JPH0559686U - Target position detection device for magnetic tape - Google Patents

Abstract

(57) [Summary] [Purpose] In a magnetic tape device, the fact that the magnetic tape has traveled to the target position is detected without causing a time delay, and accurate and prompt control of tape travel is executed to determine the R / W position. Prevent errors. [Structure] A target value is set in advance in the register 5, and the number of output pulses of the pulse generator 3 that generates pulses corresponding to the running of the magnetic tape 1 is counted by the counter 4, and the comparator 6 sets the count value and the target value. A coincidence signal (target position detection signal) is obtained at the time when the coincidence of values is detected. In addition, selector 7
Has been set in advance to output a coincidence signal to the controlled object, and the signal is directly output to the controlled object. [Effect] The delay time is drastically shortened as compared with the conventional detection / control operation by software in the microcomputer circuit, and the tape position can be controlled accurately and promptly.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a magnetic tape target position detection apparatus, which is an apparatus for accurately detecting the target position when a tape is moved minutely in a magnetic tape apparatus and preventing an error in the R / W position with respect to the magnetic tape. Regarding

[0002]

[Prior Art]

 A magnetic tape device used as an external recording device of a computer system is required to improve the recording density of a magnetic tape and to set a target position quickly and accurately at the time of R / W. It is necessary to execute it with high accuracy.

Conventionally, tape position control in a magnetic tape device has been executed by the configuration shown in FIG. 2, and relies on software control using a microcomputer circuit. That is, a target set value is set in advance in the RAM 13 through the I / O port 12 of the microcomputer circuit 11, and a pulse from the pulse generator 15 that generates a pulse according to the movement of the magnetic tape 14 is passed through the I / O port 12 through the I / O port 12. The CPU 16 counts the number of input pulses and monitors whether or not the target set value matches, and outputs a control signal related to the task specified in advance at the time of the match. ing. The ROM 17 stores the control program according to the above procedure, and the CPU 16 executes control according to the program.

[0004]

[Problems to be solved by the device]

 By the way, in the conventional software control by the microcomputer circuit, it takes too much time to compare and monitor the pulse count value and the target set value and read the control signal by the interrupt processing when they match, and When controlling a minute movement, an error occurs due to the delay time, so there is a limit to the precise control of the tape movement amount. In addition, the microcomputer circuit often controls the entire system, and if the above procedure is executed, the load becomes heavier and the margin for executing other tasks becomes smaller.

Therefore, the present invention provides a target position detection device that enables quick and accurate position control by executing the detection of the target position of the magnetic tape by hardware, and at the same time, the burden on the system control unit. It was created for the purpose of reducing the.

[0006]

[Means for Solving the Problems]

 According to the present invention, in a magnetic tape device, a pulse generator that generates a pulse each time the magnetic tape moves a certain amount, a counter that counts the number of output pulses of the pulse generator, and a numerical value corresponding to a target position are set. And a register for comparing the count value of the counter and the set value of the register, and outputting a signal when the values match, the magnetic tape target position detecting apparatus according to the invention. ..

Further, if the output of the comparator is input to a selector connected to a plurality of output destinations and the output signal of the comparator is output to the selected output destination, a control operation using a coincidence signal is performed. It can be executed quickly.

[0008]

[Action]

 Since the pulse generator generates a pulse each time the magnetic tape moves a fixed amount, the count value of the counter gives the moving amount of the magnetic tape as digital data. Here, a typical pulse generator is a combination of a tachometer and a pulse generation circuit, and a tachometer such as a rotary encoder.However, control bits are written in advance at regular intervals on the control track of a magnetic tape. In such a case, it may be a device that detects the bit and generates a pulse. On the other hand, the register is preset with a numerical value corresponding to the target position of the magnetic tape. This value is uniquely determined when the target position is determined because the amount of movement of the pulse generator and the number of pulses generated between them are known.

Then, the comparator outputs a match signal when the count value of the counter and the set numerical value of the register match. However, since the match is detected in the hardware configuration, the delay time is not detected in the software operation. Much shorter.

In the magnetic tape device, the coincidence signal is used as a stop signal, a write / read start signal, etc., but if the destination (control destination) is set in advance by using a selector, the signal Can be sent directly to the control destination. That is, the signal can be directly output to the head driver or the like without passing through the system controller such as the microcomputer circuit, and the time delay can be further eliminated.

[0011]

【Example】

 An embodiment of the present invention will be described below with reference to FIG. This figure is a block circuit diagram of the tape target position detection unit in the magnetic tape device. 1 is the magnetic tape, 2 is the roller provided in the running system of the magnetic tape 1, and 3 is the roller rotation detection of the roller 2. Pulse generator (tachometer and pulse generation circuit) that generates a pulse every rotation of a fixed angle, 4 is reset by the system control unit, a counter that counts the number of pulse inputs of pulse generator 3, 5 is system control Register that allows numerical values to be set from the section, 6 is a comparator that detects the match between the count value of counter 4 and the set value of register 5, and 7 is the control destination that is switched by the system control unit and the output signal of comparator 6 is switched. A selector (multiplexer) 8 for outputting to the system control unit.

In this circuit, for example, when writing start is executed from the state where the magnetic tape 1 is stopped, the operation is as follows. First, when executing the write operation, it is necessary to record on the magnetic tape 1 at specified intervals, so after the start of running the magnetic tape 1, a waiting operation such as running a fixed distance (ΔL) to start writing Will be required.

Therefore, when a write start instruction is given to the system control unit 8 from the operation unit (not shown), the system control unit 8 resets the counter 4 to 0 and sets the register 5 Set the target value to, output the switching control signal to the selector 7, and switch the selector 7 to the connection state (connection state to W in the figure) to the control target (driver of the write head etc.) that operates during writing. .. The target value set in the register 5 is a numerical value corresponding to the number of pulses obtained from the pulse generator 3 when the magnetic tape 1 travels for the above-mentioned constant distance (ΔL), and the numerical value is set in advance. It is stored in the system control unit 8, and the system control unit 8 immediately reads out the write start instruction and sets it in the register 5 when the write start instruction is given.

When the initial setting operation is completed, the system control unit 8 activates the drive motor (not shown) of the magnetic tape running system to move the magnetic tape 1, but in response to the movement amount, The pulse generator 3 generates a pulse, and the count value of the counter 4 is incremented each time the pulse is generated.

Then, the count value of the counter 4 increases as the magnetic tape 1 is continuously run, and when the magnetic tape 1 has run for the above-mentioned fixed distance (ΔL), the count value of the counter 4 and the set value of the register 5 coincide with each other. Then, the comparator 6 immediately outputs the coincidence signal to the selector 7. On the other hand, since the selector 7 is preliminarily connected to the control target at the time of writing, the coincidence signal is directly output to the driver of the write head or the like, and writing to the magnetic tape 1 is immediately started.

Writing by this waiting operation needs to be executed after the magnetic tape 1 is moved by a very small amount, and a slight time error is directly connected to an error in the writing position. However, according to this circuit, The hardware consisting of the counter 4, the register 5, and the comparator 6 can detect the arrival at the target position extremely quickly, and can execute accurate write control without causing delay time. Further, even in the read mode or stop control, the system control unit 8 can execute the initial setting procedure and shift to the read or stop operation, thereby executing the same rapid tape position detection / control. it can.

Therefore, on the system control unit 8 side, the initial setting operation is completed and the motor start is only started, and the subsequent time-series monitoring control becomes unnecessary, and other tasks are executed in the meantime. It will be possible.

[0018]

[Effect of the device]

 The present invention having the above-described configuration has the following effects. According to the invention of claim 1, the target position of the magnetic tape can be detected by a hardware circuit including a counter, a register and a comparator, instead of the conventional detection by the software using the microcomputer circuit. The detection speed can be dramatically improved, enabling highly accurate and accurate tape position control. For example, in the case of the conventional microcomputer circuit, a delay time of about 100 μsec was generated in detecting the target position, but according to the present invention, the delay time can be shortened to about 100 nsec. According to the second aspect of the invention, the output of the comparator can be directly output to the control target selected by the selector, and the control operation can be executed more quickly. The present invention also has the advantage of reducing the load on the system controller in the magnetic tape device and ensuring a margin for executing other tasks.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of an embodiment of a magnetic tape target position detecting device of the present invention.

FIG. 2 is a circuit diagram of a target position detecting device for a magnetic tape according to a conventional technique.

[Explanation of symbols]

1 ... Magnetic tape, 2 ... Roller, 3 ... Pulse generator, 4 ... Counter, 5 ... Register, 6 ... Comparator, 7 ... Selector, 8
… System control unit.

Claims (2)

[Scope of utility model registration request] 1. In a magnetic tape device, a pulse generator that generates a pulse each time the magnetic tape moves a certain amount, a counter that counts the number of output pulses of the pulse generator, and a numerical value corresponding to a target position are set. A target position detecting device for a magnetic tape, comprising: a register which is operated and a comparator which compares a count value of the counter with a set numerical value of the register and outputs a signal when the values match. 2. The target position detecting device for a magnetic tape according to claim 1, further comprising a selector which is connected to the plurality of output destinations and which outputs the output signal of the comparator to the selected output destination.