TILT APPARATUS FOR CATHODE RAY TUBE DISPLAY

Abstract: An apparatus provides a user-adjustable viewing angle for a cathode ray tube (CRT) display. The CRT may be rotated in either of two directions by depressing a control bar located along the front bezel of the display. Once set to the desired position, the control bar is released and the CRT is inhibited from rotating in both directions. Thus, the CRT may be locked in a variety of positions to suit the particular user or environ­ mental conditions.

Description: 1. Field of the Invention The invention relates generally to the area of cathode ray tube (CRT) display devices including those commonly used for terminals and personal computers. The viewing angle is a critical ergonomic factor for such devices and may be affected by several factors including the height of the user, personal preference and glare. A user-adjustable viewing angle or tilt mechanism is therefore desirable to produce an adaptable display which will operate satisfactorily under varying conditions. 2. Description of the Prior Art One tilt mechanism known in the prior art provides a CRT which rotates within its enclosure and which is retained in the desired position by friction. Because the frictionnal force is minimized to permit smooth rotation, accidental or casual contact with the CRT frequently results in a loss of position. More importantly, the CRT cannot be locked in position during shipment and handling, which may result in damage to the display. Another tilt mechanism is known by US-A-4 471 931. A CRT monitor tilt mechanism includes a CRT housing, a locking mechanism and a separate, external support sleeve. The support sleeve is both a support for the housing and a rotation means. In order to rotate, or tilt, the CRT, a user must reach to the side of the CRT and apply a force to depress a lever to unlock the locking mechanism, then, while keeping the lever depressed, she must supply additional force to the CRT housing either to push or pull it to the desired position. The CRT will not rotate in any direction without the additional pushing or pulling force from the user. Using such known mechanism, the entire CRT unit rotates and thus the user must supply sufficient force to rotate both the CRT and the CRT housing. The user is typically required to use two hands to rotate the CRT - one hand to depress the side lever unlocking the CRT and the other hand to supply the additional pushing or pulling force to the CRT housing. Thus, this prior mechanism is not easy to use. The present invention aims at providing an easier to use mechanism. Furthermore, the present invention integrates the pivot support means with the CRT housing, eliminating the need for a separate support and rotation means. The present mechanism, on the other hand, requires no additional manufactured piece, such as the external support sleeve, so avoiding adding weight and cost to the unit. SUMMARY OF THE INVENTION The present invention provides a tilt apparatus for a CRT by which the user may adjust the viewing angle. The apparatus rotates the CRT within its enclosure and positively locks the CRT in a desired position. The apparatus comprises a control bar which may be depressed to freely rotate the CRT in either of two directions to a desired viewing angle. When the control bar is released, a toothed extension of the control bar engages an arcuate gear thereby inhibiting the rotation of the CRT in both directions. The teeth of the arcuate gear may be arranged such that a series of uniformly spaced viewing angles are provided. In addition, the engagement of the toothed extension with the arcuate gear is sufficient to inhibit rotation of the CRT during shipment. BRIEF DESCRIPTION OF THE DRAWINGS This invention is pointed out with particularity in the appended claims. The above and further advantages of this invention may be better understood by referring to the following description taken in conjunction with the accompanying drawings, in which: Figure 1 is an isometric view of a computer which includes a CRT display having a user-adjustable viewing angle; Figure 2 is an exploded view of the device shown in Figure 1; Figure 3 is a cross-sectional view of the preferred embodiment of a cathode ray tube tilt apparatus constructed in accordance with the present invention; and Figure 4 is an enlarged view of the arcuate gear member shown in Figure 3. DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT Figure 1 is an isometric view of a CRT display device having a user-adjustable viewing angle. A computer 12 comprises a processor unit 14 and an expansion box 4. The processor unit 14 comprises a cathode ray tube or CRT 6 which is disposed within a frame 8. A cover 2 is attached to a bottom panel 16. A control bar 10 is disposed laterally along the lower front portion of frame 8. As may be seen more clearly in Figure 2, which is an exploded view of the computer 12 shown in Figure 1, frame 8 receives the CRT 6, which is shown in dashed lines. Two sockets 22, only one of which is visible, extend backward from the lower corners of the frame 8. Two pivot members 24 (only one of which is visible) are attached to and extend laterally from opposite sides of the frame 8. As explained in detail below, the frame 8 may be attached to the CRT 6 such that pivot members 24 are located forward of the center of gravity of the CRT 6. The frame 8 comprises a recessed lip 30 which extends laterally along the lower front portion the frame. Two supports 26, both of which are attached to the bottom panel 16, each provide a bearing 28. An angle adjustment level 32 comprises the control bar 10, two pivot members 18 (only one of which is visible), a toothed portion 20 and a spring 30. A stiffener member 34 is disposed along the length of lever 32. Referring now to Figure 3, which is a cross-sectional view of an assembled tilt apparatus constructed in accordance with the preferred embodiment, the control bar 10 is disposed above the recessed lip 30 and the pivot members 18 are disposed within the sockets 22. The upper surface of control bar 10 comprises a plurality of ribs 46. A plurality of fasteners 36 serves to attach the stiffener member 34 to the lever 32. The spring 30 is attached to the stiffener member 34 by way of fasteners 44. The spring 30 is disposed between the angle adjustment lever 32 and a brace member 38. An arcuate gear member 40 comprising a plurality of teeth 42 is disposed beneath the lever 32. The toothed portion 20 is engaged with the arcuate gear member 40. Figure 4 is an enlarged view of the arcuate gear member 40 shown in Figure 3. Each of teeth 42 comprises a rounded upper edge 48 and adjoining teeth are separated by notches 50. The teeth 42 and notches 50 may be sized to provide a series of uniform increments of rotation. The operation of the CRT tilt apparatus may be understood with further reference to Figure 3. As a user depresses the control bar 10 downward over the recessed lip 30, the angle adjustment lever 32 rotates about the pivot members 18 thereby causing the toothed portion 20 to move upward and disengage from the arcuate gear member 40. The spring 30 simultaneously compresses against the brace member 38 thereby providing a sensation of resistance to the user, which indicates that the toothed portion 20 is disengaged. The user may then continue to depress the control bar 10 while exerting a slight push or pull on the control bar 10. A slight push causes a clockwise rotation of the frame 8 about the pivot members 24 whereas a slight pull causes a counterclockwise rotation. In addition, if the CRT 6 is attached to the frame 8, as described above, whereby the pivot members 24 are located forward of the center of gravity of the CRT 6, the CRT 6 will have a natural tendency to rotate in a counterclockwise direction. The result is a tilting of the CRT 6 with respect to the user. Subsequently, when the desired viewing angle is reached, the user may release the control bar 10 whereby the spring 30 expands and forces the toothed portion 20 to engage the arcuate gear member 40. Once the toothed portion 20 engages the arcuate gear member 40, the frame 8 and CRT 6 are "locked" in position.

Claims: 1. An image display unit (14) including display means (6) for displaying images, the display means including an image display face, said image display unit (14) comprising : A. a frame (8) for supporting said image display means, said frame having pivot means (24) located approximate to said image display face and at a point forward of the center of gravity, of said display means (6) a portion of said display means extending rearwardly beyond said frame (8) ; B. a housing (16) containing said pivot means and said portion of said display, said housing including integral pivot support means (26) for supporting said pivot means (24) thereby providing for rotation of said frame (8) about a horizontal axis ; C. adjusting means for rotating said frame (8) about said axis, and thereby varying the angular position of said image display means (6), said adjusting means including ; locking means (10, 20, 40) controllable from the front of said image display means to lock and unlock the angular position of said image display means, said locking means being positioned so that said frame rotates with the normal of said image display face rotating downwardly when said locking means is unlocked and a force is applied to said locking means in the downward direction; means for urging said frame to rotate such that the normal of said image display face rotates upwardly when said locking means is unlocked but no force is applied thereto; said locking means being comprised of: a. a gear (40) fastened to said housing ; b. a control bar (10, 32) disposed at the front of said image display means and pivotably (18) attached to said frame, said control bar being actuated by depressing said bar in a direction opposite the direction in which said frame is urged to rotate by said urging means. 2. The image display unit of claim 1, wherein said locking means is further comprised of : a. a toothed member (20) extending from said control bar (10, 32) and responsive to said control bar (10, 32) ; and b. a spring (30) urging said toothed member into engagement with said gear (40) ; c. whereby : said toothed member (20) normally engages said gear (40) thereby locking said frame (8) against rotation, and said toothed member (20) is disengaged from said gear (40) by actuation of said control bar (10, 32), thereby unlocking said frame means (8) and permitting rotation of said frame about said axis. 3. The image display unit of claim 1 or 2, wherein said gear (40) is an arcuate gear. 4. The image display unit of claim 1 characterized in that the toothed member (20) is connected to said control bar (10) by an adjusment lever (32) rotatable about pivot members (18). 5. The image display unit of claim 1, wherein the center of gravity and the mass of said image display means (6) and said frame (8) are such that the display face rotates upwardly under the force of gravity when said locking means (10, 20, 40) is unlocked. 6. The image display unit of claim 1, wherein said control bar (10) is disposed in a recess in said frame (8) which extends laterally across the lower front portion of said frame.

Inventors: KILLIAN,  JOHN C., KLEEMAN, MICHAEL W, KILLIAN, JOHN C.
Applicants: DIGITAL EQUIPMENT CORPORATION
Application year: 1987
Main classification: F16M11
IPC codes: F16M11, G09F9, H04N5, H05K7