JPH09190940A - Flyback transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve durability and surely prevent the discharge of high voltage by interposing an insulating material in the gap between a winding and core. SOLUTION: An insulating resin board 20 is interposed in each gap between each winding wound on a bobbin 2 and the thin part 5b of each core 5A and 5B and between the lower flange of the bobbin 2 and the center 5c of the core 5B on high voltage side. Hereby, the backlash or the dislocation of the bobbin 2 and each core 5A and 5B which is easy to occur at manufacture and assembly of a small-sized flyback transformer 1 can be prevented surely. Moreover, a highly accurate small-sized flyback transformer 1 can be obtained. Moreover, the lower flange 2e of the bobbin 2 and the center 5c of the core 5B on high voltage side cease to contact with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flyback transformer (FBT) for supplying a high voltage or the like to a cathode ray tube (CRT) for a viewfinder of a video camera.

[0002]

2. Description of the Related Art For example, a small flyback transformer for supplying a high voltage to a cathode ray tube for a viewfinder of a video camera is known. Explaining this in detail with reference to FIG. 4, the small flyback transformer 1 ′ includes a bobbin 2 around which a low-voltage (primary) winding 3 and a high-voltage (secondary) winding 4 are wound, and these bobbin 2 And a pair of upper and lower cores 5A arranged so as to face the windings 3 and 4, respectively.
5B, a high voltage output high voltage wire 8 connected to the high voltage winding 4 via a rectifying element 6 and the like, and a video camera (not shown) connected to the bobbin 2 and connected to the low voltage winding 3 Terminal pins 9 mounted on the circuit board
A casing-type outer case 10 that covers the bobbin 2 and the cores 5A, 5B and the like and has an open upper surface, a lid 11 that covers the upper opening of the outer case 10, and a metal that covers the outer case 10. It is made up of a box-shaped shield case 12 which is made of metal.

This small flyback transformer 1'has a high voltage of several thousand V (for example, 3000 V (p / p) for a cathode ray tube for a viewfinder of a video camera.
The DC voltage of 2200 V obtained by rectifying the AC voltage of p)) and the focus voltage are supplied, and the heater voltage and other required voltages are supplied to the circuit side of the circuit board.

[0004]

In the conventional small flyback transformer 1 ', (1) when the high voltage winding 4 rises due to loose winding, the space between the high voltage side core 5B and the core 5B is narrowed, and space discharge occurs. (This discharge part is indicated by arrow A in FIG. 4)
Or (2) when the lower flange portion 2e on the high voltage side of the bobbin 2 comes into contact with the core 5B on the high voltage side due to a positional deviation during assembly, the winding surface of the high voltage winding 4 and the core 5B on the high voltage side.
(3) The surface of the silicon insulation film 8a of the high-voltage electric wire 8 that outputs a high voltage is the electric wire core wire. During the terminal soldering process, the component such as chlorine contained in the flux deteriorates the surface insulation resistance, and for example, the core 5B comes into contact with the high-voltage leak current of about 1 μA, which causes a leak discharge (this discharge portion is indicated by an arrow C in FIG. 4). There was a risk that Since the starting voltage of these discharges decreases due to humidity, conventionally,
As a small flyback transformer 1 ″ shown in FIG. 5, as a discharge prevention measure, an insulating resin agent 13 such as silicone or epoxy resin is applied or filled in a portion where moisture enters or a high voltage portion where there is a risk of discharging. I was there.

However, in the above discharge prevention measures, it is necessary to have skill in the work for handling the resin in the manufacturing process, and the number of management items for manufacturing such as management of equipment and resin and limitation of the number of products has been increased. In addition, there is a risk of corona discharge when bubbles (voids) are generated inside due to uneven work. Further, due to the increase in weight due to the filling of the insulating resin agent 13, the increase in resin price, and the increase in the number of man-hours, it is not possible to reduce the cost and the size and weight of the flyback transformer 1 ″.

[0006] Therefore, the present invention provides a small and lightest flyback transformer capable of improving durability performance and surely preventing high voltage discharge.

[0007]

In a flyback transformer having a bobbin around which primary and secondary windings are respectively wound, and a core arranged so as to face the bobbin and the winding respectively. An insulating member is interposed in the gap between the winding and the core.

Since the insulating member is interposed in the gap between the winding wire and the core, it is not necessary to fill the insulating resin, so that the flyback transformer which is inexpensive and lightweight can be manufactured. Moreover, since the gap between the winding and the core is reliably shielded by the insulating member, electric discharge, which is likely to occur due to infiltration of moisture during this period, is surely prevented.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

1 to 3 show a small flyback transformer (FBT) according to an embodiment of the present invention.
Cathode ray tube for video camera viewfinder (CR
T) or a high voltage (for example, 3000 V (p /
It supplies a required voltage such as a rectified AC voltage of p) of 2200 V) or a heater voltage. The small flyback transformer 1 includes a resin bobbin 2 on which a low-voltage (primary) winding 3 and a high-voltage (secondary) winding 4 are wound, respectively, and the bobbin 2 and the windings 3 and 4 face each other. And a pair of upper and lower U-shaped cores 5A, 5B made of a conductive metal, and a high-voltage wire 8 for high-voltage output connected to the high-voltage winding 4 via a rectifying element 6 and a capacitor 7. A plurality of C-shaped terminal pins 9 attached to the bobbin 2 and connected to the low voltage winding 3 and mounted on a circuit board for a video camera (not shown), the bobbin 2 and the pair of cores 5A, 5B and the like, a casing-type outer case 10 having an open upper surface side, a lid 11 that covers the upper surface opening 10a of the outer case 10, and a casing type made of a non-conductive metal that covers the outer case 10. And the shield case 12 of

As shown in FIGS. 1 and 2, the bobbin 2 has a rectangular tubular body portion 2a, an upper flange portion 2b integrally formed on the upper portion of the body portion 2a, and a central portion of the body portion 2a. It has a pair of middle flange portions 2c and 2d formed integrally with each other, and a lower flange portion 2e formed as a pair below the lower portion of the body portion 2a. The low-voltage winding 3 is wound between the upper flange portion 2b and the middle flange portion 2c of the bobbin 2, and the bobbin has a pair of middle flange portions 2c and 2d and between the middle flange portion 2d and the lower flange portion. The high-voltage winding 4 is wound between the wire 2e and 2e. Also, the body portion 2a of the bobbin 2
The thick-walled portion 5a of the core 5A on the low-pressure side is loosely inserted on the upper side, and the thick-walled portion 5a of the core 5B on the high-pressure side is loosely inserted on the lower side in the body portion 2a of the bobbin 2. A pair of rectifying elements 6'and 6 "are mounted on the upper flange portion 2b of the bobbin 2.

As shown in FIGS. 2 and 3, a notch 10b extending from the upper surface opening 10a to the bottom is formed at a corner of one side wall of the outer case 10. Further, the lid body 11 is formed in a substantially square plate shape, and a rectangular hole portion 11a is formed at a position facing each terminal pin 9. This lid 1
A vertical piece 11b fitted into the cutout 10b is integrally formed at the corner portion of the outer case 10 facing the cutout 10b. Further, an upper surface opening 12a is formed on the upper surface side of the shield case 12, and a cutout 12b is formed at a position facing the cutout 10b of the outer case 10.
Is formed. The lower side of each of the cutouts 10b, 12b of the outer case 10 and the shield case 12 causes the high-voltage electric wire 8
A part of is going out. Furthermore, a tongue-shaped bent piece 12c is integrally formed on the upper edge of the shield case 12, and the outer case 10 and the lid body are provided inside the shield case 12 by bending the bent piece 12c. 11 and 11 can be stopped.

As shown in FIG. 1, between the windings 3 and 4 and the thin portions 5b of the cores 5A and 5B, and between the lower flange portion 2e of the bobbin 2 and the central portion 5c of the high voltage side core 5B. An insulating resin plate (insulating member) 20 is interposed in each gap.
As shown in FIGS. 1 and 2, the insulating resin plate 20 includes a vertical piece portion 21 and a horizontal piece portion 22 that extends horizontally at a lower edge of the vertical piece portion 21 via a substantially arc-shaped corner portion. An L-shaped rib portion 23 located at one end of each of the vertical piece portion 21 and the horizontal piece portion 22, and a tip portion of the rib portion 23 that extends parallel to the horizontal piece portion 22 and has an upper outer surface formed into a substantially arc shape. The electric wire contact portion 24 is formed. Each portion 21 to 24 of the insulating resin plate 20 is integrally formed by plastic molding of polyphenylene sulfide (PPS) resin, and the rear portion of the rib portion 23 serves as a gate portion 25 for molding. The vertical piece 21 of the insulating resin plate 20 is inserted into the gap between each winding 3, 4 and the thin portion 5b of each core 5A, 5B, and the horizontal piece 22 of the insulating resin plate 20 is a bobbin 2 Is inserted into the gap between the lower flange portion 2e and the central portion 5c of the high-voltage side core 5B, and the wire contact portion 24 of the insulating resin plate 20 is attached to the insulating film 8a of the high-voltage output high-voltage electric wire 8. It comes to abut. This allows
The tip side of the rib portion 23 of the insulating resin plate 20 and the wire contact portion 2
4 is located around the outer peripheral surface of the thick portion 5a of the core 5B on the high pressure side. In addition, the plate thickness of the vertical piece 21 and the horizontal piece 22 of the insulating resin plate 20 is the same as the bobbin 2 and each core 5.
When the gap between A and 5B is, for example, about 0.15 mm, it is formed to have a wall thickness of about 0.1 mm, and the rib portion 23 and the wire contact portion 24 are formed to have a wall thickness larger than that.

According to the small flyback transformer 1 of the above-described embodiment, between the windings 3 and 4 wound around the bobbin 2 and the thin portions 5b of the cores 5A and 5B, and the lower flange portion of the bobbin 2. Since the insulating resin plate 20 is interposed in each gap between the 2e and the central portion 5c of the high-voltage side core 5B,
The bobbin 2 and the cores 5A and 5B, which are likely to be loosened during the manufacturing and assembly of the small flyback transformer 1, and the positional deviation can be reliably prevented, and the small flyback transformer 1 with high accuracy can be provided. Since the positional deviation between the bobbin 2 and the cores 5A and 5B can be prevented, that is, the horizontal piece 21 of the insulating resin plate 20 is located between the lower flange portion 2e of the high pressure side of the bobbin 2 and the center of the high pressure side core 5B. Since the lower flange portion 2e of the bobbin 2 and the central portion 5c of the core 5B on the high voltage side do not come into contact with each other by being interposed between the portion 5c, the winding surface of the high voltage winding 4 and the core 5B on the high voltage side. The internal space and the creepage distance from the central portion 5c can be reliably ensured, and the occurrence of discharge, which is likely to occur due to infiltration of moisture during this time, can be reliably prevented.

Further, even if the high-voltage winding 4 rises due to looseness and the gap between the high-voltage winding 4 and the thin portion 5b of the high-voltage side core 5B is narrowed, a vertical piece of the insulating resin plate 20 is left in the gap. Since the portion 21 is interposed, space discharge does not occur in the gap, and the surface of the silicon insulating film 8a of the high-voltage wire 8 that outputs a high voltage is surface-insulated by the chlorine component of the solder flux. Even if the resistance deteriorates, the high voltage wire 8
Since the wire contact portion 24 of the insulating resin plate 20 is interposed between the high-voltage side thick portion 5a of the core 5B and the high-voltage side core 5B, the high voltage of the high-voltage electric wire 8 leaks and the high voltage side Core 5B
There is no risk of discharge. Further, since the insulating resin plate 20 prevents moisture from entering between the high-voltage winding 4 and the high-voltage side core 5B, it is possible to reliably prevent the discharge and the decrease in the starting voltage that are likely to occur due to the infiltration of moisture. .

Also, as in the conventional small flyback transformer 1 "shown in FIG. 5, an insulating resin agent 13 such as silicone or epoxy resin is applied to a portion where moisture enters or a high voltage portion where there is a risk of discharge. Since no filling and discharge prevention measures are taken, no skill is required for the work in the manufacturing process, and the number of manufacturing man-hours and manufacturing control items are reduced, and the cost is greatly reduced accordingly. Further, it is possible to further reduce the weight of the entire small flyback transformer 1 as compared with the case where the insulating resin agent 13 is filled in. Furthermore, since the insulating resin plate 20 is made of PPS resin, It is flexible and does not require skill to handle it during assembly, and the bobbin 2 and cores 5A, 5
Since the gap of the assembly dimension of the component such as B is used, there is a great advantage that safety measures can be taken without causing a design change or a mold change.

According to the above-described embodiment, the insulating member is a plastic product obtained by integrally molding an insulating resin plate with PPS resin. However, the insulating member is not limited to the PPS resin product, and may be a polyester film or insulating paper. A bent product or the like may be used. Also, a small flyback transformer that supplies a high voltage to a cathode ray tube for a viewfinder of a video camera has been described, but the transformer is not limited to a small flyback transformer, and a high voltage can be applied to a cathode ray tube of a television receiver or the like. It is needless to say that the above-described embodiment can be applied to a large flyback transformer that supplies the.

[0018]

As described above, according to the present invention, the bobbin around which the primary winding and the secondary winding are wound, and the core disposed so as to face the bobbin and the winding, respectively. In the provided flyback transformer, since the insulating member is interposed in the gap between the winding and the core, the insulating member can surely secure the gap between the winding and the core. It is possible to reliably prevent high voltage discharge from the winding to the core. Further, since the insulating member is interposed in the gap between the winding wire and the core, it is not necessary to fill the gap between the winding wire and the core with insulating resin as in the conventional case. It is possible to further reduce cost and size and weight.

[Brief description of the drawings]

FIG. 1 is a sectional view of a small flyback transformer showing an embodiment of the present invention.

FIG. 2 is an exploded perspective view of the small flyback transformer.

FIG. 3 is a perspective view of the small flyback transformer.

FIG. 4 is a sectional view of a conventional small flyback transformer.

FIG. 5 is a cross-sectional view of a conventional small flyback transformer having an inside filled with an insulating resin.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Small flyback transformer 2 ... Bobbin 2e ... Fun raji part 3 ... Low voltage (primary) winding 4 ... High voltage (secondary) winding 5A ... Low voltage side core 5B ... High voltage side core 20 ... Insulating resin plate (insulation Element)

Claims (2)

[Claims] 1. A flyback transformer comprising a bobbin around which primary and secondary windings are respectively wound, and a core arranged so as to face the bobbin and the winding, respectively. A flyback transformer characterized in that an insulating member is interposed in a gap between the core and the core. 2. The flyback transformer according to claim 1, wherein an insulating resin plate made of resin is used as the insulating member, and the insulating resin plate is provided between the winding and the core to form a flange portion of the bobbin. A flyback transformer integrally formed so as to extend to the high voltage electric wire side for high voltage output connected to the core and to the winding.