JPS6149746B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for displaying the usage time and remaining time of a tape such as a video tape recorder.

Conventionally, tape counters have been generally used to display the amount of tape used in VTRs, tape recorders, and the like. This is a device that supplies the rotation of the reel to a mechanical counter via a belt and displays it as a 3- to 4-digit number, and has the following drawbacks.

(1) The amount of tape used is only displayed relatively based on the number of reel rotations, and cannot be converted into time and displayed. (2) When a partially used tape is loaded, it is unclear how much time is left. (3) It is not possible to cue by specifying an arbitrary time.

Due to the above-mentioned drawbacks, the user has to visually check the amount of tape to be wound and feel the approximate position. As a result, tape recording time is insufficient, resulting in inconveniences such as not being able to record a desired program, or having to repeat fast-forwarding, rewinding, and replaying many times to find the beginning.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to provide a device that displays the amount of tape used and the amount remaining in terms of time, and allows the user to cue up any desired position using a keyboard.

In order to achieve the above object, the present invention detects the rotational angular velocity of the take-up reel and the supply reel, as well as the running speed of the tape, and uses these values to calculate the used amount or remaining amount of the tape using a microcomputer (hereinafter referred to as (abbreviated as microcomputer) or wired.
In addition to calculating and displaying the information using logic, we adopted a method in which when the tape is stopped, a signal indicating that the tape has stopped is used to maintain the time display of the amount of tape used or remaining amount immediately before the tape stops.

The present invention will be explained using an example. Fig. 1 is a mechanical diagram showing the tape running state of a home VCR, Fig. 2 is a block diagram showing an embodiment of the present invention, and Fig. 3 is a block diagram showing an embodiment of the present invention.
The figure is a flowchart for explaining the operation of the microcomputer used in FIG.

Figure 1 shows the state during recording and playback.
5 is a cylinder, 5 is a capstan, 6 is a cassette half, 8 is a supply reel, and 10 is a take-up reel. Here, the parameters are defined as follows.

Tape running speed...v, supply reel rotational angular speed...w ₁ , supply reel hub radius...R, supply reel side radius (with tape wrapped)...r ₁ ,
Supply reel tape projected area...S ₁ , Take-up reel rotational angular speed...w ₂ , Take-up reel hub radius...R, Take-up reel side radius (with tape wound)...r ₂ , Take-up Reel tape projected area...
…S ₂ , total tape projected area…S ₀ , tape length…
L, Tape thickness...D, Tape remaining time...T ₁ ,
Tape usage time... _T2 , total tape time... _T0The following relationship holds between these parameters.

r ₁ w ₁ = r ₂ w ₂ = v (1) S ₀ = S ₁ + S ₂ = DL (2) T ₀ = T ₁ + T ₂ (3) S ₁ = π(r ² ₁ − R ² ) (4 ) S ₂ = π (r ² ₂ − R ² ) (5) The remaining tape time T ₁ and usage time T ₂ are (2), (3)
Therefore, T ₁ =S ₁ /S ₀ T ₀ (6) T ₂ =S ₂ /S ₀ T ₀ (7). Therefore, from equations (4), (5), and (6), T ₁ =S ₁ /S ₁ +S ₂ T ₀ =π(r ₁ ² −R ² )/π(r ₁ ² −R ² )+
π(r ₂ ² - R ² )T ₀ r ₁ ² -R ² /r ₁ ² -r ₂ ² -2R ² T ₀ (8) Substituting equation (1) into equation (8), the remaining tape time T ₁
teeth becomes. Also, the tape usage time T ₂ can be calculated using the same formula.
It is expressed as (10).

Alternatively, it can also be obtained from _T2 = _T0 - _T1 .

Generally, the thickness D of the tape is very thin compared to the absolute precision in production, and there are large variations in tape thickness. The method for detecting the remaining time must be such that the above-mentioned variation in tape thickness does not affect the method, but in the present invention, equations (9) and (10) do not include the tape thickness D. No problem. Furthermore, the reel hub radius R is a sufficiently large value with respect to the absolute accuracy in production, and does not have much influence.

Therefore, by accurately measuring the rotational angular velocities w ₁ and w ₂ of the reels and the tape running speed v, and substituting them into equation (9) or equation (10), the relationship between the tape running speed during playback or recording can be determined. For example,
Even in slow-motion playback or quick-motion playback of a VTR, the remaining tape time T ₁ or tape usage time T ₂ can be determined with high precision. Moreover, when tape running is stopped, the value calculated with high accuracy using the above formula (9) or (10) immediately before tape running is held, so that, for example, VTR
Even when the device is in still operation, the remaining battery time or usage time can be displayed with greater accuracy.

Specific means for realizing the above method are shown in Figures 2 and 3.
This will be explained using figures.

21 is a rotational angular velocity detector of the supply reel, which obtains a rotational angular velocity detection signal 23 of the supply reel. Similarly, the take-up reel rotation angular velocity detection signal 24 is obtained by the take-up reel rotation angular velocity detector 22. On the other hand 2
A tape running speed detector 5 detects, for example, the rotational angular velocity of the capstan 5 and outputs a tape running speed detection signal 26.

The signals 23, 24, and 26 mentioned above are input to the microcomputer 27. Since the microcomputer operates using the oscillator 28 as a reference clock, for example, find out how many reference clocks are input during one revolution of both reels and the capstan, and calculate the rotational angular velocities w ₁ and w ₂ and tape running speed v. Obtainable. These are processed by a microcomputer according to the flowchart in Figure 3, and the remaining amount time T ₁ or usage time is calculated using equations (9) and (10).
T ₂ is calculated and the value is displayed on the digital display 29 in terms of time. Further, when the tape running is stopped, the display is maintained by interrupting the microcomputer with the tape running stop signal 30.

Next, a case where the functions of the present invention are further improved will be explained using FIGS. 2 and 4. For example, for home use
When using a VTR in recording mode, the user wants to check the remaining time, but in playback mode, it is easier to check the usage time.

Therefore, the remaining amount of time is determined by the mode switch 31.
It is possible to select T ₁ and usage time T ₂ .
On the other hand, use the 10 key 32 to specify an arbitrary tape address time, and when the time matches, the capstan stop signal 33 is generated and the capstan 5 is stopped, making it a quick motion operation. It becomes possible to cue up. Calculate the remaining amount time using the detected signals of w ₁ , w ₂ and v, and determine whether the signal of mode switching switch 31 is the remaining amount time or the usage time, and if it is the usage time, T ₂
Calculate usage time T ₂ from =T ₀ −T ₁ . 10 keys 32
If an address is specified by the key input signal, the capstan is stopped when the specified time Tx is reached. The value calculated in this flow is displayed on the numerical display 29. Note that when the tape running is stopped, it is the same as the above case.

Next, a circuit according to an embodiment of the present invention will be explained in detail using FIG. The light from the light emitting diode 39 is received by the phototransistor 40 through a slit provided in the supply reel, and the light from the light emitting diode 39 is received by the phototransistor 40.
47, the input voltage to the microcomputer 27 is set to high level during reception, and set to low level at other times. Therefore, if the slits are properly positioned, input voltages of higher levels will be generated in sequence. Since the microcomputer 27 has a reference clock using the oscillator 28, the interval of the above-mentioned high level input is calculated to the microcomputer 27, and the angular velocity of the supply reel is calculated.
You can get w ₁ . Also in the circuits shown by 58 to 56, the light from the light emitting diode 49 is received by the phototransistor 50 through the slit provided in the take-up reel, and the angular velocity w ₂ of the take-up reel can be obtained in the same manner as above. . Further, by means of circuits 94 to 102, a phototransistor 97 receives light from a light emitting diode 95 through a slit provided in a disk fixed to the rotating shaft of the capstan, and thereafter the tape running speed v can be obtained. The microcomputer 27 calculates the remaining amount time or usage time using equations (9) and (10) from the rotational angular velocity w ₁ , w ₂ tape running speed v and the total tape time T ₀ known in advance. Then, the calculated value is input to the digital display 29 via the resistors 103 to 109, and the digital display 29 is driven by the display driver 113.

110 is a tape running stop signal input terminal from the mechanical control section of the VTR, etc., and the high level input when stopped and the low level input when running are connected to diode 1.
11, is obtained to the microcomputer 27 via the resistor 112, and the microcomputer holds the immediately previous displayed value on the display 29 in response to the stop input.

On the other hand, the circuits shown at 58 to 93 are 10-key input sections for specifying tape addresses, and switch 5
8. A diode 59 and a resistor 60 input a high level voltage when the switch is ON and a low level voltage when the switch is OFF to the microcomputer 27. In the same way, input ON/OFF of the switch using a set of the three elements mentioned above to the microcontroller. 58, 59, and 60 are circuits that notify the start of tape addressing; 61, 62, and 63 are circuits that notify the end of tape addressing and the execution of cueing; 64 to 93 are the 10 keys 0 to 9; This is a circuit that notifies you of the number designation. Based on these inputs, the microcomputer 27 executes cueing,
Compare the tape address specification time and remaining amount or usage time, and when they match, motor driver 3
7, the drive of the capstan motor 38 is stopped. Reference numerals 34, 35, and 36 are mode switching units that select and switch between the remaining amount of time and the usage time depending on the high or low level of the input voltage.

As explained above, according to the present invention, the remaining time or usage time of the tape can be expressed in hours without affecting the tape running speed during recording and playback, that is, even during still, slow, quick playback, and high-density recording. It can be displayed with high accuracy. Moreover, by simply attaching the tape and rotating it around once, the remaining amount of time or usage time can be calculated and displayed. Furthermore, by specifying the desired time address using the keyboard, you can quickly find the beginning of the time. Furthermore, it is clear that the circuit of the present invention can be realized at low cost by using a microcomputer or the like.

[Brief explanation of the drawing]

Fig. 1 is a mechanical diagram showing the tape running state of a VTR. Fig. 2 is a block diagram showing one embodiment of the present invention.
4 is a flowchart showing the operation of the microcomputer used in the present invention, and FIG. 5 is a specific circuit diagram of an embodiment of the present invention. 1...Cylinder, 5...Capstan, 8...
Supply reel, 10... Take-up reel, 12... Pinch roller, 21... Supply reel rotation angular velocity detector, 22... Take-up reel rotation angular velocity detector, 2
5...Tape running speed detector, 27...Microcomputer, 29...Display device, 31...Mode switching device, 3
2...10 key, 33...capstan stop signal.

Claims (1)

[Scope of Claims] 1. A tape running time display system for a tape recorder using magnetic tape and equipped with a supply reel and a take-up reel, which displays the rotational angular velocities w ₁ and w ₂ of the supply reel and take-up reel and the tape running time. Detect the speed v, input these detected values, the total tape time r ₀ , and the reel hub radius R into a microcomputer, and calculate at least one of the remaining tape time r ₁ and tape usage time r ₂ by the following formula; 1. A tape running time display method for a tape recorder, which is characterized by calculating and displaying the calculated time according to the following. 2. When tape running is stopped, at least 1 of the previous remaining tape time r ₁ and tape usage time r ₂
2. A tape running time display method for a tape recorder according to claim 1, wherein one display is maintained.