JPS58158089A - Discriminating device of diameter of reel hub - Google Patents

Abstract

PURPOSE:To recognize the remaining time of a tape, by providing the 1st and the 2nd detecting means which detect the rotation periods of a supply and a take up reels respectively, the arithmetic parts which discriminate reel hub diameters from the detection signals, and an output part which outputs the arithmetic result. CONSTITUTION:The remaining time of a cassette tape, etc., is known by recognizing hub diameters (d) during a constant-speed run and then detecting both rotation periods of the supply and take up reels. The detection parts 1 and 4 for the rotation periods of the supply and take up reels detect the rotation periods respectively and the hub diameters are discriminated by the arithmetic parts 3 and 2 from the sum of the rotation periods; and the output part 5 outputs the remaining time of the tape. Consequently, the remain-time of the tape is known easily.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reel hub diameter identification device for a tape remaining time output device, etc., which is particularly useful for tape recording and reproducing equipment such as a video tape recorder (hereinafter abbreviated as VTR).

When recording on and playing back a cassette tape using a VTR, it would be convenient to be able to know how far the tape has progressed and how much tape remains, even when the cassette tape is loaded into the VTR body.

Mechanical counters that are linked to the reel rotation axis that have been used in the past can identify the movement of the tape, but because they do not have a linear relationship with time, they cannot accurately determine the elapsed time or remaining time. .

For this reason, one way to accurately know the remaining time on the tape is to
When the tape is running at a constant speed, the rotation period of the tape supply reel is detected and the remaining time of the tape is determined through arithmetic processing.

The principle is as follows.

If the length of the tape wound on the supply reel is β, the thickness of the tape is 81, the diameter of the tape wound on the supply reel is p, and the diameter of the reel's nozzle is d, then β is It is expressed as

Here, the relationship between the rotational angular velocity ω and the tape movement speed V is υ=-ω (2)
Also, the relationship between the rotation period T(l) and the rotation angle ω is as follows.By substituting the above equation (6) into equation (1), since the tape speed V during recording and playback is constant, The remaining time t of the tape is given by: If the tape thickness S is constant, the remaining time υ of the tape can be calculated from the rotation period T by knowing the noop diameter d.

For example, in VH8 standard video cassette tapes, there are two types of hub diameter d: d1 = 26mm and d2 = e2■, and they are used depending on the tape length (recording time), but for general users, the knob diameter is Not only is it troublesome to visually identify the time, but if you make a mistake, the remaining time will be displayed incorrectly.

The present invention makes it possible to automatically and reliably identify the reel nozzle diameter with a simple configuration, and by knowing the reel rotation period for any type of tape, it is possible to accurately identify the reel nozzle diameter. This allows you to know how much time is left. Hereinafter, the present invention will be explained based on illustrated embodiments. FIG. 1 is a block diagram of the main parts of this embodiment. In the figure, reference numeral 1 denotes a supply side reel rotation period detection section, the output of which is given to the calculation section 2 for calculating the remaining time. Identification of the knob diameter is performed by a calculation section 3 for hub diameter identification, and its output is given to the calculation section 2. The input information for identifying the diameter of the reel is obtained from the supply side reel rotation period detection section j and the take-up side reel rotation period detection section 4 provided separately.

The remaining time on the tape is output as an electrical signal by the calculation section 2, and the remaining time is displayed in numbers by the output section 6. Note that the output unit 6 may include a function of displaying the remaining time (tape recordable time or remaining playback time) in numbers on a part of the picture tube screen of the television receiver, for example.

The recording and playback time of cassette tapes according to the VH8 standard is 2o9r - 120 minutes, and the nope diameter is specified as d = 26■ when it exceeds 60 minutes, and 62 when it is less than 60 minutes, and the diameter of the tape on the supply side The relationship between the rotation period and the elapsed recording and reproducing time of the tape is shown in FIG. In FIG. 2, curve a is the rotation period of the supply side reel for a 120 minute tape, and curve 2 is the rotation period of the supply side reel for a 60 minute tape. Since the hub diameters are different, the rotation cycles of the supply reels are similar even if the tape lengths are different, and it is difficult to identify the hub diameters only from the rotation cycles of the supply reels. Further, the curve C in FIG. 2 is the rotation period of the 120-minute tape take-up reel, and the curve d is the rotation period of the 6-minute tape take-up reel. Although the difference in rotation period depending on the diameter of the nozzle is obvious, it cannot be distinguished regardless of the elapsed time.

The present invention detects the rotation period of the supply reel and the rotation period of the take-up reel, and uses arithmetic processing to identify the hub diameter regardless of the elapsed time. The identification is made using the sum of the rotation periods of each reel.

That is, the rotation period TtI of the supply reel)19 The rotation period T of the take-up reel. The relationship between 2 and 2 is as shown in Figure 3 for each length of tape. ), the elapsed time trajectory is clearly different from T,,1+T, as shown by the broken line in the figure. By appropriately selecting k such that 2=, the hub diameter can be identified.

If we transform equation (a) and find the value of k within the discernible range, we can obtain the following value, as shown in Figure 3, where T is the recordable (playback) time of the tape. ,... diameter (
d) has a small diameter hub of dl (=26-) and the recordable (playback) time (7) is 12 degrees (=120 minutes), ...... (9) Also, the possible recording (reproduction) time (7) for a large-diameter hub with a hub diameter (d) of d2 (=62al) is T2° (=
For a cassette tape of 20 minutes), the following margins are QQ. Therefore, 11, sts < k < 12. ss
, , , , If you set the value of k in the range of aυ, then using this as a reference, the value of ("ml""a+2)"
The hub diameter can be identified.

Also, with large diameter hub reels, T-
If you set the condition o), in this case, it becomes 11.5
By setting k as 6<k<11.68, the hub diameter can be identified even when a large diameter hub reel with any tape length is used.

As described above, according to the present invention, the rotation period Tw1.
Just by knowing Tt1,2, the hub diameter can be accurately identified by calculation, and as mentioned above, it can be identified regardless of the reel hub diameter or tape length. This is also useful when obtaining torque control information during reel driving.

In addition, in the above explanation, the constant running speed V was explained as being constant, but in a VTR, the running speed can be switched between 2 to 3 types, and the reel rotation period and identification conditions are different. , these can be set in proportion to the running speed, and conditions can be easily set according to each running speed.

Needless to say, identification is possible.

[Brief explanation of drawings]

FIG. 1 is a block diagram of main parts of an embodiment of the present invention, and FIG.
The figure is a characteristic example diagram showing the rotation period of each reel, and FIG. 3 is a characteristic example diagram showing the rotation period of each reel using the tape length as a parameter. 1... Supply side reel rotation period detection section, 2, 3.
. . . Calculation section, 4 . . . Take-up side reel rotation period detection section, 6 . . . Output section. Name of agent: Patent attorney Toshio Nakao and one other person
Figure 1 Δ Figure 2 Recording Yari J1 Raw 适逼旼阀(intermediate) Figure 13 W2

Claims (2)

[Claims] (1) a first detection means for detecting a signal proportional to the rotation period of the supply reel; a second detection means for detecting a signal proportional to the rotation period of the take-up reel; It is equipped with a calculation unit that identifies the hub diameter from the signal detected by the detection means, and an output unit that outputs the calculation result, and it is equipped with a calculation unit that outputs the calculation result, and it is equipped with a calculation unit that outputs the calculation result. A reel hub diameter identification device characterized in that the reel hub diameter is identified by determining a wholesale value of a cycle. (2) When the running speed of the tape is 33, 35 cm/crown, the identification value k of the sum of the rotation periods of each reel is 11.55<
The reel hub diameter identification device according to claim 1, wherein the reel hub diameter identification device is set in a range of k<12.35.