JPS63148408A - Magnetic head - Google Patents

Abstract

PURPOSE:To avoid the output deterioration of a magnetic head due to attachment of an adhesive matter by forming grooves to the magnetic tape rubbing surface of the head and also protruded streaks which extend along the rubbing direction of a magnetic tape and have contacts with both end parts of a pad with a space secured to the magnetic tape to reduce the pressure contact force between the part and the tape. CONSTITUTION:The linear grooves 15 and 15 are formed in the prescribed width on a tape rubbing surface 6 and along the both edges of the coming-in side and the going-out side of a magnetic tape at a magnetic core part 2. The fixing agent 4 is removed out of the groove parts 15. Then, the protruded streaks 16 and 16 are formed on the surface 6 to sandwich an opening part 5a where the core is exposed on the surface 6 and then to enclose a magnetic tape rubbing area. Thus, both streaks 16 extend over the entire width of the surface 6 and along both edges of an approximately oblong surface 6 in the direction parallel to the tape rubbing direction. As a result, an adhesive matter is prevented from attaching to the part of the core 2 as the tape rubs. Then, the press contact force of a pad 11 is reduced and the wear of a magnetic core part is suppressed.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a magnetic head that records or reproduces information by pressing a magnetic tape against a magnetic tape sliding surface with an exposed magnetic core using a pad and sliding the magnetic tape relative to the magnetic tape. [Prior Art] This type of magnetic head is used, for example, in a cassette tape recorder to record audio analog signals. There is a magnetic head for recording and reproducing, and the conventional structure of this head is generally as shown in FIG. 3. The head shown in FIG. 3 is configured as a 4-channel, auto-reverse type. Each of the magnetic cores indicated by reference numeral 2 has a magnetic gap G on its tip surface, and a coil (not shown) is wound around the rear part (not shown). Then, each of the magnetic cores 2 is fitted into a shield case 5 with a spacer plate 3, 3' having a shielding function sandwiched therebetween, and fixed with a fixing material 4 such as resin to form a magnetic helad 1. be done. Note that the upper surface of the shield case 5 in the figure is a magnetic tape sliding surface (hereinafter abbreviated as sliding surface) 6 that slides on a magnetic tape (not shown), and on the sliding surface 6, the shield case 5
The tip end surface of each magnetic core 2 is exposed through the opening 5a formed in the magnetic core 2. The fixing material 4 is also exposed. Furthermore, tape guides 7.7 are fixed to the side surface of the shield case 5 for guiding the magnetic tape in contact with both edges of the sliding surface 6 on the magnetic tape entrance side and the magnetic tape exit side. With this structure, the magnetic helad l slides onto the magnetic tape 9 of the tape cassette 8 in the state shown in FIG. 4 during recording and reproduction in the cassette tape recorder. As shown in FIG. 4, during recording and reproduction, the position of the sliding surface 6 of the magnetic helad 1 protrudes beyond the position where it just contacts the magnetic tape 9 when the magnetic tape 9 is stretched in a straight line as shown by the dotted line. It is pushed out so that only H is projected. The protrusion H is 1.8 according to the IEC (International Electrotechnical Commission) standard.
It is set at ±0.5mm. Also, inside the magnetic tape cassette 8 is a pad spring 1.
The pad 11 elastically supported by the magnetic pad 1
The pad 11 is configured to press the magnetic tape 9 against the sliding surface 6 of the magnetic disk l by the elastic force of the pad spring 10. The magnetic tape 9 is wound around a pair of reels 12.12', and depending on the feeding direction, the magnetic tape 9 is wound around a pair of capstans 13.1.
3' by a pinch roller 14 or 14'. By rotationally driving the reel 12 or 12' and the capstan 13 or 13', the magnetic tape 9 is fed in the direction indicated by the arrow or in the opposite direction, and is slid onto the magnetic disk l for recording and reproduction. It is done. [Problems to be Solved by the Invention] By the way, in such a configuration, as the magnetic tape 9 slides against the magnetic heald l, the adhesive substance such as the binder in the magnetic tape 9 becomes attached to the magnetic helad 1. There was a problem in that it adhered to the sliding surface 6 and caused a decrease in head output. As the magnetic tape slides, the adhesive first adheres to the 4 parts of the fixing material on the sliding surface 6, and then spreads and adheres to the 2 parts of the magnetic core, causing a decrease in head output, especially in automotive drives. Under high temperature and high humidity conditions, such as in the case of , adhesive substances adhere quickly, and the output may drop by 3 dB or more after just 10 hours of sliding, for example. Therefore, as a countermeasure to this problem, in addition to the structure shown in FIG. 3, grooves 15 and 15 are formed along both sides of the magnetic tape entrance side and exit side of the magnetic core 2 portion on the sliding surface 6 as shown in FIG. A structure has been proposed in which the fixing material 4 in this portion is removed. However, although this structure is effective in preventing the adhesion of sticky substances, the pressure of the pad 11 that presses the magnetic tape against the sliding surface 6 is concentrated on the magnetic core 2, so that the magnetic core 2 is abraded. For example, 20 on a magnetic tape
There was a problem in that more than 301 Lm of wear occurred during approximately 0 hours of sliding running, resulting in so-called spacing loss and a decrease in head output. FIG. 6 shows data supporting that the amount of wear on the core part depends on the pressure of the pad 11. In the sliding state of the magnetic tape in FIG. 4, the amount of protrusion H of the magnetic head is changed, and The figure shows the results of measuring the amount of wear on two parts of the magnetic core according to the conditions. The amount of wear is the amount of wear after sliding the magnetic tape for 200 hours under conditions of a temperature of 40° C. and a humidity of 70%, and was measured using a surface roughness meter. As shown in FIG. 6, when the protrusion amount H is 1.0 mm or more, the protrusion amount H increases, and the amount of wear increases rapidly. As the amount of protrusion H increases, the pressure on the pad 11 increases, so it can be seen that the greater the pressure on the pad 11, the greater the amount of wear. [Means for Solving the Problems] In order to solve the above-mentioned problems, according to the present invention, the magnetic tape is pressed against the magnetic tape sliding surface where the magnetic core is exposed by a pad, and the magnetic tape is relatively slid. In a magnetic head that records or reproduces information by moving the magnetic head, a groove is provided on the magnetic tape sliding surface at least along the side edge of the magnetic core on the magnetic tape entry side, and the groove extends along the magnetic tape sliding direction. A structure is adopted in which protrusions are provided that contact both ends of the pad at a distance from the magnetic tape to reduce the pressure force of the pad against the magnetic tape. [Function] This structure prevents adhesive substances from adhering to the magnetic core as the magnetic tape slides through the grooves provided on the sliding surface, and also prevents adhesive substances from adhering to the magnetic core through the protrusions. The pressure contact force of the pad is reduced, and wear of the magnetic core portion can be suppressed. [Example] Hereinafter, details of an example of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 shows, as an embodiment of the present invention, the structure of a four-channel auto-reverse type magnetic head for a cassette tape recorder, similar to the conventional examples shown in FIGS. 3 and 5. 1st
In the figure, parts common to those in FIGS. 3 and 5 are given the same reference numerals, and their explanations will be omitted. As shown in FIG. 1, in the magnetic herad l of this embodiment, the fifth
Similar to the conventional example shown in the figure, in addition to the structure of the conventional example shown in FIG. .15 was formed, and the fixing material 4 in this groove portion was removed. In addition to this structure, in this embodiment, protrusions 16 and 16 are provided on the sliding surface 6, that is, on the upper surface of the shield case 5. In detail, the protrusions 16.16 are provided so as to sandwich the opening 5a in which the magnetic core 2 of the sliding surface 6 is exposed, and to sandwich the magnetic tape sliding area of the sliding surface 6, when viewed from above in the figure. It is formed to extend along both edges of the substantially rectangular sliding surface 6 parallel to the tape sliding direction, that is, to extend over the entire width of the sliding surface 6 along the tape sliding direction. Further, the width of the protrusions 16.16 is set so that they do not touch both side edges of the magnetic tape and are spaced from both side edges of the magnetic tape by a predetermined distance. When the magnetic tape slides during recording and reproduction, protrusions 16 and 16 come into linear contact with both ends of the pad l1 that presses the magnetic tape 9 against the sliding surface 6, protruding from both side edges of the magnetic tape. It is configured to reduce pressure contact force. That is, the protrusions 16.degree. 16 press the pad 11 in a direction relatively away from the sliding surface 6, thereby reducing the pressing force of the pad 11. According to this embodiment, adhesion of adhesive substances to the magnetic core 2 portion due to sliding movement of the magnetic tape is prevented via the grooves 15.15, and adhesion of adhesive substances via the protrusions 16.16. By reducing the pressure contact force of the pad 11, wear of the magnetic core portion can be suppressed. Note that if the height of the protrusion 16 (the amount of protrusion from the sliding surface 6) is too low, it will not have the effect of reducing the pressure contact force of the pad, and if it is too high, the pad 11 will not be able to properly contact the magnetic tape, resulting in poor spacing. Loss occurs, and the magnetic characteristics of the head deteriorate, especially the stability of high frequencies. In order to obtain the effect of reducing the pressure contact force of the pad and to enable the pad to be pressed with an appropriate pressure contact force that suppresses spacing loss over the entire width of the magnetic tape, the height of the protrusion should be 0.01 or more layers. It is desirable that the distance be 0.5■■ or less.Also, as mentioned earlier, the protrusions 16 and 16 are supposed to contact the pad 11 at a distance from (both side edges of) the magnetic tape. In order to obtain the necessary pressing force over the entire width of the magnetic tape, it is desirable to set the interval to be greater than or equal to the height h of the protrusion 16. Further, in order to obtain the effect of preventing the adhesion of sticky substances to grooves 15 and 15, the depth thereof must be at least 0.1 layer so that the bottom surface of *15 does not come into contact with the magnetic tape. In addition, the width of the groove 15 in the sliding direction of the magnetic tape must be 0.5 parts or more;
．． If it is less than 5-■, it becomes easy for sticky substances to accumulate due to the narrow width, and the adhesion of sticky substances increases. Also, the length of @15 should be at least long enough to cover the entire both side edges of the magnetic core part. Of course. By setting the height of the protrusions 18.16 and the distance from the magnetic tape, and the depth, width, and length of the grooves 15.15 in this way, adhesion of sticky substances can be prevented as described above, and the head output can be improved. It is possible to prevent a decrease in the wear resistance of the head and improve the wear resistance of the head by reducing the pressure contact force of the pad. Furthermore, according to this embodiment, due to the synergistic effect of the protrusions 16.16 and the grooves 15.15, the magnetic tape causes a stick-slip phenomenon due to friction with the head during tape running, and audible sound is generated. So-called tape squeal can be effectively prevented. Next, a head dirt (adhesive) adhesion test, abrasion test, and tape squeal test, which were conducted to confirm the effects of this embodiment, and their results will be described below. In each test, the head of this example had the structure shown in Fig. 1 and the height of the protrusion was 0.1 s layer, and the head of the comparative sample had conventional example 1 with only the groove 15.15 shown in Fig. 5. things and,
As Conventional Example 2, the test was carried out for the case shown in FIG. 3 in which neither grooves nor protrusions were provided. For the dirt adhesion test, humidity was 55 for each of the above heads.
The magnetic tape was allowed to slide for 20 hours in an atmosphere with a temperature of 50% RH and a humidity of 50% RH, and the change in the reproduction frequency characteristic after sliding with respect to the initial reproduction frequency characteristic was determined. In addition, as an abrasion test, each head was subjected to 20 sliding runs of magnetic tape in an atmosphere with a temperature of 40°C and a humidity of 70% RH.
The test was carried out for 0 hours, and the wear amount of the magnetic core compared to the initial state was determined using a surface roughness meter. A retest was also conducted on five heads each of the example and conventional example 1.2, and the average and standard deviation S of each of the five heads were determined. The results are shown in the table below. As is clear from this table, the head of this embodiment is the conventional example 1.
．． Both the change in playback frequency characteristics and the amount of wear are smaller than those of any of the heads in 2. In particular, the playback frequency characteristics are significantly smaller than those of Conventional Example 2, and the amount of wear is lower than that of Conventional Example 1.
It can be confirmed that according to this example, it is possible to effectively prevent the adhesion of sticky substances and to improve the abrasion resistance. On the other hand, in the tape squeal test, the temperature was 50℃ for each head.
The magnetic tape was slid and run in an atmosphere with a humidity of 50% RH, and the time from the start of running to the occurrence of tape squeal was determined. As a result, tape squeal occurred in 28 hours in Conventional Example 1 and 22 hours in Conventional Example 2, whereas tape squeal occurred in 1 hour in this example.
According to the six examples in which no tape squeal occurred even after 00 hours, it can be confirmed that tape squeal can be extremely effectively prevented. By the way, the head 2 of this embodiment shown in FIG. 1 is constructed as a 4-channel auto-reverse type. The head is fixed and is slid in both forward and reverse directions by the magnetic tape. On the other hand, for example, in the case of a two-channel rotating reverse type head, the head is rotated depending on the tape running direction, and the head is relatively slid on the magnetic tape only in one direction. As another embodiment, only one groove 15 may be provided along only the side edge of the magnetic core 2 on the magnetic tape entry side on the sliding surface 6, as in the two-channel rotating reverse type head shown in FIG. The effect of preventing sticky substance adhesion can be obtained in the same way.

【Effect of the invention】

As is clear from the above description, according to the present invention, in a magnetic head that records or reproduces information by press-contacting a magnetic tape with a pad to a magnetic tape sliding surface with an exposed magnetic core and sliding the magnetic tape relatively. , a groove is provided on the magnetic tape sliding surface at least along the side edge of the magnetic tape entry side of the magnetic core, and a groove is provided at both ends of the pad extending along the magnetic tape sliding direction and spaced from the magnetic tape. By adopting a structure with protrusions that contact and reduce the pressing force of the pad against the magnetic tape, it is possible to prevent a decrease in the output of the magnetic head due to the adhesion of sticky substances associated with the sliding of the magnetic tape, and
Excellent effects such as improved ll11 abrasion resistance of the magnetic head and effective prevention of tape squeal can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the structure of a magnetic head according to an embodiment of the present invention, FIG. 2 is a perspective view of a magnetic head according to another embodiment of the invention, and FIG. 3 is a perspective view showing the structure of a conventional magnetic head. 4 is an explanatory diagram of the magnetic tape sliding state in the tape cassette of the same head, FIG. 5 is a perspective view of another conventional head, and FIG. 6 is an illustration of the magnetic head in the tape sliding state of FIG. 4. It is a diagram showing the relationship between the amount of protrusion H and the amount of wear. 1...Magnetic head 2...Magnetic core 4...Fixing material 5...Shield case 6...Sliding surface 11...Pad 15...Groove
16...Toujo Rut: To Kume, Rinto Sai Mishiri of 7th figure 3 figure 4 temporary meeting.

Claims (1)

[Scope of Claims] 1) In a magnetic head that records or reproduces information by pressing a magnetic tape against a magnetic tape sliding surface with an exposed magnetic core with a pad and sliding it relative to the magnetic tape, the magnetic tape sliding surface has an exposed magnetic core. A groove is provided along at least the side edge of the magnetic tape entry side of the magnetic core, and the groove extends along the sliding direction of the magnetic tape and contacts both ends of the pad at a distance from the magnetic tape. A magnetic head characterized by being provided with protrusions that reduce pressure applied to the magnetic head. 2) The magnetic head according to claim 1, wherein the amount of protrusion of the protrusion from the sliding surface is set so that the pad can be pressed against the magnetic tape with a required pressure contact force. . 3) The amount of protrusion of the protrusion from the sliding surface is 0.01 mm.
The magnetic head according to claim 1 or 2, wherein the magnetic head is set to 0.5 mm or less. 4) The magnetic head according to claim 1, wherein the groove is formed to have a depth of 0.1 mm or more and a width of 0.5 mm or more in the sliding direction of the magnetic tape.