JPH08310041A - Levitation type radiation energy projection head for high-speed lighter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high resolving power and a high recording speed by supporting the wt. of a structure by the air bearing pressure generated by a floating head and equilibrating the floating force of the floating head with the centrifugal force applied to the floating head. SOLUTION: A floating head 10 is attached to a locating structure like a bending member 12 and a balance wt. 14 is attached to a pivot arm 16 in the direction opposite to the floating head 10 and the bending member 12. The pivot arm 16 is attached to a rotor 18 by a rotary shaft 20. Light 42 is emitted from the floating head 10 in order to expose a medium 24 and, at the same time, a pressurized air bearing 44 is formed between the floating head and the medium 24. When the rotor 18 is rotated, centrifugal force is applied to the floating head 10 and the floating head 10 moves outwardly toward the medium 24 in a radial direction and air passing through the gap between the floating head 10 and the medium 24 is compressed to form a positive air bearing. By this constitution, the floating head 10 is floated on the surface of the medium 24 at an accurate interval.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to the field of photography, photomechanical processes, and image-forming systems in which light rays are scanned onto the surface of a photosensitive medium to form an image.

[0002]

BACKGROUND OF THE INVENTION In order to form an image on a silver halide film or other photosensitive medium, the medium must be exposed to light rays having sufficient exposure power. . At the same time, the light beam must be applied only to a limited part of the medium to be exposed.
A myriad of systems are known that use remotely operated scanning light sources, fibers, optical paths, mirrors, lenses, etc. to project a beam of light onto a desired spot of a photosensitive medium. When the medium is photosensitive for color processing,
Three light sources, or three separately independently modulated spectral bands must be used.

For example, FIG. 1 illustrates an incoherent light source and lens system for focusing a portion of a light beam that is directed through a mask onto a receiving medium. The light collection efficiency is poor because a significant proportion of the emitted light is not imaged through the lens and does not reach the light receiving medium.

US Pat. No. 4,961,080 issued to Henderson et al. On Oct. 2, 1990 discloses a scanning shaft system wherein a laser beam is reflected on a surface to be imaged. For this purpose, a plurality of mirrors are fixed around the drum. This mirror images through an opening in the surface of the drum whose axis is central.

US Pat. No. 4,918,465 issued to Morita on April 17, 1990 discloses a system using three light sources to produce a full color image. This light source is separated from the image drum. Fiber optics are used to transmit light to the photosensitive material on the surface of the drum.

US Pat. No. 4,544,259, issued to Kanaoka et al. On Oct. 1, 1985, discloses a system with a colored light source and multiple light guides. Many light sources with the same color are used to increase the amount of light energy and increase the printing speed. The bundle of ray guides is provided with a lens system at the print end to focus the rays on smaller spots.

US Pat. No. 4,797,691 issued to Akiyoshi et al. On Jan. 10, 1989 discloses a side printhead structure in which light rays from an LED are guided to a printing area by a ray guide. Has been done.

US Pat. No. 4,907,034 issued Mar. 6, 1990 to Doi et al. Discloses a system for producing color images on a photosensitive medium. The light beam is guided from a plurality of light sources to the medium by an autofocus lens.

US Pat. No. 4,684,228 granted to Holthusen on Aug. 4, 1987
A photo-generating device using a laser beam is disclosed.
There, mirrors are used to direct the laser beam at the media on a rotating drum.

US Pat. No. 4,479,133, issued to Shiozawa et al. On Oct. 23, 1984, discloses a beam rotating recorder having a rotor containing a light source that emits light. The medium is mounted on a semi-circular frame and the rotor is moved above the medium by a lead screw.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a writing head in which a light beam rotates. This head can record with high resolution and high recording speed. This is a very effective levitating head system,
The system houses one or more light sources and levitates the head at very small distances from the media without damaging the head. Since the light source (s) are / are levitated in close proximity over the photosensitive medium, a lens system for projecting light rays is not needed, thus reducing the loss of light energy in the system. This causes the system to require a small amount of energy to expose the medium and generate a small amount of heat to provide sufficient light output.

In accordance with the present invention, the write head is designed to minimize the gap between the surface of the photosensitive medium and the flying head. The levitation head automatically creates an air bearing pressure to support the weight of the structure, and further, this levitation force balances with the centrifugal force applied to the levitation head by the rotational movement of the media recorder, Is designed.

The one or more light sources are preferably mounted on a metal foil overlying the floating head structure. The holes in the metal foil above each light source cause the light source to emit light and directly irradiate the surface of the photosensitive medium. The distance between the light source and the medium surface is controlled by the levitation distance of the levitation head and the thickness of the metal foil. The size and shape of the spot of the light beam on the medium are controlled by the distance of the hole of the metal foil from the medium and the size and shape of the hole. Therefore, the state of the light beam is accurately determined by the physical characteristics set in the levitation head.

In the preferred embodiment, the levitation head has a final form that is made from a ceramic material and is molded into a strong, lightweight structure. However, the levitation head is also made of metal, plastic, or composites of many materials. The heat sink (cooling device) provides a heat dissipation path through which the waste heat generated by the light source is dissipated in the air flow around the structure of the head. The heat sink is made of metal, with copper being particularly suitable.

The levitation head is attached to a positioning structure, such as a gimbal or flexure, which is connected to a pivot arm attached to the rotor. When the rotor rotates, centrifugal force acts on the pivot arm to move the head toward the medium. The positioning structure floats the head and adapts it to any irregularities on the surface of the media and drum. The head moves radially outward in the direction of the medium and levitates on an air cushion that is controlled similarly to the flying heads of aircraft wings and hard disks.

[0016]

DETAILED DESCRIPTION OF THE INVENTION In the following detailed description of the embodiments of the invention, the following reference is made to the accompanying drawings. FIG. 1 is a diagram of a prior art exposure system.
FIG. 2 is a sectional view of a printing apparatus having a floating head according to an embodiment of the present invention. FIG. 3 is a top view of the levitation head of FIG. 2 detailing the location of the positive pressure air bearing pocket and the light source. 4 is a cross-sectional view of the floating head of FIG. 3 showing the metal foil air dam, slot, heat sink, and light source. FIG. 5 is a partially enlarged view of the printing apparatus showing the position of the light beam. FIG. 6 is an enlarged view that clearly shows the light rays that are emitted and the steady air gap. FIG. 7 shows an improved device according to the invention similar to that of FIG. 8 to 11 are diagrams showing design curves for optimizing the shape size of the rectangular pocket. 12 and 13 are views showing a second embodiment of the present invention. FIG. 14 shows another embodiment of the invention in which an LED package is attached to a cantilevered positioning structure. FIG. 15 is a diagram showing another embodiment of the present invention similar to FIG.

FIG. 2 shows a cross section of a printing device with a wing-shaped structure for providing light energy to a photosensitive medium. The levitation head 10 is attached to a positioning structure such as the flexure member 12. In another embodiment of the present invention, a positioning device using a gimbal is described below. The locating structure allows adjustment of the levitating head's roll and pitch to the forces acting on it. A counterweight 14 is attached to a pivot arm 16 opposite the levitation head 10 and the flexure member 12. The pivot arm 16 is attached to the rotor 18 by a rotating shaft 20. A tubular member 22 having a cylindrical media support surface surrounds the rotor mechanism. The medium 24 is held on the support surface in a vacuum-like manner.

3 and 4 are a top view and a side view, respectively, of a levitation head 10 made of a ceramic having a width dimension B and a length L. FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. The recessed pockets 26, which are hatched for clarity, are formed, in part, by an aerodynamically curved opposite the media-bearing surface of the tubular member 22 in the final structure (FIG. 2). Shaped as a slot in the curved surface of the suspended head 10. In FIG. 3, for pocket 26, B ₁ is the width dimension and L ₁ is the length dimension.

Metal foil sheet 2 adhered to the slot
8 acts as an air dam in the slot to complete the pocket 26. Air passing over this slot becomes a dead end at the air dam, providing positive pressure on the curved surface of the levitation head,
It is forcibly sent upward. The metal foil 28 has a plurality of holes 30 made to allow light to pass through the metal foil. The metal foil sheet 28 has a height dimension h ₁ -h ₂ , where h ₁ is the distance from the bottom of the slot making the pocket 26 to the emulsion surface of the medium 24 and h ₂ is the curve of the flotation head. It is the distance from the formed surface to the photosensitive emulsion surface of the medium. In the preferred embodiment, a plurality of light sources, LEDs 32, are shown underneath the metal foil cut holes 30. Below each LED is a copper heat sink 34.

FIG. 5 is a cross-sectional view of the levitating head taken along line 5-5 of FIG. In the illustrated embodiment, the heat sink is made of five copper strips. 3 under the LED
The individual copper strips 34 are slightly shorter than the two outer copper strips 36 so that the copper strips 36 bond to the metal foil sheet 28. The copper strip serves both as a heat sink and an electrical connection member. The heat sink 34 is connected to the LED with solder or a conductive polymer. with this,
The anode is connected to the LED 32. Also, the connection of the cathode to the LED is made between the diode and the metal foil sheet. This connection is also made by solder or conductive polymer, but is not necessarily limited thereto. Cathode connections to the underside of the levitation head are provided by copper strips 36 located at each end of the heat sink. Cathode heat sink 36
Are connected to the metal foil 28 with solder or a conductive polymer. An inner sheet 38 of cloth or plastic between each piece of copper provides electrical insulation between the heat sinks. Electrical signal connections to the structure are made possible by soldering the metal lines underneath the flying head to individual heat sinks. A sheet 40, called Kapton, is connected to the metal foil with an adhesive to accurately position the holes and provide electrical isolation between the LEDs.

The structure consisting of the heat sink, the metal foil and the LED is connected to a ceramic floating head with an adhesive material. The holes 30 of the metal foil sheet 28 are filled with an optically transparent polymer to prevent dust particles from covering the light source.

FIG. 6 is an enlarged view of the head that floats with respect to the medium. The air gap is shown greatly enlarged for clarity. A ray of light 42 is emitted from the levitating head to expose the medium. At the same time, a pressurized air bearing 44 is created between the flotation head and the media. When the rotor 18 rotates in the direction of arrow 46, centrifugal force is applied to the levitation head 10. The flotation head moves radially outward toward the media 24,
The air passing between the flotation head and the media is compressed creating positive air bearings. This allows the levitation head to
Levitated at precise intervals on the surface of the.

As can be seen best in FIG. 7, the very close distance between the mask of the light source and the medium makes it possible to optimize the size and shape of the optical spot compared to the prior art of FIG. Therefore, the optical loss can be minimized. More rays are collected on the medium without the need for a lens and without the loss of rays associated with the lens. Therefore, in order to obtain an effective amount of light at the writing spot, the dissipation of the output can be suppressed to a small level. Also, it does not require a lens system to focus the light rays on the spot because it is close to the medium. The size of the beam spot is controlled by the distance of the levitating head from the medium and the size of the opening. Since there is no lens system, the levitating head is light and inexpensive to manufacture. The low mass of the levitating head allows the levitating head to accurately follow irregularities and eccentricity of the surface to be written.

The air bearing pressure created by the relative motion of the moving levitating head and the stationary medium causes the centrifugal force on the levitating head to maintain a defined space between the levitating head and the medium. You must support your strength. As shown in FIG. 3, the geometry of the floating head pocket 26 can be optimized depending on the shape and speed of the head. The pocket shape can be rectangular or trapezoidal,
In the trapezoid, the pocket becomes narrower from the tip toward the wall of the air dam. Also, the depth of the pockets can be graded so that they have a minimum depth at the wall of the air dam and a maximum depth at the tip of the levitation head. Having a sloped and trapezoidal shape slightly increases the load bearing capacity, but is difficult to manufacture.

As shown in FIG. 3, bearing load optimization is described for a simpler, uniformly deep rectangular pocket. Also, such optimization applies to pockets having sloped and trapezoidal shapes as well. The optimization is done using the well-known numerical analysis of the Reynolds lubrication equation. This equation determines the pressure created between two surfaces when one is moving relatively quickly relative to the other, as is the case with sliders and media. In the analysis, five unitless parameters affect bearing performance. They are derived from the actual geometry of the slider and the desired distance between the slider and the medium,
And 6 are shown. These five dimensionless parameters are: 1) B ₁ / B, where B is the total width of the slider, B ₁ is the total width of the pocket, 2) L ₁ / L, where L is the total length of the slider, L ₁ is the total length of the pocket, 3) h ₁ / h ₂ , where h ₂ is the desired space between the slider and the medium, h ₁ -h ₂ is the depth of the pocket, 4) B / L, slider width vs. length And 5) Λ = 6 μUB / h ₂ Pa, where Λ is a dimensionless number of bearings, which is derived from relative velocity U, air viscosity μ, and atmospheric pressure Pa.

Another dimensionless bearing number Λ _L is defined by the following equation. _{Λ L = ΛL / B = 6μUL} / h 2 Pa , and, dimensionless bearing load W 'is W' = W / BLPa where W is the actual bearing load. To optimize the slider for maximum bearing load,
Knowledge of the correlation between the five dimensionless parameters and W'is sufficient. FIG. 8 shows the correlation between width-to-length ratio (B / L) and dimensionless load for the following three bearing numbers. Λ _L = 0.35, 0.5
5, and 1.

The figure shows that for a given speed range of the slider and a fixed slider length, the maximum bearing load occurs when the lateral width to length ratio of the slider is 2.8. The graph assumes the following equation. By knowing the optimum value of h ₁ / h ₂ = 3.5 B ₁ / B = 0.75 L ₁ / L = 0.7 B / L, other variables can be optimized. FIG. 9 shows the correlation between pocket lateral width ratio (B ₁ / B) and dimensionless bearing load for Λ _L = 0.35, 0.55, and 1. The optimum value is B ₁ / B =
It is 0.84. The graph assumes the following equation. h ₁ / h ₂ = 3.5 B / L = 2.8 L ₁ / L = 0.7

FIG. 10 shows the correlation between the pocket length ratio (L ₁ / L) and dimensionless bearing load for Λ _L = 0.35, 0.55, and 1. The optimum value is
L ₁ /L=0.675. The graph assumes the following equation. h ₁ / h ₂ = 3.5 B / L = 2.8 B ₁ / B = 0.84 Figure 11 shows that the ratio of pocket thickness to Λ _L = 0.35, 0.55, and 1 ( ₂ shows the correlation between H ₁ = h ₁ / h ₂ ) and the dimensionless bearing load. The optimum value is H ₁
= 3.5. The graph assumes the following equation. L ₁ / L = 0.675 B / L = 2.8 B ₁ / B = 0.84

The application of this knowledge requires consideration in the slider design, for example, the system limitation that the light source is 0.5 millimeters away from the medium and that the width is 1 inch. In such a case, h ₂
= 0.0005 inch and B = 1 inch.

From the above, h ₁ = 1.75 mm and a pocket depth of 1.25 mm. Since the slider length is B / L = 2.8, L = 0.357
Will be inches. The length of the pocket is L ₁ / L = 0.675
Therefore, L ₁ = 0.241 inch. Also, since the width of the pocket is B ₁ / B = 0.84, B ₁ = 0.84
Inches. This completely defines the geometry of the slider. The actual bearing load can be obtained by extrapolation from FIGS. 8 to 11 if the velocity of the slider, the air viscosity, and the ambient atmospheric pressure are known.

In addition, FIGS. 8-11 show how the air bearing load is sensitive to the tolerances of the flying head geometry parameters. The resulting air bearing pressure must support the centrifugal force on the levitating head and maintain a defined clearance between the levitating head and the medium.

12 and 13 illustrate a second embodiment of the present invention. The levitation head 50 is attached to the gimbal positioning structure 52. The gimbal positioning structure allows control of the levitating head's roll, pitch, and yaw with respect to the forces acting on the levitating head. A counterweight 54 is attached to the pivot arm 56 opposite the floating head 50 and the gimbal positioning structure 52. The pivot arm is attached to the rotor 58 by the rotation shaft 60. A tubular member 62 having a cylindrical media support surface surrounds the rotor structure. The medium 64 is held on the support surface by means such as vacuum.

The gimbal positioning structure 52 has a mounting arm 66 with a socket for accommodating a gimbal head 68 held by a spring clip 70. The elastomer pad 72 is the mounting arm 6
Acts as a damper to the movement of the levitating head with respect to 6.

The pivot arm 56 includes the pivot ring 7
4 urges the rotating shaft 60 in the counterclockwise direction. A light beam is emitted from the LED 76 of the levitating head to expose the medium. At the same time, a positively pressurized air bearing is created between the flotation head and the media. Rotor 58 is arrow 7
When rotated in the 8 direction, centrifugal force is exerted on the levitation head 50 in the opposite direction to the force of the pivot spring 74 and the adjustable counterweight 54. The flotation head moves radially outward toward the media 64 and the air passing between the flotation head and the media is compressed to create a positive air bearing. This allows the levitating head to levitate over the surface of the medium 64 at a precise distance.

14 and 15 illustrate two alternative embodiments of the present invention. In FIG. 14, the LED package 80 is attached to a cantilever-supported flexible positioning structure 82. The positioning structure enables control of the roll and pitch of the LED package by the forces exerted on the LED package. This positioning structure is attached to the rotor 84. A tubular member 86 having a cylindrical media support surface surrounds the rotor. The medium 64 is held on the support surface by means such as vacuum.

A positively pressurized air bearing is created between the flexing positioning structure 82 and the media by an air pocket recess made in the media side surface of the positioning structure. When the rotor 84 is turned in the direction of arrow 88, centrifugal force is exerted on the LED package against the fluid force of the air passing between the levitating head and the medium. This allows the levitating head to levitate over the surface of the medium at a precise distance.

The implementation shown in FIG. 15 except that the trailing edge of the flexible support structure 90 for the LED package 91 is guided by a bracket 92 attached to the leading edge of the rotor 94. The form is similar to that of FIG. Although a color writer (color writing device) having a plurality of light sources has been described above, a single light source monochrome writer is effective within the scope of the present invention.

[Brief description of drawings]

FIG. 1 is a diagram showing a conventional exposure system.

FIG. 2 is a sectional view showing a printing apparatus having a floating head according to an embodiment of the present invention.

3 is a top view of the levitation head of FIG. 2 detailing the location of the positive pressure air support pocket and the light source.

[Fig. 4] Air foil of metal foil, slot, heat sink,
4 is a cross-sectional view of the flotation head of FIG. 3 showing the light source and.

FIG. 5 is a partially enlarged view of the printing apparatus showing the positions of light rays.

FIG. 6 is an enlarged view clearly showing the irradiated light rays and a steady air gap.

7 shows an improved device according to the invention similar to that of FIG.

FIG. 8 shows a design curve for optimizing the rectangular pocket geometry.

FIG. 9 shows a design curve for optimizing the rectangular pocket geometry.

FIG. 10 is a diagram showing a design curve for optimizing the shape size of a rectangular pocket.

FIG. 11 is a diagram showing a design curve for optimizing the shape size of a rectangular pocket.

FIG. 12 is a diagram showing a second embodiment of the present invention.

FIG. 13 is a diagram showing a second embodiment of the present invention.

FIG. 14 illustrates another embodiment of the invention in which an LED package is attached to a cantilevered positioning structure.

FIG. 15 is a view similar to FIG. 14, showing another embodiment of the present invention.

[Explanation of symbols]

 10 Floating Head 16 Pivot Arm (Floating Head Support Member) 22 Cylindrical Member (Medium Support Member) 24 Medium

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Stephen James Adamson United States California California 92064 Poway Tree Creek Crest Street 13232 (72) Inventor Jeremiah Finbarre Connolly United States California 92129 Sun Diego Wy Street 14606

Claims (1)

[Claims] 1. A medium support member for accommodating a recording medium having sensitivity to light beam radiation, and means for projecting at least one light beam having radiant energy toward the medium support member.
And a support member for the levitation head, wherein the first surface of the levitation head is the levitation head with respect to a second surface facing the first surface. The head is formed to have a shape such that an air bearing is formed between the first surface and the second surface when the head moves relative to each other, and is sensitive to the levitation head and the radiation of rays. To create an air bearing between the media surface,
One of the medium supporting member and the floating head supporting member is driven so as to relatively move the floating head and a surface of the contained recording medium that is sensitive to radiation of light. Writer (writing device).