JPH03186771A - Medium inspecting device - Google Patents

Abstract

PURPOSE:To simplify the observation of a defective part by adding a delaying circuit for delaying a read-out signal by an arbitrary time to a comparator for outputting low/high of the read-out signal from a medium, and a monostable oscillator for outputting one pulse thereby. CONSTITUTION:The device is constituted of a comparator 1 for inputting a read-out signal S1 and comparing it with a comparison voltage E1 and outputting a comparison output signal S2 of low/high, a monostable oscillator 2 which is actuated by the signal S2 and outputs one pulse, and a delaying circuit 3 for inputting the signal S1 and delaying it by an arbitrary time portion. In such a way, so far as the signal 1 always intersects the comparison voltage by a prescribed period, the oscillator 2 is not actuated by the signal 2 at any time, therefore, the pulse output is delayed by 25% from the signal 1 and becomes an off-state, and by this on/off state, a defect detection is decided. The signal S1 is delayed by an arbitrary time portion by the circuit 3 and outputted as a delayed read-out signal S4. In such a way, since the read-out signal S1 is delayed so as to synchronize with a defect detecting signal, the observation of a defective part can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a medium inspection apparatus, and particularly to a medium inspection apparatus for detecting defects in magnetic storage media.

[Technological environment]

In recent years, the demand for peripheral storage devices using magnetic storage media has increased significantly, and high productivity and high efficiency are also required in the production and inspection processes of magnetic storage media.

Generally, in the inspection process for magnetic storage media, a total inspection is performed, so labor-saving and unmanned inspection equipment is the norm.

However, when a defect is discovered in a medium, the cause of the defect must be analyzed and investigated back to the previous manufacturing line, and in defect inspection, there is a function that outputs not only the inspection result but also a readout signal indicating the defect. It's becoming necessary.

[Conventional technology]

A conventional magnetic storage medium inspection device includes a comparator that inputs a read signal, compares it with a comparison voltage, and outputs a LOW/HIGH signal, and a LOW signal output from the comparator.
/HIGH signal and a monostable oscillator that outputs one pulse.

Next, a conventional medium inspection device will be described in detail with reference to the drawings.

FIG. 3 is a block diagram showing an example of a conventional medium inspection device.

The medium inspection device shown in FIG. 3 has a comparator 1 which inputs a read signal S1, compares it with a comparison voltage E1, and outputs a comparison output signal S2 of LOW/HIGH, and a comparison of LOW/HIGH outputted from a comparator l. The monostable oscillator 2 is activated by the output signal S2 and outputs one pulse.

FIG. 4 shows signals in the medium inspection device shown in FIG. 3.

The operation of this medium inspection device will be explained below with reference to FIGS. 3 and 4.

Input readout signal S1 to comparator 1 and compare voltage E
Compare with 1. By setting the comparator 1 so that it outputs a HIGN signal when the readout signal S1 becomes a higher voltage than the comparison voltage E1, and a LOW signal when it becomes a lower voltage, the voltage of the readout signal S1 is compared. If it is lower than the voltage, it can be detected as a defect, and the comparator 1 inspects the amplitude level of the read signal.

The monostable oscillator 2 receives the L output from the comparator 1.
It is activated by the OW/HIGH comparison output signal S2 and outputs one pulse.

The pulse width at this time is 1.25 of the period of the read signal S1.
This 1.25 times the time is the time required to transition from the peak to the zero cross point in one cycle from peak to peak of the readout signal (1.25 times the time).
/4 cycles> is set.

It has been confirmed that if this time is set, amplitude level testing can be performed stably.

If the read signal always crosses the comparison voltage at a constant period, the monostable oscillator 2 is always activated by the comparison output signal S2 and the pulse output is maintained at HIGH.

If there is a defect in the medium and the readout signal S1 does not cross the comparison voltage E1, the monostable oscillator 2 will not be activated by the comparison output signal S2, so the pulse output will be 2 times lower than the readout signal.
It becomes OFF state with a delay of 5%, and this signal's 0N10FF
Defect detection is determined based on the state.

[Problem to be solved by the invention]

However, in such a conventional medium inspection device, since the defect detection signal is output with a delay compared to the actual readout signal, as a method for observing the defective portion of the readout signal, (1)-degree readout signal and The defect detection signal is stored in a storage device such as a storage oscilloscope, and the defective portion is observed using the defect detection signal as a guide.

(2) Repeatedly inspect the defect detection area and synchronize an oscilloscope with the area ahead of the defective area (for example, an inspection start signal) and observe using a function such as a delay sweep.

However, they have the disadvantage of requiring the use of expensive measuring instruments and inefficient methods that slow down testing.

[Means to solve the problem]

The medium inspection device of the present invention includes a comparator that inputs a read signal read from a medium, compares it with a comparison voltage, and outputs a LOW/HIGH signal, and a monostable oscillator that is activated by the output signal of the comparator and outputs one pulse. , and a delay circuit that inputs the readout signal and delays it by an arbitrary amount of time.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

The magnetic storage medium inspection device of the present invention includes a comparator that inputs a read signal, compares it with a comparison voltage, and outputs a LOW/HIGH signal, and a LO output from the comparator.
It is configured to include a monostable oscillator that is activated by the W/HIGH signal and outputs one pulse, and a delay circuit that inputs the read signal and delays it by an arbitrary amount of time.

Next, the medium inspection device of the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

The medium inspection device shown in FIG. 1 includes a comparator 1 that inputs a read signal S1, compares it with a comparison voltage E1, and outputs a LOW/HIGH comparison output signal S2, and a LOW/HIGH comparison output signal output from the comparator 1. Monostable oscillator 2 that is started by S2 and outputs one pulse, and readout signal S
1 and a delay circuit 3 for delaying an arbitrary amount of time.

FIG. 2 shows signals in the medium inspection device shown in FIG.

The operation of this medium inspection device will be described below with reference to FIGS. 1 and 2.

Input readout signal S1 to comparator 1 and compare voltage E
Compare with 1. The comparator 1 is set so that a LOW signal is output when the readout signal S1 becomes a voltage higher than the comparison voltage E1 and the HIGH1 becomes a lower voltage. If the amplitude is low, it can be detected as a defect, and the comparator 1 inspects the amplitude level of the read signal.

The monostable oscillator 2 receives L output from the comparator 1.
It is activated by the OW/HIGH comparison output signal S2 and outputs one pulse. The pulse width at this time is set to be 1.25 times the period of the read signal S1.

This 1.25 times the time is set as the time obtained by adding the time (1/4 cycle) for transition from the peak to the zero cross point to one cycle from peak to peak of the read signal.

It has been confirmed that if this time is set, amplitude level testing can be performed stably.

If the read signal always crosses the comparison voltage at a constant period, the monostable oscillator 2 is always activated by the comparison output signal S2 and the pulse output is maintained at HIGH.

If there is a defect in the medium and the readout signal S1 does not cross the comparison voltage E1, the monostable oscillator 2 will not be activated by the comparison output signal S2, so the pulse output will be 2 times lower than the readout signal.
It becomes OFF state with a delay of 5%, and this signal's 0N10FF
Defect detection is determined based on the state.

The readout signal S1 is delayed by an arbitrary amount of time in the delay circuit 3 and outputted as a delayed readout signal S4.

The delay time is preferably about 1/2 cycle so as to be synchronized with the timing of the defect detection signal.

〔Effect of the invention〕

The media inspection device of the present invention delays the readout signal so as to be synchronized with the defect detection signal, making it extremely easy to observe defective areas.Also, since the signal can be observed in real time during inspection, the index time of the inspection device can be adjusted. It has the effect of having no influence.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a timing chart of signals in the embodiment of the present invention shown in FIG. 1, and FIG. 3 is a block diagram showing a conventional example.
FIG. 4 is a timing chart of signals in the conventional example shown in FIG. 1... Comparator, 2... Monostable oscillator, 3...
・Delay circuit, ...readout signal, 2..comparison output signal, S3..defect detection signal, S4..delayed readout signal.

Claims (1)

[Claims] A comparator that inputs a readout signal read from a medium, compares it with a comparison voltage, and outputs a LOW/HIGH signal, a monostable oscillator that is activated by the output signal of the comparator and outputs one pulse, and inputs the readout signal. and a delay circuit for delaying by an arbitrary amount of time.