JPH0487092A - Video tape recorder - Google Patents

Abstract

PURPOSE:To shorten time needed for a fast forward (FF) and rewind (REW) operations of a video tape recorder VTR by setting the tape speed at the highest level allowable to the VTR within a prescribed period from the starting time points of both FF and REW modes. CONSTITUTION:When an FF or REW operation is started, a reel drive motor is controlled at first with a 2nd speed control signal received from a 2nd speed control means 31. When the tape speed reaches a 1st high speed level, the reel drive motor is controlled with a 1st speed control signal received from a 1st speed control means 32 respectively. That is, the tape speed reaches the highest level Vt attainable with a VTR in a short prescribed period after the tape is wound up with the FF or REW operation. This speed Vt is kept up to a point D approximate to the tape termination. As a result, the total time needed for the tape FF and REW operations can be shortened.

Description

[Detailed description of the invention] (b) Industrial application fields The present invention relates to video tape recorders (VTRs).

(b) Fast forwarding (FF) or rewinding (REW) in conventional technology VTRs)
It is preferable to set the tape speed as high as possible because the winding time can be shortened.

By the way, when the brake is applied to stop tape movement near the end of winding from the FF or REW state, the amount of tape movement (A) during braking by this brake is:
The faster the tape speed at the time the brake is applied, the more it increases. In particular, the brake is designed to detect and apply the leader tape at the end of the tape, so if the value of the movement amount (A) exceeds the leader tape length, very high tension will be applied to the tape, causing the tape to break. Problems such as this occur.

Conventionally, fast forwarding or rewinding operations in a VTR are performed by rotating a reel stand at a constant speed using a capstan motor, and therefore the tape speed gradually increases from the start of winding and reaches its maximum at the end of the tape.

As mentioned above, when a leader tape is detected, a brake is applied to the reel stand to slow down the tape speed and reduce the tape tension that occurs when tape winding is finished, thereby preventing tape breakage. In order to prevent this from occurring, it is necessary to limit the tape speed at the time of applying the brake to a certain upper limit value. In other words, conventionally, the reel stand was rotated at a constant rotational speed so that the tape speed was the highest speed at which no tape breakage occurred when the brake was applied.

(c) Problems to be Solved by the Invention As mentioned above, in conventional VTRs, the tape speed reaches its maximum near the end of the tape, so the time required for FF and REW cannot be sufficiently shortened.

The present invention therefore seeks to overcome such drawbacks.

(d) Means for Solving the Problems In order to solve the above problems, the video tape recorder of the present invention includes: a reel winding diameter detecting means for constantly detecting the winding diameter of the reel of a tape cassette; and a reel winding diameter detecting means. a first speed control means for generating, based on the detection output, a first speed control signal for obtaining a reel rotation speed for transporting the tape at a constant first high speed; second speed control means for generating a second speed control signal for obtaining a reel rotation speed that gradually increases from the first speed to the first high speed; and a second speed control signal output from the first and second speed control means. 1st, iI
and control means for controlling the reel drive motor based on the speed control signal of No. 2, and the control means is configured to:
First, the reel drive motor is controlled by a second speed control signal outputted from the second speed control means, and when the tape speed reaches the first high speed, the first speed control signal outputted from the first speed control means is The reel drive motor is controlled by a speed control signal.

(e) Effect: According to the above configuration, the tape speed can be brought to the maximum speed without suddenly applying a large tension.

(f) Examples Examples of the present invention will now be described with reference to FIGS. 1 to 6.

Figure 1 shows the main blocks of a VTR embodying the present invention.
The figure is a diagram for explaining changes in the tape moving speed according to the present invention.As is clear from this figure, in the present invention, when the tape starts to be wound by the FF or REW operation, a predetermined period (described later) ( (This period is short), the tape speed reaches the highest speed V, (hereinafter referred to as steady movement speed V) obtained by the VTR, and this is the point RD near the end of the tape.
The tape is transported at this speed v1 until . Note that the tape speed ■ here is the corresponding V
This is the maximum speed limited by the strength of the TR mechanism, the maximum rotation speed of the motor, etc.

When the tape is completely wound, the tape end speed is the maximum speed V at which the tape does not break, etc.
(hereinafter referred to as the tape end speed ■). Therefore, according to the present invention, the time required for tape FF and REW can be reduced as a whole.

Next, to explain the operation of the block diagram in FIG. 1, l is a supply (S side) reel, 2 is a take-up (T side) reel,
Both reels 1. The supply and take-up reel stands (not shown) on which the reel units 2 and 2 are mounted and are rotationally driven by a motor drive circuit (capstan motor drive or reel motor drive circuit, etc.) 15 are provided with an optical system that measures the number of revolutions. S to detect
Side and T side steering wheel rotation detectors 3 and 4 are provided, and S side and T side steering wheel pulses nl are provided according to the number of rotations of each knoll.
+n! emits.

6.7 is an S-side and T-side rotation period measurement circuit that calculates the rotation periods T3 and T of the S-side and T-side wheels from the S-side and T-side wheel pulses and the reference clock obtained from the tarlock generation circuit 5. It is.

Specifically, this rotation period measuring circuit 6.7 measures the rotation of each reel by counting the number of reference taroks included within one period of each reel pulse, which is generated once per rotation of each reel. The period T3, T, can be determined. Note that the period of the reference clock is set to be sufficiently shorter than the period of the reel pulse.

The rotation period T of both reels measured in this way,
.
is supplied to the adder circuit IO.

11, when the tape cassette is installed in the VTR, the FF
Alternatively, before the REW operation is executed, it is a tape type discrimination circuit that discriminates the type of tape cassette and performs initial settings. to be transferred;
The sum of the squares of the rotation periods T, , T, obtained at this time (T,
"+T,") is obtained from the adder circuit 10.

That is, to explain this in more detail, the tape cassette is
When the FF or REW button is pressed immediately after insertion into R, a tape speed control signal for performing the pseudo CUE mode is supplied from the servo circuit 30 to the motor drive circuit 15 via the first signal selection circuit 31. The tape is transported at the above running speed v0. Therefore, the first signal selection circuit 31 is switched to select the output of the servo circuit 30 until the tape type determination circuit 11 finishes determining the tape type. Note that the pseudo-CUE mode is similar to the normal CUE (high-speed playback) mode in that it has almost the same tape feed (tape speeds are not exactly the same), but is different from the CUE mode in that it does not output video signals. It is the mode of becoming.

By the way, let Ro and R1 be the reel winding diameters of S-side and T-side wheels 1 and 2, and let the tape wire winding amount [(hub area)
+ (Tape area) If C is C, then C=π・R1'+π・R1...■ holds true, while R-=V a ・T −/2 π, R1=V
Since o ·T, / 2 yr, it is expressed as C=V, mushroom (T, +T,'')/4π...■.

Here, the tape wire winding amount C is the type of tape cassette (
T-60, T-90, T-120, etc.), and the tape type discrimination circuit 11 stores the total winding amount C for each type of tape cassette in the internal memory in advance as discrimination data. are doing. Therefore, if (T, "+T,") is calculated, the total winding amount C can be obtained from the above formula 0, so the tape type discrimination circuit 11 internally calculates the total winding amount C obtained from this formula 0. By comparing the C values in the memory, the type of tape cassette inserted into the VTR is determined based on the matched C value, and the total winding amount C is supplied to the arithmetic circuit '12.13.

In this way, when a tape cassette is inserted into a VTR, the type of tape cassette is first determined and the total tape winding amount C is obtained, but after this, the FF or REW operation is started. and its FF or REW
At the start of operation, the reel winding diameter R of the S side and T side spools,
R, is calculated by the arithmetic circuits 12 and 13.

The arithmetic circuit 13 calculates the number of rotations (number of reel pulses) nl of the reel 2 obtained from the T-side reel detection circuit 4 and the number of rotations (number of reel pulses) nl of the reel 1 obtained from the S-side reel detection circuit 3. The tape wire winding amount C from the tape type discrimination circuit 11 is obtained, and the following equation (2) is calculated to calculate the T-side thread diameter R0.

The arithmetic circuit 12 also calculates the number of revolutions 01 of the reel 2 obtained from the T-side reel detection circuit 4 and the S-side reel detection circuit 3.
The number of revolutions of reel 1 obtained from n.

Then, the tape warp winding amount C from the tape type discrimination circuit 11 is obtained, and the following formula (2) is calculated to calculate the S-side reel diameter R1.

The path 14 obtains the reel diameter data R1 of the S-side reel 1 supplied from the arithmetic circuit 12, and sets the REW speed to a constant maximum speed V, (V,: the amount of tape movement per second). The reel rotation speed is determined from the following 0 formula, and the motor drive circuit 15 is set so that the reel reaches the rotation speed determined by this 0 formula.
outputs a 4KPWM (4KH2 pulse width modulated wave) signal that controls the

When FF is performed, the optimum speed calculation circuit 14 obtains the reel diameter data R, of the T-side spool 2 supplied from the calculation circuit 13, and obtains the maximum speed V at which the FF speed is constant (
V,: amount of tape movement per second) is calculated from the following 0 formula, and the motor drive circuit 15 is controlled so that the reel reaches the rotation speed determined by this 0 formula. Outputs a 4KH2 pulse width modulated wave) signal.

In addition, when REW is performed, the maximum speed calculation circuit performs the above operation, that is, when the tape type determination circuit 11 finishes determining the tape type at the same time as the optimum speed calculation, the first signal selection circuit 31 selects the 4KPWM output circuit. 34 (a PWM signal whose duty ratio changes from 37% to 100% as shown in FIGS. 6(a) to 6(b')). Since the selection is made, the pseudo FF output from the 4KPWM output circuit 34
The signal is input to the motor drive circuit 15 via the second and first selection circuits 32, 31. Note that the duty ratio of the pseudo FF signal given to the motor drive circuit 15 is 37% to 10.
As it increases to 0%, the rotational speed of the motor increases.

The second selection circuit 32 selects the input from the comparison circuit 32.
Based on the output of That is, the comparison circuit 32 compares the 4KPWM signal output of the maximum speed calculation circuit and the 4KPWM output of the 4KPWM output circuit 34 whose duty ratio gradually increases, and if the two do not match, the 4KPWM output circuit 3
4, and if they match or 4KPWM is not larger than that, the second signal selection circuit 32 is controlled to select the output of the optimum speed calculation.

First, the FF button is pressed (time point [.] in FIG. 5), and after the above-described tape type discrimination operation period (period t0 to t1 in FIG. 5) ends, the time period (
During [, ~t8 period] in FIG. 5, the first signal selection circuit 31
selects the pseudo FF signal output from the servo circuit 30 and gives this pseudo FF signal to the motor drive circuit 15, and after tI in FIG. 5, the first signal selection circuit 31 selects the output of the second signal selection circuit 32 is selected and applied to the motor drive circuit 15. Then, when the timer setting time expires (in Figure 5 [
4KPWM from the 4KPWM output circuit 34
The signal duty changes from 37% to 100%, but at this point (at time t8 in Fig. 5, the 4KPWM circuit
Since the KPWM signal and the output of the optimum speed calculation circuit 14 do not match, the second selection circuit 32 selects the output of the 4KPWM circuit 34.

Then, when the output signal of the 4KPWM circuit 34 and the output signal of the optimum speed calculation circuit 14 match or become larger (at time t4 in FIG. 5), the comparison circuit 33 selects the second selection circuit 3.
2, the output of the optimum speed calculation circuit 14 is selected, and from this point on, the T side selects the output of the optimum speed calculation circuit 14.
The rotation speed is controlled so that the tape is always moved at a target speed (maximum speed) Vl given by .

If the tape speed suddenly reaches the maximum speed vl due to FF operation, undesired tension will be added to the tape and there is a risk of the tape being damaged.
When winding is started by the EW operation, the tape speed increases over a short predetermined period. ! Since the tape is set at the highest speed V, no undesirable force is applied to the tape and there is no risk of the tape being damaged.

Note that the explanation regarding FIG. 5 is for FF, but for R
The same applies to the case of EW, and the case of REW operation will be easily understood.

By the way, as shown in Fig. 2, the tape speed near the end of the tape changes from V to V in RD (speed down point).
The operation of switching to is performed as follows.

That is, in the case of FF, the reel diameter R1 of the S-side reel is calculated by the arithmetic circuit 12, and the J-reel diameter data R1 is supplied to the comparison circuit 16.

As shown in FIG. 4, the tape type discrimination circuit 11 uses predetermined speed down point data Rh [(Rh) = (hub diameter of various tapes: RFI) + (predetermined tape diameter: Rh=
RR)] is stored in the internal memory, and this data R5 is input as the other data to the comparison circuit 16.

Then, when the data R2 from the tape type discrimination circuit 11 and the data R0 from the arithmetic circuit 12 match, the comparator circuit 16 sends the data to the optimum arithmetic circuit 14 based on a command from the comparator circuit.
obtains the reel diameter data R1 of the T-side knoll 2 supplied from the arithmetic circuit 13, calculates the reel rotation speed at which the FF speed becomes a constant speed V from the following 0 formula, and uses this 0 formula. The motor drive circuit 15 is controlled to achieve the determined rotational speed.

Further, in the case of REW, the reel diameter R5 of the T-side reel is calculated by the arithmetic circuit 12, and the reel diameter data R1 is supplied to the comparison circuit 16.

Then, when the data R from the tape type discrimination circuit 11 and the data R1 from the calculation circuit 13 match, the comparison circuit 16 causes the maximum speed calculation circuit 14 to receive the data supplied from the calculation circuit 12 based on a command from the comparison circuit. Obtain the reel diameter data R, of the S-side reel 1, and set the speed V at which the FF speed is constant,
Find the reel rotation speed such that
The motor drive circuit 15 is controlled to achieve the rotation speed determined by the formula.

Find the S-side reel diameter according to the following formula.

FIG. 3 is a block diagram showing another embodiment of the configuration within the broken line frame A' in FIG. 1, that is, the tape type discrimination circuit system.

When the configuration shown in FIG. - S side and T side reel pulse number data C and D (in other words, C and D indicate the number of rotations of the reel) are obtained from the reel rotation detection circuits 3 and 4.

Then, the S side reel diameter calculation circuit 16 outputs data C and
The T-side thread diameter calculation circuit 17 uses the data D to calculate the next 0
Find the T-side hole diameter according to the formula.

These reel diameter data R,,R, are input to the tape type discrimination circuit 11, which performs calculations based on the formula 0, calculates the tape warp winding amount C, and stores it in advance in the internal memory. Compare the tape warp winding amount data C of the tape type stored in
It operates to determine the type of tape cassette installed in the TR.

In Figure 2 above, the tape speed is set to V at Ro a little before the end of the tape because even tapes of the same type have variations in tape length, so the safe end speed is set a little earlier to absorb the variations. This is to take it with you.

In addition, in Fig. 1, the part surrounded by the - dotted chain line frame is 1
Needless to say, it can be constructed using a chip microcomputer.

As described above, according to this embodiment, since the tape speed is brought to the maximum speed allowed by the VTR over a predetermined period from the start of FF or REW, there is a sudden increase in the tape speed at the start of FF or REW. No tension is applied to the tape, eliminating the risk of damage to the tape. Further, near the end of the tape, the tape is transported to the final end at the maximum speed that does not cause the tape to break based on the knoll diameter, so the time required for FF and REW can be shortened as much as possible.

(g) Effects of the Invention As described above, according to the present invention, the time required for FF or REW can be shortened as much as possible without damaging the tape.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the main parts of a video tape recorder embodying the present invention, Fig. 2 is a diagram for explaining the operation of the main parts, and Fig. 3 is a block diagram of the main parts of a video tape recorder embodying the present invention. FIG. 4 is a diagram showing speed-down points; FIG. 5 is a diagram for explaining part of the operation of the video tape recorder of the present invention; 1N
FIG. 6 is a diagram showing the output signal waveform of the 4KPWM output circuit. (3)...S side reel rotation detection circuit, (4)...T
Side slide rotation detection circuit, (6)...S side rotation period measurement circuit, (7)...T side rotation period measurement circuit, (8)...
・5 arithmetic circuits, (9)... arithmetic circuits, (10)...
Addition circuit, (11)... Tape type discrimination circuit, (12
) (13)...Arithmetic circuit, (14)...Optimum speed arithmetic circuit, (15)...Motor drive circuit, (30)...
... Servo circuit, (31) ... First selection circuit, (32
)...second selection circuit, (33)...comparison circuit, (3
4)...4KPWM output circuit, (35)...timer circuit. Figure 2

Claims (1)

[Claims] (1) Reel winding diameter detection means for constantly detecting the winding diameter of the reel of the tape cassette; and reel rotation for transporting the tape at a constant first high speed based on the detection output of the reel winding diameter detection means. a first speed control means for generating a first speed control signal for obtaining a number of reel rotations; a second speed control means for generating two speed control signals; and first and second speed control signals output from the first and second speed control means.
control means for controlling the reel drive motor based on a speed control signal of the reel drive motor;
First, the reel drive motor is controlled by a second speed control signal outputted from the second speed control means, and when the tape speed reaches the first high speed, the first speed control signal outputted from the first speed control means is A video tape recorder adapted to control a reel drive motor with a speed control signal.