JPS6153790B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape time display method that calculates and displays the remaining amount of tape or running time by detecting the rotational speed of the supply reel or take-up reel in a cassette tape recorder. be.

Conventionally, various tape time display methods have been known that calculate and display the remaining amount or running tape time, but in all of these methods, the tape time calculation and display are based on recording and playback settings. This is only done when driving at high speed. Therefore, once you perform fast forward or rewind, the tape time display becomes random, and if you want to know the tape time during fast forward or rewind, you must switch to constant speed recording or playback each time. However, the disadvantage is that the operation is extremely cumbersome.

The present invention has been made in order to solve the above-mentioned drawbacks of the conventional technology, and its purpose is to eliminate the need for switching to constant-speed running each time, and to maintain continuous speed during fast-forwarding and rewinding as well as during constant-speed running. To provide a tape time display method for a cassette tape which can calculate and display the tape time.

To this end, the present invention calculates and displays the tape time by detecting the rotational speed of the reel (supply side or take-up side) when the cassette tape is running at a constant speed, and when running fast forward/rewind. The tape time is calculated and displayed by detecting the rotation speed of the reel based on the rotation speed of the reel and the tape time immediately before switching to running.

Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a diagram for explaining an arithmetic expression for calculating the remaining tape time T used in the embodiment of the present invention. In the same figure, supply side reel SR
If the radius of the hub is r _p , the tape thickness is d, and the radius of the remaining tape is r _s , then the supply reel SR
The total length l of the tape wound on can be expressed by equation (1).

l=π/d( _rs2 ⁻ _rp2 )...(1) Therefore, if the tape runs at ^a constant speed _vp (speed during playback and rewinding), the remaining time T is as follows: It can be expressed by equation (2).

T=l/v _p =π/v _pd ( _rs ² − r _p ² ) ...(2) In this case, the rotational speed V _s of the supply side reel SR when the radius of the remaining tape is _rs is, It is expressed as V _s =v _p / _2πrs (3). Therefore, from the above equations (2) and (3), the remaining amount time T can be expressed by the following equation (4).

T=v _p /4π _d × (1/V _s ) ² −π/v _pd r ² …
(4) Here, d, r _p , v _p are numerical values fixed in advance depending on the type of tape and tape recorder, that is, constants. Therefore, these constants d, r
If _p and v _p are given in advance, the remaining amount time T during constant speed running can be easily determined by detecting the rotational speed V _s of the supply reel.

On the other hand, during fast forwarding and rewinding, the tape does not run at a constant speed, so the rotational speed V _s
cannot be calculated using equation (3), and the remaining amount time T cannot be calculated using equation (4). Therefore, find it as follows.

In other words, the remaining amount time T is calculated using equation (4).
After calculating , the remaining amount time t when the supply reel rotates n times (-n when rewinding) during fast forwarding or rewinding is given by the tape radius being (r _s −nd), so ( According to formula 2) t=π/v _pd {( _rs −nd) ² −r _p ² } =π/v _pd (rs ₂ −2ndr _s +n ² d ² −r _p ² ) =πd ^/ v _p n ² _−2πrs /v _p n+π/v _pd (
r _s ² −r _p2 ) =πd/v _p n ² −2π r _s /v _p n+T (5). Here, according to equation (3), 2πr _s /v _p =1/V _s , so by substituting this into equation (5), t=πd/v _p n ² -1/V _s n+T ...( 6) can be obtained.

Therefore, if you memorize the rotational speed V _s and remaining amount time T during constant speed running immediately before starting fast forwarding or rewinding, and measure the rotation speed n of the reel after fast forwarding or rewinding, then ( Using equation 6), it is possible to approximately sequentially determine the remaining tape time even during fast forwarding and rewinding.

FIG. 2 is a diagram for explaining an arithmetic expression for calculating the tape running time t _s used in the embodiment of the present invention. In the same figure, the take-up reel
When the radius of the DR hub is r _p , the tape thickness is d, and the tape is wound n times on the take-up reel, the length l ₁ of the outer tape can be expressed by equation (7).

l ₁ =2π(r _p +nd) ...(7) Therefore, the total length l of the magnetic tape when it is wound n times can be expressed by equation (8).

Here, since r _p ≫d/2, equation (8) can be expressed as equation (9).

l=2π _o (r _p +d/2n) ...(9) Then, when the tape is running at a constant speed v _p in the x direction, the running time t _s from the start of winding to the present is given by equation (10). can be shown.

t _s =l/v _p =2π/v _p n(r _p +d/2n)...
(10) In this equation (10), A=πd/v _p , B=2π
If r _p /v _p , this equation (10) can be expressed as equation ((11)).

t _s = A _o ² + B _o ... (〓) Note that A is a value determined by the tape thickness d and tape speed v _p , and B is a value determined by the hub radius r _p and tape speed v _p . Incidentally, the rotation speed V _R of the take-up reel can be obtained by differentiating n in equation (10) with respect to t, and can be expressed by equation (12).

V _R =dn/dt=1/2A _o +B...(12) In this case, the rotational speed V _R of the take-up reel immediately after resetting the counter that counts the number of turns n of the take-up reel is V _RR Then, the tape thickness d is extremely thin, approximately 18 μ or less, and the hub radius r _p
is approximately 11 mm and the number of turns n is 1, so 2A _o ≪
It becomes B.

Therefore, from equation (12), B _R after reset
can be calculated using the following formula.

B _R = 1/V _RR ... (13) Also, A _R after reset is calculated from equation (12) as A _R = 1/2 _o (1/V _R - B _R ) ... (14) You can ask for it.

Therefore, first, the values B _R and A _R obtained by performing a reset process at the start and using equations (13) and (14) after the reset, and the value n of the counter that counts the number of turns n after the reset are used. te, no.
By performing the calculation shown in equation (11), the running time t _s
is required. Furthermore, even if the tape is reset in the middle of the tape, the running time from the reset position can be displayed.

FIG. 3 is a block diagram showing one embodiment of the present invention. In the figure, SR is the supply side reel and DR is the take-up side reel, and these reels SR and
Rotating disks a and b are attached to the rotating shaft of the DR, and the rotation of these rotating disks a and b is detected by sensors (magnetic sensor or photoelectric sensor, etc.) Sa and Sb. , Sb to reel SR, DR
A pulse signal corresponding to the rotation period of the motor is extracted. Note that the switch determines which of the pulse signals obtained from sensors Sa and Sb is used to calculate the tape time (remaining amount or running).
Selected by SW ₁ . Next, 10 calculates the tape time using the above-mentioned arithmetic formula, and if the operations are not performed in accordance with the predetermined order of operations, the tape time is calculated using the numerical display segment of the tape time display. It is an arithmetic control section that executes control for instructing to drive at a constant speed, displaying errors, etc., and is equipped with an arithmetic section CPU and memories RAM and ROM.

Next, 11 is a display driver, and 12 is a display device for displaying tape time. SW ₂ is a remaining amount mode switch that indicates the remaining amount time as the tape time displayed on the display 12, SW ₃ is a running mode switch that indicates the running time as the tape time displayed on the display 12, and SW ₄ is a cassette tape Type of (C
-30, C60, C90); SW ₅ is a reset switch for returning the entire device to its initial state; SW ₆ is a tape selection switch for displaying the remaining time during fast forwarding and rewinding; (6) V in the formula
This is a storage instruction switch for storing _s and T in memory RAM.

By the way, although the arithmetic control section 10 has a microcomputer type hardware configuration, the arithmetic section
A tape time meter and revolution counter are provided using the CPU's working register. The memory ROM stores programs corresponding to flowcharts as shown in FIGS. 4 to 6 in order to execute predetermined arithmetic and control operations.
Constants necessary for tape time arithmetic processing (hub
_p , tape thickness d, tape speed v _p , etc.) are stored.

The operation of the tape time display device of the embodiment shown in FIG. 3 will be explained below using the flowcharts shown in FIGS. 4 to 6.

FIG. 4 shows a main program for executing arithmetic and control operations, and after power is turned on, the entire device is initialized by operating the reset switch _SW5 or by an initialization signal synchronized with power-on. After this, the main program shown in FIG. 4 is first executed. That is, step 1 in FIG.
At 00, whether the remaining amount mode or the running mode is selected is determined by the output signals of the switches SW ₂ and SW ₃ . As a result, if the remaining amount mode is to display the remaining amount time, the process advances to step 101, a remaining amount time routine, and a program for displaying the remaining amount time is executed. On the other hand, if the mode is to display the running time,
The program advances to step 102, a running time routine, in which a program for displaying running time is executed. After this, proceed to step 103 and press the reset button SW _5.
Determine whether or not it is on. reset switch
If SW ₅ is on, the next step 104 resets the tape time meter. Thereafter, in step 105, it is determined whether or not the storage instruction switch SW ₆ is in the on state. If the switch SW ₆ is in the on state, in the next step 106, the content of the tape time meter (T in equation (6)) is determined. and the most recently detected rotational speed V _s are stored in the memory RAM. When this process is completed, step 100
Return to and repeat the same process.

FIG. 5 shows steps 101 and 10 in FIG.
This is a flowchart showing in detail the common parts of the remaining amount time routine and running time routine of No. 2. In the same figure, when processing first proceeds to the remaining amount time routine or running time routine, in step 200, the character "PLAY" is displayed using the numeric display segment of the display 12. In other words, an instruction is given to the operator to perform constant speed playback or recording. In this case, the characters "PLAY" can be displayed as shown in FIG. 7 by utilizing the numeric display segments of the display 12.

Next, in step 201, it is determined whether the playback or recording button has been pressed according to the character display of "PLAY". If the fast forward or rewind button is suddenly pressed without pressing the play or record button, step 202
This is determined in step 203, and then step 203
The ``PLAY'' character display will blink, indicating an error message indicating an operational error. This error display will not be canceled until reset switch SW ₅ is operated, and after operating reset switch SW ₅ , the process returns from step 204 to step 220 again.
You will be prompted to redo the operation. In addition, the error display not only flashes all the letters "PLAY" but also displays the letters P, L, A,
Since there are various methods such as displaying Y individually one by one, it is sufficient to apply the method that is easiest for the operator to understand.

On the other hand, if the operator performs the correct operation according to the word "PLAY" displayed in step 200, that is, if he presses the record or play button,
In step 205, the character "-" is displayed on display 1.
Display on 2. That is, a display indicating that the process has now shifted to detecting the rotation period of the reel and calculating the tape time is displayed. Thereafter, the rotation period (speed) of the reel is detected as shown in steps 206-209. in this case,
Each time a rotation pulse is input, the "-" display is sequentially shifted to the right as shown in FIGS. 8a to 8d. This allows the operator to know that the reel rotation period detection process is being executed correctly. The rotation period is detected in this manner, and when the process is completed, the process proceeds to the next step 210, where the tape time is calculated using the above-mentioned arithmetic expression. Then, in the next step 211, the calculated tape time is displayed on the display 12. If reset switch SW ₅ is operated at this stage, Step 2
12 returns to step 200, the word "PLAY" is again displayed on the display 12, and the contents of the tape timer are reset. If reset switch SW ₅ is not engaged, the program returns from step 212 to step 210 and calculates the tape time for each reel rotation period.

FIG. 6 is a flowchart showing details of the tape time calculation routine in step 210 of FIG. In the same figure, when moving to the tape time calculation routine, it is first determined in step 300 whether or not a rotation pulse has been input, and in the next step 301, a rotation counter that stores the number of rotations n for each rotation of the reel is checked. Update content. At this time, the record or play button is pressed,
If one rotation has been completed, the process proceeds to the next step 306 based on the judgments in steps 302 and 305, and the calculation formula for constant speed running (Equation (4) or Equation (11)) is used.
(expression) is executed. In this case, the remaining amount mode switch
If SW ₂ is in the ON state, the remaining tape time is calculated by the above-mentioned equation (4). Further, if the running mode switch SW ₃ is in the ON state, the tape running time is calculated by the above-mentioned equation (11). When the tape time calculation is completed in this way, the content "n" of the revolution counter is reset in the next step 307, and then the display 12 is reset in step 308.
Display the colons continuously. Then, proceed to step 211 in FIG. 5, display the tape time,
Thereafter, while the recording or playback button is pressed, the tape time is calculated for each rotation of the reel. Thereafter, when the recording or playback button is turned off to stop tape running, the program stops at step 300 in FIG. 6, and the tape time display continues to stop changing. However, if memory instruction switch SW ₆ is pressed here,
An interrupt program (not shown) causes the program execution to jump from step 300 in FIG. 6 to step 105 in FIG. Stored in memory RAM. After this, the program skips steps 200 and 205 in FIG. 5 because the device is not in its initial state, and returns to step 300 in FIG. 6. In this state, when the fast forward or rewind button is pressed, the process proceeds to step 303 based on the determination made in step 302 in FIG. 6, where the fast forward/rewind calculation formula is executed. When this calculation is completed, in step 304, the display 12
The colon blinks to notify that the display 12 is currently displaying the approximate calculated tape time.

As explained above, in the present invention, when the cassette tape runs at a constant speed, the reel (supply side or take-up side)
The tape time is calculated and displayed by detecting the rotational speed of the reel, and during fast forwarding and rewinding, the rotational speed of the reel is detected based on the rotational speed of the reel and tape time immediately before switching to fast forwarding and rewinding. By doing so, the tape time is calculated and displayed.

Therefore, the tape time during fast-forwarding and rewinding can be known without switching to constant-speed running each time, which is extremely effective in terms of operability.

In the embodiment, the calculation formula for the tape time during fast forwarding and rewinding has been explained only for the remaining amount time, but it can also be implemented based on the same concept for the running time.

[Brief explanation of the drawing]

1 and 2 are diagrams for explaining the tape time calculation formula used in the present invention, FIG. 3 is a block diagram showing an embodiment of a tape time display device to which the present invention is applied, and FIG. 4 6 is a flowchart showing an example of a program used in the tape time display device shown in FIG. It is a figure which shows the example of a display during operation, and the example of an error display. 10... Arithmetic control unit, 11... Display driver, 12... Display unit, SW ₁ ... Sensor changeover switch, SW ₂ ... Remaining amount mode switch, SW ₃ ... Traveling mode switch, SW ₄ ... Tape selection switch,
SW ₅ : Reset switch, SW ₆ : Memory instruction switch, SR: Supply side reel, DR: Take-up side reel.

Claims (1)

[Claims] 1 In a tape time display method that detects the rotational speed of the supply reel or take-up reel of a cassette tape recorder and calculates and displays the remaining tape time or tape running time, when the cassette tape is running at a constant speed, the rotational speed is The tape time is calculated and displayed based on , and during fast forwarding/rewinding, the tape time is calculated by detecting the rotational speed of the reel based on the rotation speed and the tape time immediately before switching to fast forwarding/rewinding. A tape time display method characterized in that the tape time is displayed as follows.