U.S. patent number RE40,676 [Application Number 11/057,106] was granted by the patent office on 2009-03-24 for scanner unit for an optical position measuring device.
This patent grant is currently assigned to Dr. Johannes Heidenhain GmbH. Invention is credited to Wolfgang Holzapfel, Elmar Mayer, Siegfried Reichhuber.
United States Patent |
RE40,676 |
Holzapfel , et al. |
March 24, 2009 |
Scanner unit for an optical position measuring device
Abstract
A scanning unit for an optical position measuring device, which
is suited for optically scanning a scale graduation, to produce
positionally dependent scanning signals on the basis of scale
graduation. The scanning unit includes a carrier element, at least
one optoelectronic component, which is arranged on the carrier
element, a radiation-sensitive or a radiation-emitting surface
region of the component being oriented to face away from the
carrier element. Provision is also made for at least one
electrically conductive connector lead between the carrier element
and a contacting region of the component. An at least
semi-transparent cover element is arranged directly on the
radiation-sensitive and/or radiation-emitting surface region of the
component. In this case, the cover element is arranged in such a
way with respect to the component that the contacting region of the
component is not covered by it and, in addition, the thickness of
the cover element is selected so as to ensure that the top side of
the cover element exceeds the height of the connector lead in the
contacting region.
Inventors: |
Holzapfel; Wolfgang (Obing,
DE), Mayer; Elmar (Nu.beta.dorf, DE),
Reichhuber; Siegfried (Stein/Traun, DE) |
Assignee: |
Dr. Johannes Heidenhain GmbH
(Traunreut, DE)
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Family
ID: |
7858363 |
Appl.
No.: |
11/057,106 |
Filed: |
February 11, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
09251066 |
Feb 18, 1999 |
06519044 |
Feb 11, 2003 |
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Current U.S.
Class: |
356/616;
250/237G; 356/630; 356/634 |
Current CPC
Class: |
G01D
5/34715 (20130101); H01L 2224/48091 (20130101); H01L
2224/48091 (20130101); H01L 2924/00014 (20130101) |
Current International
Class: |
G02B
11/14 (20060101); H01J 5/16 (20060101) |
Field of
Search: |
;356/616 ;250/237
;257/433 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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296 09 523 |
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Nov 1997 |
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DE |
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19855307 |
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Aug 1999 |
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DE |
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0 577 088 |
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Jan 1994 |
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EP |
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2194635 |
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Mar 1988 |
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GB |
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9-189514 |
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Jul 1997 |
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JP |
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Other References
Copy of photograph of "IC-OE" product of iC-Haus GmbH, marked as
"Enclosure A" Oct./Nov. 1997. cited by other .
Invoice dated Jul. 14, 1997 of iC-Haus GmbH to Max Stegmann GmbH,
marked as "Enclosure B" (English-language translation provided).
cited by other .
"Eidesstattliche Versicherung" ("Affirmation in Lieu of Oath") of
Dr. Heiner Flocke, dated Jun. 15, 2006, marked as "Enclosure C"
(English-language translation provided). cited by other .
"Strukturestueckliste" ("Structure Bill of Materials") for SCM 70
encoder of Max Stegmann GmbH, marked as "Enclosure D"
(English-language translation provided) Nov. 20, 1997. cited by
other .
"Eidesstatliche Versicherung" ("Affirmation in Lieu of Oath")of
Josef Siraky, dated Jun. 20, 2006, marked as "Enclosure E"
(English-language translation provided). cited by other .
Invoice dated Jan. 23, 1998 of Max Stegmann GmbH to Indramat GmbH,
marked as "Enclosure F" (English-language translation provided).
cited by other .
Dip. Ing. Martin Dachroth, "Mini Disc (MiDi) Technology in Focus:
Optical MiDi Encoder with Centric Scanning," Sick/Stegmann Nov.
2004. cited by other .
T. Matoba et al., "Photosensor Array for Optical Encoder",
Electronics and Communications in Japan, Part II, Electronics, Bd.
75, Nr. 1, Jan. 1992, pp. 56-63. cited by other .
Examination Report dated Dec. 9, 2004, German Patent and Trademark
Office, German Application No. 198 55 307.2. cited by
other.
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Primary Examiner: Slomski; Rebecca C
Attorney, Agent or Firm: Kenyon & Kenyon LLP
Claims
What is claimed is:
1. A scanning unit for an optical position measuring device for
optically scanning a graduation of a scale to produce positionally
dependent scanning signals, the scanning unit comprising: a carrier
element; a first optoelectronic component disposed on the carrier
element and having a radiation-sensitive or radiation-emitting
surface region and contacting region, the surface region facing
away from the carrier element; an encapsulant arranged in the
contacting region of the first optoelectronic component; a first
electrically conductive connector lead disposed between the carrier
element and the contacting region, the first connector lead having
a first height in the contacting region; and an at least
semi-transparent cover element, the cover element having the
graduation and a top side, the cover element being arranged
directly on the surface region so that the contacting region is not
covered by the cover element, a height of the top side exceeding
the first height.
2. The scanning unit as recited in claim 1 wherein the carrier
element is a board with integrated signal lines.
3. The scanning unit as recited in claim 1 wherein the cover
element is made of glass.
4. The scanning unit as recited in claim 1 wherein the cover
element is adhesively mounted on the first optoelectronic
component.
5. The scanning unit as recited in claim 1 wherein the first
connector lead is a bonding wire.
6. The scanning unit as recited in claim 1 wherein the first
optoelectronic component is a light source or a detector
element.
7. The scanning unit as recited in claim 1 wherein the cover
element has the graduation on a side facing the first
optoelectronic component.
8. The scanning unit as recited in claim 7 wherein the graduation
is a transmitting or scanning graduation scale.
9. The scanning unit as recited in claim 7 wherein the graduation
includes a plurality of subregions having subregion
graduations.
10. The scanning unit as recited in claim 1 further comprising a
second optoelectronic component disposed on the carrier element,
the first and second optoelectronic components being integrated in
a flat carrier substrate.
11. The scanning unit as recited in claim 10 wherein the cover
element is arranged over a surface region of the second
optoelectronic component, the cover element having a fine subregion
graduation at least in a subregion, the first and second
optoelectronic components being optoelectronic detector
elements.
12. The scanning unit as recited in claim 1 wherein the cover
element has a pocket-shaped recess in the contacting region.
13. The scanning unit as recited in claim 12 comprising support
elements, the cover element resting on the support elements in edge
regions adjacent to the recess.
14. A scanning unit for an optical position measuring device for
optically scanning a graduation of a scale to produce positionally
dependent scanning signals, the scanning unit comprising: a carrier
element; a first optoelectronic component disposed on the carrier
element and having a radiation-sensitive or radiation-emitting
surface region and contacting region, the surface region facing
away from the carrier element; a first electrically conductive
connector lead disposed between the carrier element and the
contacting region, the first connector lead having a first height
in the contacting region; and an at least semi-transparent cover
element, the cover element having the graduation, a top side, a
pocket-shaped recess in the contacting region, the cover element
being arranged directly on the surface region so that the
contacting region is not covered by the cover element, a height of
the top side exceeding the first height.[.. wherein the cover
element has.]. .
15. The scanning unit as recited in claim 14 further comprising
support elements, the cover element resting on the support elements
in edge regions adjacent to the recess.
16. A scanning unit for an optical position measuring device for
optically scanning a graduation of a scale to produce positionally
dependent scanning signals, the graduation includes a plurality of
subregions having subregion graduations, the scanning unit
comprising: a carrier element; a first optoelectronic component
disposed on the carrier element and having a radiation-sensitive or
radiation-emitting surface region and contacting region, the
surface region facing away from the carrier element; a first
electrically conductive connector lead disposed between the carrier
element and the contacting region, the first connector lead having
a first height in the contacting region; an at least
semi-transparent cover element, the cover element having the
graduation on a side facing the first optoelectronic component, the
cover element having a top side, the cover element being arranged
directly on the surface region so that the contacting region is not
covered by the cover element, a height of the top side exceeding
the first height; and an encapsulant arranged in the contacting
region of the first optoelectronic component.
17. The scanning unit as recited in claim 16 wherein the carrier
element is a board with integrated signal lines.
18. The scanning unit as recited in claim 16 wherein the cover
element is made of glass.
19. The scanning unit as recited in claim 16 wherein the cover
element is adhesively mounted on the first optoelectronic
component.
20. The scanning unit as recited in claim 16 wherein the first
connector lead is a bonding wire.
21. The scanning unit as recited in claim 16 wherein the first
optoelectronic component is a light source or a detector
element.
22. The scanning unit as recited in claim 16 wherein the graduation
is a transmitting or scanning graduation scale.
.Iadd.23. A scanning unit for an optical position measuring device
for optically scanning a graduation scale to produce positionally
dependent scanning signals, the scanning unit comprising: a carrier
element; a first optoelectronic component disposed on the carrier
element and having a radiation-sensitive or radiation-emitting
surface region and a contacting region, the surface region facing
away from the carrier element; an encapsulant arranged in the
contacting region of the first optoelectronic component; a first
electrically conductive connector lead disposed between the carrier
element and the contacting region, the first connector lead having
a first height in the contacting region; and an at least
semi-transparent cover element, the cover element having a
graduation and a top side, the cover element being arranged
directly on the surface region so that the contacting region is not
covered by the cover element, a height of the top side exceeding
the first height..Iaddend.
.Iadd.24. The scanning unit as recited in claim 23 wherein a height
of the encapsulant adjacent the cover element is substantially
equal to the height of the top side..Iaddend.
.Iadd.25. A scanning unit for an optical position measuring device
for optically scanning a graduation scale to produce positionally
dependent scanning signals, the scanning unit comprising: a carrier
element; a first optoelectronic component disposed on the carrier
element and having a radiation-sensitive or radiation-emitting
surface region and a contacting region, the surface region facing
away from the carrier element; a first electrically conductive
connector lead disposed between the carrier element and the
contacting region, the first connector lead having a first height
in the contacting region; and an at least semi-transparent cover
element, the cover element having a graduation, a top side, and a
pocket-shaped recess in the contacting region, the cover element
being arranged directly on the surface region so that the
contacting region is not covered by the cover element, a height of
the top side exceeding the first height..Iaddend.
.Iadd.26. A scanning unit for an optical position measuring device
for optically scanning a graduation scale to produce positionally
dependent scanning signals, the scanning unit comprising: a carrier
element; a first optoelectronic component disposed on the carrier
element and having a radiation-sensitive or radiation-emitting
surface region and a contacting region, the surface region facing
away from the carrier element; a first electrically conductive
connector lead disposed between the carrier element and the
contacting region, the first connector lead having a first height
in the contacting region; an at least semi-transparent cover
element, the cover element having a graduation on a side facing the
first optoelectronic component, the graduation including a
plurality of subregions having subregion graduations, the cover
element having a top side, the cover element being arranged
directly on the surface region so that the contacting region is not
covered by the cover element, a height of the top side exceeding
the first height; and an encapsulant arranged in the contacting
region of the first optoelectronic component..Iaddend.
.Iadd.27. The scanning unit as recited in claim 26 wherein a height
of the encapsulant adjacent the cover element is substantially
equal to a height of the top side..Iaddend.
.Iadd.28. The scanning unit as recited in claim 1 wherein a height
of the encapsulant adjacent the cover element is substantially
equal to the height of the top side..Iaddend.
.Iadd.29. The scanning unit as recited in claim 16 wherein a height
of the encapsulant adjacent the cover element is substantially
equal to the height of the top side..Iaddend.
.Iadd.30. A scanning unit for an optical position measuring device
for optically scanning a graduation scale to produce positionally
dependent scanning signals, the scanning unit comprising: a carrier
element; a first optoelectronic component disposed on the carrier
element and having a radiation-sensitive or radiation-emitting
surface region and a contacting region, the surface region facing
away from the carrier element; an encapsulant arranged in the
contacting region of the first optoelectronic component; a first
electrically conductive connector lead disposed between the carrier
element and the contacting region, the first connector lead having
a first height in the contacting region; and an at least
semi-transparent cover element, the cover element having a top
side, the cover element being arranged directly on the surface
region so that the contacting region is not covered by the cover
element, a height of the top side exceeding the first
height..Iaddend.
.Iadd.31. A scanning unit for an optical position measuring device
for optically scanning a graduation scale to produce positionally
dependent scanning signals, the scanning unit comprising: a carrier
element; a first optoelectronic component disposed on the carrier
element and having a radiation-sensitive or radiation-emitting
surface region and at least one contacting region, the surface
region facing away from the carrier element; an encapsulant
arranged at least in the at least one contacting region; a
electrically conductive connector lead disposed between the carrier
element and each contacting region, each connector lead
encapsulated in the encapsulant; and an at least semi-transparent
cover element, the cover element having a top side, the cover
element arranged directly on the surface region, the cover element
not covering any of the at least one contacting regions, a height
of the encapsulant adjacent the cover element substantially equal
to a height of the top side..Iaddend.
.Iadd.32. The scanning unit as recited in claim 31 wherein the
carrier element is a board with integrated signal
lines..Iaddend.
.Iadd.33. The scanning unit as recited in claim 31 wherein the
cover element is made of glass..Iaddend.
.Iadd.34. The scanning unit as recited in claim 31 wherein the
cover element is adhesively mounted on the first optoelectronic
component..Iaddend.
.Iadd.35. The scanning unit as recited in claim 31 wherein each
connector lead is a bonding wire..Iaddend.
.Iadd.36. The scanning unit as recited in claim 31 wherein the
first optoelectronic component is a light source or a detector
element..Iaddend.
.Iadd.37. The scanning unit as recited in claim 31 wherein the
cover element has a graduation..Iaddend.
.Iadd.38. The scanning unit as recited in claim 37 wherein the
graduation is a transmitting or scanning graduation
scale..Iaddend.
.Iadd.39. The scanning unit as recited in claim 37 wherein the
graduation includes a plurality of subregions having subregion
graduations..Iaddend.
.Iadd.40. The scanning unit as recited in claim 31 further
comprising a second optoelectronic component disposed on the
carrier element, the first and second optoelectronic components
integrated in a flat carrier substrate..Iaddend.
.Iadd.41. The scanning unit as recited in claim 40 wherein the
cover element is arranged over a surface region of the second
optoelectronic component, the cover element having a fine subregion
graduation at least in a subregion, the first and second
optoelectronic components being optoelectronic detector
elements..Iaddend.
.Iadd.42. The scanning unit as recited in claim 31 wherein the
cover element has a pocket-shaped recess in the contacting
region..Iaddend.
.Iadd.43. The scanning unit as recited in claim 42 comprising
support elements, the cover element resting on the support elements
in edge regions adjacent to the recess..Iaddend.
.Iadd.44. The scanning unit as recited in claim 37 wherein the
graduation is arranged on a side of the cover element facing the
first optoelectronic component..Iaddend.
.Iadd.45. The scanning unit as recited in claim 37 wherein the
graduation is arranged on the top side of the cover
element..Iaddend.
.Iadd.46. The scanning unit as recited in claim 31 wherein further
electronic evaluation components to process the scanning signals
are arranged on the carrier element..Iaddend.
.Iadd.47. The scanning unit as recited in claim 46 wherein at least
one further amplifier module is arranged on the carrier
element..Iaddend.
.Iadd.48. The scanning unit as recited in claim 46 wherein at least
one further interpolator module is arranged on the carrier
element..Iaddend.
.Iadd.49. The scanning unit as recited in claim 34 wherein the
cover element is adhesively mounted on the first optoelectronic
component by an adhesive that is transparent to an applied
wavelength..Iaddend.
.Iadd.50. The scanning unit as recited in claim 49 wherein the
adhesive does not contain any constituents which could diffuse into
an underlying component..Iaddend.
.Iadd.51. The scanning unit as recited in claim 39 wherein a
plurality of optoelectronic detector elements are arranged on the
carrier element and are covered with a single cover element, having
four partial areas with subregion graduations arranged in front of
radiation sensitive areas of the optoelectronic detector
elements..Iaddend.
.Iadd.52. A scanning unit for an optical position measuring device
for optically scanning a graduation scale to produce positionally
dependent scanning signals, the scanning unit comprising: a carrier
element; an optoelectronic component disposed on the carrier
element and having a radiation-sensitive or radiation-emitting
surface region and at least one contacting region, the surface
region facing away from the carrier element; an electrically
conductive connector lead disposed between the carrier element and
each contacting region; an at least semi-transparent cover element,
the cover element having a graduation, the graduation including a
plurality of subregions having subregion graduations, the cover
element having a top side, the cover element arranged directly on
the surface region, the cover element not covering any of the at
least one contacting regions; and an encapsulant arranged at least
in the at least one contacting region, each connector lead
encapsulated in the encapsulant, a height of the encapsulant
adjacent the cover element substantially equal to a height of the
top side..Iaddend.
.Iadd.53. The scanning unit as recited in claim 52 wherein the
carrier element is a board with integrated signal
lines..Iaddend.
.Iadd.54. The scanning unit as recited in claim 52 wherein the
cover element is made of glass..Iaddend.
.Iadd.55. The scanning unit as recited in claim 52 wherein the
cover element is adhesively mounted on the optoelectronic
component..Iaddend.
.Iadd.56. The scanning unit as recited in claim 52 wherein each
connector lead is a bonding wire..Iaddend.
.Iadd.57. The scanning unit as recited in claim 52 wherein the
optoelectronic component is a light source or a detector
element..Iaddend.
.Iadd.58. The scanning unit as recited in claim 52 wherein the
graduation is a transmitting or scanning graduation
scale..Iaddend.
.Iadd.59. The scanning unit as recited in claim 52 wherein the
graduation is arranged on a side of the cover element facing the
optoelectronic component..Iaddend.
.Iadd.60. The scanning unit as recited in claim 52 wherein the
graduation is arranged on the top side of the cover
element..Iaddend.
.Iadd.61. A position measuring device, comprising: a scale
graduation; and a scanning unit configured to optically scan the
graduation scale to produce positionally dependent scanning
signals, the scanning unit including: a carrier element; a first
optoelectronic component disposed on the carrier element and having
a radiation-sensitive or radiation-emitting surface region and at
least one contacting region, the surface region facing away from
the carrier element; an encapsulant arranged at least in the at
least one contacting region; a electrically conductive connector
lead disposed between the carrier element and each contacting
region, each connector lead encapsulated in the encapsulant; and an
at least semi-transparent cover element, the cover element having a
top side, the cover element arranged directly on the surface
region, the cover element not covering any of the at least one
contacting regions, a height of the encapsulant adjacent the cover
element substantially equal to a height of the top side..Iaddend.
Description
FIELD OF THE INVENTION
The present invention is related to a scanning unit for an optical
position measuring device.
RELATED TECHNOLOGY
Known optical position measuring devices include a scanning unit
which is movable in relation to a graduation scale and which is
used to produce positionally dependent scanning signals. For this,
a plurality of optoelectronic components, such as light sources,
designed as LEDs, and detector elements, designed as photoelements,
are generally configured on the scanning unit side. In this
context, scanning signals, which are modulated as a function of
displacement, are produced via the photoelements when the
graduation of the scale is scanned. As a general rule, the
photoelements are arranged on carrier elements, for example boards
or printed-circuit boards designed for this purpose. The
radiation-sensitive surface regions of the photoelements are
oriented to face away from the carrier member. Connector leads, or
bonding wires, which must be placed between the carrier element and
the contacting regions of the photoelements, are used for the
contacting of the photoelements. As in the case of the
radiation-sensitive surface regions, the contacting regions are
arranged on the side of the photoelements that faces away from the
carrier element. The connector leads constituted as bonding wires
must be reliably protected to ensure that no damage is caused
during the measuring operation by any scale movement in relation to
the scanning unit. A problem however arises especially when the
optical scanning principle selected for the particular case
stipulates a very small distance between the optoelectronic
components and the scale that is scanned by these components.
Therefore, to protect the connector leads, the European Patent No.
0 577 088 A2 proposes arranging the photoelements on the carrier
member, subsequently contacting these elements using bonding wires,
and thus applying a suitable transparent encapsulating material
over the contacting regions and the radiation-sensitive surface
regions of the photoelements. As a last step, the surface of the
encapsulating material is patterned to produce the required
scanning graduation. If, however, the optical scanning principle
selected in the particular case requires a smallest possible
distance between the radiation-sensitive surface regions of the
components and the scanning graduation, then the arrangement
proposed by European Patent No. 0 577 088 A2 is unsuitable.
Furthermore, an arrangement of this kind requires graduation of the
transparent encapsulant, and this cannot be done with the same
precision as can, for instance, graduation of a separate glass
scanning plate.
Equally unsuited for this kind of requirement for a small distance
between the radiation-sensitive surface regions and the scanning
graduation is an arrangement disclosed in U.S. Pat. No. 4,703,176.
It proposes placing a scanning plate having a suitable scanning
graduation at a finite distance above a plurality of optoelectronic
detector elements. In this context, the scanning plate extends with
its surface over the entire area of the detector elements,
inclusive of the corresponding, adjacent contacting regions. The
bonding wires for contacting the detector elements are protected
from mechanical damage in this case by the scanning plate disposed
above them. However, the distance provided between the
radiation-sensitive surface regions and the scanning graduation is,
again, too large for certain- optical scanning principles in
particular when a compact type of construction is needed.
It is furthermore known from Japanese Patent Document No. 09-189514
to arrange a transparent glass plate over a graduated detector
arrangement of a scanning unit, the glass plate being arranged and
dimensionally sized to protect the bonding wires required for the
contacting from mechanical damage during a measuring operation.
What is problematic in this case is that the detector elements in
this kind of scanning unit design already include the scanning
graduation, so the result is less flexibility when designing the
corresponding position measuring devices.
Fundamentally similar problems result when it is required to
arrange other optoelectronic components, such as light sources
having radiation-emitting surface regions, in conjunction with
prearranged transmitting graduations in a compact scanning unit of
an optical position measuring system.
SUMMARY OF THE INVENTION
An object of the present invention is to devise a scanning unit for
an optical position measuring device, which is able to provide
reliable protection from mechanical damage to connector leads even
with a required small distance between the radiation-sensitive or
radiation-emitting surface regions of optoelectronic
components.
The present invention provides a scanning unit for an optical
position measuring device, suited for optically scanning a scale
graduation structure (10), to produce positionally dependent
scanning signals on the basis of the scale graduation, comprising:
a) a carrier element (2; 21; 31) b) at least one optoelectronic
component (3a, 3b, 3c, 3d; 23a, 23b.123b.2, 23b.3, 23b.4, 23c; 33c,
33d), which is arranged on carrier element (2; 21; 31), a
radiation-sensitive or a radiation-emitting surface region of the
component (3a, 3b, 3c, 3d; 23a, 23b.123b.2, 23b.3, 23b.4, 23c; 33c,
33d) being oriented to face away from the carrier element (2; 21;
31); c) at least one electrically conductive connector lead (6a,
6b, 6c, 6d; 26a-26i; 36c, 36d) between the carrier element (2; 21;
31) and a contacting region (5a, 5b, 5c, 5d; 25a-25i; 35c, 35d) of
the component (3a, 3b, 3c, 3d; 23a, 23b.123b.2, 23b.3, 23b.4, 23c;
33c, 33d); and d) an at least semi-transparent cover element (4;
24; 34), which d1) at least in subregions has a graduation (7a, 7b,
7c, 7d; 27; 37c, 37d); and which d2) is arranged directly on the
radiation-sensitive and/or radiation-emitting surface region of the
component (3a, 3b, 3c, 3d; 23a, 23b.123b.2, 23b.3, 23b.4, 23c; 33c,
33d) in such a way that the contacting region (5a, 5b, 5c, 5d;
25a-25i; 35c, 35d) of the component (3a, 3b, 3c, 3d; 23a,
23b.123b.2, 23b.3, 23b.4, 23c; 33c, 33d) is not covered by it; and
d3) the thickness of the cover element (4; 24; 34) is selected so
as to ensure that the top side of the cover element (4; 24; 34)
exceeds the height (h.sub.B) of the connector lead (6a, 6b, 6c, 6d;
26a-26b; 36c, 36d) in the contacting region (5a, 5b, 5c, 5d;
25a-25i; 35c, 35d).
Further advantageous features of the present invention include
that: (a) the carrier element (2; 21; 31) may be designed as a
board with signal lines integrated therein; (b) the cover element
(4; 24; 34) may be made of glass; (c) the cover element (4; 24; 34)
may be adhesively mounted on the component (3a, 3b, 3c, 3d; 23a,
23b.123b.2, 23b.3, 23b.4, 23c; 33c, 33d); (d) the connector lead
(6a, 6b, 6c, 6d; 26a-26i; 36c, 36d) may be constituted as bonding
wire; (e) an encapsulant, i.e. an encapsulating material, (8) may
be arranged in the contacting region (5a, 5b, 5c, 5d; 25a-25i) of
the component (3a, 3b, 3c, 3d; 23a, 23b.1, 23b.2, 23b.3, 23b.4,
23c); (f) the optoelectronic component (3a, 3b, 3c, 3d; 23a, 23b.1,
23b.2, 23b.3, 23b.4, 23c; 33c, 33d) may be designed as a light
source or as a detector element; (g) the cover element (4; 24; 34)
may have a graduation on- the side that faces the component (3a,
3b, 3c, 3d; 23a, 23b.1, 23b.2, 23b.3, 23b.4, 23c; 33c, 33d); (h)
the graduation may be designed as a transmitting or scanning
graduation scale; (i) a plurality of subregions, i.e. partial
regions, having graduations (7a, 7b, 7c, 7d) may be arranged on the
cover element (4); (j) a plurality of optoelectronic components
(23a, 23b.1, 23b.2, 23b.3, 23b.4, 23c) may be arranged on the
carrier element (21) as components integrated in a flat carrier
substrate (23); (k) the cover element (24) arranged over the
optoelectronic components (23a, 23b.123b.2, 23b.3, 23b.4, 23c) may
bear a fine graduation (27) at least in subregions, and a plurality
of components (23b.1, 23b.2, 23b.3, 23b.4) may be designed as
optoelectronic detector elements that are integrated in the carrier
substrate (23); (1) the cover element (34) has a pocket-shaped
recess (39c, 39d) in the contacting region (35c, 35d); and/or (m)
in the edge regions adjacent to the recess (39c, 39d), the cover
element (34) may rest on support elements (38a, 38b).
By applying the measures of the present invention, it is easily
possible to prevent mechanical damage to the contacting regions of
the detector elements or to the corresponding contacting leads.
Thus, this area of the scanning unit can be reliably protected,
even when working with a small scanning distance, a small distance
between the scanning unit and a scale graduation scanned by it.
In one possible specific embodiment of the scanning unit according
to the present invention, it is also possible to realize a very
small distance between a radiation-sensitive surface region of a
detector element and the required scanning graduations, so that a
total system results having an altogether very compact type of
construction.
Since the graduation provided in front of the particular intended
component is arranged in each case on a separate covering element,
this component can be manufactured independently of the carrier
element or of the optoelectronic components, ie generally known
precision graduation methods can be used for this purpose. On the
other hand, it is not possible to pattern encapsulant with this
kind of precision.
Furthermore, in another specific embodiment of the scanning unit
according to the present invention, besides a graduation on the
covering element, an-additional graduation of the component in
question can also be provided on its radiation-sensitive or
radiation-emitting surface region. It is also possible in such a
variant for the components to be additionally designed as an
integral component of the carrier element.
Another variant provides for configuring recesses or pockets in the
vicinity of the contacting leads on the covering element side. The
recesses, i.e., the remaining thickness of the covering element, in
these regions are dimensionally sized to protect the contacting
leads. This specific embodiment proves to be favorable for
miniaturized scanning units, in particular, since an adequate
bearing surface is then available for the covering element.
Of course, scanning units designed in accordance with the present
invention are able to be used both in conjunction with linear
measuring systems, as well as in conjunction with rotary measuring
systems.
BRIEF DESCRIPTION OF THE DRAWINGS
Further advantages of, as well as details pertaining to the
scanning unit of the present invention are revealed in the
following description of exemplary embodiments, on the basis of the
figures, in which:
FIG. 1a shows a schematized, side sectional view of a first
specific embodiment of the scanning unit according to the present
invention in conjunction with a scale graduation scanned
therewith;
FIG. 1b shows a plan view of the scanning unit of FIG. 1a;
FIG. 2a shows a schematized, side sectional view of a second
specific embodiment of the scanning unit according to the present
invention;
FIG. 2b shows a plan view of the scanning unit of FIG. 2a; and
FIG. 3 shows a schematized, side sectional view of a third specific
embodiment of the scanning unit according to the present
invention.
DETAILED DESCRIPTION
A first specific embodiment of a scanning unit designed in
accordance with the present invention is, elucidated in the
following on the basis of the two FIGS. 1a and 1b. FIG. 1a shows a
schematic sectional view of a scanning unit 1 according to the
present invention in conjunction with a linear graduation scale 10
which bears an incremental graduation and is scanned by the
scanning unit. In this exemplary embodiment, an incident-light
measuring system (reflective light system) is shown, i.e., the
incremental scale graduation 10 is composed in a generally known
way of periodically arranged reflecting and non-reflecting regions.
Of course, the measures of the present invention elucidated in the
following can also be used in measuring systems of a different
design, for example in code measuring systems, transmitted light
measuring systems, etc. Moreover, provision can also be made, of
course, for a plurality of incremental graduations arranged in
parallel, i.e., reference marks on the scale, etc. Scanning unit 1
and graduation scale 10 are arranged so as to be movable in
relation to one another in measuring direction, x and coupled, for
example, to the tool and workpiece of a numerically controlled
machine tool, when the positions of the tool and the workpiece in
relation to one another need to be determined with great
precision.
In this case, scanning unit 1 according to the present invention
includes a carrier element 2, upon which are arranged
optoelectronic components 3a, 3b, 3c, 3d designed as detector
elements, used for detecting light reflected by graduation scale 10
and modulated as a function of position. Photoelements are
preferably used for this purpose. Printed-circuit boards or
suitable boards with printed circuit traces arranged therein are
suitable for use as carrier element 2. In addition, evaluation
elements may be arranged in integrated form in or on carrier
element 2. A light source, preferably designed as an LED, is
provided on the side of scanning unit 1.
Detector elements 3a-3d are configured with their
radiation-sensitive surface regions facing away from carrier
element 2, these regions are oriented in the direction of scanned
graduation scale 10. Arranged directly on the radiation-sensitive
surface regions of detector elements 3a-3d is, in addition, an at
least semi-transparent platelike cover element 4, preferably made
of glass. In this specific embodiment of scanning unit 1 of the
present invention, cover element 4 is usually denoted as a scanning
unit plate; Cover element 4 is dimensionally sized with respect to
its planar dimensions, i.e., length 1 * width b and arranged on
detector elements 3a-3b in such a way that the lateral contacting
regions 5a, 5b, 5c, 5d of these components 3a-3d are not covered by
cover element 4. It is thus ensured that in each case, in these
contacting regions 5a-5d, at least one electrically conductive
connector lead 6a, 6b, 6c, 6d can be applied, which is connected,
on the other hand, to carrier element 2 or to printed circuit
traces arranged thereon. Connector leads 6a-6d are conventional
bonding wires, which connect components 3a-3d to the circuit
traces--not shown--on carrier element 2. This enables a connection
to be established with downstream evaluation elements, in which
scanning signals are processed in a known manner. Evaluation
elements of this kind, such as amplifier modules, interpolator
modules, etc. can be arranged on carrier element 2, as well as
moved spatially away therefrom.
In the depicted exemplary embodiment, cover element 4 has
altogether four flat partial regions, each having a graduation 7a,
7b, 7c, 7d arranged therein. Provided here in each case as
graduations 7a, 7b, 7c, 7d are periodic grating structures, which
are alternately transparent or opaque (impervious) to the applied
wavelength. The partial regions having graduations 7a-7d are each
arranged in front of the radiation-sensitive surface regions of
detector elements 3a-3d and are used, accordingly, in a well known
manner as scanning gratings when optically scanning incremental
graduation scale 10.
As is evident, in particular, from the sectional view in FIG. 1a,
cover element 4 in this specific form is provided with a graduation
on that side which directly faces the radiation-sensitive surface
regions of the subjacent detector elements 3a-3d. A suitable
adhesive is used in this case to secure cover element 4 to the
radiation-sensitive surface regions of detector elements 3a-3d. In
this context, this adhesive should be transparent to the applied
wavelength and not contain any constituents which could diffuse
into the underlying component.
For protection of contacting regions 5a-5d and, in particular, of
electrical connector leads 6a-6d, the resulting layer thickness
h.sub.A, which includes the thickness of cover element 4, of the
adhesive layer, as well as the thickness of detector elements
3a-3d, are selected as follows. The present invention provides for
this thickness h.sub.A to be selected so that the top side of cover
element 4 exceeds height h.sub.B of connector lead 6a-6d in
contacting region 5a-5d, i.e., one selects h.sub.A>h.sub.B. The
resulting edge structure thus ensures in a simplest manner that
bonding wires 6a-6d are protected in this region from any
mechanical damage caused by scale graduation 10 that is movable in
relation to the bonding wires. This is also the case when merely a
small (scanning) distance is provided between scanning unit 1 and
graduation scale 10. In practical applications, the thickness
h.sub.A to be preferably selected is about
h.sub.A.gtoreq.h.sub.B+0.1 mm.
To still additionally protect electrical connector leads 6a-6d in
the contacting region, finally provision can also be made, as in
the illustrated exemplary embodiment, after cover element 4 has
been placed over the radiation-sensitive surface regions of
detector elements 3a-3d and the contacting has taken place, for an
encapsulant 8 to be deposited in the region of the leads as shown
in FIG. 1a. For this purpose, so-called "glob top" encapsulants are
suitable, for instance.
While in the illustrated exemplary embodiment of FIGS. 1a and 1b,
the measures of the present invention were elucidated in
conjunction with the detector elements, reference is also made at
this point to the fact that identical measures can likewise be
employed for other optoelectronic components in scanning units of
optical position measuring systems. Thus, it is possible, for
instance, at any time to protect the contacting regions from other
optoelectronic components, such as light sources, in the form of
LEDs, in identical fashion. In this case, a cover element can
likewise be arranged in the manner described directly in front of
the radiation-emitting surface regions of the LEDs. In this
context, the cover element can likewise contain subregions having a
graduation, which then function as a transmitting graduation scale
or transmitting grating in the scanning unit. The measures of the
present invention are thus able to be applied to other
optoelectronic components.
FIGS. 2a and 2b elucidate a second possible specific embodiment of
the scanning unit according to the present invention. While FIG.
2a, in turn, shows a lateral, schematized sectional view, a plan
view of one part of the scanning unit is shown in FIG. 2b.
In this specific embodiment, a flat carrier substrate 23 is
arranged on a carrier element 21. This carrier substrate 23 is made
of a semiconductor material, which includes individual subregions
having different functions. Thus, for instance, individual
subregions are designed as detector elements 23a, 23b.123b.2,
23b.3, 23b.4, 23c, whose radiation-sensitive surface regions are
oriented, in turn, away from carrier element 21. Other subregions,
for example, can already assume the function of evaluation
components, act as integrated evaluation elements. Moreover, on its
periphery, carrier substrate 23 also includes contacting regions
25a-25i, via which, in turn, an electrically conductive connection
can be established in each case among detector elements 23a,
23b.123b.2, 23b.3, 23b.4, 23c or other components integrated in
carrier substrate 23, as well as with evaluations elements arranged
downstream therefrom, by way of electrical connector leads 26a-26i
in the form of bonding wires.
Also arranged in this exemplary embodiment, in turn, over the
radiation-sensitive surface regions of detector elements 23a,
23b.123b.2, 23b.3, 23b.4, 23c is a cover element 24 in the form of
a glass plate having length l, width b, and thickness h.sub.A. As
in the preceding exemplary embodiment, cover element 24 is so
configured or arranged with respect to size and placement that
contacting regions 25a-25i of detector elements 23a, 23b.123b.2,
23b.3, 23b.4, 23c and possibly of other integrated components
arranged laterally next to the radiation-sensitive surface regions,
cannot be covered by them. Provision is made, in turn, at
contacting regions 25a-25i for connector leads 26a-26i in the form
of bonding wires, via which the electrically conductive connection
of the components on carrier substrate 23 is made with downstream
evaluation components.
Height h.sub.A, which includes the height of cover element 24 and
the height of carrier substrate 23 is selected, in turn, so that
h.sub.A>h.sub.B. Provision is thus made for the top side of
cover element 24 to exceed the height of connector leads 26a-26i in
contacting regions 25a-25i.
In this exemplary embodiment, a graduation 27 in front of the
radiation-sensitive surface region, i.e., a scanning unit
graduation is merely required for the middle detector element of
detector elements 23a, 23b.123b.2, 23b.3, 23b.4, 23c. In contrast
to the exemplary embodiment elucidated above, this graduation 27 or
scanning unit graduation is not arranged entirely on cover element
24; it is rather additionally provided to use a roughly graduated
detector element, one that already has a rough graduation as an
integral component of the radiation-sensitive surface region. For
this, four detector regions 23b.123b.2, 23b.3, 23b.4 are provided
in the illustrated example. A further graduation 27 in the form of
a fine grating graduation is arranged, as in the previous exemplary
embodiment, on the bottom side of cover element 24.
In principle, this exemplary embodiment can provide for arranging a
suitable encapsulant in contacting regions 26a-26i as an additional
protective measure.
A third possible specific embodiment of the scanning unit according
to the present invention is elucidated on the basis of FIG. 3,
which, in turn, shows a side sectional view of the same. With
respect to the components, etc. this exemplary embodiment
corresponds, in turn, to that of FIGS. 1a and 1b. The following
will refer merely to differences from the preceding variants.
Arranged on a carrier element 31, in turn, are one or a plurality
of detector elements 33c, 33d, whose radiation-sensitive surfaces
are oriented away from carrier element 31. Arranged directly on,
e.g., adhesively mounted on radiation-sensitive detector elements
33c, 33d is again cover element 34 in the form of a glass plate
having graduations 37c, 37d. Graduations 37c, 37d function more or
less, in turn, as scanning unit graduations.
To protect connector leads 36d, 36c provided in this specific
embodiment for contacting detector elements 33c, 33d, cover element
34 has pocket-shaped recesses 39c, 39d in contacting regions 35c,
35d. Recesses 39c, 39d, i.e., the residual thickness of cover
element 34 over recesses 39c, 39d, are dimensionally sized to
facilitate problem-free placement of connector leads 36d, 36c in
this region. Disposed above connector leads 36c, 36d in this
specific embodiment is the thinly formed cover element 34 in the
recess region. This protects contacting (connector) leads 36c, 36d,
so they cannot be damaged by the-scale graduation that is movable
in relation thereto. In the edge regions in question, cover element
34 rests on support elements 38a, 38b, which are arranged on
carrier element 31. Recesses 39c, 39d in glass cover element 34 are
able to be fabricated and dimensionally sized to achieve the
desired result using an ultrasonic boring method.
Of course, the measures elucidated on the basis of the second and
third exemplary embodiment can also be implemented in conjunction
with other optoelectronic components, such as light sources, etc.
The individual measures elucidated on the basis of the exemplary
embodiments can, of course, also be combined and altered.
Semi-transparent as used herein means partially transparent.
* * * * *