JPS61105751A - Video tape recorder - Google Patents

Abstract

PURPOSE:To make it possible to fast-feed and rewind in an unloading state and to prevent the abrasion of a drum and a head by automatically switching an unloading state to a load state as a remaining tape quantity reaches to a prescribed value. CONSTITUTION:When a recorder operates to fast-feed or rewind in an unloading state, rotating period detecting elements 7 of a supply and a take-up reels 5 and 6 generates a pulse of a frequency indicating a period of rotation and supply it to a remaining tape quantity detecting device 8. The device 8 constantly computes a remaining tape quantity and generates a pulse in very interval of 1/6 total ape length, and a judging device 9 judges the starting travel of high speed fast feed or high speed rewind. At this point, a threading motor 10 operates to proceed to a fast feed or rewind mode set with the ape loaded in a loading state, and then a sensor detects the starting of ending point of the tape.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a video tape recorder that allows fast forwarding and rewinding operations only when the tape is loaded. This made it possible.

[Conventional technology]

Traditional video tape recorder (VTR)
In devices where fast forwarding and rewinding are performed with the tape loaded on the drum, the sensors that detect the beginning and end of the tape are generally located at a distance from the tape cassette, as shown in Figure 3. It is set in. In the figure, (1) is a drum, (2) is a sensor, (3) is a tape, (4) is a tape cassette, (5) is a supply reel, and (6) is a tape cassette.
) indicates the take-up reel. Further, FIG. 10A shows a state in which the tape is loaded, and FIG. 10B shows a state in which the tape is not wound (unloaded). As can be seen from these figures, sensor (2) cannot detect the beginning and end of the tape when it is unloaded, so the tape cannot be fast forwarded! D (F
F) or rewinding R11d) is performed only when the tape is loaded.

[Problem that the invention seeks to solve]

If the tape is turned OFF or REWed while the tape is loaded as described above, the drum will wear out and the head will wear out at about 2,000 to 3,000 degrees, and the head will also wear out. This is necessary when dubbing a tape.
F. This is especially a problem with commercial VTRs that require a large number of REWs.

Therefore, the present invention provides F even when the tape is unloaded.
This is an attempt to solve the above problems by enabling F or REW operation.

[Means for solving problems]

In the present invention, an element for detecting the rotation period is attached to the supply and take-up reel of the tape cassette, and the output signal is sent to the remaining tape amount detection means to calculate the remaining amount of tape, so that the remaining amount of tape is kept at a constant value. By automatically switching the unload state to the load state, the FF in the unload state of a VTR that performs FF and REW in the tape load state
F' or REV operation is possible.

[Effect]

Now, in the reel of the tape cassette, let us say that the supply side is the S side and the take-up side is the T side, and the radius of the reel hub of the y0z cassette is r = the radius when the tape is wound on the s side rt"'T
(Radius ω when the tltl tape is wound = S
side rotational angular velocity ω, = rotational angular velocity V on the T side - tape speed t - tape thickness T, = rotational period on the 8th side (f8 - frequency) Tt = rotational period on the T side (ft - frequency) t, = Length of the tape wound on the S side (i.e. remaining amount) L = total length of the tape, then V - ω1ira - ωtrL - - - - - - - -
-(1) Substitute equation (2) into equation (1), v=2πr,/T, =2πrt/Tt...
・・・・・・・・・・・・・・・(3) 2π Therefore, T s =r m ・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
・・・(4)'rt=Q,rc r, ・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・
(5) Here, since the tape winding area is the length multiplied by the thickness, the tape winding areas on the S side and the T side are respectively Lll-t=rcrB2-gro2= π(y, 2−r,
2) -------------(6) (L-t,)t
=π body−πr0−π(rL−ro)・・・・・・・・・
...(7) Transforming equation (6), rs'=¥10r02, so r B=! −−−−−−−−−−−−−−−−
−(8) Similarly, rt”J”” ” + r,'
(9) π (8) # Substituting equations (9) into equations (4) t and (5), we get T, = 77... on ■ T, = 2x rπ〒π...・・・・・・・・・
...α) Obtain V π. Therefore, if we detect T s7'r t,
Since the right side of the α→ equation is a constant except for t8, t, (tape remaining amount) can be determined. Furthermore, since the term tape speed M is eliminated in equation (2), it is possible to detect the remaining amount of tape in FF, REV, etc., regardless of the tape speed V. By solving the α → equation for t, the following equation is obtained.

Therefore, by calculating the formula 01, the remaining amount of Citeno can be obtained.

By switching from the unload state to the end state when the remaining amount of tape reaches a certain value, the sensor can detect the beginning and end of the tape (see FIG. 3A).

〔Example〕

The present invention will be specifically explained below with reference to the illustrated embodiments.

FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, (7) is the supply or take-up reel (5) or (
6) is a rotational period detecting element attached, (8) is a tape remaining amount detecting means, (9) is a determining means, and 00 is a threading motor that puts the tape in a loaded state. The rotation period detecting element (7) may be, for example, a reflective two-photon electron device in which a reflecting plate having a plurality of teeth is attached to the reel stand on the S side and the T side and is disposed opposite to the reflecting plate.

Other types of frequency generators (FG) can also be used. The rotation period detection element (7) generates a pulse with a frequency representing the rotation period of the reel. The tape remaining amount detection means (8) is a circuit that calculates the remaining tape amount t by receiving the signals representing T8 and Tt according to the above equation 0, but in a hard logic configuration, the null is very large, so it is It is possible to use a computer (or microprocessor). The remaining tape amount detection means (8) outputs pulses for each predetermined length or fixed section of the tape while calculating the remaining amount of tape. Additionally, a signal indicating which division the 9th ruth belongs to is added to this. The determining means (9) is a circuit that determines the first or last section of the tape depending on the running direction of the tape, but in reality, it uses a microcomputer in combination with the remaining tape amount detecting means (8). It is a good idea to The threading motor ◇O operates in response to a signal from the determining means (9) indicating the first or last section of the tape, and puts the tape in a loaded state.

FIG. 2 is a tape diagram for explaining the operation of the system of FIG. 1. Figure A shows the case of fast-forwarding operation, and Figure B shows the case of rewinding operation. In these figures, 1/6~
5/6 indicates the remaining amount of tape from the start or end of the tape as a percentage of the total length from the start to the end. In other words, 5/6 represents the first 1/6 point, 4/6 represents the second 1/6 point, and so on, 1/6 represents the fifth 1/6 point.

That is, the example shown in the figure shows a case where the entire length of the tape is divided into six equal parts and divided into six sections. Further, H, FF represents high-speed fast forwarding, and H, REW represents high-speed rewinding. The OFF or REW operation speed in the unloaded state can be made faster than the FF or REW operation speed in the loaded state from the tape-wound position (for example, about 1.4 times, so for convenience it is It was expressed in

In FIG. 2, the FF or RW operation in the unloaded state can be performed from the beginning or end of the tape, but it can also be performed from the middle. When the FF or REW operation is performed in the unloaded state, the rotation period detection elements (7) attached to the supply and increase reels (5) and (6) generate a pulse train of frequencies representing the rotation period. and use this as the tape remaining amount detection means (
8). The tape remaining amount detection means (8) is based on the above formula α
The remaining amount of tape is calculated from time to time based on 5/6.
, 4/6, . This pulse also includes a signal indicating what division it is in. Judgment means (9)
is the point where the remaining tape amount is 1/6, that is, H, FF or H,
Determine the starting point of the last section with respect to the tape running direction of RIilW. In the illustrated example, it is sufficient to determine the fifth category from the beginning. Threading: Motor α1 operates at this point to load the tape, and HlFF or H,R
The EV state shifts to the FF or REW state in which the tape is loaded. In the loaded state, the sensor (2) can detect the beginning and end of the tape. FIG. 2 shows a state in which the H, FF or H, R11W operation transitions to the FF or REV operation at the starting point of the last section (hatched).

In the above example, the total length of the tape is divided into six sections, but it is also possible to further increase the number of sections.

In addition, due to improved accuracy of tape-related equipment, HoFF or I
It is also possible to switch the LREW operation to FF' or RIilW operation. In the figure, this is indicated by cross-hatched areas. Note that the means for switching from the unload state to the load state does not need to be limited to the threading motor.

〔Effect of the invention〕

As explained above, according to the present invention, the following various remarkable effects can be obtained.

(a) In a VTR that performs fast forwarding and rewinding operations while the tape is loaded, the life of the drum and head can be extended by performing fast forwarding or rewinding operations while the tape is unloaded.

(b) Since the fast forwarding or rewinding operation can be performed at a faster speed (approximately 1.4 times) than the conventional fast forwarding or rewinding operation speed, the fast forwarding or rewinding time can be shortened.

0 Conventional mechanical parts and system control devices can be used, and it is only necessary to add a microcomputer to control these system control devices.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a tape diagram for explaining its operation, and FIG. 3 is a schematic diagram showing a conventional example. (5), (6)...Reel, (7)...Reel rotation period detection means, (8)...Remaining tape amount detection means,
(9)...Determination means, 00...Means for switching the tape unload state to load state O PA2. - < =

Claims (1)

[Claims] In a video tape recorder that performs fast forwarding/rewinding operations and tape end detection only when the tape is loaded onto a rotating magnetic head drum, there is an element that detects the rotation period of the reel of the tape cassette, and an element that receives the output signal of this element. means for detecting the remaining amount of tape; means for determining whether the remaining amount of tape has reached a predetermined value upon receiving an output signal from the remaining tape amount detecting means; and determining the unloaded state of the tape based on the output signal from the determining means. A video tape recorder comprising means for switching the tape to a loaded state, thereby enabling fast forwarding and rewinding operations when the tape is unloaded.