Source: http://www.google.com/patents/US5610752?dq=6519629
Timestamp: 2014-03-10 00:24:29
Document Index: 730815939

Matched Legal Cases: ['art. 10', 'art.\n11', 'art. 13', 'art.\n15', 'art 2', 'art 2']

Patent US5610752 - Optical reader with vibrating mirror - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsSystems embodying the invention include a vibrating arm having one side on which is mounted a reflective surface for sweeping a beam of light across a target whose contents are to be read. The vibrating arm includes a bar of magnetic material pivoted about its center so as to be able to rotate freely...http://www.google.com/patents/US5610752?utm_source=gb-gplus-sharePatent US5610752 - Optical reader with vibrating mirrorAdvanced Patent SearchPublication numberUS5610752 APublication typeGrantApplication numberUS 08/405,538Publication dateMar 11, 1997Filing dateMar 16, 1995Priority dateMay 27, 1992Fee statusPaidPublication number08405538, 405538, US 5610752 A, US 5610752A, US-A-5610752, US5610752 A, US5610752AInventorsHiroshi HayakawaOriginal AssigneeOpticon Inc.Export CitationBiBTeX, EndNote, RefManPatent Citations (5), Referenced by (32), Classifications (15), Legal Events (8) External Links: USPTO, USPTO Assignment, EspacenetOptical reader with vibrating mirrorUS 5610752 AAbstract Systems embodying the invention include a vibrating arm having one side on which is mounted a reflective surface for sweeping a beam of light across a target whose contents are to be read. The vibrating arm includes a bar of magnetic material pivoted about its center so as to be able to rotate freely (i.e., be "movable"). The ends of the "movable" bar are located between the side walls of a stationary (i.e., non-moving or fixed) yoke of magnetic material with a driving coil located between the ends of the movable bar and the side walls of the stationary yoke. The stationary yoke is of magnetic material for concentrating a magnetic field encompassing the movable bar, the coil and the stationary yoke. The combination of the movable bar and the yoke are configured to produce a magnetic field such that with no current in the driving coil, the movable bar has a defined equilibrium (or rest) position and when the movable bar is displaced from its equilibrium position a magnetic restoring torque is present such that the movable bar oscillates about its equilibrium, position. In a preferred embodiment the bar is a permanent magnet and the yoke is made of magnetic material. A varying current signal is selectively supplied to the driving coil to control the frequency and amplitude of the vibrations of the movable bar.
What is claimed is: 1. A scanning device comprising:a movable arm of length L and width W, having one side on which is fixedly mounted a first reflective surface for receiving a light beam and for projecting the light beam across a target spaced externally from the scanning device; said movable arm being of magnetic material and being pivoted about its center to permit the arm to rotate freely about its center; stationary, non-moving, components, external to the movable arm, including a driving coil and a fixed yoke; said driving coil formed of a plurality of turns of wire closely wound about each other and located between the movable arm and said fixed yoke, said driving coil for receiving an electric current for selectively causing movement of said movable arm; and said fixed yoke being formed of magnetic material, and having sides, with the movable arm located between the sides of the fixed yoke for producing a magnetic circuit coupling the fixed yoke with the movable arm and for establishing an equilibrium position for the movable arm, the magnetic circuit being arranged such that when said movable arm is displaced from its equilibrium position, and in the absence of a current in said driving coil, a restoring torque is present tending to cause the movable arm to oscillate about its equilibrium position. 2. The scanning device as claimed in claim 1 wherein said fixed yoke has four sides fully enclosing the sides of the driving coil and the movable arm.
3. The scanning device as claimed in claim 1 wherein said fixed yoke is generally U shaped having three sides; one side extending along the length of the movable arm and the other two sides extending perpendicularly to the ends of the arm.
4. The scanning device as claimed in claim 1 wherein said movable arm is a permanent magnet.
5. The scanning device as claimed in claim 1 wherein a second reflective surface is mounted on the movable arm, the second reflective surface being mounted on a side of the arm opposite to the side than the one on which the first reflective surface is mounted.
6. The scanning device as claimed in claim 5 wherein said second reflective surface is for receiving the light reflected from the target illuminated by the projected light beam.
7. The scanning device as claimed in claim 1 wherein a holding frame is positioned within the fixed yoke and wherein said movable arm is mounted within said holding frame.
8. The scanning device as claimed in claim 1 wherein the magnetic field produced by the combination of said movable arm and said fixed yoke is of a generally rectangular nature with a middle transverse line in the center of the rectangle defining two generally square shaped regions, with the equilibrium position of said movable arm lying along the transverse line.
9. A scanning device comprising:a movable part with front and rear sides a holder; a fixed yoke and a driving coil generally square shaped; said movable part comprising a movable arm mounted on a rotating axis supported by said holder and arranged to rotate freely, and said movable part comprising a permanent magnet magnetized perpendicularly to the direction of said rotating axis; said fixed yoke comprising at least three sides; said movable part located between a pair of opposite, facing, sides of said fixed yoke; said movable part and said fixed yoke producing a magnetic circuit of generally rectangular shape with a middle transverse line inside the rectangle forming two generally square shaped regions; said driving coil located at the same center core as that of said fixed yoke; and a first reflective mirror mounted on the front side of said movable part. 10. A scanning device as claimed in claim 9 further comprising a second reflective mirror mounted on the rear side of said movable part.
11. A scanning device claimed in claim 9 wherein said movable part includes two permanent magnets located at the two ends of the movable part with a movable yoke located between the two permanent magnets, and said movable yoke coupling the two permanent magnets mechanically and magnetically.
12. A scanning device comprising:a movable part having a front side and a rear side; a holder; a fixed yoke; a fixed magnet; a rectangular shaped driving coil; said movable part comprising a movable arm rotating about an axis supported by said holder so as to rotate freely; said fixed yoke having at least three sides and a general "U" like shape; said movable part being located between a pair of opposite, facing, sides of said fixed yoke; said fixed magnet being located between said opposite sides of said fixed yoke, said movable part being on a line perpendicular to said rotating axis; said movable part and said fixed yoke defining a magnetic circuit having a generally rectangular shape with a middle transverse line inside the rectangle defining two generally square shaped regions; said driving coil being is located at the same center core as that of said fixed yoke; and a first reflective mirror fixedly mounted on the front side of said movable part. 13. A scanning device as claimed in claim 12 wherein said movable part is a permanent magnet.
14. A scanning device as claimed in claim 12 further including a second reflective mirror fixedly mounted on the rear side of said movable part.
15. A scanning device comprising:a reflective mirror mounted on a movable part; a holder; a fixed yoke; a driving coil; said movable part comprising a movable arm mounted on a rotating axis supported by said holder so as to rotate freely; said movable part comprising a magnet magnetized perpendicularly to the direction of said rotating axis; said fixed yoke having at least three sides; said movable part being located between a pair of opposite, facing, sides of said fixed yoke; said movable part and said fixed yoke comprising a magnetic circuit having a generally square shape; and said driving coil (9) being wound around said opposite sides of said fixed yoke. 16. A scanning device as claimed in claim 15 wherein said movable part includes two magnets located at the two ends of the movable arm and a movable yoke located between the two magnets for coupling them mechanically and magnetically.
17. A scanning device as claimed in claim 15 wherein said opposite sides of said fixed yoke facing the outer edges of said movable part are shaped like an arc between the stop position of said movable part and the maximum position of its rotating angular movement.
18. A scanning device as claimed in claim 15 further comprising a mechanical spring component.
This application is a continuation-in-part of my previously filed patent application, filed May 27, 1992, entitled Vibrating Mirror, bearing Ser. No. 07/889,603, now U.S. Pat. No. 5,436,753, and whose teachings are incorporated herein by reference.
DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1A there is shown a vibrating mirror assembly comprising a rectangular movable arm 2, designed to rotate and/or vibrate back and forth about a shaft 25. The rotation of the arm 2 is illustrated by the double headed arrows shown in FIG. 1A. The vibrating movable arm 2 includes sections 21a and 21b, which are permanent magnets interconnected by a yoke 22. The yoke 22 is located between magnets 21a and 21b coupling them magnetically and mechanically. The rectangular arm 2 may be a bar of length, L, width, W, and height, H, as shown in FIG. 1G. The ends of the bar need not be straight as shown, but could be curved, concavely or convexly. The yoke 22 may be of "ferrous" or any suitable magnetic material and it may be referred to as a "movable" yoke to differentiate it from the "stationary" yoke 7.
The movable part 2 and the fixed yoke 7 produce a closed, "FIG. 8" like, magnetic circuit as shown in FIG. 1D. In a preferred embodiment, the center core or point of the driving coil 9 is located at the same center point as that of fixed yoke 7, as shown in FIG. 1E. A first reflective mirror, "scanning mirror" 11, is mounted on one side (i.e., in front) of the movable arm 2 and a second reflective mirror, light receiving mirror 12, is mounted on the other side (i.e., behind) the movable arm 2.
Magnetic spring force (rotating moment)=(k)(sin &#920;)   (1)
I(d.sup.2 &#920;/dt.sup.2)+c(d&#920;/dt)+(k)(sin &#920;).+-.f=0(2)
I(d.sup.2 &#920;/dt.sup.2)+c(d&#920;/dt)+(k)(sin &#920;)=0(3)
Rotating moment due to AC magnetic field=(Pcoswt)(cos &#920;)(4)
The magnetic spring force (k)(sin Θ) due to the permanent magnets 21a, 21b and the rotating moment due to the AC magnetic field (Pcoswt)(cos Θ) are operative on the movable part 2 at the same time. The vibration equation for this condition may be expressed, approximately, as follows:
I(d.sup.2 &#920;/dt.sup.2)+c(d&#920;/dt)+(k)(sin &#920;)=(Pcoswt)(cos &#920;)                                                  (5)
As may be deduced from equations (4) and (5) the angular vibration and the amplitude of oscillation (i.e., reverse rotating vibration or induced vibration) is determined by the amplitude and frequency of the AC current. When the rotating angle Θ is small, sin Θ is approximately equal to Θ and cos Θ is approximately equal to
1. Therefore, the vibration equation may be reduced as follows:
I(d.sup.2 &#920;/dt.sup.2)+c(d&#920;/dt)+k&#920;=(P)(coswt)(6)
Note that a mirror 12 (not shown in this view) could be mounted on the back side of movable arm 2. The back side 161 of the holder could be cut out, or be transparent, or include a lens arrangement for a mirror 12 mounted on the back side of movable arm 2. Alternatively, the holder 16 and bearing portion could be made to depend from the top and bottom sides of yoke 7. It should be evident that many different packaging arrangements are possible to enable the movable arm 2 to have a first mirror on its front side and a second mirror on its back side, with the movable arm vibrating as taught herein.
The attraction force due to the static magnetic field between the movable magnets 21a and 21b and the adjacent opposite side 7a, 7b is active at all times. That is, the magnetic spring force (rotating moment) is applied to return the movable arm 2 to stand-still (equilibrium) position (as shown in FIG. 4) which is the position where the movable magnets 21a, 21b and the opposite sides 7a and 7b are closest to each other.
When an AC current is supplied to the driving coils 9a, 9b, an AC magnetic field is generated which goes across the movable magnets 21a, 21b and the movable magnetic element yoke 22 in the same direction. This AC magnetic field causes the movable arm to rotate alternately in one direction and then in the opposite direction.
Optical Information Reading Device FIG. 6 illustrates an optical information reading device embodying the inventive vibrating mirror assembly of this patent application.
Thus, it is important to note that the use of the second "reflective" mirror 12 for sensing the light reflected from the target 103 provides a significant advantage in that there is greater emphasis on, and capture of, the signal resulting from the portion of the target being illuminated by the light source. Therefore, there is a significant increase in the signal-to-noise ratio since the effect of ambient light is reduced.
FIGS. 4A, 4B and 4C, represent a top view, front view and side view, respectively, of another embodiment of a vibrating mirror assembly embodying the invention;
BACKGROUND OF THE INVENTION This invention relates to optical readers and in particular to optical readers including means for sweeping a light beam across a target and sensing the light signals reflected from the target.
FIGS. 7B and 7C show the single plane/face mirror (m) and the stepper motor (gm) which are independently constructed and respectively connected with a rotating driving axis.
OBJECT OF THE INVENTION It is an object of this invention to reduce the size (e.g. height, width and depth) of a vibrating mirror assembly used to reflect a beam of light and to project it across a target.
SUMMARY OF THE INVENTION Systems embodying the invention include a vibrating arm having one side on which is mounted a reflective surface for sweeping a beam of light across a target whose contents are to be read.
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