GB2193380A

GB2193380A - High frequency signal suppression component

Info

Publication number: GB2193380A
Application number: GB08714913A
Authority: GB
Inventors: Randall Cross Clayburn
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1986-06-30
Filing date: 1987-06-25
Publication date: 1988-02-03
Anticipated expiration: 2007-06-25
Also published as: KR950009656B1; JPS6327005A; CA1297148C; DE3721427C2; SG31165G; GB2193380B; GB8714913D0; DE3721427A1; HK61895A; KR880001143A

Description

1 GB2193380A 1

SPECIFICATION drawings, in which:

FIGURE 1 is a block and schematic diagram High frequency signal suppression compo- of a portion of a video display apparatus; nent FIGURE 2 is an isometric view of a high 70 frequency signal suppression component em This invention relates to high frequency signal bodying the present invention; suppression components such as for use in FIGURE 3 is a cross-sectional plan view of video display apparatus. the signal suppression component shown in Video display apparatus, such as television FIGURE 2; and receivers or computer monitors, may incorpor- 75 FIGURE 4 is a cross- sectional plan view of ate circuitry that either generates or is suscep- the component shown in FIGURE 2, fitted on tible to high frequency interference signals. In a conductor.

order to attenuate the propagation of these FIGURE 1 illustrates a portion of a video high frequency signals, or reduce the amount display apparatus including a horizontal or line of high frequency energy that reaches particu- 80 rate deflection circuit 10 and a power supply larly sensitive circuitry, signal suppression circuit 11. Horizontal deflection circuit 10, components may be placed along the conduc- which may be of a conventional resonant re tor paths or component leads leading to or trace-type, includes horizontal driver circuitry exiting from the circuits or components that 12 that receives horizontal or line rate syn are desired to be isolated. These components, 85 chronizing pulses from a source of synchroniz which may be of a tubular form, are typically ing signals (not shown) via a terminal 13.

manufactured of a material, such as nickel-zinc Horizontal driver circuitry 12 generates switch ferrite, or a similar soft ferrite material, that ing pulses which are applied to the base of a act as high frequency chokes and attenuate horizontal output transistor 14 via a transfor- high frequency current flowing in the circuit or 90 mer 15. The collector of output transistor 14 component conductors. These shield beads, is coupled via a high frequency signal suppres also referred to as ferrite beads, are placed sion component 16, such as a ferrite shield over appropriate circuit or component leads. bead, to the cathode of a damper diode 17, The- size of the bead and type of material one terminal of a retrace capacitor 20, and from which the bead is formed are selected 95 one terminal of a deflection winding 21. The based on the signal attenuation characteristics other terminal of deflection winding 21 is desired. These characteristics are supplied by coupled via an S-shaping capacitor 22 to the manufacturers of the shield or ferrite ground. The emitter of output transistor 14, beads, such as Fair-Rite Products Corp., for the anode of diode 17, and the other terminal example. 100 of capacitor 20 are also coupled to ground.

The horizontal deflection output circuit and Output transistor 14 produces horizontal the horizontal deflection flyback pulse-derived deflection current in deflection winding 21 that power supplies comprise circuits where the generates an electromagnetic field in order to previously described ferrite beads may be re- deflect the electron beams produced by a quired. The horizontal output circuit, for 105 cathode ray tube (not shown). Signal suppres example, incorporates fast switching diodes sion component 16 is present to attenuate the that generate spurious high frequency signals. high frequency spurious signals generated by The horizontal or line rate signal, of the order the switching of damper diode 17.

of 15.75 kHz, for example, associated with Power is applied to output transistor 14 these circuits, may cause the ferrite beads to 110 from a source of potential of the order of vibrate against the mounting circuit board or + 130 volts via a primary winding 23 of a against components or conductors, producing power supply transformer 24. Flyback or reso audible tones that may be distracting or un- nant retrace pulses produced by the switching pleasant to the video display apparatus user. of output transistor 14 appear across primary Gluing each of the ferrite beads in place to 115 winding 23. By transformer action, voltages prevent vibration is lime consuming, and con- are produced across secondary winding 25 sequently increases the cost of the video dis- and high voltage winding 26. High voltage play apparatus. winding 26 produces the high voltage or ultor In accordance with an aspect of the present potential for the cathode ray tube (not shown) invention, a high frequency signal suppression 120 at a terminal designated +HV. The current component comprises a magnetically permea- produced by the voltage developed across ble member having a passage formed through secondary winding 25 is rectified by a diode it. An elastic material, located within the pas- 27 via a signal suppression component 30, sage, permits an electrical conductor to be such as a ferrite bead, and charges a capaci inserted through the passage and forms an 125 tor 31 via a similar signal suppression compo elastic layer between the conductor and the nent 32 in order to produce a load circuit member, supply voltage at a terminal designated +V.

An embodiment of the present invention, In FIGURE 1, this voltage is illustratively used given by way of example, will now be de- to power horizontal driver circuitry 12. Signal scribed with reference to the accompanying 130 suppression components 30 and 32 act to 2 GB2193380A 2 attenuate high frequency spurious signals pro- cuit board.

duced by alternating current flow in diode 27, Component 38 may be formed, for example, for example. by dipping member 33 in a container of the Signal suppression components 16, 30, and desired elastic material 36, or by placing 32 are representatively shown as component 70 member 33 in elastic material 36 and then 38 in FIGURES 2, 3, and 4. Component 38 removing the excess elastic material by suc comprises a magnetically permeable member tion. In either process, a plug of elastic ma 33, illustratively shown as having a cylindrical terial 36 will remain in passage 34 of member form in FIGURES 2 and 3. Signal suppression 33.

components having noncircular cross-sections 75

Claims

are of course possible. Member 33 is illustra- CLAIMS tively manufactured

of a soft ferrite material, 1. A high frequency signal suppression com- I such as nickel-zinc ferrite, magnesium-zinc fer- ponent comprising:

rite, or manganese-zinc ferrite, for example. a magnetically permeable member having a Member 33 has a longitudinal passage 34 80 conductor-receiving passage formed there formed through it that defines an inner wall through; and of member 83. Passage 34 is filled with a an elastic material disposed within said pas plug of an elastic material 36, illustratively sage, said material permitting an electrical comprising a silicone rubber compound manu- conductor to be inserted therethrough and factured, for example, by Dow Corning Corpo- 85 forming a resilient layer between said conduc ration in a variety of formulations under the tor and said member.

trade name Sylgard. The desired character-
2. The component defined in Claim 1, istics of elastic material 36 are such that a wherein said elastic material substantially pre conductor or wire 37, shown in FIGURE 4, vents the vibration of said member on said such as the conductor between the collector 90 conductor when current flows in said conduc of output transistor 14 and diode 17, may be tor.

inserted through elastic material 36 and con-
3. The component defined in Claim 1, sequently through passage 34 without distort- xAiherein said elastic material adheres to said inq or bending conductor 37. The diameter of conductor for maintaining said member in passage 34 is chosen such that elastic ma- 95 place on said conductor without additional at terial 36 forms a resiliant layer or cushion 40 tachment means.

between the inner wall 35 of member 33 and
4. The component defined in Claim 1, conductor 37. Layer 40 acts as a damping or wherein said elastic material comprises a sili attenuating agent to substantially prevent the cone rubber.

vibration of component 38 on conductor 37, 100
5. The component defined in Claim 1, and therefore substantially eliminates any gen- wherein the viscosity of said elastic material is eration of audible signals when horizontal or chosen in accordance with the size of said line rate current is flowing in conductor 37. member.

Component 38 therefore eliminates the need
6. A line rate deflection circuit for a video to glue or otherwise restrain the movement of 105 display apparatus comprising:

signal suppression components in order to an output circuit incorporating an output de prevent audible vibration. The viscosity of vice providing a line rate deflection current in elastic material 36 may be selected to pro- a conductor; and duce optimum vibration attenuation based on a high frequency signal suppression means the particular application and location of the 110 located on said conductor, the suppression signal suppression component 38. For means comprising a magnetically permeable example, the use of the combination Dow member having a passage formed there Corning Sylgard 527 and Sylgard 567 in vari- through for receiving said conductor, and an ous ratios produces a wide range of material elastic material disposed within said passage viscosities. It is therefore possible to select a 115 for forming a resilient layer between said con particular compound ratio that will result in ductor and said member.

optimum signal attenuation for a particular ap-
7. The circuit defined in Claim 6, wherein plication or location of suppression component said elastic material substantially prevents au 38. dible vibration of said member due to said line The adhesion between elastic material 36 120 rate current flowing in said conductor.

and conductor 37 is.sufficient to hold compo-
8. The circuit defined in Claim 6, wherein nent 38 in place on conductor 37 during as- said elastic material adheres to said conductor sembly of the video display apparatus without for maintaining said member in place on said the need for additional attachment means. conductor without additional attachment This greatly simplifies assembly as it elimi- 125 means.

nates the need for manually maintaining signal
9. A resonant retrace power supply circuit suppression components in place on their re- for a video display apparatus comprising: a spective conductors or electrical component transformer incorporating a winding producing leads, for example, until those conductors or a line rate current in a conductor; and P5 electrical components are inserted into a cir- 130 a high frequency signal suppression means 3 GB2193380A 3 located on said conductor and comprising a magnetically permeable member having a passage formed therethrough for receiving said conductor, and an elastic material disposed within said passage for forming a resilient layer between said conductor and said member.
10. A high frequency signal suppression component substantially as herein described with reference to the accompanying drawings.

Published 1988 atThe Patent Office, State House, 66/71 High Holborn, London WC 1 R 4TP. Further copies may be obtained from The Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Burgess & Son (Abingdon) Ltd. Con. 1/87.