the remaining amount time Ts can be obtained by calculating the above-mentioned equation (4).

FIG. 5 is a block diagram showing a third embodiment of the present invention, in which the same parts as in FIGS. 1 and 4 are denoted by the same reference numerals, and their explanation will be omitted.

This embodiment is similar to the rotation period T in the second embodiment shown in FIG.
Instead, the remaining amount time Ts is determined by detecting the rotational angular velocity u) of the supply reel.

Therefore, the rotational angular velocity of the supply reel! Rotational angular velocity detection means SO for detecting D is provided.

This rotational angular velocity detection means 50 can be realized by providing a disk having a large number of equally spaced slits coaxially with the supply reel hub 1 and optically detecting the number of slits passing through within a predetermined time. Further, for example, as described in the example of FIG. 1, magnetic detection may be used.

The rotational angular velocity W of the supply reel detected by the rotational angular velocity detection means 50 is sent to the calculation means 51.

The calculation means 51 is provided with a reference signal generation means 52 that generates a reference signal υ corresponding to the tape withdrawal speed during loading, and inputs the reference signal υ and rotational angular velocity W to the division circuit 12, and calculates υ/ Get W.

Thereafter, by performing similar processing in the same circuit as the calculation means 11 in FIG. 1 or the circuit after the 2nd east circuit 13 of the calculation means 41 in FIG.
s can be found.

〔Effect of the invention〕

As described above, according to the present invention, in a magnetic tape recording and reproducing apparatus having a tape loading mechanism, the tape is pulled out only from the supply reel during loading, and the rotational state of the supply reel at that time is detected. Since the remaining amount of tape is calculated, the remaining amount of time on the tape can be known before starting recording or playback by simply setting the tape in the device and loading it.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a first embodiment of the invention, and FIG. 2 is a schematic diagram showing an example of a tape rope ink mechanism of a magnetic tape recording/reproducing apparatus to which the invention is applied. FIG. 3 is a block diagram showing an example of a means for keeping the tape drawing speed constant during loading. FIG. 4 is a block diagram showing the structure of a second embodiment of the present invention. FIG. 5 is a block diagram showing the configuration of a third embodiment of the present invention. 1... Supply side reel hub 2... Winding side reel hub 3... Tape Day... Tape end detection device 10... Rotation angle detection means 11.41.51... Calculation means 40... Word-of-mouth period detection means 50...Rotation angular velocity detection means Fig. 1 Fig. 2

Claims (1)

[Claims] 1. In a magnetic tape recording and reproducing device having a tape loading mechanism that pulls out and loads a predetermined amount of tape from a reel, the tape is always pulled out only from the supply reel except when the end of the tape is detected during loading. The present invention is characterized by being provided with a tape drawer, a rotational state detection means for detecting the rotational state of the supply reel during loading, and a calculation means for calculating the remaining amount of tape based on the detection result by the rotational state detection means. Tape remaining amount detection device. 2. The tape remaining amount detection device according to claim 1, wherein the rotation state detection means is a rotation angle detection means for detecting the rotation angle of the supply reel. 3. The method according to claim 1, wherein the tape drawing means is a means for drawing out the tape from the supply reel at a constant speed, and the rotation state detection means is a rotation period detection means for detecting the rotation period of the supply reel. Tape remaining amount detection device. 4. The tape drawing means is means for drawing out the tape from the supply reel at a constant speed, and the rotational state detection means is rotational angular velocity detection means for detecting the rotational angular velocity of the supplying reel. Tape remaining amount detection device.