JPH01184649A - Tape position detector - Google Patents

Abstract

PURPOSE:To rapidly detect a tape position with a simple constitution by executing a prescribed operation based on the measured value of a reel having the small number of windings. CONSTITUTION:Pulses generated respectively by a supply reel system rotation detecting pulse generator 10a and a take-up reel system rotation detecting pulse generator 10b are counted by reel system counters 11a, 11b to decide the reel having the small number of windings high in a rotation angular velocity in a comparison circuit 14. In an arithmetic circuit 15, based on the diameter RS, RT of the winding of the supply reel or the take up reel small in the number of the windings, an operation by equations I or II is executed and the residual quantity time TI of the tape is displayed on a display device 21. According to this detecting system, the tape position is rapidly detected and displayed with the simple constitution. In the equation RO is the diameter of the hub, t is the thickness of the tape, V is the tape speed and L is the total length of the tape.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a tape position detection device mounted on a magnetic recording/reproducing device such as a video tape recorder (VTR).

(Prior Art) Conventionally, this type of tape position detection device obtains information such as the rotation or rotation period of a preset one of a pair of reels on which tape is inserted, and then calculates this information. A method has been adopted in which the tape position (including the remaining amount of tape) is determined by substituting and calculating into a predetermined formula.

However, in the above-mentioned tape position detection device, when the tape position of the tape cassette becomes unknown due to high-speed running mode such as fast-forward playback, the measurement reel is rotated a predetermined number of times (for example, after returning to constant-speed running mode). Since the position cannot be detected until the reel completes one revolution (1 rotation), if there are many tape wraps on the reel on the measuring side, the time required to detect the rotation will be longer, which will cause the problem of longer detection time. was.

For example, when the winding side is used as a measurement reel, the closer to the tape end (the state where there is more tape wound on the winding side reel and almost no tape on the supply side reel), the longer it takes to detect the remaining amount. . Furthermore, when the supply side is used as a measurement reel, the closer the tape is to the top (a state in which a large amount of tape is wound on the supply side reel and almost no tape on the take-up side reel), the longer it takes to detect the remaining amount.

(Problems to be Solved by the Invention) As described above, in the conventional tape position detection device, it takes a long time to detect the tape position.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a tape position detection device that has a simple configuration, can speed up tape position detection, and can improve detection accuracy. purpose.

[Structure of the Invention] (Hth Means for Solving the Problems) The present invention provides tape running means for running the tape from one of the first and second reels in the other direction in response to a tape position detection request signal; reel rotation detection means for detecting rotations of the first and second reels and generating detection pulses; reel system counting means for counting each detection pulse of the reel rotation detection means; and reel system counting means. a control means for controlling the counting period of the reel; a comparison means for comparing the output of the reel system counting means to determine which reel has a smaller winding diameter among the first and second reels; a capstan system counting means for detecting rotational pulses of a capstan for running the tape in response to the output of the reel system counting means regarding the reel; and a tape position based on the output of the capstan system counting means and a tape type discrimination signal. It is constructed by comprising a calculation means for determining the calculation means, and a display means for displaying the calculation result of the calculation means.

(Function) According to the above configuration, the tape position is such that one of the first and second reels with the smaller number of turns is selected as the measurement reel,
Tape position is detected. Therefore, since measurements are always made with the tape winding diameter being approximately 1/2 or less, the startup time can be shortened and the detection time can be made as quick as possible.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a tape position detection device according to an embodiment of the present invention, in which 10a and 10b are respective supply (
Supply reel rotation detection pulse generator (hereinafter referred to as SRI' generator) that detects the rotation of the reel (supply) and Tick-up reel rotation detection pulse generator (hereinafter referred to as TRP generator) that detects the rotation of the take-up (take-up) reel. ). This SRP and TRP generator 10a.

Each output pulse of 10b is supplied to reel system counters lla and llb for reel counting, respectively.

The counting period and timing of the reel counters lla and llb are controlled by measurement control circuits 12a and 12b, respectively. The measurement control circuits 12a, 1
The operation of 2b is controlled based on a control signal from a logic control circuit 13 for system control.

Further, each output of the reel type counters lla and llb is supplied to a comparison circuit 14. The comparison circuit 14 compares and examines the input count values, determines which reel has the smaller number of turns, and supplies the determination result to the arithmetic circuit 15. at the same time,
The outputs of the reel system counters lla and llb are supplied to measurement control circuits 16a and 16b for capstan system control. The measurement control circuits 16a and 16b respectively control the operation of capstan counters 17a and 17b for capstan counting only during a period when the input count value is a predetermined value. This capstan system counter 17a.

17b is supplied with the output of a capstan rotation detection pulse generator 18 for detecting the rotation of a capstan motor (not shown) that drives the tape. Cab stan motor (
(not shown) is drive-controlled via a tape running control circuit 19 which is controlled by the logic control circuit 13.

The outputs of the capstan counters 17a and 17b are supplied to the arithmetic circuit 15, and are provided as tape type determination data and tape remaining amount determination data. This calculation circuit 1
A tape type signal input circuit 20 is connected to 5, and parameters corresponding to the tape type are variably set, and the remaining amount of tape corresponding to the tape type is determined as described below.
The calculation result is output to the display 21.

The arithmetic circuit 15 calculates the supply reel winding diameter R8 (the radius of the tape winding amount) and the pick-up reel winding diameter RT (
Find the radius of the tape winding amount.

R8 is Rs-((capstan radius)/(number of capstan pulses per capstan rotation))×(supply reel 1
The number of capstan pulses per rotation) can be determined as follows, and RT can also be determined in the same way. Then, the total length of the tape is L1, the tape thickness is t1, the hub diameter is RO (radius), and from R82+RT2-(L-t)/2R0, the value of the rigidity determined by the tape type of Rs2+RT2 is determined, and the hub diameter is Different tape types are required. In this case, for long-time tapes whose recording time exceeds 120 minutes (SP mode), the tape thickness t
Since it differs depending on the type of tape, it is designated each time by a tape type signal from the tape type determination signal input circuit 20.

Next, the remaining tape time TI is calculated as TI-π(R52-Ro2)/(tV) ・-(1) where V is the tape feed speed during recording and the cycle of the supply reel is measured.
So, when measuring the period of the pick-up reel, TI-L/V-π(R72-Ro 2)/(tv)
...(2), where L/V=yr (Rs2+R722Ro 2)/(tV
)...(
The formula 3) holds true. As a result, once the cycles of the supply and pick-up reels are measured and the type of tape is determined, the remaining amount of tape can be determined by measuring the one reel with the smaller winding diameter using formula (1) or (2). is found.

In the above configuration, for example, when the tape constant speed running state in the tape position detectable mode is switched to the tape high speed running state in the tape position undetectable mode, the reel system counter 11a.

11b and a capstan system counter 17a.

17b. Then, when the tape position detectable mode is switched again, the logic control circuit 13 measures the control signals from the control circuits 12a, 12b and 16a, 16b.
and sets the reel counters 11a, llb and capstan counters 17a, 17b to measurement mode. As a result, capstan system counter 17.17b
measures the rotation period of the supply and pick-up reels. Furthermore, the logic control circuit 13 is a measurement control circuit 12a.
, AJ of n rotations from either one of the outputs of 12b.
When it is detected that one constant period has ended, the counted values of the capstan system counters 17a and 17b are supplied to the arithmetic circuit 15. This arithmetic circuit 15 is supplied with the selection signal that has been compared and considered by the comparison circuit 14, and the remaining tape is determined from the same amount of tape windings on one reel of the supply with a smaller winding diameter and the pick-up reel according to this selection signal. is obtained as described above, and the result of the calculation is output to the display 21 for display.

In this way, the tape position detection device selects one of the supply reel and the pick-up reel with a smaller number of tape windings as the measurement reel, and detects the tape position by determining the tape winding amount of this measurement reel. It was configured as follows. According to this, the tape position is always measured when the tape winding diameter is approximately 1/2 or less, so the time for rotating the predetermined number of measurement reels is shortened compared to the conventional method. This makes it possible to speed up the detection time as much as possible, and also to reduce the effects of tape thickness, uneven winding, etc., which can also contribute to improving detection accuracy.

For example, T-160 used in VHS type VTRs.
In the case of this tape, it is now possible to measure both the tape top and the tape end in 2.5 seconds, compared to the conventional 9 seconds at the tape top and 2.5 seconds at the tape end.

Note that this invention is not limited to the above embodiments, but also includes
It goes without saying that various modifications can be made without departing from the spirit of the invention.

[Effects of the Invention] As detailed above, according to the present invention, there is provided a tape position detection device that has a simple configuration, can speed up tape position detection, and can improve detection accuracy. can be provided.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a tape position detection device according to an embodiment of the present invention. 10a, 10b.S and TRP generator, 11a. 1 l b ... Reel system counter, 12a, 12b
. 16a, 16b...Measurement control circuit, 13...Logic control circuit, 14...Comparison circuit, 15...Arithmetic circuit, 17a, 17b...Capstan system counter, 18
...Capstan rotation detection pulse generator, 19...
Tape running control circuit, 20...Tape type discrimination signal input circuit, 21...Display device. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] tape running means for running the tape from one of the first and second reels to the other in response to a tape position detection request signal; and a tape running means that detects the rotation of the first and second reels and generates each detection pulse. Compare the generated reel rotation detection means, the reel system counting means for counting each detection pulse of this reel rotation detection means, the control means for controlling the counting period of this reel system counting means, and the output of the reel system counting means. and a comparison means for determining which reel has a smaller winding diameter among the first and second reels, and running the tape in response to the output of the reel system counting means regarding the reel determined by the comparison means. A capstan system counting means for detecting rotational pulses of the capstan, a calculation means for determining the tape position from the output of the capstan system counting means and a tape type discrimination signal, and a display means for displaying the calculation result of the calculation means. A tape position detection device comprising: