JPH0517857Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Technical Field of the Invention] This invention relates to a rotary transformer used in video tape recorders and the like. [Technical background of the invention and its problems] In the two-head video tape recorder (VTR), which currently dominates home video,
The circuit configuration is such that signals induced in the first channel head and the second channel head are transmitted to a subsequent amplifier (AMP) through a rotary transformer. At this time, the characteristics required of the rotary transformer are that the characteristics of the first channel and the second channel are the same, and the inductance L of each channel and the coupling coefficient k (k is the degree of magnetic coupling between the two windings) ) is given by. If the above characteristics are not the same, there will be a difference in the magnitude (amplitude) of the video signal transmitted to the AMP in the subsequent circuit through the rotary transformer.
Amplitude adjustment is required at the AMP using a variable resistor, etc. The structure to make the inductance L the same was proposed earlier (1973-
14100). Here, the area between the winding groove and the inner edge of the core in the fixed core and rotating core is S ₁ , S ₂
When S 3 and S ₃ are 1/S ₁ +1/S ₂ =1/S ₂ +1/S ₃ , the excitation inductances of both winding pairs become equal. In other words, when S ₁ =S ₃ , the same inductance is obtained. However, in reality, since the leakage inductance is different for each channel, the substantially same inductance is S ₁ = S ₃
It cannot be resolved by doing this. Furthermore, even if substantially the same inductance is obtained as described above, each channel will not have the same coupling coefficient, so amplitude adjustment in the AMP cannot be avoided. Therefore, the applicant of the present application solved the above problem by making the groove depth of each channel different, as shown in FIG. 4, and proposed a rotary transformer that could be used without adjustment (Japanese Utility Model Publication No. 59-15465). In FIG. 4, 1 is a stator, and coil windings 4 are contained in annular grooves 2 and 3 arranged concentrically.
and 5 are arranged. Also, opposite to this, a rotor 6 is provided at a location where it faces the stator 1.
are similarly provided with annular grooves 7 and 8, and the annular groove 7
and 8 are provided with coil windings 9 and 10.
Here, the annular grooves 2 and 7 are connected to the other annular groove 3.
and 8. With this configuration, the engagement coefficient k can be adjusted by varying the depth of the annular groove, so that the same value k can be achieved.
For example, in order to obtain almost the same L, we can use the previous technology and calculate the relationship 1/S ₁ + 1/S ₂ = 1/S ₂ + 1/S ₃ ∴S ₁ = S ₃ for this rotary transformer. If utilized in the configuration, the same L and the same k can be substantially achieved, and the circuit can be made without adjustment. Incidentally, the annular grooves 7 and 8 having different depths are simultaneously processed using a grinding device and a specially shaped grinding wheel. FIG. 5 is a plan view of this grinding wheel, and FIG. 6 is a sectional view taken along line A'-A in FIG. This grinding wheel 11 is constructed by embedding fan-shaped grindstone pieces 12a and 12b in a base body 14, which are arranged concentrically and have different heights. The annular grooves 7, 8 having different depths are formed by such a grinding wheel 11.
The fan-shaped grindstone pieces 12a, 1
2b is severely worn, the fan-shaped grindstone pieces 12a,
It is essential to modify the shape of 12b. However, this shape modification requires that the height of the fan-shaped grindstone pieces 12a, 12b be adjusted with high precision at the same time that the tip end shapes of the fan-shaped grindstone pieces 12a, 12b are modified to short shapes. Since this work not only requires skill but also is very time-consuming, a new problem has arisen in that it becomes an obstacle to improving the production efficiency of the starter 1 and rotor 6 and further reducing the cost of the rotary transformer. [Purpose of the invention] The present invention was made in view of the above circumstances, and its purpose is to have extremely small differences between channels in leakage inductance and coupling coefficient, so that it can be used without adjustment. Our goal is to provide rotary transformers at low prices. [Summary of the invention] The present invention provides a rotary transformer having a stator and a rotor, each consisting of a flat core member, with a plurality of concentric annular grooves formed on each opposing surface, and windings mounted in these annular grooves. The annular grooves of the stator and rotor are formed to have the same depth, and each annular groove has a thickness so that it becomes shallower from the inside to the outside of the stator and rotor, and the opposing annular grooves have the same depth. It is characterized by the arrangement of different insulating members. [Embodiments of the invention] Hereinafter, the invention will be specifically explained using examples. FIG. 1 is a sectional view of a rotary transformer according to an embodiment of the present invention, in which 16 is a stator, 17 is a rotor, and 18 is a rotating shaft to which the rotor 17 is fixed. The stator 16 is a flat plate type with annular grooves 20, 21, 22 of the same depth concentrically provided on one surface of a circular core, and insulating members of different thicknesses (for example, mylar) formed in the annular grooves 20, 21, 22. film)
By arranging 23, 24, 25, the annular groove 2
This insulating member 2
The windings 26, 27, and 28 are mounted on the windings 3, 24, and 25, respectively. The rotor 17 is also constructed in the same manner as the stator 16, and insulating members 30, 31, and 32 having different thicknesses are provided in annular grooves 30, 31, and 32 of the same depth.
3, 34, and 35, and these insulating members 33, 3
The windings 36, 37, and 38 are mounted on the windings 4 and 35, respectively. Even in this case, the opposing annular grooves of the stator 16 and rotor 17 have the same depth. The rotary transformer 15 with the above configuration has three
Although it is a channel, insulating members 23, 2
4, 25 and 33, 34, 35, the annular grooves 20, 21, 22 and 30, 31, 3
Since the depths of the two can be made substantially different,

【table】

【table】

【table】

[Table] As is clear from comparing Tables 1 and 3,
By using the insulating members 23, 24, 25, 33, 34, and 35, the difference in leakage inductance between each channel can be reduced, and as is clear from comparing Tables 2 and 4. , it is also possible to reduce the difference in coupling coefficient between each channel. Of course, the insulating members 23, 24, 25, 33, 3
It goes without saying that by adjusting the thickness of channels 4 and 35, the difference between the channels described above can be further reduced. In this embodiment, insulating members of different thicknesses are arranged in a plurality of annular grooves ground to the same depth, so that the depths of each annular groove are substantially different, and the insulating member is Since the stator 16 and rotor 17 are constructed by mounting windings on the members, it is possible to reduce the difference in leakage inductance between each channel and the difference in coupling coefficient between each channel. of
When applied to a VTR, etc., there is no need to adjust the gain of the amplifier (AMP), and the device can be used without adjustment. Also, the stator 16 and the rotor 17
annular grooves 20, 21, 22, 30, 31,
In the grinding of No. 32, since the same depth is sufficient, the fan-shaped grindstone pieces 40a, 40b, 4 of the same height are used.
0c can be used, and the shape of the grinding wheel 39 can be easily modified in a short time. This improves the production efficiency of the stator 16 and rotor 17, and further improves the rotary transformer 11. This has the advantage that costs can be reduced. Furthermore, insulating members 23, 24, 25, 33, 3
By using 4,35, the distributed capacitance can be made smaller, so the frequency characteristics, especially the high-frequency characteristics, in signal transmission of the rotary transformer can be improved, which is extremely advantageous in improving image quality in VTRs, etc. Become. One embodiment of the present invention has been described above, but
The present invention is not limited to the above embodiments,
Needless to say, various modifications are possible. For example, in the above embodiment, a three-channel rotary transformer has been described, but the present invention can also be applied to a two-channel rotary transformer or a rotary transformer with four or more channels. In addition, in the above embodiment, the fan-shaped grindstone pieces 40a, 40
Although the annular groove is ground using the grinding wheel 39 having the grinding wheels b and 40c, the shape of the grinding wheel pieces is not limited to the fan shape. [Effects of the invention] As detailed above, according to the invention, it is possible to provide a rotary transformer at low cost that has extremely small differences in leakage inductance and coupling coefficient between channels and can be used without adjustment. .

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a rotary transformer that is an embodiment of the present invention, FIG. 2 is a plan view showing an example of a grinding wheel used for grinding an annular groove in the rotary transformer of FIG. 1, and FIG. 4 is a sectional view of a conventional rotary transformer, FIG. 5 is a plan view showing an example of a grinding wheel used for grinding the annular groove in the rotary transformer shown in FIG. 4, and FIG. 6 is a sectional view taken along line B'-B. is a sectional view taken along line A'-A in FIG. 16... Stator, 17... Rotor, 20,2
1, 22, 30, 31, 32... annular groove, 23,
24, 25, 33, 34, 35...Insulating member, 2
6, 27, 28, 36, 37, 38...Winding.

Claims (1)

[Scope of utility model registration request] In a rotary transformer having a stator and a rotor, each consisting of a flat core member, with a plurality of annular grooves concentrically formed on each opposing surface and windings mounted in these annular grooves, the annular grooves of the stator and rotor have the same depth. Insulating members of different thicknesses are arranged in each annular groove so that the grooves become shallower from the inside to the outside of the stator and rotor, and the opposing annular grooves have the same depth. A rotary transformer.