U.S. patent application number 12/782384 was filed with the patent office on 2010-11-04 for laboratory instrument with a protected working compartment.
This patent application is currently assigned to METTLER-TOLEDO AG. Invention is credited to Bruno Nufer, Siegfried Zeiss.
Application Number | 20100276213 12/782384 |
Document ID | / |
Family ID | 39295603 |
Filed Date | 2010-11-04 |
United States Patent
Application |
20100276213 |
Kind Code |
A1 |
Zeiss; Siegfried ; et
al. |
November 4, 2010 |
LABORATORY INSTRUMENT WITH A PROTECTED WORKING COMPARTMENT
Abstract
A laboratory instrument with a housing containing a weighing
cell has a working compartment that is connected to the housing.
The working compartment has a floor, a top cover, a rear wall, a
front wall and two sidewalls. Arranged in the working compartment
is a load receiver which is connected to the weighing cell. Also
connected to the housing is at least one guiding device which
serves to guide a linear movement and simultaneous swivel movement
of individual portions of the front wall or the entire front
wall.
Inventors: |
Zeiss; Siegfried;
(Wolfhausen, CH) ; Nufer; Bruno; (Illnau,
CH) |
Correspondence
Address: |
STANDLEY LAW GROUP LLP
6300 Riverside Drive
Dublin
OH
43017
US
|
Assignee: |
METTLER-TOLEDO AG
Greifensee
CH
|
Family ID: |
39295603 |
Appl. No.: |
12/782384 |
Filed: |
May 18, 2010 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
PCT/EP2008/063266 |
Oct 3, 2008 |
|
|
|
12782384 |
|
|
|
|
Current U.S.
Class: |
177/180 |
Current CPC
Class: |
E05D 15/408 20130101;
E06B 3/5045 20130101; E05Y 2900/538 20130101; G01G 21/286 20130101;
E05Y 2900/20 20130101; E05D 1/04 20130101; E05Y 2900/60 20130101;
E05D 1/02 20130101 |
Class at
Publication: |
177/180 |
International
Class: |
G01G 21/28 20060101
G01G021/28 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 19, 2007 |
EP |
07121016.5 |
Claims
1. A laboratory instrument having a working compartment with access
from three sides thereof when at least partially opened, the
instrument comprising: a housing that contains a weighing cell and
which comprises a floor, a top cover, a front and a rear wall, and
a pair of sidewalls that delimit the working compartment, the
sidewalls and the front wall each being arranged to slide linearly
between a closed position and an open position, a load receiver,
arranged in the working compartment and connected to the weighing
cell; and at least one guiding device that guides the front wall,
as a unit or as a plurality of coupled portions, in an angular
swivel movement, as well as the linear sliding movement, between
the open and closed positions, such that simultaneous at least
partial opening of each of the two sidewalls and the front wall
provides the access.
2. The laboratory instrument of claim 1, wherein: an angle of
swivel of the front wall, as a unit or as a plurality of coupled
portions, relative to the housing is dependent upon a linear
displacement distance of the front wall from the closed
position.
3. The laboratory instrument of claim 2, wherein: the rear wall and
the floor of the working compartment are wall portions of the
housing.
4. The laboratory instrument of claim 1, wherein: the at least one
guiding device has at least one horizontally oriented swivel
axis.
5. The laboratory instrument of claim 1, wherein: the at least one
guiding device has at least one vertically oriented swivel
axis.
6. The laboratory instrument of claim 1, wherein: the front wall is
configured as a plate-shaped rigid unit; and the at least one
guiding device comprises: at least one swivel-pivoted linear guide
of the front wall; and at least one means for guiding, arranged
between the front wall and the housing and serving to control the
swivel movement dependent on a linear displacement distance of the
front wall from the closed position.
7. The laboratory instrument of claim 6, wherein: the at least one
swivel-pivoted linear guide is arranged on the top cover in the
area of a front edge or of a lateral edge.
8. The laboratory instrument of claim 6, wherein: the guiding means
is selected from the group consisting of: a swiveling connector
link, a guiding rail, a pull-cord arrangement and a guide groove
with a guide body.
9. The laboratory instrument of claim 6, wherein: the guiding means
is a drive mechanism control device which controls a drive source
for the swiveling movement of the front wall, dependent on the
linear displacement movement of a linear drive source of the front
wall.
10. The laboratory instrument of claim 6, wherein: the at least one
swivel-pivoted linear guide comprises a swivel pivot and, serving
to guide the linear movement of the front wall, at least one of: a
guide rail, a guide groove, a guide roller or a guide body.
11. The laboratory instrument of claim 6, further comprising: a
positioning ledge, arranged in the area of the front edge of the
floor and serving to provide a stable seat for the front wall.
12. The laboratory instrument of claim 11, wherein: the positioning
ledge has a groove with a V-shape or a U-shape.
13. The laboratory instrument of claim 1, wherein: the front wall
is a single piece that is elastically flexible or is a
configuration of a plurality of lamellar sections that are
articulately connected to each other; and the at least one guiding
device comprises a guide track or a guide groove.
14. The laboratory instrument of claim 1, further comprising: a
seal for the working compartment is provided on at least one of:
the sidewalls, the top cover, the front wall and, if present, the
positioning ledge.
15. The laboratory instrument of claim 1, wherein: the top cover is
arranged for linear sliding movement relative to the housing.
16. The laboratory instrument of claim 1, wherein: the at least one
drive mechanism is connected to at least one of: the sidewalls, the
top cover and the front wall.
17. The laboratory instrument of claim 3, wherein: the front wall
is configured as a plate-shaped rigid unit; and the at least one
guiding device comprises: at least one swivel-pivoted linear guide
of the front wall; and at least one means for guiding, arranged
between the front wall and the housing and serving to control the
swivel movement dependent on a linear displacement distance of the
front wall from the closed position.
18. The laboratory instrument of claim 3, wherein: the front wall
is a single piece that is elastically flexible or is a
configuration of a plurality of lamellar sections that are
articulately connected to each other; and the at least one guiding
device comprises a guide track or a guide groove.
19. A laboratory instrument having a working compartment with
access from three sides thereof when at least partially opened, the
instrument comprising: a housing that contains a weighing cell and
which comprises a floor, a top cover, a front and a rear wall, and
a pair of sidewalls that delimit the working compartment, the
sidewalls and the front wall each being arranged to slide linearly
between a closed position and an open position, the rear wall and
the floor being wall portions of the housing; a load receiver,
arranged in the working compartment and connected to the weighing
cell; and at least one guiding device that guides the front wall,
which is configured as a plate-shaped rigid unit, in an angular
swivel movement, as well as the linear sliding movement, between
the open and closed positions, the swivel movement having an angle
of swivel that depends upon a linear displacement distance of the
front wall from the closed position, each of the at least one
guiding devices comprising: at least one swivel-pivoted linear
guide of the front wall; and at least one means for guiding,
arranged between the front wall and the housing, that controls the
swivel movement dependent on a linear displacement distance of the
front wall from the closed position, such that simultaneous at
least partial opening of each of the two sidewalls and the front
wall provides the access.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation under 35 USC .sctn.120 of
PCT/EP2008/063266, filed 3 Oct. 2008, which is in turn entitled to
benefit of a right of priority under 35 USC .sctn.119 from European
patent application 07 12 1016.5, which was filed 19 Nov. 2007. The
content of each of the applications is incorporated by reference as
if fully recited herein.
TECHNICAL FIELD
[0002] The disclosed embodiments relate to a laboratory instrument
with a working compartment, a housing which contains a weighing
cell, and a load receiver which is arranged in the working
compartment and connected to the weighing cell, further with a
floor, a top cover, a rear wall, a front wall and two sidewalls,
which delimit the working compartment against the surrounding space
of the laboratory instrument.
BACKGROUND OF THE ART
[0003] Laboratory instruments of this kind serve for example as
analytical balances in many fields of industry, particularly in
laboratories of research- and development departments, and also in
production facilities, for example in quality control.
[0004] An analytical balance with a working compartment is
described in detail in U.S. Pat. No. 4,700,793 A, which is
commonly-owned, although now expired. Analytical balances are
balances with a high resolution of the weighing result.
Consequently, even the smallest extraneous influences affecting the
weighing object or the load receiver can cause an error in the
weighing result. The extraneous influence factors are rarely
stable, and this can lead to situations where the exact weight of
the weighing object cannot be determined. To protect the weighing
system from being influenced by the ambient environment, a working
compartment is therefore enclosed with a so-called draft
shield.
[0005] As described in U.S. Pat. No. 4,700,793 A, the draft shield
of an analytical balance has in most cases two slidable sidewalls
and possibly also a slidable top cover, as the delivery of the
weighing material to the load receiver usually occurs from the
side, in some cases also from above. Normally, the front wall is
rigidly connected to the housing of the balance, acting as a
supporting element and thereby lending stability to the draft
shield. Whenever possible, "slicing" closure means are preferred,
meaning that for example slidable sidewalls are preferred over
swiveling sidewalls. The closure means in the present context are
referred to as "slicing" if in their opening and closing movements
they slice the air and thus cause only a very small amount of air
movement. This helps that the air inside the working compartment
comes to rest very quickly. In addition, the air in the working
compartment is shifted around only to a minimal extent, so that the
temperature inside the weighing compartment can settle into a
relatively stable profile over the height of the weighing
compartment. In comparison, closure means that swivel will set
large air masses into motion inside the weighing compartment. For a
short time during opening and closing, a pressure difference occurs
between the working compartment and the ambient space, with the
pressure then equalizing itself through leaks in the draft shield,
whereby air movements are caused again inside the working
compartment.
[0006] A draft shield further needs to be of a stable design to
hold its shape, so that harmful air movements of the ambient
environment will not deform the walls and no air movements which
could occur as a result of such deformations will propagate into
the working compartment.
[0007] To facilitate the cleaning of the working compartment and in
particular the sidewalls, a draft shield is proposed in
commonly-owned U.S. Pat. No. 6,686,545 B2, whose front wall and
sidewalls can be released from a form-fitting attachment by means
of a swivel movement and can be removed from the balance through a
subsequent pulling movement. The top cover is connected by a linear
sliding guide to the balance housing which serves as rear wall and
can be pushed back horizontally over the balance housing, whereby
the draft shield is set open in the upward direction. Furthermore,
the top cover can also be separated from the linear sliding guide
by means of a swiveling movement.
[0008] With the trend to introduce time-optimized work processes,
one finds more and more applications where different operations are
performed, either simultaneously or following each other, directly
in the working compartment without repeatedly putting the weighing
object on and off the load receiver. This applies in particular to
the preparation of solutions or powder mixtures. The design of a
multi-functional working compartment is disclosed for example in
commonly-owned U.S. Pat. No. 6,603,081 B2. This reference
demonstrates how a multitude of devices such as for example
dosage-dispensing units, holder devices for source containers and
receiving containers, protective shield panels, indicator displays
and the like can be installed on a temporary basis in the working
compartment in a way that is optimized for a specific work process.
As a result, an analytical balance which was originally designed
only for weighing becomes a multi-functional laboratory
instrument.
[0009] The draft shield devices of the known state of the art are
optimized primarily for putting a weighing object on the load
receiver and/or removing the weighing object after the weighing.
These movements normally occur from the side, so that a serial
weighing process involving a plurality of weighing objects can be
performed in an optimal way for example if the objects to be
weighed are delivered to the load receiver from the left side and,
after the weighing, are taken off the load receiver from the right
side. Furthermore, the weighing materials can also be delivered to
the load receiver from above if the top cover is slidable.
[0010] However, the broadening of the functionality of the
laboratory instruments described above makes it necessary to
provide better access to the working compartment. It is therefore
the object to propose a working compartment which is improved in
regard to its accessibility during the work process.
SUMMARY
[0011] This task is solved by a laboratory instrument with the
features described in the independent claim 1.
[0012] A laboratory instrument comprising a housing containing a
weighing cell and further comprising a working compartment which is
delimited by a floor, a top cover, a rear wall, a front wall, and
two sidewalls. The two sidewalls are slidable in a linear movement
between an open position and a closed position. Also arranged in
the working compartment is a load receiver which is connected to
the weighing cell. The laboratory instrument comprising at least
one guiding device in an arrangement where the front wall, or
several parts of the front wall that are coupled to each other, are
guided by the guiding device so that they can slide in a linear
movement as well as swivel in an angular movement between an open
position and a closed position. As a result of the sidewalls being
slidable and the front wall being able to slide as well as swivel,
the working compartment is accessible from three sides if the
sidewalls and the front wall are in their open positions at the
same time. Of course, the sidewalls and the front wall can also be
set at intermediate positions in between the open and closed
positions, if necessary.
[0013] By having access from three sides, working in the working
compartment is made considerably easier. Access from the side in
this context refers only to the accessibility of the working
compartment by way of the approaches laid open by the sidewalls and
the front wall. The terms "top, bottom, front, rear, and side" as
used farther below refer to the spatial dimensions of a laboratory
instrument set up in a normal operating position.
[0014] The swivel angles of the front wall or of individual parts
of the front walls relative to the housing are tied to the linear
sliding displacement of the front wall. The swivel angle is always
enclosed between the swiveling part of the front wall and the
corresponding part of the housing. The swivel angle in the closed
position of the front wall is always 0.degree. and thus defines the
spatial direction of the corresponding part of the housing.
[0015] The front wall as described herein meets a long-felt need
for better accessibility of the working compartment, which the
designs of the known state of the art cannot offer. The reason why
this is not possible with state-of-the-art designs is that
laboratory instruments with a working compartment have to meet a
number of different requirements. On the one hand, the dimensions
of the instrument may not be too large, so that the instrument will
still fit into existing laboratory work stations. On the other
hand, accessibility through the sidewalls needs to be maintained
because, for example in the weighing of toxic substances the front
wall should stay closed in order to serve as a protective
shield.
[0016] The front wall with its ability to slide and swivel relative
to the housing, with the swivel angle being tied to the amount of
linear sliding displacement as a result of the guiding device,
provides in combination with the slidable sidewalls the ideal
solution to meet the foregoing requirements. First of all, access
to the working compartment is excellent, as the front wall in its
open position does not cover up any of the sidewalls and the
working compartment can therefore always be accessed from the side.
Second, the combined sliding and swiveling movement essentially
slices the air, and the influence of air turbulence which would be
caused by a pure swiveling movement is minimized. Third, with the
simultaneous swiveling of the front wall the free space that is
required above the working compartment is significantly reduced in
comparison to the space required with a purely linear sliding
movement of the front wall, which in turn leads to significantly
reduced height dimensions for example in fume hoods or glove
boxes.
[0017] A configuration where the rear wall and the floor of the
working compartment are wall portions of the housing is conducive
not only to a very compact design of the laboratory instrument but
also to a very stable, deformation-resistant working
compartment.
[0018] The at least one guiding device can have at least one
horizontally oriented swivel axis Y and/or at least one vertically
oriented swivel axis Z. Of course, the at least one guiding device
can have a horizontal as well as a vertical swivel axis at the same
time.
[0019] In a first embodiment of the laboratory instrument, the
front wall is configured as a plate-shaped rigid unit. The guiding
device of the plate-shaped front wall includes at least one
swivel-pivoted linear sliding guide as well as at least one guide
means which is arranged between the front wall and the housing and
serves to control the swivel movement by tying it to the linear
sliding movement.
[0020] With preference the at least one swivel-pivoted linear
sliding guide is arranged in the area of a front edge or in the
area of a lateral edge of the top cover. Furthermore, the guide
means can have the form of a swiveling connector link, a guiding
rail, a pull-cord arrangement or a guide groove with a guide
body.
[0021] However, the coordination which ties the swivel movement to
the linear sliding movement of the front wall does not necessarily
have to be accomplished by mechanical means. If mechanically
separate drive sources are provided for the swivel movement as well
as for the linear sliding movement of the front wall, the kinematic
profile of the two movements can be freely selected and, if
compatible with the way in which these drive sources are
controlled, it can also be changed in any desired way. To perform
such tasks, drive mechanisms with a piezoelectric element are
particularly well suited. They have the advantage that little space
is required to accommodate the drive source. The drive mechanism is
small and compact and can therefore be mounted in any desired
location. As a further advantage, the build-up of electrostatic
charges on the drive mechanism or any of its parts is avoided. The
drive mechanism is further free of any magnetic or magnetizable
parts which could interfere with the operation of a weighing cell
that is based on the principle of electromagnetic force
compensation.
[0022] The at least one swivel-pivoted linear guide preferably has
a swivel pivot and at least one guide rail, guide groove, guide
roller or guide body serving to guide the linear sliding movement
of the front wall. The guiding groove holds a guide portion of the
front wall. Ideally, there are two swivel-pivoted linear guides
which hold two opposite edge portions of the front wall, so that
the front wall is held captive in the linear guides but still
remains free to slide in a straight line. It is also conceivable
that at least one guide groove is arranged on at least one side of
the working compartment and the front wall is guided in the guide
groove by means of at least two guide bodies. A configuration of
this kind likewise contains the combination of the features of a
swivel-pivoted linear guide and a guide means and therefore must be
considered to form part of the invention.
[0023] In order to secure the closed front wall as much as possible
against horizontal movement through a stationary constraint, a
positioning ledge with a V-shaped and/or U-shaped channel can be
arranged in the front-edge area of the floor to serve as a stable
seat for the front wall.
[0024] In a second embodiment of the laboratory instrument, the
front wall can be designed either in one elastically flexible piece
with the ability to bend at a bending axis, or with a plurality of
lamellar sections which are articulately connected to each other.
As a guide for a front wall of this kind, the laboratory instrument
can have at least one guiding device which includes a guide track
or a guide groove. This guide track or guide groove extends along
two edges of the working compartment which meet at a corner of the
latter. Preferably, the guide track or guide groove does not change
direction abruptly in a sharp angle but rather forms a curve at
said corner. The guide track or guide groove is laid out in such a
way that the front wall in the open position does not cover up a
sidewall and thus does not prevent the sidewall from being
opened.
[0025] In order to protect the working compartment even better from
the influence of the ambient environment, the sidewalls and/or the
top cover and/or the front wall and/or the positioning ledge can be
provided with seals that serve to make the working compartment
airtight. A working compartment that is sealed off in this manner
can at the same time serve as a safety barrier, for example if the
work involves toxic substances.
[0026] Preferably, the sidewalls and/or the top cover and/or the
front wall are connected to at least one dedicated drive mechanism.
The latter can be configured in such a way that all walls are
opened simultaneously.
[0027] As a further possibility the front wall, for example, could
be divided horizontally, with the upper half being arranged so that
it can slide upwards and swiveled to the back about a horizontal
axis. The lower half could be configured with several parts, with
the swivel axis likewise arranged horizontally so that the lower
part of the front wall can be pushed into a space below the floor.
Using an analogous concept, the embodiment just described can also
be applied to an arrangement with vertically oriented swivel
axes.
BRIEF DESCRIPTION
[0028] Details of the laboratory instrument can be found in the
description of the embodiments that are shown in the drawings,
wherein:
[0029] FIG. 1 represents a laboratory instrument in a
three-dimensional view in a first embodiment, with a working
compartment shown in the closed state, whose sidewalls can be moved
along a straight line and whose front wall can be moved between an
open position and a closed position through a linear upward
movement while simultaneously swiveling backwards about a
horizontal swivel axis;
[0030] FIG. 2 is a side view of the laboratory instrument of FIG. 1
with a working compartment that is accessible from three sides,
shown in the open state;
[0031] FIG. 3 represents a laboratory instrument in a
three-dimensional view in a second embodiment, with a working
compartment whose front wall is of a multi-part configuration,
wherein the front wall sections can be moved sideways and towards
the back in straight lines, while at the same time individual
sections can swivel about a vertical swivel axis;
[0032] FIG. 4A is a plan view of a part of a flexible front wall
that is capable of elastic bending about a bending axis;
[0033] FIG. 4B is a sectional view the same part of the front wall
as FIG. 4A;
[0034] FIG. 5A is a plan view of a part of a front wall of a
multi-part configuration, whose lamellar sections are connected to
each other by connector elements that are capable of elastic
bending;
[0035] FIG. 5B is a sectional view of the same part of the front
wall as FIG. 5A;
[0036] FIG. 6A is a plan view of a part of a front wall of a
multi-part configuration, whose lamellar sections are connected to
each other by hinges which are formed on the lamellar elements;
and
[0037] FIG. 6B is a sectional view of the same part of the front
wall as FIG. 6A.
DETAILED DESCRIPTION
[0038] FIG. 1 shows a three-dimensional view of a laboratory
instrument 100 in a first embodiment, with a working compartment
110 shown in the closed state and with a housing 120 adjoining the
weighing compartment. The floor 111, the rear wall 112 and the top
cover 113 of the working compartment 110 are configured as parts of
the housing 120. The working compartment 110 is delimited at the
sides by two sidewalls 114, 115 which are guided by tracks 121, 122
and thereby constrained so that they can only slide to the back in
a linear movement. The working compartment 110 is delimited towards
the front by a plate-shaped rigid front wall 116.
[0039] The front wall 116 is constrained by two linear sliding
guides 125, 126 which are pivotally connected to the housing 120
and thus are part of a guiding device for the front wall 116. One
of the two linear sliding guides is arranged in each corner area of
the front edge 117 of the top cover 113 with the ability to pivot
about a horizontal swivel axis Y, so that two edges 118, 119 of the
front wall which lie opposite each other can be held by the linear
guides 125, 126. To allow the front wall 116 to be guided in linear
motion, each of the linear guides 125, 126 has a U-shaped
lengthwise groove which is matched to the dimensions of the edge
portions 118, 119 of the front wall 116. As the front wall is
folded back over the top cover, it does not encroach on the access
to the side walls.
[0040] Arranged between the front wall 116 and the housing 120 is a
guide means 130 which serves to constrain the swivel movement by
tying it to the linear sliding movement. The guide means 130 is
likewise part of the guiding device. The guide means 130 in this
embodiment is a simple connector link, whose ends are articulately
connected to the front wall 116 and to the housing 120,
respectively. The pivot axes of the guide means 130 are arranged
parallel to the swivel axis Y of the pivoted linear guides 125,
126. As soon as the front wall 116 is moved upwards, for example
manually or with the help of a drive mechanism, the guide means 130
also causes the front wall 116 to simultaneously tilt to the back
about a horizontal swivel axis. Of course, instead of a connector
link, one could also use flexible guide means, for example a
pull-cord arrangement.
[0041] Furthermore, instead of a connector link the guide means 130
can also consist of at least one guide groove and at least one
guide pin that is constrained in the guide groove. While this
configuration may tend to be more expensive to produce, it allows
the path of movement of the front wall 116 relative to the housing
120 to be brought into better agreement with the spatial situation
surrounding the laboratory instrument 100. It is also conceivable
that there is at least one guide groove on at least one side and
that the front wall 116 is guided in the guide groove by means of
at least two guide pins. A configuration of this kind combines the
features described above, i.e. a linear guide capable of swiveling
in combination with a guide means, and must therefore likewise be
considered as part of the invention.
[0042] However, the coordination which ties the swivel movement to
the linear sliding movement of the front wall does not necessarily
have to be accomplished by mechanical means. If mechanically
separate drive sources are provided for the swivel movement as well
as for the linear sliding movement of the front wall, the kinematic
profiles of the two movements can be freely selected as well as
changed in any desired way, if it is compatible with the way in
which these drive sources are controlled, specifically with the
control- and regulating device of the drive sources. To perform
such tasks, drive mechanisms with a piezoelectric element are
particularly well suited. They have the advantage that little space
is required to accommodate the drive source. The drive mechanism is
small and compact and can therefore be mounted in any desired
location. As a further advantage, the build-up of electrostatic
charges on the drive mechanism or any of its parts is avoided. The
drive mechanism is further free of any magnetic or magnetizable
parts which could interfere with the operation of a weighing cell
that is based on the principle of electromagnetic force
compensation.
[0043] FIG. 2 shows the laboratory instrument 100 of FIG. 1 in a
view from the side with the working compartment 110 in the open
state. All of the elements that were described in the context of
FIG. 1 carry the same reference symbols. With the front wall 116
being pushed up and swiveled to the back, and with the sidewalls
114 (one of them invisible) being pushed to the back, this
illustration offers an unobstructed view of the devices arranged in
the working compartment 110. Due to the front wall 116, these
devices are accessible from three sides, which improves and
simplifies the conditions for performing work inside the working
compartment 110 to an extraordinary degree. Installed in the
working compartment 110 is a dosage-dispensing device 140 whose
dispensing head 141 is arranged above a load receiver 150. The load
receiver 150 is functionally connected to a weighing cell (not
shown in the drawing) which is enclosed in the housing 120. The
weighing signals of the weighing cell are transmitted to a control-
and regulation unit 142, by means of which the outlet aperture of
the dispensing head 141 can be varied in response to the weighing
signal. To receive the dosage material delivered by the dispensing
head 141, a receiving container 160 is placed on the load receiver
150.
[0044] As is clearly evident from FIG. 2, the minimally required
free space above the laboratory instrument 100 is dictated by the
length of the guide means 130. Although FIG. 2 shows the front wall
only in the open position, it clearly illustrates that the swivel
angle .alpha. of the front wall 120 relative to the housing 120
depends on the linear distance s by which the front wall 116 has
been moved in relation to the housing 120.
[0045] Preferably, as many as possible of the parts that enclose
the working compartment 110, particularly the front wall 116 and
the sidewalls 114, 115 and possibly also the top cover 113 are made
of transparent material, so that the inside of the working
compartment 110 is visible from the outside also in the closed
position.
[0046] As already mentioned above, the working compartment should
be designed to be as stable as possible in regard to maintaining
its shape. In order to lend more stability to the front wall 116
when the latter is in its closed position, there can be a
positioning ledge 123 arranged in the area of the front edge of the
floor 111. The positioning ledge 123 has a V-shaped groove 124 in
which the bottom edge of the front wall 116 is seated when the
latter is in its closed position. Preferably, the edge portions of
the sidewalls 114, 115 that face towards the front wall 116 have
seals 128. In the groove 124, there can likewise be an elastic seal
129 arranged which not only seals the bottom-facing edge of the
front wall 116 but also, in case the front wall 116 is closed
manually, softens the impact in the groove 124. Furthermore, some
parts of the housing 120 can likewise be provided with seals 127 in
order to seal the working compartment 110 as tightly as possible
against the ambient environment of the laboratory instrument 100.
The sealing of the working compartment 110 can have a dual
function. First, air currents which affect the weighing signal are
kept away from the load receiver 150 and the receiving container
160. Second, the caulking and sealing of the working compartment
110 serves as a safety barrier for example if toxic pulverous
substances are to be dispensed in the weighing compartment 110.
[0047] Of course, the first embodiment of the preceding description
can also have a vertically oriented swivel axis instead of the
horizontally oriented swivel axis Y, in which case the front wall
116, logically, cannot be folded back over the top cover 113 but
rather over a sidewall 114, 115.
[0048] FIG. 3 shows a laboratory instrument 200 in
three-dimensional view in a second embodiment which likewise has a
housing 220 and a working compartment 210. The floor 211, the rear
wall 212 and the top cover 213 of the working compartment 210 are
configured as parts of the housing. The working compartment 210 is
delimited on the sides by two sidewalls 214, 215 which are guided
in tracks 221, 222 and can be pushed to the back in a straight-line
movement. The working compartment 210 is further delimited towards
the front by a front wall 216 which has a multi-part configuration.
It consists essentially of a plurality of lamellar sections 290
which are articulately connected to each other. The front wall 216
is guided by guide tracks 225, 226 arranged, respectively, in the
floor 211 and the top cover 213 and serving as guiding devices.
These guide tracks 225, 226 extend along the front edge and one
side of the laboratory instrument 200. These tracks have
essentially one guide groove in which guide bodies (not shown in
this drawing) are guided that are arranged at the lamellar sections
290. Depending on the configuration and the stability of the
arrangement, it is of course also possible to have only one guiding
device. As is clearly evident from FIG. 3, the guide track of the
front wall 216 is designed so that the front wall 216 moves over
the sidewall 215 when the latter is in its open position and the
lateral access to the working compartment 210 which has been freed
of the sidewall 215 is not covered up by the front wall.
[0049] Unlike the front wall shown in FIG. 2, with the
configuration of FIG. 3 only individual portions, i.e. lamellar
sections 290 of the front wall 216 are swiveled as a result of a
linear displacement s. It can also be clearly seen in FIG. 3 that
the swivel angle .beta. depends on the amount of linear
displacement s of the front wall 216 relative to the housing
120.
[0050] As shown in FIG. 3, the track 221 and the guide track 225
can be formed in one part in the area of the sidewall 214. When a
front wall 216 of a multi-part configuration, i.e. with articulated
sections, is combined with a guide track 225, 226 having a guide
groove, the parts or lamellar sections 290 of the front wall 216
can be moved in a linear displacement to the side and to the back,
while at the same time individual sections are swiveled about a
vertical swivel axis Z.
[0051] It is considered self-evident that various further
developments of this concept are conceivable, for example that the
front wall 216 is split vertically down the middle into two parts
and the first part can be pushed to the right side and the second
part to the left side of the laboratory instrument 200. Further
embodiments are also conceivable where the individual parts can be
swiveled about at least one horizontal swivel axis. This horizontal
swivel axis can be arranged in the area of the top cover 213 as
well as in the area of the floor 211 or in both areas.
[0052] Furthermore, combinations of the embodiment shown in FIG. 1
with the embodiment shown in FIG. 3 are definitely possible. For
example, the front wall could be split horizontally, with the upper
half being able to slide upwards and swivel to the back as in FIG.
1. The lower half could have a multi-part configuration analogous
to the embodiment of FIG. 3, with the swivel axis being arranged
horizontally, thereby allowing the lower part of the front wall to
be pushed back into a space below the floor.
[0053] FIGS. 4 to 6 show different design variants of multi-part
front walls of the kind used in the laboratory instrument
illustrated in FIG. 3.
[0054] In FIG. 4A, a first example is shown of a front wall 316
that has a plurality of sections. The front wall 316, only a
portion of which is illustrated in a fragmentary view, is made of
one piece and designed with the flexibility to bend elastically
about a bending axis. To make the front wall 316 sufficiently rigid
to resist bending in the vertical direction but allowing it to flex
about a vertically arranged swivel axis, the front wall has a
plurality of bending zones 392 extending vertically and configured
as thin flexure joints. The thin flexure joints 392 are represented
more clearly in FIG. 4B which shows a sectional view of the
fragmentary portion of the front wall 316 that is shown in FIG. 4A.
To guide the front wall 316 in the guide means without jamming,
several guide bodies 391 are arranged along the border area 393 of
the front wall 316. It is considered self-evident that front walls
316 of this type can only be made of elastic materials for example
of a transparent polymer.
[0055] FIG. 5A shows in plan view a portion of a second embodiment
of a front wall 416 of multi-part configuration, whose individual
lamellar sections 490 are connected to each other by elastically
flexible connector elements 492. An arrangement of this kind is
particularly appropriate if the individual lamellar sections 490
are made of a relatively inflexible material, for example glass.
The structural composition of the front wall 416 can be seen even
better in FIG. 5B which represents a sectional view of the front
wall 416 of FIG. 5A. On the fork-shaped profiles of the elastically
flexible connector elements 492, glide-bearing points are formed
which are functioning as guide bodies in the guide tracks. Thus, it
is not necessarily required to install additional a guide
bodies.
[0056] FIG. 6A shows in plan view a portion of a front wall 516 of
multi-part configuration, whose individual lamellar sections 590
are connected to each other by hinges 597 which are formed on the
lamellar sections 590. As shown in FIG. 6B which represents a
sectional view of the front wall 516 of FIG. 6A, the hinge 597 is
divided into a hinge pin 598 and a hinge bracket 599. The lamellar
section 590 extends between the hinge pin 598 and the hinge bracket
599 and is integrally connected to them. As a result, the front
wall 516 in this multi-part configuration can be produced by using
a simple extrusion profile which can be cut into sections of equal
length, whereupon the individual sections can be connected by
sliding them into each other. Furthermore, a guide body 591 which
is arranged in the border area 593 can be formed of a portion of
the hinge pin 598 or can be solidly connected to the latter. The
front wall 516 further has an elastic seal 596 at its end section
590.
* * * * *