JPH0544725B2 - - Google Patents

Description

[Detailed Description of the Invention] (1) Technical Field of the Invention The present invention relates to a write circuit of a magnetic tape device.
In particular, the present invention relates to a write current adjustment circuit that can adjust the write current according to write conditions such as occurrence of data dropout or peak shift.

(2) Prior Art and Problems In conventional magnetic tape devices, dropouts occur when a waveform recorded during writing is detected due to defects or foreign matter adhering to the magnetic tape. If the write current is increased to compensate for this, the resolution will deteriorate. The write current is determined by taking these into consideration, but once the write current is set,
There is a drawback that proper writing is not always performed due to the magnetization state of the magnetic tape, deviation of the magnetic head, aging, etc.

(3) Object of the Invention The object of the invention is to provide a write current adjustment circuit that can always perform good writing even if the states of the magnetic tape and magnetic head change.

(4) Structure of the Invention In order to achieve the above object, the write current adjustment circuit of the present invention includes an amplitude detection circuit for detecting a dropout of a waveform recorded during writing, and an output of the amplitude detection circuit in a magnetic tape device. a dropout counter that counts dropout information obtained from the dropout information, a phase shift detection circuit that detects the phase shift of the recorded waveform, a phase error counter that counts the phase error signal output from the phase shift detection circuit; The present invention is characterized in that it includes a write current determination section that determines an optimal write current value from both output values of a pop-out counter and a phase error counter, and that the write current can be adjusted according to the written state.

(5) Examples of the invention FIG. 1 is a diagram explaining the principle of the present invention.

In a magnetic tape device, when the write current is increased according to the magnetization characteristics of the write head,
The number of waveform data dropouts and the number of phase errors due to phase shift show opposite trends. That is,
When the write current is low, the effects of magnetic tape defects, foreign matter adhesion, magnetic head deviation, and aging are significant, resulting in a large number of dropouts, but as the write current increases, the number of dropouts decreases. do. On the other hand, the influence of saturation characteristics appears, the resolution deteriorates, and the number of peak shifts, that is, the number of parts with large phase shifts, increases rapidly. If the write current is increased as shown, the number of dropouts decreases and the number of phase errors due to peak shifts increases. Therefore, by counting the number of drop-outs and the number of peak-outs, it is determined whether the current write current is appropriate or inappropriate, and the current write current is set to an appropriate position in the region. This is then stored in memory and used.

FIG. 2 is an explanatory diagram of the configuration of an embodiment of the present invention.
In the same figure, the light amplifier circuit 1 is a non-volatile
According to the write current value previously stored in the RAM 2 according to the procedure described later, a current is caused to flow through the write head (WH) in accordance with the write data to write on the magnetic tape. After writing, the waveform read out from the read head (RH) is amplified by the read amplifier circuit 4 and subjected to discrimination processing to determine whether it is noise or a small differential waveform.

The final analog waveform is sent to the amplitude detection circuit 5,
Dropout of waveform data is detected. Further, the waveform digitized in the read amplifier circuit 4 is sent to a variable frequency oscillator (VFO) 6, and its clock component is extracted from the read data. The read data applied here uses, for example, the Group Coding Record (GCR) method as a modulation method, and is recorded using the NRZi method, both of which have clock components in the data. The clock and read data of the VFO 6 are phase-compared in a phase shift detection circuit 7.
The phase shift of the read data depends on the magnitude of the peak shift based on the magnetization saturation characteristic, and when this is greater than a certain value, a phase error signal is output. The control circuit 3 has a dropout counter ₃₁ and a phase error counter ₃₂ , and receives the dropout signal from the amplitude detection circuit 5 to the dropout counter ₃₁ .
The phase error signal from the phase shift detection circuit 7 is sent to the phase error counter ₃₂ , and in accordance with external control information, the write current determining section ₃₃ determines whether the write current is appropriate based on the count values of both counters. If it is determined to be inappropriate, the write current is set at an appropriate position within the area shown in FIG. 1, for example, and the write current value in the nonvolatile RAM 2 is rewritten to correct the write current to an appropriate value. The control circuit 3 is constituted by a microprocessor, and is prepared with a write current adjustment program that sets the appropriate value to a count value that is a predetermined count away from the intersection of the characteristics.

(6) Effects of the Invention As explained above, according to the present invention, in a magnetic tape device, a dropout of a recorded waveform is detected and counted during writing, and a phase shift of the recorded waveform is detected. The optimum write current value is determined from both count values by detecting the phase shift and counting phase error signals that exceed a certain phase shift. As a result, the write current is always adjusted to an appropriate value, so that both the dropout value and the phase error value are suppressed to below allowable values, thereby ensuring the quality of write data.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the principle of the present invention, and FIG. 2 is a diagram explaining the configuration of an embodiment of the present invention, in which 1 is a write amplifier circuit, 2 is a non-volatile RAM, 3 is a control circuit, and 3 ₁ is a droplet amplifier circuit. 3 ₂ is a phase error counter, 3 ₃ is a write current determination section, 4 is a read amplifier circuit, 5 is an amplitude detection circuit, 6 is a variable frequency oscillator (VFO), and 7 is a phase shift detection circuit.

Claims (1)

[Claims] 1. In a magnetic tape device, an amplitude detection circuit detects dropout (missing) of a recorded waveform during writing, a dropout counter counts dropout information obtained from the output of the amplitude detection circuit, and a dropout counter detects dropout information obtained from the output of the amplitude detection circuit. A phase shift detection circuit that detects a phase shift, a phase error counter that counts the phase error signal output from the phase shift detection circuit, and an optimal write current value determined from the output values of both the dropout counter and the phase error counter. What is claimed is: 1. A write current adjustment circuit, comprising a write current determination section that adjusts a write current according to a written state.