JPS5823340A - Tape tension controller - Google Patents

Abstract

PURPOSE:To keep tension to an optimum value, by inputting a change in output resistance of a distortion meter caused with the press-contacting of a tape to a bridge, detecting the output change of the bridge and comparing the change with an initial set voltage and controlling the reference voltage. CONSTITUTION:An output of a high frequency oscillator 12 drives detectors 10 and 13. The detector 10 is a distortion meter detecting the pressing force of a tape and forms one side of a bridge and the output voltage of the bridge is fluctuated depending on the press-contacting force. This voltage variation is amplified 11 and synthronizingly detected 13, the output is compared 14 with an initial set voltage V01 and the output of the comparator 14 is given to a reference voltage V02 providing the optimum tape tension to control a supply side capstan motor 15. The changeover of tape speed is made by switching the reference voltage V03 for a speed changeover section 16, initial voltage and reference voltage changeover sections 17 and 18, and a take-up side capstan motor 19. Thus, the tape tension at each tape speed can be kept constant.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a tape recorder having a tape running system.
This relates to a tape tension control device for I&

Generally, the tape tension of the tape running system changes in response to the winding diameter of the tape reel and the torque of the reel stand. However, various methods have been proposed in which variations in tape tension cause changes in the recorded or reproduced signal level, variations in tape speed, detect the diameter, and control the torque of both reel motors. However,
The tape tension control available in such a method is not sufficient and causes fluctuations in tape tension.

- Therefore, an object of the present invention is to provide a tape tension control device that can solve the above problems.

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

Fig. 1 is a diagram showing the relationship between the strain gauge and the tape that constitute the detector according to the present invention, where (!] is the tape, and ) is pressed against the tape iTl during recording or playback, and the resistance value changes depending on the tape tension. A strain gauge (2) is a strain gauge support that supports a strain gauge formed of metal foil that changes in temperature. In addition, as shown in Fig. 2 (resistance value of strain gauge (1)
H and R constitute a bridge circuit, and this bridge circuit serves as a tape tension detector.Such a bridge circuit has (・When we apply a voltage of Voltage (e changes). Figure 3 is a diagram showing the position of the target gauge in the recording or playback state, +01 is the cassette, +31 (31 is the reel axis, +
a) tj+ is a reel hub, +51 +51 is a capstan, +61 tai is a guide, +71 +71 is a pinch roller, (8) is an erasing head, and (9) is a recording/reproducing head capable of recording or reproducing. In the rose loop dual capstan system as shown in Figure 3,
The strain gauge is arranged to detect the tension of the closed loop formed by the capstan +51 (i.e., the tension of the tape (te) in contact with the recording/reproducing head (9)).

Next, a tape tension control device having a strain gauge having such a configuration will be explained.

FIG. 4 is a block diagram showing the basic configuration of the tape tension control device according to the present invention, where αG is a detector including a bridge circuit, I is an amplifier that amplifies the output of the detector αG, (2)
A high-frequency oscillator JQ3, which supplies a high-frequency sine wave as a power source for the detector 1G, is a detector that synchronously detects the output of the high-frequency oscillator α2 and the output of the amplifier aυ. (141 is a comparator that compares the initial setting voltage (Vo) corresponding to the optimal tape tension in the closed loop with the output of the detector α3. α9
is a capstan motor on the supply side, and is controlled by adding or subtracting the output of the comparator α- to a reference voltage (Vo) set in advance to give the optimum tape tension in the tape running system.The voltage output from the bridge circuit. Since the rate of change in the resistance value of the gauge (which makes up the bridge) is 10-1 at maximum, it is necessary to amplify it as small as a few mV.However, it is difficult to simply amplify such a small input. In this case, it is inconvenient to use the output due to the influence of noise, etc. Therefore, in the present invention, a high frequency (for example, 15 KHz) sine wave from the high frequency oscillator is used as the power source of the detector U, and the amplified sine wave is used. The latter output is synchronously detected with the output of the high frequency oscillation 'a-' to obtain the OC output.This output and the voltage [initial setting voltage (Vo)] corresponding to the closed loop and appropriate tape tension are used. A comparator (141) compares.

Here, when the output (Vl) of the detector α3 is vl>Vo1, the comparator (141) outputs a negative differential voltage, V+(Voj, a minute voltage or current proportional to the positive power failure device) to the supply side cap. The reference voltage (Vo) of the stun motor αS is added to control the rotation speed of the supply side capstan motor so that the tape tension within the loop is optimal.

@Figure 5 is a block diagram showing an embodiment of the present invention, where tm is a tape speed switching section, αη is an initial setting voltage switching section, and the initial setting voltage (( Vol). In response to switching of the reference voltage switching unit C1 and tape speed switching unit αe, the reference voltage (Vo) for driving the supply side capstan motor is switched.In such a tape tension device, the tape speed is changed to 2. .38+o/s When switched to either 4.76 tn/s or 9.55rn/-, in response to switching of the tape speed switching section 061, the initial setting voltage switching section +171.Reference voltage switching section 18 and the winding side By switching the reference voltage (Vo) of the capstan motor a, the tape tension at a selected tape speed can be controlled to be constant.

As described in detail above, according to the present invention, the tape tension in the tape running system is detected by a pressure sensitive element, and the back tension mechanism is controlled by the control means based on the detection output, and it also responds to tape speed switching. Since the control means is changed over, it is possible to keep the tape tension constant at each tape speed.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the strain gauge and tape according to the present invention, Figure 2 is a diagram showing a bridge circuit in which one side is the resistance of the target gauge, and Figure 3 is the position of the target gauge in the recording or playback state. FIG. 4 is a block diagram showing the basic configuration of the tape tension control device of the present invention, and FIG. 4 is a block diagram showing an embodiment of the present invention. (11...Strain gauge, (10...Detector, (111
...Amplifier, uz...High frequency oscillator, (1T...Detector, 0Φ...Comparator, Stop...Supply side capstan motor, u61...Tape speed switching unit. Fig. 1 Figure 2 Figure 4 Figure 5

Claims (1)

[Claims] (1) A detector for detecting tape tension in a tape running system in a pressure-sensitive confectionery, and controlling a back tension mechanism so that the tape tension in the tape running system is constant based on the output of the detector. What is claimed is: 1. A tape tension control device comprising: a control means for controlling the tape speed; and a switching means for switching the control means in response to a change in tape speed. (21 The control means includes a comparator, and the comparator compares the output of the detector with an initial setting voltage set in advance corresponding to the optimum tape tension in the tape running system, and uses the comparison output to control the back tension mechanism. (3) The switching means is configured to control the tape tension control device according to claim 1. The tape tension control device according to claim 11, wherein the initial setting voltage is switched.