JPH0419605B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field to which the Invention Pertains] The present invention relates to a device for accumulating the wear amount of a magnetic head, which influences the recording/reproducing performance in a magnetic recording or reproducing device.

[Description of prior art]

Conventionally, in magnetic recording/playback equipment (VTB),
The only way to determine the degree of wear on a magnetic head was to remove the head from the rotor and measure the gap steps using a microscope. However, this method is very time-consuming and
Furthermore, when reattaching and fixing the magnetic head to the rotor, it is necessary to readjust the amount of protrusion from the rotor circumferential surface. Therefore, in conventional VTRs, methods such as adding up the usage time and replacing the magnetic head when a certain amount of time has been reached have been used. however,
Since wear of the magnetic head does not necessarily depend only on usage time, it has not been possible to know exactly when to replace it.

That is, wear of the magnetic head is caused by friction caused by relative movement between the magnetic head and the recording medium while they are in contact with each other, and this wear condition depends on the relative movement speed of the magnetic head and the recording medium, the usage conditions, That is, it changes depending on the operation mode (for example, playback, recording, fast forward, still, etc.).

For this reason, there has been a problem in that it is not possible to detect the state of wear even by simply accumulating the usage time of the magnetic head, and it is not possible to detect the appropriate time for replacement.

[Object of the present invention]

The present invention has been made to solve the above problems, and does not measure the usage time of the magnetic head, but by counting the usage status of the magnetic head by changing it according to the operating mode. The present invention aims to realize a magnetic head wear totaling device that can accurately estimate the wear state of a magnetic head.

[Summary of the invention]

The apparatus according to the present invention includes: a magnetic head/medium contact detection means for detecting contact between a magnetic head and a medium such as a magnetic tape; a signal generating means for generating a signal of a predetermined frequency; A magnetic head wear amount accumulating device comprising: a counting means for counting frequency signals from a signal generating means in accordance with a signal from a detecting means; The invention is characterized by comprising a correction means for changing the input count value.

Preferably, the correction means includes a count correction section that corrects the frequency of the signal input to the counting means by a predetermined count set in advance in accordance with the operation mode.

Further, the correction means may be composed of an oscillator that outputs a signal with a frequency that changes depending on the operation mode as the frequency signal generated by the signal generation means.

[Explanation of Examples]

FIG. 1 is a block diagram showing an example of a device according to the present invention. In this figure, M is a motor that drives the head drum, 1 is a signal generating means connected to this motor M and outputting a frequency signal corresponding to the rotational speed of the motor M, and a pulse generator connected to the rotating shaft of the motor M. a frequency dividing circuit 1 that divides the frequency of the PG pulse from the pulse generator 11;
It is composed of 2. 2 is a magnetic head/medium contact detection means for detecting contact between the magnetic head and a medium such as a magnetic tape, which uses a loading completion detection sensor such as a micro switch conventionally attached to a VTR. . 3 is an AND gate circuit which inputs the frequency signal from the signal generating means 1 and the signal from the magnetic head/medium contact detecting means 2; 4 is the frequency from the signal generating means 1 applied via the AND gate circuit 3; Counting means for counting signals, 5 is a display for displaying the counted value of the counting means 4, for example, a display using a liquid crystal or a light emitting element.

According to the apparatus configured in this way, when tape loading is completed, the magnetic head and the magnetic tape come into contact, and the magnetic head/medium contact detection means 2 outputs a signal indicating logic "1", for example. , and the AND gate circuit 3 is opened. In this state, the motor M is already rotating (the head drum is rotating), and pulses of a frequency corresponding to the rotation speed of the head drum are output from the PG 11. This pulse signal is frequency-divided by a frequency dividing circuit 12 and then passed through a gate circuit 3 and counted by a counting means 4. The count value of the counting means 4 is displayed on the display 5. Note that the counting means 4 is preferably non-volatile so that the counted value is not lost even if the power is cut off.
Therefore, the counted value by the counting means 4, that is, the value displayed on the display 5, is not simply the cumulative total of usage time, but the frequency corrected according to the number of rotations of the head drum, that is, the operating mode. This value corresponds to the cumulative number of rotations of the head drum when the magnetic head and magnetic tape are in contact with each other.

Here, the number of rotations of the head drum when the magnetic head and magnetic tape are in contact corresponds to the amount of wear on the head, and from the cumulative rotational value of the head drum displayed on the display 5, it is possible to determine the amount of wear on the magnetic head. can be inferred.

Therefore, when the value displayed on the display 5 reaches a predetermined cumulative value determined in advance through experiments or the like, it becomes possible to take appropriate measures such as replacing the magnetic head.

After replacing the magnetic head, the count value of the counting means 4 shall be cleared by manual operation or the like.

FIG. 2 is a block diagram showing another embodiment of the device according to the present invention. In this embodiment, the counting means 4 is configured to include a coefficient correction section 6 that corrects the frequency of the pulse signal output from the AND gate circuit 3 according to the operation mode. In the coefficient correction section 6, 61, 62, 63...
6n is each counter, 60 is each counter 61
OR gate circuit into which the signal from ~6n is input, 6
A switch circuit 6 selects and applies the pulse signal from the AND gate circuit 3 to one of the counters 61 to 6n in accordance with the signal from the mode detection circuit 67. In addition, 7 switches between play mode, slow mode, still mode, etc.
The mode detection circuit 67 detects which mode is selected by the mode changeover switch 7 which is conventionally attached to the VTR.

Each of the counters ₆₁ , _{62 ,} . The state is experimentally determined and set in advance. Therefore, for example, in the case of the play mode, the switch circuit 66 applies the pulse signal from the AND gate circuit 3 to the counter 61 in response to the signal indicating the play mode from the mode detection circuit 67, and here The number of pulses is corrected to correspond to the wear state of the head, and the corrected number of pulses is counted by the counter 40 via the OR gate circuit 60. In the slow mode, still mode, etc., the switch circuit 66 similarly applies a pulse to the counter according to the corresponding mode. Therefore, according to this embodiment, a number of pulses are applied to the counter 40, which more accurately represents the wear state of the head than the one shown in FIG. 1, depending on each mode.

In addition, each set value α ₁ to αn of the counters 61 to 6n
It is desirable that these set values can be changed as appropriate, and that these set values can be maintained even if the power is turned off.

FIG. 3 is a block diagram showing still another embodiment of the apparatus according to the present invention. In this embodiment, the signal generating means 1 includes a voltage generating circuit 13 to which a signal from a mode detecting circuit 67 is applied, and a voltage controlled oscillator (VCO) that oscillates at a frequency corresponding to the voltage signal from this voltage generating circuit 13. )14 and
Frequency divider 15 that divides the signal from this VCO 14
It is composed of Here, the voltage generation circuit 13 is set with each voltage value determined by experimentally determining the state of wear of the head from the tape running state in each mode, and is set in accordance with the mode detected by the mode detection circuit 67. The voltage value is
Applied to VCO14. Therefore, according to this embodiment, when a signal is detected from the magnetic head/medium contact detection means 2, a pulse signal with a frequency corresponding to the mode at that time is applied to the counting means 4 via the AND gate circuit 3. be done. Therefore, like the embodiment shown in FIG. 2, the wear state of the head can be displayed more accurately on the display 5 than in the embodiment shown in FIG.

[Effects of the present invention]

As explained above, according to the present invention, the operating time of the magnetic head is not simply accumulated, but is accumulated by accumulating the count value corrected according to the change in the operating condition (contact condition) depending on the operation mode. Since the amount of wear on the magnetic head is detected accurately by analogy, there is an advantage that the state of wear on the magnetic head can be accurately detected.

For this reason, maintenance such as inspection and replacement of the magnetic head,
In addition, management can be performed accurately.

Furthermore, in order to count the amount of wear on the head, it is possible to construct a simple configuration by using a switch, etc. that is conventionally added to a VTR, etc., and the amount of wear can be easily known.

Therefore, it is possible to accurately estimate the wear state of the head from the cumulative usage time of the head, and maintenance and management such as inspection and replacement of the head can be performed appropriately.

[Brief explanation of drawings]

1 to 3 are block diagrams showing an example of an apparatus according to the present invention. DESCRIPTION OF SYMBOLS 1... Signal generation means, 2... Magnetic head/medium contact detection means, 3... AND gate circuit, 4...
Counting means, 5...display device.

Claims (1)

[Scope of Claims] 1. A detection means for detecting contact between a magnetic head and a recording medium in a magnetic recording/reproducing apparatus, a signal generation means for generating a signal of a predetermined frequency, and a signal generating means for generating a signal from the detection means. A magnetic head wear amount accumulating device having a counting means for counting a frequency signal from the signal generating means according to the operation mode of the magnetic recording/reproducing device, the correction for changing the input count value to the counting means according to the operation mode of the magnetic recording/reproducing device. What is claimed is: 1. A magnetic head wear amount accumulating device characterized by comprising means. 2. Claim 1, wherein the correction means comprises a counting correction section that corrects the frequency of the signal input to the counting means by a predetermined coefficient set in advance in accordance with the operation mode. Magnetic head wear cumulative device. 3. The method according to claim 1, wherein the correction means comprises an oscillator that outputs a signal with a frequency that changes depending on the operation mode as the frequency signal generated by the signal generation means. Magnetic head wear totaling device.