JPS6218602A - Circuit mounting processing structure for rotary head drum - Google Patents

Abstract

PURPOSE:To reduce the man-hour by providing a rotor magnet on the lower face of an upper rotating drum and providing a rotation detecting circuit on the upper face of a lower fixed drum and mounting a head amplifier circuit and the rotation detecting circuit as one body with a shared substrate. CONSTITUTION:A rotary head drum consists approximately of an upper rotating drum 35, a magnetic head 36 attached to the upper rotating drum 35, a rotary transformer 37 which transmits and receives signals to and from the magnetic head 36, a rotor magnet 38 of a rotation detecting means which is attached to the lower face of the upper rotating drum 35, and a shared substrate 39 on which a head amplifier 39a the rotation detecting circuit, etc. are mounted. A cavity 43 contributing to the effective use is formed by the upper rotating drum 35 and a lower fixed drum 33 because the rotor transformer 37a is fixed to the upper rotating drum 35, and the head amplifier 39a is stored in this cavity 43, that is, the amplifier 39a is incorporated in the rotary head drum.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a rotating head drum used in a video tape recorder, etc., and in particular, a process for mounting a head amplification circuit and a rotation detection circuit on a single substrate. This is related to the structure that was created.

[Prior Art] Conventionally, there is a rotary head drum of this type as shown in FIG. This device includes a rotary drum 5 having a magnetic head l, which is rotatably driven by a shaft 3 to a lower fixed drum 2 via a bush 4, and a signal is transmitted to the magnetic head l via cables 13a and Bb. A rotor transformer 7a and a stator transformer 7b constituting a disc-shaped rotary transformer for delivering and receiving, a rotor magnet 8 rotated together with the upper rotating drum 5, and a rotation detecting means consisting of a rotation detecting substrate 9 slightly opposed to the rotor magnet 8; Coil 11 and motor rotor 12 that constitute the motor
This is a rough outline.

The stator transformer 7b is fixed to the web of the lower fixed drum 2, and the rotor transformer 7a is fixed to the end surface of the cylindrical portion of the bush 4. cable 6a and cable eb
are connected by a rotor transformer relay plate 13, and are connected to the rotor transformer 7a through a guide hole formed in the upper rotating drum 5 and a guide hole formed in the bushing 4.

The cable 6c connected to the stator transformer 7b passes through a guide hole formed in the web of the lower fixed drum 2, and is connected to the shielded cable 6d at the stator transformer relay plate 14 fixed to the circumferential surface of the lower fixed drum 2. , the shielded cable cd is pulled out from the connector 14a of the stator transformer relay board 14, and connected to a head amplifier 15 that amplifies the output signal from the magnetic head l.

This head amplifier 15 is housed in a shield case.

On the other hand, a mounting plate 18 is fixed to a bushing 17 fixed to the shaft 3 with a set screw 18, and a motor rotor 12 is mounted on the upper surface of the bushing 17, and a rotor magnet 8 is mounted on the lower surface of the bushing 17. The 0-rotation detection substrate 9 shown in FIG. The signal from this rotation detection board 9 is supplied to the motor drive board 20 via the cable 6e.

The coil 11 is attached to the lower surface of a coil mounting board 21 having a connector 21a at the end.
1a and the motor drive board 20 are connected by a cable 6r. Note that 22a and 22b are pole bearings.

[Problems to be Solved] However, according to the above-mentioned conventional rotating head drum,
There are the following problems.

That is, the rotational speed detection substrate 9. Since there are a large number of boards such as the stator transformer relay plate 14 and the cables 6c to be routed, not only is the assembly work complicated, but it is also an obstacle to downsizing the rotary head drum.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to provide a circuit mounting structure for a rotary head drum that can reduce the number of circuit boards and cables, and reduce the number of man-hours.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the configuration of the circuit-mounted processing structure for a rotary head drum according to the present invention includes an upper rotary drum having a magnetic head and rotationally driven with respect to a lower fixed drum. , a rotary head drum having a rotary transformer for transmitting signals to the magnetic head, and a rotation detecting means consisting of a rotor magnet rotated together with the upper rotating drum and a rotation detecting circuit slightly opposed to the rotor magnet. A cylindrical rotary transformer is used as the rotary transformer, and the stator transformer is fixed near the axis of the lower fixed drum, and the rotor transformer is installed inside the upper rotating drum, and the rotor transformer is installed inside the cavity defined by the upper rotating drum and the lower fixed drum. , a head amplification circuit that amplifies the output signal from the magnetic head via a rotary transformer is provided, and the rotor magnet is provided on the lower surface of the upper rotating drum, and a rotation detection circuit is provided on the upper surface of the lower fixed drum. Moreover, the head amplifier circuit and the rotation detection circuit are integrally mounted on this using a common substrate.

[Example] Next, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a half-cut front view showing a rotary head drum to which an embodiment of the circuit mounting processing structure for a rotary head drum according to the present invention is applied.

This rotating head drum has a coil 30 that constitutes a motor.
and a motor rotor 31, a shaft 32 rotationally driven by the motor rotor 31, and a lower fixed drum 3 fixed by interposing pole bearings 32a and 32b between the shaft 32.
3, an upper rotating drum 35 attached to the shaft 32 with a bushing 34, a magnetic head 36 attached to the upper rotating drum 35, a rotary transformer 37 for transferring signals to the magnetic head 36, and an upper rotating drum 3.
Rotor magnet 3 as a rotation detection means attached to the bottom surface of 5
8, and a common board 38 on which a head amplifier 39a, a rotation detection circuit, etc. are mounted.

The rotary transformer 37 is a cylindrical rotary transformer, and consists of an outer rotor transformer 37a and an inner stator transformer 37b. The transformer 37b is fixed to the lower fixed drum 33. The rotor transformer 37a is connected to the magnetic head 3B via a cable 40a, and the stator transformer 37b is connected to the head amplifier 39a mounted on the common board 38 via a cable 40b attached to the common board 39. has been done. The common substrate 39 is fixed to the web of the lower fixed drum 33, and a window 33c is formed in a part of the peripheral wall of the lower fixed drum 33.
The overhanging portion 39b of the common substrate 39 is exposed to the outside through the window 33c. A transformer pattern 38F is formed near the center of the common substrate 39, and the stator transformer 3
An amplifier pattern 39c for soldering the cable 40b from 7 is formed. A connector 41 is attached to the projecting portion 39b. The head amplifier 39a is connected to a connector 41 via an amplifier pattern 39c, and a cable 42 is led out from the connector 41.

In this way, the cylindrical rotary transformer 37 is used, and the rotor transformer 37a is not fixed to the bushing 34 but to the upper rotating drum 35, which contributes to effective utilization of the upper rotating drum 35 and the lower fixed drum 33. A cavity 43 is defined, and the head amplifier 39a can be accommodated in the cavity 43, that is, incorporated into the rotating head drum.

With this configuration, the head amplifier 39a is placed close to the rotary transformer 37, so the cable length is short and the S/N ratio is improved. In addition, since the head amplifier 38 itself is always shielded by the upper rotating drum 35 and the lower fixed drum 33, a conventional shield case is no longer required, and the number of parts can be reduced.
Manufacturing costs can be lowered.

The rotor magnet 38 is directly attached to the lower surface of the upper rotating drum 35 and rotates in the cavity 43 integrally with the rotation of the upper rotating drum 35.

The rotating rotor magnet 38 is attached to the common substrate 38.
An FG pattern 39d and a PG pattern 39e are formed to detect changes in the magnetic field. The FG pattern 39d is for detecting the rotational speed of the upper rotating drum 35, and P
The G pattern 39e is used to detect the phase of the upper rotating drum 35.

The rotor magnet 38 slightly faces the FG pattern 39d and the PG pattern 39e on the common substrate 39. In this example, the gap is 0.15 to 0.25+a+
It is about s.

A guide hole 33d is bored in the web of the lower fixed drum 33. A coil attachment plate 44 is fixed to the lower surface of the lower fixed drum 33, and the coil 30 is attached to this lower surface. Further, a motor drive circuit 45 is provided on the upper surface of the coil mounting plate 44. A cable 40b drawn out from the FG pattern 39d and PG pattern 39e on the common board 39 is connected to the motor drive circuit 45 directly below through the guide hole 33d.

The motor rotor 31 is attached to a mounting plate 4B, which is fixed to the shaft 32 with a bush 47. The coil 30 slightly faces the motor rotor 31, and in this embodiment, the gap is 0.2 to 0.
It has about 31 layers.

Thus, due to the definition of the cavity 43, direct attachment of the rotor magnet 38 to the underside of the upper rotating drum 35 can be achieved for the reasons discussed above.

With this configuration, the rotor magnet 38 and the common substrate 3
9(7) F G pattern 39d and PG putter 738
It becomes easy to adjust the gap with e. Conventionally, the -F section rotating drum 35 is assembled to the lower fixed drum 33,
Although the sleeve height L2 is obtained by post-processing so that the specified value of the head height Ll is +0 to +io#Lm, the mounting surface of the rotor magnet 38 to the upper rotating drum 35 is preliminarily set to approximately L3±0.05+sm. Just by processing, the gap between the rotor magnet 38 and the FG pattern 39d and PG pattern 39e on the common substrate 39 will automatically become about 0.2 to 0.3 .

Furthermore, since the flatness of the upper rotary drum 35 and the lower fixed drum 33 is essentially controlled to an accuracy of GM order, concentricity and gap unevenness do not pose any problem.

On the other hand, by effectively utilizing the cavity 43, the head amplifier 39a
The rotation detection circuit consisting of the FG pattern 39d and the PG pattern 39e is mounted on a single common board 39.

According to this configuration, the number of substrates and cables can be reduced compared to the conventional one, the assembly work can be simplified, and a low-cost rotary head drum can be provided.

Furthermore, by disposing the motor drive circuit 45 on the lower fixed drum 33, the connection from the rotation detection circuit to the motor drive circuit 45 can be made using a short cable 40b, so that the signal from the PG pattern 39e, which is normally weak at 7 to 8 mV, is The S/N ratio is improved.

[Effects of the Invention] As explained above, according to the circuit Ba processing structure of the rotary head drum according to the present invention, a cylindrical rotary transformer is used as the rotary transformer, and the stator transformer is fixed near the axis of the lower fixed drum. At the same time, a rotor transformer is provided inside the upper rotating drum, and a head amplification circuit for amplifying the output signal from the magnetic head via the rotary transformer is arranged in the cavity defined by the upper rotating drum and the lower fixed drum. The rotor magnet is provided on the lower surface of the upper rotating drum, and a rotation detection circuit is arranged on the upper surface of the lower fixed drum, and the head amplification circuit and the rotation detection circuit are integrated into this using a common substrate. Since it is specifically installed, it has the following effects.

In other words, by effectively utilizing the cavity, the head amplification circuit and the rotation detection circuit are mounted on a single board, reducing the number of boards and cables, reducing man-hours, and creating a small and low-cost rotating head drum. can be provided.

[Brief explanation of the drawing]

FIG. 1 is a half-cut front view showing a rotary head drum to which an embodiment of the circuit-mounted processing structure for a rotary head drum according to the present invention is applied. FIG. 2 is a plan view showing a common substrate used in the rotary head drum. FIG. 3 is a half-cut front view showing an example of a conventional rotary head drum. 30-Ichiban coil 31 fist--Motor rotor 32--Shaft 33--Lower fixed drum 33a, 33b--Pole bearing 33cm--Window 33d--Guide hole 34--1 bush 35---Top rotation Drum 36, fist, magnetic head 37, rotary transformer 37a, rotor transformer 37b, stator transformer 38th, rotor magnet 39, common board 39a, head amplifier 39b1, overhang 38C・Amplifier pattern 39d --- FG pattern 39e ・Kenkai PG pattern 40a, 40b, 42 *a a cable 41...
- Connector 43...Fist cavity 44...Fist coil mounting plate 4511...Motor drive circuit 48...Mounting plate 47...Button.

Claims (1)

[Claims] An upper rotating drum that has a magnetic head and is driven to rotate with respect to a lower fixed drum, a rotary transformer that transfers signals to the magnetic head, a rotor magnet that rotates together with the upper rotating drum, and a rotor magnet that is slightly opposed to this. In a rotary head drum having a rotation detection means constituted by a rotation detection circuit, a cylindrical rotary transformer is used as the rotary transformer, a stator transformer is fixed near the axis of the lower fixed drum, and a stator transformer is fixed to the inner side of the upper rotating drum. A rotor transformer is provided in the upper rotating drum, and a head amplifying circuit for amplifying the output signal from the magnetic head via the rotary transformer is disposed in a cavity defined by the upper rotating drum and the lower fixed drum. The rotor magnet is provided on the lower surface of the rotating drum, the rotation detection circuit is arranged on the upper surface of the lower fixed drum, and the head amplification circuit and the rotation detection circuit are integrated into this using a common substrate. A circuit-mounted processing structure for a rotating head drum characterized by the fact that it is equipped with a