JPS58194182A - Display of tape running time - Google Patents

Abstract

PURPOSE:To attain the display of accurate tape running time, even if the tape speed is changed, without changing the diameter of a timer roll or the number of pulses of an encoder in a VTR, etc., by cancelling the accumulation of errors. CONSTITUTION:A photodetector 3 receives a light irradiated from a light emitting element 4 and outputs a signal in response to the amount of received light. This output signal is converted into a pulse signal (C1 pulses per one second) at a pulse converting circuit 5. A counter 6 consists of a C1-notation counter, counts the number of pulse signals, and a tape running time converting circuit 7 converts the output of the counter 6 into a 60-notation number for the tape running time display. A tape running time display circuit 8 displays the data in the 60-notation for the tape running time display. In changing the tape speed without changing the diameter of the timer roll 1 and the number of pulses of the encoder 2, let a maximum integer not exceeding the number C2 of the pulse signals outputted for one second be [C2], then the tape running time converting circuit 7 converts the data for the tape running time display so as to be changed by one second every time the count value of the counter 6 reaches [C2]. When the output pulse signal of the counter 6 is counted by N pulses at a counter 9, a count value set circuit 10 sets the counter 6 as a ([C2]+1)-notation counter so as to cancel the accumulation of errors.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a display device for displaying the running distance and time of a tape-shaped body in a magnetic recording/reproducing device (VTR) or the like.
The configuration is such that it can be easily shared by models with different tape running lengths per unit time.

Conventionally, for example, because the running speed of the magnetic tape was different between an LD'PAL VTR and an NTSC (J) VTR, the tape running time display device was changed from an NTSC VTR to a PAL VTR.
When converting the system to a VTR, it is necessary to change the diameter of the timer roller that rotates as the tape runs, or change the number of pulses of the encoder attached to the timer roller, and then count the pulse signals. The problem was that we had to change the means to do so.

The present invention provides means for solving the drawback that when changing the tape running speed, the means for generating pulse signals, such as the diameter of the timer roller or the number of encoder pulses, must be changed.

An embodiment of the present invention will be described with reference to FIG.

Now, the diameter of the timer roller 1 that rotates as the tape 1o runs is D(a), the number of pulses of the encoder 2 is p (hals/pulse), and the first tape speed is V1(B).
/ Watari). The light receiving element 3 receives the light emitted from the light emitting element 4 and outputs a signal according to the amount of light received. This output signal is converted into a pulse signal by the pulse conversion circuit 6. It becomes 1 second. In order to correctly determine the tape running time, C1 must be an integer. Therefore, the values of P and D are determined so that C1 is an integer. 1st counter 6
is constituted by a C-1 counter and counts the number of pulse signals, and the tape running time conversion circuit 7 converts the output of the first counter 6 into a sexagesimal number for displaying the tape running time. The tape running time display circuit 8 displays a sexagesimal number for displaying the tape running time.

In this sound installation 5, the diameter and workpiece of the timer roller 1 are
Adjust the tape speed to V2 without changing the number of pulses of coder 2.
(mm/W), the number of pulse signals output per second 02 is 2xP C2 = - (Pulse/5eC) ...... (Historic D x π. Even if C2 is an integer For example, set the first counter 6 to C.
By simply changing from a 1-base counter to a 2-base counter, it is possible to obtain the tape running time when the tape speed f: V1 is changed from V2 to V2. However, if we take a VH8 system VTR, which is a recent home VTR, as an example, vl is N.
Letting the tape speed of the TSC system be the tape speed of the PAL system and v2 be the tape speed of the PAL system, then V 1 = 33, 35 (rm/sec) V 2
= 23, 39 (tIaIL/5ec). Substituting this value into formula (4) gives 23.39 Therefore, O)
Substituting into the formula to find the value of P, P≧6282K (K
is a natural number) (8), and in reality, such a coder 2 is extremely difficult to manufacture. Therefore, if the diameter of the timer row 2-1 and the number of pulses P of the encoder 2 are determined so that C1 becomes an integer, it can be considered that C2 will not become an integer. Therefore, the largest integer not exceeding 02 is (C2) (hereinafter the largest integer not exceeding n [
n]), each time the count value of the first counter 60 reaches [C2], the tape running time conversion circuit 7 converts the data for displaying the tape running time so that it changes by 1 second. However, in this error, 1 is [C2] K 1=--1 (crown) ... (phantom) 2 Therefore, the first counter 6 is set as the [C2] decimal counter and the tape running time is If you keep searching, 1 will accumulate in the error. Therefore, when the second counter 9 counts eight pulse signals output from the first counter 6, the count value setting circuit 1o sets the first counter 6 to ([C2)+
Set it to the IJ hex counter to cancel out the accumulation of errors.

When the first counter 6 is a ((C2)+1) base counter, the actual time "R2" corresponding to a one-second change in the display is [C2)+1 "R2""
11)2, and the error 2 becomes [C2)+1, 2=-1... (12)2. When the first counter 6 is set to [C2] base and the second counter -9 counts 8 output pulses of the first counter 6, the first counter 6 is set to ((02)
)-M) In order to find N to minimize the error as much as possible, N must be an integer in constructing the second counter 9 that first finds N' using the following equation. Therefore, if N' is an integer, N=N/L, and N'
If N is not an integer, it is necessary to consider whether to set N to [N'] or [N']+1 depending on each case. Substitute numerical values and graph the change in error over time.

V 1 = 33, 35 (mm /5eC) V2 =
23.39 (asthma/5ec) D = 31, 8469 (111111) P = 90 From equation (1) CI = 30 From equation (2) 02 = 21.04047976 [
C2]=21 From equation (10) K 1 = -1,9238991X
10"' (crown) From formula (12) K 2 = 4.5603634X1
0-2 (SeC) From equation (13), using values of N'=23.7Q370378 or more, the relationship between the error between the tape running time and the display time is shown in FIGS. 2 and 3. The error time represents the value of (actual tape running time) - (display time). In this case 2
It can be seen that for the time tape, the error is smaller when N=24 than N-23.

As described above, according to the present invention, without changing the diameter of the timer roller or the number of pulses of the encoder,
This has the effect of enabling accurate tape running time display even when the tape speed is changed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the tape running time display device according to the present invention, and FIGS. 2 and 3 are graphs showing display time errors in the tape running time display device according to the embodiment of the present invention. be. 1... Timer mouth ~ 12... Encoder, 3... Light receiving element, 4... Light emitting element, 5... Pulse conversion circuit , 6... ・First counter, 7... Tape running time conversion circuit, 9...
...Second counter, 10...Count value setting circuit. Name of agent: Patent attorney Toshio Nakao and one other person Figure 1/1c'Rus'

Claims (1)

[Claims] pulse generating means for generating a pulse signal each time a tape of a certain length runs, and a pulse signal from the pulse generating means when the tape runs at a first tape speed;
a first counter that counts as a binary counter and counts as a binary counter when the tape is running at a second tape speed;
counting means, counting the counting output of the first counting means during running at the second tape speed, and varying the value of m2 of the first counting means according to the counting output for every V pieces. A tape running time display device comprising a second counting means and a display means for displaying the output of the first counting means as a tape running time.