JP2640048B2 - Tape running time display method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for displaying the remaining time of a tape and the time of use, such as a video tape recorder.

[0002]

2. Description of the Related Art A conventional device for displaying a remaining time of a tape or a use time of a video tape recorder or the like will be described with reference to FIG. (See JP-A-2-81389) In FIG. 2, reference numerals 1 and 2 indicate supply (S side) and winding (T side).
Reels on the S side and T on which these reels are mounted.
The S-side and T-side rotation detectors 3 and 4 composed of optical sensors are disposed on the side reel base, respectively, so that the cycles change according to the rotation of the S-side and T-side reels 1 and 2. Side reel pulses Ps and Pt are output. Incidentally, these reel pulses Ps and Pt are generated 12 times each time each reel makes one rotation.

Next, the S-side reel pulse Ps is supplied to an S-side period counter 5 and the T-side reel pulse Pt is supplied to a T-side period counter 6. The S-side cycle counter 5 outputs an S-side reel pulse.
The clock of a fixed period generated from the clock generator 7 is counted while 12 Ps are generated, and the S-side reel 1 is counted.
Is detected. On the other hand, the T-side cycle counter 6 similarly detects the rotation cycle Tt of the T-side reel 2.

The outputs of the S-side and T-side period counters 5 and 6 are input to arithmetic circuits 8 and 9, respectively, and after squaring the rotation periods Ts and Tt, they are input to an addition circuit 10 and a tape amount calculation circuit 13. .

The addition circuit 10 calculates the sum of the squares of the rotation periods Ts and Tt (Ts ² + Tt ² ), and supplies this value to the tape type discrimination circuit 11. Here, assuming that the tape winding diameter including the reel hubs of the S-side and T-side reels 1 and 2 is Rs and Rt, and the total area including the hub area is S, the following equation is established.

[0006]

(Equation 3)

Assuming that the tape running speed at this time is V, the following equation is obtained.
(a)

[0008]

(Equation 4)

[0009] Here, the total area S is, for example, T-120, T-90, T-60 in the case of the NTSC system.
Since the value is unique depending on the tape type such as (Ts ² + T
If t ² ) is obtained, the total area is obtained from equation (b), and the tape type can be determined from the total area S in a determination table prepared in advance. The discrimination result thus determined is supplied to the tape data designating circuit 12, and data on the radius r of the reel hub, the tape thickness t, and the total length L of the tape are output to the tape amount calculating circuit 13 in accordance with each tape type. The tape data designating circuit 12 stores in advance a reel hub radius r, a tape thickness t, and a total tape length L corresponding to each tape type.

The tape amount calculation circuit 13 includes arithmetic circuits 8 and 9
, The square value of the rotation period Ts, Tt, the reel hub radius r, the tape thickness t, and the total length L of the tape from the tape data designating circuit 12, and the tape running speed V, V ₀ are substituted into an arithmetic expression described later. Calculate the remaining tape or tape usage time. Here, the remaining tape amount and the usage time are calculated by the following equations (c) and (d).

[0011]

(Equation 5)

The tape running speed V is specified by an instruction signal from a servo circuit 14 for controlling the rotation of a capstan for running the tape during reproduction or recording. That is,
In the case of NTSC, when an instruction signal indicating that the mode is the standard (SP) mode is given, V = 33.35 mm / sec, twice (LP)
In the mode, V = 16.67 mm / sec, and in the triple (EP) mode, V = 11.11 mm / sec is substituted into the equations (c) and (d). Similarly, in the case of CUE / REV, data corresponding to each mode is substituted into the equations (c) and (d).

The tape running speed V ₀ is the speed at which the user runs the tape on the PLAY or REC from the current tape position, and can be arbitrarily set by the user. Therefore, the tape running speed V ₀ is obtained by calculating the SP, LP, and EP data according to the equations (c) and (d), similarly to the tape running speed V described above.
Is assigned to

The calculation of the remaining tape amount or the tape usage time in the tape amount calculation circuit 13 is performed by the S-side and T-side cycle counters 5 and 6 by using the rotation cycle T
It is executed every time s and Tt are detected, that is, every rotation of the S-side and T-side reels, and the user can arbitrarily select whether to calculate the remaining tape time or the tape usage time. ing.

According to the above-mentioned arithmetic expressions (c) and (d), the remaining tape amount and the tape usage time can be accurately calculated only in the constant speed running mode. Therefore, as a method of calculating the remaining tape amount and the tape usage time in all the tape running modes including the constant speed running mode, the arithmetic circuits 8 and 9 calculate the square values of the rotation periods TFs and TFt in all the tape running modes and the tape data. The reel hub radius r, the tape thickness t, and the total length L of the tape from the designation circuit 12 and the tape running speed mode V ₀ when the user runs the tape on the PLAY or REC from the current tape position are substituted into an arithmetic expression described later. Then, the remaining tape amount or the tape usage time is calculated. Here, the remaining tape amount and the usage time are calculated by the following equations (e) and (f).

[0016]

(Equation 6)

[0017] Incidentally, designated by an instruction signal from the external switch tape running speed V ₀ is adapted to be arbitrarily set user as described above (not shown), thus the tape running speed V ₀ is, SP 33.35mm / sec in mode, 16.67mm / sec in LP mode, 11.11mm / sec in EP mode
Is substituted into the equations (e) and (f).

Further, when a non-constant speed running mode such as FF / REW is performed for the first time after the magnetic tape is mounted on the video tape recorder, the tape type is not determined, the reel hub radius r and the tape thickness are not determined. t and the total length L of the tape are not known. Therefore, the mode is forcibly set to the constant-speed running mode, the tape type is determined, and then the mode shifts to FF / REW.

The tape remaining amount or tape usage time calculated as described above is displayed on the display 16 via the display control circuit 15.

[0020]

In the prior art described above, when calculating the remaining tape amount and the tape usage time, the total length L of the tape is substituted into the arithmetic expressions (c), (d), (e) and (f) as constants. The drawback is that when a magnetic tape having a variation in the overall length L, such as a soft tape for a movie, is inserted into a video tape recorder, the remaining tape time and the tape usage time cannot be accurately displayed. was there.

[0021]

SUMMARY OF THE INVENTION The present invention detects a tape running speed V and a rotation period Ts, Tt of a supply reel and a take-up reel during a constant speed running, and calculates a total area S from the detected values. And the tape thickness t and the reel hub radius r selected according to the calculated value and the calculated value.
The set tape running speed V ₀ , the rotation cycles TFs and TFt of the supply reel and the take-up reel in the current tape running mode.
Is detected, the remaining tape time T ₁ and the tape usage time T ₂
Is calculated and displayed.

[0022]

According to the above-mentioned method, the remaining tape time and the tape usage time can be displayed with high accuracy even when the entire length of the tape varies.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

First, as shown in FIG. 1, the radius of the reel hub of the S-side and T-side reels is r, the radius of the S-side reel is Rs, the radius of the T-side reel is Rt, the total length of the tape is L, and the tape thickness is t. Further, V is the tape running speed in the constant speed running mode, Ts and Tt are the rotation cycles of the S side and T side reels at that time, and V ₁ is the tape running speed in the all tape running modes including the constant speed running mode. Assuming that the rotation cycles of the S side and T side reels are TFs and TFt, the total tape area S can be expressed by the following equations, respectively.

[0025]

(Equation 7)

It can be modified as follows.

If the rotational angular velocity of each reel is ω,
Tape running speed V ₁ in all the tape running mode can be represented by the following formula,

[0028]

(Equation 8)

Can be expressed as

Here, assuming that the tape running speed mode when the tape runs from the current tape position is V ₀ , the remaining tape time T ₁ can be expressed by the following equation.

[0031]

(Equation 9)

As described above, since the calculation formulas (j) and (k) of the remaining tape time T ₁ or the tape usage time T ₂ do not include the entire length L of the tape, it is not affected by the variation of the entire length of the tape, and is thus highly accurate. The remaining tape time and the tape usage time can be calculated.

Next, specific means for realizing the above method will be described with reference to FIG. Note that the same circuits as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. A speed data designating circuit 19 determines the tape running speed V based on the mode signal from the mode determining circuit 14 and the instruction signal from the servo circuit 15, and outputs the data. Numeral 20 denotes an arithmetic circuit, which inputs the tape constant speed traveling speed V from the speed data designating circuit 19 and the square values of the rotation periods Ts and Tt from the arithmetic circuits 8 and 9, respectively, and calculates the arithmetic expressions (j) and (k). The total area S of the portion A shown is calculated.

Next, the operation will be described. First, after the magnetic tape is mounted on the video tape recorder, the PLA
When a constant speed running mode such as Y, REC, CUE / REV, or the like is performed, the S side and T side rotation detection circuits 3 and 4 generate the S side and T side reel pulses Ps and Pt in the same manner as in the related art. Output. Next, the reel pulses Ps and Pt are input to the S-side and T-side period counters 5 and 6, and the S-side and T-side rotation periods Ts and Tt are detected by a clock having a constant period. This detection value is
After being input to the arithmetic circuits 8 and 9 and squaring the rotation periods Ts and Tt, they are input to the adding circuit 10, the tape amount calculating circuit 13, and the arithmetic circuit 20.

The addition circuit 10 calculates the sum of the squares of the rotation periods Ts and Tt (Ts ² + Tt ² ) and supplies this value to the tape type discrimination circuit 11 to calculate the total area S including the hub area. Also, the type of the tape is determined. The result of the determination is supplied to the tape data designating circuit 12 and outputs data relating to the radius r of the reel hub and the tape thickness t to the tape amount calculating circuit 13 in accordance with various tape types.

The mode determination circuit 14 has a PLAY, RE
It is determined which of the constant-speed running modes, such as C and CUE / REV, is in effect, and the result of the determination is supplied to the speed data designating circuit 19. The speed data designating circuit 19 determines the tape running speed V based on the mode signal of the mode determining circuit 14 and the instruction signal from the servo circuit 15, and supplies the data to the arithmetic circuit 20.

The arithmetic circuit 20 calculates the total area S from the value obtained by squaring the tape running speed V and the above-mentioned rotation periods Ts and Tt, and supplies the value to the tape amount calculating circuit 13 and ejects the magnetic tape. Remember until

The tape amount calculating circuit 13 calculates the total area S from the arithmetic circuit 20, the reel hub radius r and the tape thickness t from the tape data specifying circuit 12, and the rotation periods TFs and TFt in the current tape running mode. Then, the remaining tape amount or the tape usage time is calculated by substituting into the arithmetic expressions (j) and (k) according to the tape running speed V ₀ set by the external switch.

When a non-constant speed mode such as FF or REW is performed for the first time after the magnetic tape is mounted on the video tape recorder, discrimination of the tape type and calculation of the total area S cannot be performed. Constant speed mode, for example, CUE
To determine the tape type and calculate the total area S.
After that, the process proceeds to FF / REW, and the above-described tape amount calculation circuit 13 calculates the remaining tape amount or the tape usage time.

The arithmetic circuit 20 calculates the total area S and stores the value when the constant-speed running mode or the non-constant-speed running mode is performed once.
Thereafter, the total area S need not be calculated until the magnetic tape is ejected.

As described above, the calculated remaining tape amount or tape usage time is displayed on the display circuit 16 via the display control circuit 15.

In the present embodiment, the arithmetic circuit 20 for calculating the total area S is separately provided. However, since the total area S is calculated in the tape type circuit 11 in the same manner, the tape type circuit 11 It may be configured as a combined use.

The portion enclosed by a hatched portion in the circuit block shown in FIG. 2 can be processed as software by a microcomputer.

[0044]

As described above, according to the present invention, even when a magnetic tape having a variation in the entire length of the tape is mounted on a video tape recorder, the remaining tape time and the tape usage time are displayed with high accuracy. be able to. Further, since it is not necessary to store the entire length of the tape, it is possible to minimize the storage capacity.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a block diagram showing a conventional tape remaining amount and tape usage time display device.

[Explanation of symbols]

 Reference Signs List 11 Tape type discriminating circuit 14 Mode discriminating circuit 13 Tape amount calculating circuit 17 Display 19 Speed data specifying circuit 20 Arithmetic circuit

Claims (1)

(57) [Claims] 1. A tape running time display system for a magnetic recording / reproducing apparatus having a supply reel and a take-up reel, wherein the tape running speed V during a constant speed run and the rotation periods Ts, Tt of the supply reel and the take-up reel. And the total area S is calculated by The tape thickness t, the reel hub radius r, the set tape traveling speed V ₀ , the supply reel and the winding in the current tape traveling mode The rotation cycle TFs and TFt of the take-up reel are detected, and at least _{one of the} remaining tape time T ₁ and the tape usage time T ₂ is calculated as follows. A tape running time display method for a magnetic recording / reproducing apparatus, wherein the tape running time is displayed based on a calculation formula.