JPH04595Y2 - - Google Patents

Description

[Detailed Description of the Invention] "Industrial Application Field" This invention relates to the structure of a carrier wave oscillator used in an RF modulator such as a video tape recorder.

"Prior Art" In a video tape recorder (VTR), a baseband video signal obtained by playing a video soft tape is input to an RF modulator, and a carrier wave supplied from a carrier wave oscillator built in the RF modulator is used to generate the video signal. AM modulated by the signal,
It is converted into a VHF or UHF band RF signal (in Japan, the RF signal of TV channel 1 or 2),
Output to the VTR's antenna output terminal. That RF
The image is played back by feeding the signal to the antenna input terminal of the monitor TV and selecting the video RF signal using the TV's tuner.

As the above carrier wave oscillator, for example, a grounded base series-tuned Colpitts oscillation circuit as shown in FIG. 8 is used. One end of the oscillation coil _L1 is grounded through a variable capacitor CV and a capacitor _C3 , and the other end is grounded through a capacitor _C4 and connected to the collector of a transistor Q. The oscillation frequency is determined by the oscillation coil _L1 and the capacitor.
Determined by the series resonant frequency with the combined capacitance of C ₃ and CV. The oscillation output is taken out from both ends of the pickup coil _L2 .

The circuit components of the carrier wave oscillator include an oscillation coil L ₁ , a variable capacitor CV, and a capacitor as shown in Figure 10.
All components except C ₃ and C ₄ are mounted on one printed circuit board 1 . Also, both ends of capacitor _C3 are variable capacitor CV
are electrically soldered in parallel. The printed circuit board 1 on which a plurality of components are mounted, the variable capacitor CV with _C3 , and the capacitor _C4 are housed and held in a common shield case 3. One electrode of the capacitor _C4 is soldered to the wall surface from the outside through a small hole provided in the side wall of the shield case 3. The other electrode of the capacitor C ₄ is placed in contact with or close to the periphery of the printed circuit board 1 . One end of the oscillation coil _L1 is soldered to the other electrode of the capacitor _C4 as shown by the arrow, and the other end is connected to the variable capacitor CV as shown by the arrow.
soldered to. Solder is applied between point P, where one end of the chiyoke coil L ₃ of the printed circuit board 1 is soldered, and the other electrode of the capacitor C ₄ to electrically connect them. In this way, the carrier wave oscillator is assembled as shown in FIG.

In the above case, the rotating shaft of the rotor of the variable capacitor CV is arranged in the direction of standing on the bottom of the shield case 3, and a driver groove is formed at the upper end of the rotating shaft.
It is called a vertical oscillator.

Configuration of Variable Condenser CV The variable condenser CV shown in FIG. 10 is composed of a spring 5, a rotor 6, a variable condenser case 7, a stator 8, and a stator board 9, as shown in FIG. The spring 5 is constructed by bending a linear metal elastic body into a U-shape. The rotor 6 has a plurality of fan-shaped blades 6b formed at equal intervals in the shape of comb teeth at right angles to a rotating shaft 6a made of metal. A driver groove 6c necessary for rotating the rotor 6 is formed at one end of the rotation shaft 6a. The variable condenser case 7 is a plate body in which a pair of end plates 7a are arranged facing each other, one edge of which is integrally connected by a side plate 7c, and the whole has a U-shape. A notch 7d having a U-shaped outer shape is formed at an edge of the substantially rectangular end plate 7a that is perpendicular to the side plate 7c. A part of the edge of the end plate 7a parallel to the side plate 7c is cut and raised to form a cut and raised portion 7e. Engagement convex portions 7f are provided on both shoulders of the end edge facing the notch 7d of the end plate 7a.
is formed. One edge of the side plate 7c is folded back inward to form a curved portion 7g.

The stator 8 has arcuate blades 8a made of metal plates.
A plurality of blades are arranged at equal intervals, and the center portion of the outer peripheral edge of each blade is integrally connected to one surface of a common metal rectangular parallelepiped portion 8b. The stator board 9 is a substantially rectangular printed circuit board with a rectangular mounting hole 9a formed in the center of the board surface and cutouts 9b formed at every four intervals of the board surface.
A solder pattern 9c is formed to surround the mounting hole 9a, and solder patterns 9 are formed at both ends of the plate surface at intervals from both sides of the solder pattern 9c.
d, 9e are formed.

The rotation shaft 6a is inserted into the notch 7d of the end plate 7a of the variable condenser case 7, while the center part of the spring 5 is engaged with the curved part 7g of the side plate 7c, and both legs 5b are aligned along the inner surface of the end plate 7a. The pivot shaft 6a is elastically pressed toward the inner side of the notch 7d, and the end of the leg portion 5b is hooked and locked by the cut-and-raised portion 7e.

The rectangular parallelepiped portion 8b of the stator 8 is inserted into the mounting hole 9a of the stator substrate 9 and soldered. Blades 8 of stator 8 attached to stator board 9
a between the blades 6b of the rotor 6, and insert the engagement protrusion 7f of the end plate 7a into the notch 9b of the stator board 9.
are engaged and soldered.

A capacitor _C3 is soldered to the variable capacitor CV assembled as described above so as to bridge the solder patterns 9c and 9e of the stator board 9.

Another structure of the carrier wave oscillator In the examples shown in FIGS. 9 and 10, the rotation shaft of the variable capacitor CV is attached perpendicularly to the bottom plate of the shield case 3, and the rotor is rotated from the opening side of the shield case 3. . However, depending on the requirements of the RF modulator or video tape recorder, a structure in which the rotation of the rotor is adjusted from the side surface of the shield case 3 is also used. An example of this is shown in FIG. In this case, the rotation axis of the rotor is arranged parallel to the printed circuit board and is called a horizontal oscillator. The shield case 3 and variable capacitor CV are dedicated to this case, and different types from those shown in FIG. 10 are used.

``Problems that the invention seeks to solve'' Video tape recorders are rapidly becoming popular, but behind the scenes, competition between manufacturers is intensifying. Good cost performance has a great impact on shear, and reducing product costs can make or break a business. This idea was made in view of the above situation, and its purpose is to streamline the assembly of a carrier wave oscillator for an RF modulator.

``Means to solve the problem'' This idea consists of an oscillation circuit including a variable capacitor for adjusting the oscillation frequency mounted on a single printed circuit board, and a shielding case covering the printed circuit board.
In the structure of a carrier wave oscillator for an RF modulator, a stator of the variable capacitor is mounted on the printed circuit board, a rotor of the variable capacitor is rotatably held in a variable capacitor case, and the stator is housed in an opening of the variable capacitor case. The variable capacitor case is attached to the printed circuit board so as to be combined with the rotor, and the variable capacitor is assembled, and the rotary shaft of the rotor is placed vertically or horizontally with respect to the printed circuit board, respectively. First and second engaging grooves for mounting the variable capacitor case on the printed circuit board are formed in the variable capacitor case, and are respectively mounted on the printed circuit board in a direction corresponding to the rotational axis of the rotor. First and second mounting legs for vertical or horizontal mounting are provided on the stator, and mounting holes for inserting the first or second mounting legs of the stator are formed in the plate surface of the printed circuit board. At the same time, an engaging protrusion that engages with the first or second engaging groove of the variable capacitor case is formed on the edge of the printed circuit board.

``Embodiment'' The parts shown in FIGS. 1 and 2 with the same reference numerals as in FIGS. 9 and 10 are the first embodiment of this invention, and a vertical oscillator is shown. ing. In this invention, all the oscillation circuits, including the variable capacitor CV, are mounted on one printed circuit board 1. Also, either vertical or horizontal oscillators can be easily assembled using the same components.

Variable Condenser CV As shown in FIG. 3, the variable condenser CV has a rotor 6 rotatably attached to a variable condenser case 7 using a spring 5. As shown in FIG. 4, the spring 5 is constructed by bending an elastic metal wire into a generally U-shape, and has a central portion 5a and a pair of leg portions 5b. It is bent to form a small U-shape in the opposite direction to the U-shape to form the locking portion 5c. As shown in FIG. 4, the variable cap case 7 has a pair of end plates 7a.
and a pair of side plates 7c. A wedge-shaped notch 7d for receiving the rotation shaft 6a of the rotor is formed in the end plate 7a as in the conventional case. The side surface 7c has a locking piece 7h for hooking and locking the spring locking portion 5c, and a leg portion 5b that presses the rotation shaft 6a of the rotor toward the inner side of the notch 7d. A locking piece 7i for locking by hanging is provided.

A first engagement groove 7j, which is used when attaching the variable cap case 7 to the printed circuit board, is formed in the front edge of the side plate 7c so that the rotation shaft 6a of the rotor is placed upright on the printed circuit board. In addition, the variable capacitor case 7 is placed on the printed circuit board 1 so that the rotating shaft 6a of the rotor lies horizontally on the printed circuit board 1.
A second engagement groove 7k, which is used when attaching to the end plate 7a, is formed on the front edge of the end plate 7a.

As shown in FIG. 5, the variable condenser case 7 has the above-mentioned notch 7d, locking piece 7h,
7i, the first and second engaging grooves 7j, 7k, etc. are formed by pressing work or the like, and then the left and right and upper and lower plate surfaces are bent forward.

As shown in FIG. 4, the stator 8 has a plurality of U-shaped blades 8a projecting from a connecting portion 8c at equal intervals in a comb-tooth shape, and a rotation shaft 6 of the rotor.
A first mounting leg 8d for attaching the stator directly to the printed circuit board in an upright or horizontal position, corresponding to the direction of a toward the printed circuit board.
A second mounting leg 8e is integrally formed to protrude from the bottom and side surfaces of the connecting portion 8c.

Printed circuit board 1 All of the oscillation circuits shown in FIG. 8 are mounted on the printed circuit board 1. As shown in FIG. 1, a mounting hole 1a is formed in the plate surface into which the first or second mounting leg 8d or 8e of the stator 8 is inserted and soldered. Further, the first or second engaging groove 7j or 7k of the variable capacitor case 7 is provided on both sides of the printed circuit board 1.
An engaging protrusion 1b for engaging with and soldering is formed protrudingly.

Assembling a vertical oscillator To construct a vertical oscillator, as shown in FIG. 1, insert the first mounting leg 8d of the stator into the mounting hole 1a of the printed circuit board with the blade 8a facing the rear of the printed circuit board 1. Then, the lower blade 8a and the surface of the printed circuit board 1 are soldered with a predetermined distance between them. Next, the variable condenser case 7 holding the rotor 6 is erected, that is, the rotating shaft 6 of the rotor is
A is placed in an upright position, the front end of the case is moved to the rear end of the printed circuit board 1, and the engaging protrusion 1b is engaged in the first engaging groove 7j and soldered. In this state, the stator 8 is arranged in an opening surrounded by the end plate 7a and the side plate 7c of the rotor 6, and the blades of the stator 8 and the blades of the rotor 6 are positioned at different positions. The lower end plate 7a of the variable capacitor case 7 is arranged between the lowermost blade 8a of the stator and the printed circuit board 1.

The shield case 3 is placed over the printed circuit board 1 on which all the circuits are mounted, and they are fixed together with solder to complete the assembly of the oscillator, as shown in FIG. 2.

Assembling the horizontal oscillator As shown in FIG. 6, the second mounting leg 8e of the stator is inserted into the mounting hole 1a of the printed circuit board 1 and soldered, and the second engagement groove 7k of the variable cap case 7 holding the rotor 6 is By engaging the engaging protrusion 1b and soldering it, the variable capacitor CV can be assembled on the printed circuit board 1 with the rotating shaft 6a horizontally, and the horizontal oscillator shown in FIG. 7 can be easily assembled. Since it is obvious, detailed explanation will be omitted.

``Effects of the invention'' According to this invention, it is possible to mount all the oscillation circuits, including the variable capacitor, on one printed circuit board, and the conventional stator board is no longer necessary.
The workability of assembly is significantly improved compared to the conventional method, and the number of assembly steps can be reduced.

Since the variable capacitor can be easily assembled on a printed circuit board either with its rotation axis upright or horizontally, there is no need to prepare separate variable capacitors with different structures for vertical or horizontal oscillators as in the past. Not at all. This standardization of variable capacitors can also be expected to reduce parts management man-hours.

[Brief explanation of the drawing]

Fig. 1 is a partially exploded perspective view showing the first embodiment of this invention, Fig. 2 is a perspective view of the first embodiment of this invention, and Fig. 3 is an enlarged view of the variable condenser case 7 holding the rotor shown in Fig. 1. 4 is a partially exploded perspective view of the variable capacitor CV shown in FIG. 2, FIG. 5 is a perspective view showing the state before the end plate 7a of the variable capacitor case 7 in FIG. 4 is bent, FIG. 7 is a partially exploded perspective view and a perspective view of the second embodiment of this invention, FIG. 8 is a circuit diagram showing an example of a carrier wave oscillator for an RF modulator of the conventional and this invention, and FIG. 9
10 and 10 are respectively a perspective view and a partially exploded perspective view of a conventional vertical carrier wave oscillator, FIG. 11 is a partially exploded perspective view of the variable condenser CV shown in FIG. 10, and FIG.
The figure is a perspective view of a conventional horizontal carrier wave oscillator.

Claims (1)

[Scope of Claim for Utility Model Registration] A carrier wave oscillator for an RF modulator has a structure in which an oscillation circuit including a variable capacitor for adjusting the oscillation frequency is mounted on a single printed circuit board, and the printed circuit board is covered with a shield case, A stator of the variable capacitor is mounted on the printed circuit board, a rotor of the variable capacitor is rotatably held in a variable capacitor case, and the stator is housed in an opening of the variable capacitor case and combined with the rotor. The case is attached to the printed circuit board to assemble the variable capacitor, and the variable capacitor case is mounted on the printed circuit board so that the rotary axis of the rotor is in an upright or horizontal position, respectively, with respect to the printed circuit board. first and second engaging grooves are formed in the variable cap case for attaching the capacitor to the printed circuit board in a vertical or horizontal direction, respectively, corresponding to the direction of the rotational axis of the rotor. two mounting legs are provided on the stator, and a mounting hole for inserting the first or second mounting leg of the stator is formed in the board surface of the printed circuit board, and a mounting hole for inserting the first or second mounting leg of the stator, and a mounting hole for inserting the first or second mounting leg of the stator. A structure of a carrier wave oscillator for an RF modulator, characterized in that an engaging protrusion that engages with an engaging groove is formed on an edge of the printed circuit board.