GB2312130A

GB2312130A - A resilient gasket attenuates vibrations from a loudspeaker in the housing of a video display apparatus

Info

Publication number: GB2312130A
Application number: GB9707147A
Authority: GB
Inventors: Kyoung Bok Kim; Byoung Chul Lee
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 1996-04-09
Filing date: 1997-04-08
Publication date: 1997-10-15
Also published as: BR9700245A; RU2121767C1; IT1289976B1; ID17813A; GB9707147D0; DE19713897A1; ITMI970411A1

Description

2312130 VIDEO DIsPLAY APPARATUS INCLUDING A LOUDSPEAKER The present

invention relates generally to a video display appliance having a loudspeaker such as a television receiver, a computer monitor, etc. More particularly, the invention relates to a video display appliance including a mechanism for holding a loudspe4ker, which can reduce vibrations generated by the loudspeaker from being transferred to a cathode ray tube and/or can enhance the bass sound characteristic of the loudspeaker.

A loudspeaker for a video display appliance generally makes acoustic vibrations by a diaphragm driven by a vibration coil A magnet is supported by a loudspeaker frame.

Thus the frame also vibrates to a certain extent at an amplitude and frequency of which cannot be disregarded. The vibrations are transmitted through the loudspeaker frame to a housing that supports a cathode ray tube, and from there to a multi-aperture color selection electrode or a shadow mask provided in the cathode ray tube. In addition, it is well known that the acoustic vibrations produced by the loudspeaker are transmitted to the cathode ray tube through the air. Accordingly the shadow mask vibrates, impairing the video quality. More specifically, electron beams emitted from electron guns interfere with each other due to the vibration of the shadow mask during their projection on a 1 fluorescent screen through apertures of the shadow mask.

The loudspeaker is installed on the front of the housing, using only a double flat baffle to prevent the loudspeaker from coming in contact with other components such as the cathode ray tube, a printed circuit board, etc. In this construction, when the diaphragm vibrates and produces sound waves, the phases of the sound waves produced at the front and back of the diaphragm are in antiphase. Thus, the sound waves tend to cancel resulting in their inadequate propagation, in particular, at the lower end of the acoustic frequency band.

A typical example of this type is FIG. 8. The shown prior art video display appliance comprises a front housing 302 with several screw threaded bosses 304 for securing a cathode ray tube 300 on the inner surface 322. In addition, the front housing is equipped with several threaded bosses 312, for securing the loudspeaker 320 to the front housing at 322. Lugs 308 on both sides of the cathode ray tube are secured to the front housing 302 by fastening screws 306 through the lugs 308 to the bosses 304 of the front housing.

The loudspeaker 320 is screwed to the bosses 312, and bears on rectangular ribs 324 integral with the inner surface 322 of the front housing j02.

With the prior art arrangements as described above, when the loudspeaker operates, the diaphragm and the magnet of the loud- speaker vibrate and the sound waves propagate forward through a grill 310 provided on the front housing 302.

The vibrations being produced from the loudspeaker 320 are transmitted through the front housing 302 to the cathode ray tube 2 300, because the loudspeaker and the cathode ray tube are secured to the front housing. Then, the vibrations are transmitted to the shadow mask 314 within the cathode ray tube 300. The electron beams emitted from the electron guns are projected on a fluorescent screen through the apertures of the shadow mask 314. When the shadow mask 314 vibrates, the electron beams are interfered with as they pass through the vibrating apertures. It is known that this interference phenomenon causes substantial reduction in the visual image quality displayed on the screen of the video display appliance.

In addition, the double baffle type loudspeaker 320 is open at its back, so that the sound waves propagate from the front and back of the loudspeaker as discussed above. The two sound waves propagated front and back tend to cancel, because they are In antiphase-.

In order to solve the above problems, an object of the present invention is to provide a video display appliance having a loudspeaker holding system capable of reducing vibrations from a loudspeaker from being transmitted to a display device, such as a cathode ray tube, as well as enhancing the bass sound characteristic.

Another object of the present invention is to provide a video display appliance having an vibration absorbing member interposed between a front housing and a loud-speaker substantially to block the vibrations transmitted from the loudspeaker to the display device.

3 A further object of the present invention is to provide a video display appliance having an enclosure provided on the back of a loudspeaker in order to improve the bass sound characteristic.

The invention is defined in the accompanying independent claims.

Some preferred features are recited in the dependent claims.

In order to achieve the above objects, there is provided a video display appliance comprising a display device, a housing to which the device is secured, a loudspeaker fixed on a side wall of the housing, and a vibration absorbing member attached to a back of the loudspeaker so as to buf f er vibrations transmitted from the loudspeaker to the cathode ray tube.

The side wall of the front housing may include at least four reinforcing ribs, and a loudspeaker holding mechanism provided between the second and third reinforcing ribs. Preferably, in order to extend the bass response, the side wall of the front housing includes a hollow cylindrical wave guide between the third and forth reinforcing ribs.

In a preferred embodiment of the present invention, the loudspeaker holding mechanism includes a rectangular guide rib surrounding the vibration absorbing member and the loudspeaker,and a number of resilient arms protruding upwards from the horizontal sides of the rib and having at their free ends bearing portions, respectively. The loudspeaker holding mechanism can hold the loudspeaker easily and quickly with the simple manipulation. As an alternative, there may be provided latches protruding upwards from the other side and bent at right angle.

The vibration absorbing member may include a rectangular pad having an 4 opening formed at its center, folding portions extending from each edge of the pad, and slots formed between the edges and the folding portions.

In addition, according to another characteristic of the present invention, the housing may comprise a back housing which Is engagable with a front housing, supporting the loudspeaker, and an enclosure surrounding the loudspeaker holding mechanism. The enclosure covers up the loudspeaker, thereby extending the bass response below the lower natural resonant frequency in air. In order to enhance the seal of the enclosure, it is preferred that an open side of the enclosure is provided with an elastic sheet.

The above objects, other aspects and advantages of the invention will become apparent by describing the preferred embodiments thereof with reference to the accompanying drawings, in which:

FIG. 1 is an exploded perspective view showing an embodiment of a video display appliance according to the present invention; FIG. 2 is a rear view of a front housing, provided with a gasket according to the present invention FIG. 3 is a view, partially in cross-section, of a portion of a front housing, illustrating the securing state of the loudspeaker in detail; FIG. 3A is a sectional detail view of a circle 3A in FIG. 3; FIG. 4 is a view, partially in cross-section, of a portion of a front housing, illustrating a wave guide extending between a front and back housings; FIG. 4A is a sectional detail view of a circle 4A in FIG. 4 FIG. 5 is a perspective view of a loudspeaker holding mechanism of the present invention; FIG. 6 is a sectional view of FIG. 5, illustrating a loudspeaker and a gasket mounted onto a loudspeaker holding mechanism; FIG. 7 is a sectional view similar to that of FIG. 6 and illustrates a loudspeaker and a gasket being mounted onto another loudspeaker holding mechanism; and FIG. 8 is a view illustrating a loudspeaker of a prior art video display appliance in holding position.

Referring now to FIG. 1, there is shown a video display appliance according to the present invention comprising a front is housing 10 and a back housing 50, the housings 10 and 50 being made of any suitable thermoplastic material. The front housing 10 is provided at its center with an opening 32 on which a cathode ray tube (CRT), which is not specifically shown in the accompanying drawings,is mounted. The front housing 10 generally comprises a number of analog switches 34 to control the CRT and a pair of loudspeakers 80.

A buffer gasket 82 Is interposed between the floor of a loudspeaker holding channel 12 of the front housing 10 and each loudspeaker 80.

The gasket 82 has substantially the same shape as a securing portion of the loudspeaker 80 secured to the back of the front housing 10 by means of screws 86, by which the gasket is attached to the loudspeaker.

FIG. 2 shows the back of the front housing provided 6 with the buffer gasket according to the present invention. Left and right channels of the front housing include a number of reinforcing ribs 24, 26, 28 and 30 in order to increase its rigidity. The second and third ribs 26 and 28 of the reinforcing ribs are spaced such that the buffer gasket 82 and the loudspeaker 80 are secured between them. In addition, the first and forth ribs 24 and 30 are arranged for aligning with an enclosure 50 of a back housing 56 as will be described below. The protrusion the reinforcing ribs 24 and 30 is determined to accommodate the thickness of a sealing gasket 52 around the channel which also extends between the first and forth reinforcing ribs 24 and 30 and the enclosure 56. Auxiliary side walls on which longitudinal side walls of the enclosure 56 are superposed are ided between the reinforcing ribs24 and 30, but are not shown provi in the accompanying drawings for clarity. Each of the left and right side walls has a hollow cylindrical wave guide 15 which extends from the channel between the third and forth reinforcing ribs 28 and 30. The wave guide 15 has both ends open in order to communicate the interior of the enclosure 56 with the outside through the front housing 10.

A forward opening in the wave guide through the channel is indicated by reference numeral 14. The front housing 10 includes a number of bosses 18, each boss having a screw threaded hole 20 in order to secure the back housing to at least four edges of its back using screws 57.

Referring again to FIG. 1, the back housing 50 includes a generally cubic part, of which at least one face is open. The front housing 10 is secured to the open face by means of the screws 57. More particularly, the front housing 10 is secured to the 7 back housing 50 by fastening the screws 57 to the holes 20 of the bosses 18 through screw threaded portions 58 at both sides of the back housing 50. The enclosures 56 provided on both sides of the interior of the back housing 50 are formed of a cube which mates with the first and forth reinforcing ribs 24 and 30 of the front housing 10. The enclosures 56 surround the loudspeakers 80 provided on the front housing 10.

As shown in FIG. 1, each of the enclosures 56 is open facing the front housing 10. The sealing gasket 52 is applied to each edge of the open face of the enclosure using a suitable adhesive. This sealing gasket of the back housing 50 prevents the sound waves leaking from the enclosure when the front and back housings 10 and so are engaged.

The engaging state of the above front and back housings 10 is and 50 is shown in FIGs. 3 and 4, wherein FIG. 3 illustrates the state of the buffer gasket 82 interposed between the front housing 10 and the loudspeaker Bo,and FIG. 4 illustrates the cylindrical wave guide 15 extending from the lower part of the loudspeaker 80 to the interior of the enclosure 56 of the back housing 50.

Referring to FIGs. 3 and 3A, the loudspeaker 80 is secured to the loudspeaker holding portion 12 of the front housing 10 by means of suitable fastening means such as the screws 86. The buffer gasket 80 is interposed between the holding portion 12 and the loudspeaker 80. Other means for securing the loudspeaker 80 to the front housing 10 are illustrated in FIGs. 5 to 7.

Referring to FIGs. 4 and 4A, the hollow cylindrical wave guide 15 provided between the third and forth ribs 28 and 30 8 below the loudspeaker extends into the interior of the enclosure 56 of the back housing 50. The enclosure 56 functions to extend the bass frequency response below the lower resonant frequency of the loudspeaker itself in free space, due to the influence of the compliance of the air existing within the enclosure 56. The limit on the bass response is reduced by about 1A/3 as the wave guide 15 is used as a resonance system. The length of the wave guide is determined according tothe volume of the enclosure.

Accordingly, although the present invention has a simple construction, the video display appliance may be adapted as a bass reflex loudspeaker system. More specifically, the sound waves propagate directly from the front of the loudspeaker, is and the sound waves from the back propagate towards the enclosure 56. The phase of the sound waves propagated within the enclosure is Inverted by the resonance effect of the air, such that its phase I S the same as that of the sound waves at the front of the loudspeaker. By this phenomenon, the bass frequency sound waves are reinforced, and thus the bass response is extended.

FIGs. 5 to 7 are views of a, further embodiment of a buffer gasket according to the present invention.

FIG. 5 shows a loudspeaker holding mechanism of the front housing and a buffer gasket 182. The loudspeaker holding mechanism is provided between the second reinforcing rib 26 and the third reinforcing rib 28. The holding mechanism comprises a rectangular guide rib 198 surrounding the periphery of the loudspeaker 180 and a number of resilient arms 194 protruding upward from the guide rib. The guide rib 198 formed with the resilient arms 194 is shaped in such a manner that it slightly protrudes in to the rear in order to facilitate to the access the loudspeaker. The resilient arms 194 are bent in order to flex when the loudspeaker 180 and the gasket 182 are fitted thereto, and includes at its free end a bearing portion 196 for forcing them onto the gasket.

The gasket shown in FIG. 5 may be an elastic sheet consisting of a central opening 190, a slot 192 shaped in the f orm of a sector at top and bottom, and several rectangular slots 188 to the left and right. Also, the gasket 182 comprises two pairs of folding portions 184 and 186, the pairs of folding portions each extending at a predetermined length from one of the four is sides. The slots 188 and 192 are not limited as to shape However, the dimensions of the slots are preferably determined in such a manner that the area of the folding portion contacting an upper surface of the loudspeaker 180 equals to the area of the gasket a lower surface of the loudspeaker. The reason is that allowing for elasticity coefficients above and below the loudspeaker to be substantially equal to each other, it will allow the vibration of the loudspeaker to be offset most effectively.

FIG. 6 is a sectional view of FIG.5, illustrating the mounted loudspeaker and the gasket in relation to the loudspeaker holding mechanism. Although not shown in FIG. 6, the gasket 182 is attached to the loudspeaker 180 by a suitable adhesive. The loudspeaker 180, to the back of which the gasket is attached, may be secured to the loudspeaker holding mechanism of the front housing 10 by a simple pressing operation. In securing, the resilient arm 194 is deflected and then returns to its original position when the gasket 182 contacts the holding portion 12 of the front housing. The bearing portion 196 of the resilient arm 194 is pressed towards the folding portion 186 above the loudspeaker.

As shown in FIGs. 1 and 3, the loudspeaker 80 provided with a gasket should be held on the holding portion 12 by fastening screws to holes 16. This is a labor intensive and time consuming job. According to the particular embodiment, because the loudspeaker is held by the four bearing portions, the shown loudspeaker holding mechanism does not require an additional manipulation for securing the loudspeaker.

FIG. 7 shows another embodiment of a loudspeaker holding mechanism according to the present invention. The particular embodiment comprises latches 294, replacing the lower resilient arms shown in FIGs. 5 and 6. Unlike the lower resilient arms 194, the latches 294 do not move, thereby guiding the loudspeaker as it is pressed home past the upper resilient arms 194.

While the present invention has been described and illustrated herein with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention.

12

Claims

CLAIMS:.

1. A video display apparatus comprising:

a display; a housing in which the display is secured; a speaker fixed on a wall of the housing; and a resilient member interposed between the speaker and the wall so as to attenuate vibrations transmitted from the loudspeaker to the display.

2. Apparatus as claimed in claim 1, including speaker holding means securing the speaker to the housing, the resilient means further being interposed between the speaker and the holding means.

is 3. Apparatus as claimed in claim 2, wherein the wall of the housing defines a channel and a plurality of lateral reinforcing ribs, the speaker holding means being arranged between two of the reinforcing ribs, the apparatus further comprising a wave guide extending from the channel to one side of one of the said two ribs remote from the speaker.

4. Apparatus as claimed in claim 2 in which the wave guide is open at both ends and extends through the channel.

5. Apparatus as claimed in claim 3 or 4, wherein the speaker holding means include a rectangular guide rib surrounding the resilient member and the speaker, and a number of resilient arms protruding from the sides of the rib and having at their free ends bearing portions, providing a snap-fit retention from the speaker.

13 6. Apparatus as claimed in any of claims 2 to 4, wherein the speaker holding means include a guide rib surrounding the resilient member and the loudspeaker, a plurality of resilient arms protruding into the surrounded space from at least one side of the guide rib and each having at a free end a bearing portion providing a snap-fit retention for the speaker.

7. Apparatus as claimed in claim 6, including a latch for locating the other side of the speaker and for guiding the speaker into retention by the bearing portions.

8. Apparatus as claimed in any of claims 2 to 7, is wherein the resilient member includes a sheet having a peripheral portion in registry with the speaker and defining an opening therefor, and side portions extending from the peripheral portion around the edges of the speaker such that it is also interposed between the speaker and the holding means.

9. Apparatus as claimed in claim 8, including a slot dimensioned such that an area of the peripheral portions contacting an upper surface of the speaker equals an area of the sheet contacting a lower surface of the speaker.

10. Apparatus as claimed in any of claims 1 to 9, in which the housing comprises a front housing, to which the speaker is fixed, and a back housing engageable with the front housing, the back housing defining an enclosure to one side, having an open face.

11. Apparatus as claimed in claim 10, wherein the enclosure is provided with a resilient member over the 14 open side to seal the enclosure.

12. A video display appliance comprising:

a cathode ray tube; a f ront housing to which the cathode ray tube is secured, the f ront housing having a loudspeaker holding mechanism; a back housing engaging with the front housing and including an enclosure provided on its side and having an opening formed on its side; and a loudspeaker held by the loudspeaker holding mechanism and provided on its back side with an elastic sheet; wherein the loudspeaker holding mechanism includes is a rectangular guide rib surrounding the elastic sheet and the loudspeaker, and a number of resilient arms protruding upwards from the horizontal sides of the rib and having at their free ends pressing portions, respectively.

13. The video display appliance as claimed in claim 12, wherein the enclosure is provided with an elastic sheet attached over the opening to seal the enclosure.