CN201159795Y - Twisted hinged mirror structure with two reflective surfaces - Google Patents

Abstract

The utility model discloses a torsion hinged mirror structure with a back-to-back reflection surface, which can be used in laser print image system. The utility model also discloses an optical layer and a support structure which do not influence any of the two input light beams when the two reflection light beams scan through. The hinge plate structure 10 includes a center part 12 which has a first side face 14 and a second side face 16, a pair of torsion hinges 18a and 18b, and a pair of anchor parts 20a and 20b. The anchor parts 20a and 20b can be replaced by a support frame 20. To be optimized, the hinge plate 10 can be formed by silicon substrate through etching, laser milling or other method to include a pair of support ridges 22a and 22b.

Description

Twisted hinged mirror structure with two reflective surfaces

technical field

[0001] The present invention relates to twist-hinged mirrors having back-to-back reflective surfaces and methods of making the same. The two mirrors are particularly suitable for use in laser scanning imagers for laser printers.

Background technique

[0002] Rotating or swinging twisted hinged mirrors provide a very efficient and relatively inexpensive alternative to the rotating polygonal mirrors previously used in black and white laser printers and some displays. However, color laser printers with twisted articulation drive motors have been unsuccessful in replacing color inkjet printers. The main reason for it is that laser printers require a larger volume and a larger desktop footprint than color inkjet printers. In order to successfully compete in the PC and desktop printer markets, there is a need for a color printer system that can be easily mounted on a desktop and occupy as little volume as possible. Because color inkjet printers have a small footprint and low price point, they account for a large share of the desktop color printer market.

[0003] Some laser printer manufacturers attempt to compete with inkjet printers by using what is known as a rotating polygonal mirror. According to these systems, two laser beams are directed from opposite faces towards a rotating polygonal mirror. The two optical paths are then folded and coaxially aligned to form the image and reduce the overall required volume and footprint. These systems use only one polygon and are less expensive than older compound polygon systems. However, all the problems associated with rotating polygonal mirrors remain.

[0004] Accordingly, it would be advantageous to provide a torsional articulation drive motor suitable for use in a color printer that has a smaller footprint and requires less overall volume.

Utility model content

[0005] The present invention provides twisted hinged mirror structures with back-to-back reflective surfaces and methods of making such mirrors.

[0006] More specifically, the torsionally articulated mirror structure in the described embodiments includes a central hinge plate having a pair of torsion hinges extending distally from a central region or member along the axis of rotation. The hinge plate is preferably a microelectromechanical systems (MEMS) device formed from a silicon layer or substrate. Each hinge of the pair of hinges includes a first end supported by a support structure. To facilitate installation of the torsion hinges, embodiments of the present invention further include a support frame or first and second anchor members attached to the first end of each torsion hinge. The second end of each torsion hinge is attached to and integrally formed with the central region or hinge plate member. The central region or part also includes first and second sides so as to be free to oscillate on the torsion hinge about the axis of rotation. The back surfaces of the first and second mirror layers, each having a back surface and a reflective surface, are respectively bonded to said first and second sides of the central part of the hinge plate so that the reflective surfaces face in opposite directions, and substantially parallel to each other.

[0007] For use with the twisted hinged mirror as a drive motor for a laser printer, a drive source is also included that oscillates the hinged mirror about its axis of rotation at a selected frequency. The selected frequency is preferably the resonant frequency of the mirror. A first modulated light beam is directed towards and reflected from one reflective surface; in a similar manner a second modulated light beam is directed towards and reflected from another reflective surface opposite the first reflective surface. Thus, it will be appreciated that two reflective surfaces and two modulated beams produce two modulated beams that sweep through a selected angle with each oscillation or oscillation of the mirror.

[0008] As will be appreciated by those skilled in the art, the drive source that maintains the mirror device oscillating at its resonant frequency at the desired amplitude must not obscure or interfere with either the incident beam or the reflected swept beam. Thus, a source of inertial drive provided by, for example, four piezoelectric elements coupled two by two to torsion hinges, or permanent magnets by cooperating drive coils attached to or adjacent to one or both torsion hinges, have been found to be particularly suitable.

[0009] It will also be appreciated that the twist-hinged mirror must also be mounted or supported so that the two reflective surfaces can receive and reflect the light beam. A slotted structure for supporting the twisted hinged mirror so as not to interfere with either of the two beams has also been found to be particularly effective for this aim.

Description of drawings

[0010] FIG. 1A is a perspective view of a twist-hinged mirror having two reflective surfaces in accordance with the teachings of the present invention;

[0011] Fig. 1B is an exploded view of the mirror structure in Fig. 1A;

[0012] FIG. 2 is an optical path diagram of a beam sweep caused by a twisted hinged mirror with two reflective surfaces, two laser beam sources and reflected laser beams;

[0013] FIG. 3A is a perspective view of two torsionally hinged mirrors of the present invention with an inertial drive source and a grooved support structure;

[0014] FIG. 3B is an enlarged view of the mirror and inertial drive structure, the two beams from the laser source and the sweep range of the two reflected beams;

[0015] Fig. 3 C is a further enlarged view of the mirror and inertial drive structure;

[0016] FIG. 4A is a perspective view of a twist-hinged mirror of the present invention with two laser sources and a permanent magnet and coil drive source mounted on a slotted support structure;

[0017] FIG. 4B is an enlarged view of the mirror and magnet drive structure;

[0018] Figures 5A and 5B show alternative permanent magnet and coil drive source structures applicable to the present invention; and

[0019] FIG. 6 illustrates a simple version of a twist-hinged mirror of the present invention made from or consisting of a single layer of silicon.

Detailed ways

[0020] FIGS. 1A and 1B illustrate twisted articulating mirror structures incorporating the teachings of the present invention. As shown, hinge plate structure 10 includes a central region 12 having first and second sides 14, 16, a pair of torsion hinges or shafts 18a and 18b, and a pair of anchor members or anchor members 20a and 20b. Anchor members 20a and 20b may be replaced by support frame 20, as indicated by the dashed lines in FIG. 1A. Preferably, hinge plate 10 is etched, laser milled or otherwise machined from a silicon substrate to include a pair of support ridges 22a and 22b.

[0021] The first two horizontal mirror panels or structures 24 and the second mirror panels or mechanisms 26 are each attached or bonded to the first and second sides 14 and 16 of the hinge plate 10, respectively. According to the illustrated embodiment and as can be better seen in the exploded view of FIG. 1B , each of the mirror panels 24 and 26 has two layers, which include a first truss layer 30 with ridges 32 a and 32 b and an integral truss layer 30 . Formed mirror layer 34 . Each mirror panel includes a reflective or mirror surface as indicated by numerals 36a and 36b. The two mirror plates are also preferably etched or laser milled from a silicon substrate.

[0022] FIG. 2 illustrates a simplified light path diagram of the two reflective surfaces of the twisted hinged mirror structure of the present invention. As shown, the double-sided swinging or oscillating mirror 38 is stationary in a neutral position and rotates about an axis 40 between a first extreme position 38a and a second extreme position 38b. A first light source 42 directs an incident beam 44, eg a modulated laser beam, onto a first reflective surface (right hand surface in the figure) of the oscillating mirror 38 which reflects the incident beam 44 in different directions. As the mirror structure 38 oscillates between the two extreme positions 38a and 38b, the reflected light beam 46 sweeps a deflection angle which spreads between the first outer boundary 46a and the second outer boundary 46b. In a similar manner, the second light source 48 directs the incident modulated light beam 50 onto a second reflective surface (the left hand surface in the figure). As the mirror oscillates between the first extreme position 38a and the second extreme position 38b, the reflected light beam 52 also sweeps between the first outer boundary 52a and the second outer boundary 52b. Thus, it can be seen that twisting the hinged mirror is able to simultaneously generate beam sweeps from each reflective surface. Even if not shown, those skilled in the art will appreciate that the reflected beams can then be folded on the photosensitive medium and aligned coaxially with each other to generate a single image. It will also be appreciated that the two sources 42 and 48 of the beams 44 and 50 must be positioned so that the structure supporting the mirrors or the drive source that produces the oscillation does not interfere with the incident beams 44 and 50 or the reflected sweeping beams 46 and 52 .

[0023] FIGS. 3A and 3B illustrate an inertial drive mechanism and slotted support structure that does not interfere with the light beam and is suitable for use with the twisted articulating mirror structure of the present invention with two reflective surfaces. Fig. 3C is an enlarged view of the mirror structure and piezoelectric driving source in Figs. 3A and 3B. Components that are similar to those in FIGS. 1A, 1B and 2 above have been given the same reference numerals.

[0024] FIGS. 3A and 3B illustrate two laser sources 42 and 48 that direct laser beams 44 and 50, respectively, when torsional hinged mirror 38 is rotated about axis 40 at torsional hinges 18a and 18b. are directed onto the respective two reflective surfaces 36a and 36b of the twist-hinged mirror 38 . Also as shown, there is a support structure 54 defining a slot 56 . The mirror structure 38 is supported on four piezoelectric elements 58a, 58b, 58c and 58d which are driven at a selected frequency which is preferably substantially equal to the resonant frequency of the torsionally articulated mirror 38 so that the Mirror 38 oscillates at a resonant frequency. As shown and more particularly shown in FIG. 3C, torsion hinges 18a and 18b are connected to anchor members 20a and 20b. A first pair of piezoelectric elements 58a and 58b secure anchor member 20a to support structure 54 (not shown in FIG. 3C ) on either side of torsion hinge 18a. Similarly, a second pair of piezoelectric elements 58c and 58d are secured to anchor member 20b on either side of torsion hinge 18b. Arrows 59a, 59b, 59c and 59d illustrate the motion of the piezo element causing the rocking motion. Importantly, it can be seen that due to the location of the grooved structure 54 and the laser sources, the support structure 54 or the laser sources 42 and 48 do not interfere with either the incident beams 44 and 50 or the two complete beam sweeps.

[0025] In addition to the inertial systems discussed with respect to FIGS. 3A, 3B and 3C, a permanent magnet and coil arrangement can also be used to induce oscillation of the torsionally articulated mirror. The structural support 54 and laser sources 42 and 48 shown in Figures 4A and 4B are similar to those in Figures 3A, 3B and 3C, except that the positions of the laser sources 42 and 48 have been moved to illustrate possible different arrangements. The drive system of the embodiment in Figures 4A and 4B illustrates a similar mirror structure, except that magnet mounting regions 60a and 60b are included on the torsion hinge for supporting and mounting permanent magnets 62a and 62b. Also included are electrical coils 64a and 64b which generate a magnetic flux field which interacts with the permanent magnets to cause oscillation of the mirror structure.

[0026] Figures 5A and 5B illustrate two additional torsional articulation structures using permanent magnets and electrical coils as drive sources for the two reflective surfaces suitable for the inventive torsion articulation structure.

[0027] The torsional hinge structure of FIGS. 5A and 5B is similar to that of FIG. 4B, except that magnet mounting regions 66a and 66b are not on the torsional hinge but are secured to anchors 20a and 20b. However, the magnet mounting areas 66a and 66b are in-line with the torsion hinge and lie on the axis of rotation. To help maintain the mirror vibrating at the resonant frequency and required deflection amplitude at minimum power, the torsion hinge according to the embodiment of Figures 5A and 5B is secured to anchors 20a and 20b with reduced material area. According to the embodiment of FIG. 5A , notches 68 a and 68 b separate mounting areas 66 a and 66 b from anchors 20 a and 20 b , except for small areas at 70 a and 70 b . Figure 5B works in a somewhat similar manner, except instead of cutting notches in the anchors, the regions 72a, 72b, 72c, and 72d that secure the torsion hinges 18a and 18b to the anchors 20a and 20b are thinned or reduced in thickness. Small.

[0028] Referring now to FIG. 6, a very simple version of the invention is shown etched or laser milled from a single silicon substrate or layer of material. As shown, the central portion or mirror, torsion hinges 18a and 18b and anchors 20a and 20b are all formed from a single layer of silicon. It will be appreciated that, if reflective surfaces 24 and 26 are to be used, both sides of the silicon layer must be equally reflective.

[0029] Those skilled in the art to which the utility model relates can appreciate that various additions, deletions, substitutions and other modifications can be used in the examples without departing from the scope of the claimed utility model.

Claims (9)

1. A twisted hinged mirror structure with two reflective surfaces, comprising: a pair of torsion hinges extending along the axis of rotation, each hinge of the pair having a first end mounted on the support structure and a second end; a central portion located between and supported by said second ends of each of said pair of torsion hinges so that said central portion can freely swing about said rotational axis, the central member has a first side and a second side opposite the first side; a first reflective surface on the first side of the central portion; and A second reflective surface on the second side of the central portion. 2. The torsionally hinged mirror structure of claim 1, wherein said pair of torsion hinges, said central portion, and each of said first and second surfaces are formed from a single layer of silicon. 3. A torsionally hinged mirror structure according to claim 1 or 2, wherein said pair of torsion hinges and said central portion comprise hinge plates, and said first reflective surface comprises a A first mirror layer on the first side, and the second reflective surface includes a second mirror layer bonded to the second side of the hinge plate. 4. The torsionally hinged mirror structure according to claim 1 or 2, wherein said first end of each of said pair of torsion hinges is mounted so that the torsion hinge structure can freely swing around said hinge, further comprising a drive source coupled to said twisted articulating mirror structure to oscillate said two reflective surfaces about said axis of rotation by a selected deflection angle, a first light beam is directed towards said first reflective surface and is guided by it The reflected and second light beam is directed towards and reflected by said second reflective surface such that said reflected first and second light beams sweep said selected deflection angle. 5. The torsion hinged mirror structure of claim 4, further comprising first and second anchor members connected to said first end of each of said pair of torsion hinges; and wherein said The driving source is an inertial driving source, which includes two pairs of piezoelectric drivers, one pair of piezoelectric drivers is mounted on one of the anchor members, and the other pair of piezoelectric drivers is mounted on the second anchor member. 6. The torsion hinged mirror structure of claim 4, further comprising first and second anchor members connected to said first end of each of said pair of torsion hinges; and wherein said The drive source includes a first permanent magnet mounted to a magnet support region defined on the first anchor member along the axis of rotation; and further includes a first drive mounted adjacent to the first permanent magnet. A coil induces the oscillation by providing a drive magnetic flux interacting with the first permanent magnet. 7. The torsionally articulated mirror arrangement of claim 6, wherein said magnet region on said first anchor member is defined by a slot separating The anchor member and the magnet support area. 8. The torsionally articulated mirror structure according to claim 6, further comprising a second permanent magnet mounted on a second magnet support area defined at said second anchor along said rotation axis. component, and further comprising a second drive coil mounted adjacent to the second permanent magnet. 9. The torsion hinged mirror structure according to claim 4, wherein a magnet mounting area is defined on at least one of said torsion hinges, and wherein said drive source comprises a first permanent magnet mounted on said magnet mounting area. A magnet and a first drive coil mounted adjacent to the first permanent magnet.

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