DE102017117512A1 - Method for producing a device for determining a density of a medium - Google Patents

Abstract

A method for producing a device for determining a density of a medium, comprising at least the following steps: - providing a quartz oscillator (S100) for generating an electrical oscillation with a specific frequency, a housing into which the quartz crystal is inserted, and a quartz oscillator electronics is arranged to control the quartz oscillator for generating the electrical oscillation and to provide a frequency-dependent output signal, - applying the quartz oscillator to a printed circuit board (S200) which has at least one evaluation unit and is designed so that the quartz oscillator is electrically applied after application is connected to the evaluation unit, so that the evaluation unit is supplied with the output signal, - puncturing the housing of the quartz oscillator (S300), so that the medium whose density is to be determined, can come into contact with the quartz crystal and the frequency of the quartz crystal i n Density of the density changed, wherein the housing is punctured such that at least one opening is introduced into the housing.

Description

The present invention relates to a method for producing a device for determining a density of a medium, a device for determining a density of a medium, and the use of a quartz oscillator for determining a density of a medium.

It is already known that a device with a tuning fork quartz crystal is used to determine a density of a medium. These tuning fork quartz crystals are commonly used as a sensor element without a housing, i. the tuning fork quartz crystal is open to the medium and exposed to the medium.

A disadvantage of the use of such tuning fork quartz crystals is that they are exposed to environmental influences during assembly, which can lead to the deposition and / or change the vibration behavior. Furthermore, it is also disadvantageous that due to the open use of the tuning fork quartz crystals these are not protected against mechanical effects during the actual measurement operation.

It is therefore an object of the invention to provide a device for determining a density of a medium, which is protected both during manufacture and assembly as well as in measuring operation from environmental influences and against mechanical effects.

The object is achieved by a method for producing a device for determining a density of a medium, a device for determining a density of a medium, and the use of a quartz oscillator for determining a density of a medium.

• - Bereitstellen eines Quarzoszillators, vorzugsweise in Form eines Uhrenquarzes, umfassend einen Schwingquarz, zur Erzeugung einer elektrischen Schwingung mit einer bestimmten Frequenz, vorzugsweise mit einer Frequenz von ca. 32,768 kHz, ein Gehäuse, in welches der Schwingquarz, vorzugsweise im Vakuum hermetisch, eingebracht ist und eine Schwingquarzelektronik, die dazu eingerichtet ist, den Schwingquarz zur Erzeugung der elektrischen Schwingung entsprechend anzusteuern und ein von der Frequenz abhängiges Ausgangssignal bereitzustellen;
• - Aufbringen, vorzugsweise in Form eines Lötschrittes, des Quarzoszillators auf eine Leiterplatte, welche zumindest eine Auswerteeinheit aufweist, und derartig ausgebildet ist, dass der Quarzoszillator nach dem Aufbringen elektrisch mit der Auswerteeinheit verbunden ist, so dass der Auswerteeinheit das Ausgangssignal zugeführt ist;
• - Punktieren des Gehäuses des Quarzoszillators, so dass das Medium, dessen Dichte bestimmt werden soll, in Kontakt mit dem Schwingquarz treten kann und die Frequenz des Schwingquarzes in Abhängigkeit der Dichte verändert, wobei das Gehäuse derartig punktiert wird, dass zumindest eine Öffnung in das Gehäuse eingebracht wird.

With regard to the method, the object is achieved by methods for producing a device for determining a density of a medium, in particular a gas, the method having at least the following steps:

• - Providing a quartz oscillator, preferably in the form of a quartz watch, comprising a quartz crystal, for generating an electrical oscillation with a certain frequency, preferably with a frequency of about 32.768 kHz, a housing in which the quartz crystal, preferably hermetically introduced in a vacuum and a quartz crystal electronics configured to appropriately drive the crystal for generating the electric oscillation and to provide a frequency dependent output signal;
• Applying, preferably in the form of a soldering step, the quartz oscillator to a printed circuit board which has at least one evaluation unit, and is designed such that the quartz oscillator is electrically connected to the evaluation unit after application, so that the evaluation unit is supplied with the output signal;
• - Dotting the housing of the quartz oscillator, so that the medium whose density is to be determined, can come into contact with the quartz crystal and the frequency of the quartz oscillator in dependence of the density is changed, wherein the housing is punctured such that at least one opening in the housing is introduced.

In the present case, a quartz oscillator is to be understood as a component to be used as a frequency standard in various electrical or electronic circuits. Such a quartz oscillator comprises an electronic circuit, which is introduced into a housing, for generating oscillations, which as a frequency-determining component contains an oscillating quartz located in a protective environment, in particular a protective environment having a vacuum. Thus, the quartz oscillator is a completely constructed oscillator circuit, which is available together with the frequency-determining oscillating quartz as a standard component. The term quartz oscillator is also intended to include so-called clock crystals, which produce a quartz frequency of 32.768 kHz or an integer multiple or an integral fraction of this frequency. The sine waves generated by the quartz crystal of the quartz watch are converted into square wave signals of the same frequency by an oscillator circuit.

According to the invention, it is proposed that such a standard component is used to determine the density of the medium and that the standard component is punctured after assembly or after application to the printed circuit board, so that the medium to be measured comes into contact or interact with the quartz crystal can.

The solution according to the invention has the advantage that during the mounting of the quartz oscillator on the circuit board of the quartz crystal is still protected by the not yet punctured at this time housing. After assembly, the housing is punctured and serves during the actual measurement operation the protection of the quartz crystal from mechanical influences, which could damage or influence the quartz crystal. Furthermore, the solution according to the invention has the advantage that by simple modification of a standard component, which due to the high quantities in which it is manufactured inexpensively acquirable, the density of the medium can be determined.

An advantageous embodiment of the method provides that the housing is punctured in such a way that further openings are introduced into the housing. In particular, the embodiment can provide that the housing is punctured such that at least the further openings are formed so that particles with a geometric equivalent diameter smaller than 35 microns, preferably less than 30 microns, more preferably less than 25 microns in the housing through the other openings can penetrate, so that at least the other openings serve as a particulate filter. Through the further openings which are generated by the further puncturing, a filter is formed, which protects the underlying quartz crystal against mechanical effects, such as. Particles.

By the equivalent diameter is meant a measure of the size of an irregularly shaped particle such as a grain of sand. It is calculated by comparing a property of the irregular particle with a property of a regularly shaped particle. The geometric equivalent diameter is obtained by determining the diameter of a sphere or circle with the same geometric property (surface area, volume or projection area) as the irregularly shaped particle.

A further advantageous embodiment of the method provides that the housing is punctured such that at least one opening by means of a mechanical tool, in particular a punching iron, is introduced into the housing. In particular, the embodiment can provide that the housing is punctured such that the further openings, preferably by means of a laser, are introduced into the housing after the at least one opening has been introduced by means of the mechanical tool and / or that introduced by means of the mechanical tool at least one opening after the introduction of the further openings is closed again by means of the laser.

A further advantageous embodiment of the method provides that the housing is punctured in such a way that the at least one opening and / or the further openings are introduced into the housing by means of a pulsed laser, in particular a picosecond or higher pulsed laser.

• - einen Quarzoszillator, umfassend einen Schwingquarz, vorzugsweise in Form eines Uhrenquarzes, zur Erzeugung einer elektrischen Schwingung mit einer bestimmten Frequenz, vorzugsweise mit einer Frequenz von ca. 32,768 kHz, ein Gehäuse, in welches der Schwingquarz eingebracht ist und eine Schwingquarzelektronik, die dazu eingerichtet ist, den Schwingquarz zur Erzeugung der elektrischen Schwingung entsprechend anzusteuern und ein von der Frequenz abhängiges Ausgangssignal (Sout) bereitzustellen;
• - einen Leiterplatte, umfassend zumindest eine Auswerteeinheit, wobei der Quarzoszillator auf der Leiterplatte aufgebracht ist und elektrisch mit der Auswerteeinheit verbunden ist, so dass der Auswerteeinheit das Ausgangssignal der Schwingquarzelektronik zugeführt ist;

wobei in das Gehäuse des Quarzoszillators zumindest eine Öffnung eingebracht ist, damit das Medium, dessen Dichte bestimmt werden soll, in Kontakt mit dem Schwingquarz treten und die Frequenz des Schwingquarzes in Abhängigkeit der Dichte verändern kann, und die Auswerteeinheit dazu eingerichtet ist, anhand des Ausgangssignals, welches die veränderte Frequenz repräsentiert, die Dichte zu bestimmen.With regard to the device, the object is achieved by a device for determining a density of a medium, in particular of a gas, which has at least the following:

• - A quartz oscillator, comprising a quartz crystal, preferably in the form of a quartz watch, for generating an electrical oscillation with a certain frequency, preferably with a frequency of about 32.768 kHz, a housing in which the quartz crystal is introduced and a quartz crystal electronics, which set up is to drive the oscillating crystal to generate the electrical oscillation and to provide a frequency dependent output signal (Sout);
• a printed circuit board comprising at least one evaluation unit, wherein the quartz oscillator is mounted on the printed circuit board and is electrically connected to the evaluation unit, so that the evaluation unit is supplied with the output signal of the quartz crystal electronics;

wherein in the housing of the quartz oscillator at least one opening is introduced, so that the medium whose density is to be determined, come into contact with the quartz crystal and can change the frequency of the quartz oscillator depending on the density, and the evaluation unit is adapted to, based on the output signal representing the changed frequency to determine the density.

An advantageous embodiment of the device provides that in the housing further openings are introduced. In particular, the embodiment can provide that at least the further openings are formed so that no particles with a geometric equivalent diameter smaller than 35 microns, preferably less than 30 microns, more preferably less than 25 microns can penetrate into the housing through the other openings, so that at least the serve further openings as a particle filter.

A further advantageous embodiment of the device provides that the at least one opening and / or the further openings is or are designed essentially as circular openings.

Yet another advantageous embodiment of the device provides that the printed circuit board has a first region and a second region, wherein the quartz oscillator in the first region and the evaluation are arranged in the second region, wherein the device further comprises a glass feedthrough, which between the the first and second region is provided and the quartz oscillator is electrically connected via the glass feedthrough to the evaluation unit.

A last advantageous embodiment of the device provides that the quartz oscillator as intended serves as a frequency normal and by the at least one opening in the housing for measuring the density of the medium, which can penetrate through the at least one opening, is misused.

With regard to the use, the object is achieved by the use of a quartz oscillator for determining a density of a medium, the quartz oscillator comprising a quartz crystal, preferably in the form of a quartz crystal, for generating an electrical oscillation with a specific frequency, preferably with a frequency of about 32.768 kHz , a housing in which the quartz crystal is incorporated, and a quartz crystal electronic device adapted to drive the oscillating crystal to generate the electrical oscillation and to provide a frequency dependent output signal, wherein the housing is used to determine the density of the medium for use with the quartz oscillator is punctured such that at least one opening is introduced into the housing and the quartz oscillator is exposed to the medium, so that the density changes the frequency and, correspondingly, the output signal.

• 1: einen schematischen Ablauf eines erfindungsgemäßen Herstellungsverfahrens,
• 2: ein Draufsicht auf einen Quarzoszillator, dessen Gehäuse derartig punktiert ist, dass die Öffnungen einen Partikelfilter ausbilden, und
• 3: eine erfindungsgemäße Vorrichtung zur Bestimmung einer Dichte eines Mediums.
• 1 zeigt einen schematischen Ablauf des erfindungsgemäßen Herstellungsverfahrens, welches im Wesentlichen aus drei Verfahrensschritten besteht.

The invention will be explained in more detail with reference to the following drawings. It shows:

• 1 : a schematic sequence of a production method according to the invention,
• 2 FIG. 2: a plan view of a quartz oscillator whose housing is punctured in such a way that the openings form a particle filter, and FIG
• 3 A device according to the invention for determining a density of a medium.
• 1 shows a schematic sequence of the manufacturing method according to the invention, which consists essentially of three process steps.

In a first process step S100 becomes a quartz oscillator 3 provided in the form of a standard part. The quartz oscillator 3 in this case comprises a quartz crystal 4 , a quartz crystal electronics 6 and a housing 5 , The quartz crystal 4 and the quartz crystal electronics 6 are in the case 5 introduced and hermetically encapsulated to the environment. Furthermore, the housing 5 during production of the quartz oscillator 3 at least in some areas have been vacuumized, so that at least the quartz crystal 4 in the case 5 stored in a vacuum. About the quartz crystal electronics 6 becomes the quartz crystal 4 controlled such that it oscillates electrically with a predetermined frequency or resonance frequency, preferably in the form of a sinusoidal oscillation. Furthermore, the quartz crystal electronics 6 adapted to convert the generated oscillation into square wave signals of the same frequency and as an output signal Sout at an exit pin 16 of the quartz oscillator 3 provide. Such quartz oscillators 3 are, as previously mentioned, commercially available as separately designed components in a variety of variants. It is advantageous if as a quartz oscillator 3 a conventional quartz watch is provided because it is due to the high quantities in which it is produced, economically obtainable. Watch quartz has a crystal oscillating with a frequency of 32.768 kHz or an integer multiple or an integral fraction thereof.

In a second process step S200 becomes the quartz oscillator 3 on a circuit board 8th applied. The application can be carried out, for example, by a soldering step in which the quartz oscillator 3 on the circuit board 8th is soldered. The circuit board 8th has at least one evaluation unit 7 and is formed such that the soldered quartz oscillator 3 via conductor tracks electrically to the evaluation unit 7 connected, so that of the quartz crystal electronics 6 generated output signal of the quartz oscillator Sout the evaluation unit 7 is supplied.

In a third process step S300 becomes the case 5 of the quartz oscillator 3 dotted in such a way that the housing 5 at least one inlet opening 9 for the medium 2 having. The generation of the inlet opening 9 can be done in principle by any suitable mechanical tool or a laser. As a mechanical tool, the use of a punching punch has proven to be particularly advantageous. When using a laser, it has proved to be advantageous to use a pulsed laser, for example a picosecond or also a femtosecond laser, since during its use the housing material is abruptly evaporated and thus no material parts are drawn into the vacuum-sealed housing prior to puncturing as is the case when using a non-pulsed laser. However, a disadvantage of using a pulsed laser is that the machining of the housing is relatively expensive. Because of this, as an alternative to using the pulsed laser, the use of a combination of a mechanical tool and a non-pulsed laser has been used to puncture the housing 5 exposed. Here, first, the inlet opening 9 as an initial opening in the housing 9 by a mechanical tool, for example. A punching iron, introduced and then become more openings 10 in the case 9 introduced by a non-pulsed laser, insofar as further openings in the housing are desired.

In the third method step may further be provided that the housing 5 of the quartz oscillator 3 is punctured such that more openings 10 in the case 5 be introduced. The other openings 10 and if necessary the inlet opening serve as a particle filter 11 To avoid particles with a certain diameter in the housing 5 to arrive and thus the quartz crystal 4 to protect.

Accordingly, at least the other openings 10 in this case carried out such that no particles with a geometric equivalent diameter smaller than 35 microns, preferably less than 30 microns, more preferably less than 25 microns into the housing 5 can penetrate when the case 5 the medium 2 is exposed. In the simplest case, the other openings 10 as substantially circular openings introduced into the housing, which have a diameter of less than 35 microns, preferably less than 30 microns, more preferably less than 25 microns. Conceivable, however, are other geometric designs than the circular openings. For example. the openings may also be designed in the form of a slot, wherein the slot or ggfl. the slots are then designed so that no particles with a geometric equivalent diameter smaller than 35 microns, preferably less than 30 microns, more preferably less than 25 microns can penetrate into the housing. In the event that the combination of mechanical tool and the non-pulsed laser is used for puncturing the housing, it is necessary that the inlet opening, which was introduced as an initial opening by the mechanical tool in the housing, after the introduction of the other openings the non-pulsed laser, is closed again, since the inlet opening is significantly larger than the other openings. Closing the inlet opening 9 can be done, for example, by means of an adhesive or a soldering point.

A device manufactured according to the method described above can be used to determine the density of a medium, in particular a gas. For this purpose, the dotted quartz oscillator 3 the medium 2 be exposed so that the medium 2 in the case 5 penetrate and depending on its density can dampen the electrical oscillation. On the basis of the damped electrical oscillation can thus on the density of the medium 2 be inferred. For example, this can be an evaluation unit 7 serve, which is adapted to, based on the output signal Sout of the quartz oscillator 3 one for the present medium 2 determine the corresponding density. In first approximation, is in the evaluation unit 7 a linear relationship between the frequency of the electrical oscillation of the quartz crystal 4 and the density of the medium 2 deposited.

2 shows a quartz oscillator 3 whose case 5 is punctured in such a way that the openings have a particle filter 11 form. For this purpose is in the housing 5 an inlet opening 9 introduced as an initial opening by a punching punch and after the introduction of the other openings 10 closed again by a non-pulsed laser. The particle filter 11 is in 2 formed in the form of a 5 × 10 matrix and limited to a portion of one side of the surface of the housing. In principle, however, the invention is not limited to a specific m × n matrix. Rather, it has been found that it can be beneficial to use a matrix larger than 5x10. Furthermore, it has been found that it can also be advantageous if the formation of the matrix on at least one side of the housing 5 is distributed substantially completely.

3 shows a device according to the invention 1 for determining a density of a medium, for example in the form of a gas. The device in this case comprises a quartz oscillator 3 which is prepared or punctured as described above, a printed circuit board 8th on the one hand the quartz oscillator 3 and second, an evaluation unit 7 , For example, in the form of an ASIC or a microprocessor sits and a device housing 17 into which the circuit board 8th is introduced. The quartz oscillator 3 is in one at a first end of the circuit board 8th located first area 12 , and the evaluation unit 7 in a second area located at a second end of the circuit board opposite the first end 13 arranged. The electrical connection is here via printed conductors of the printed circuit board 8th realized. At the in 3 On the left, the first and the second area go 12 and 13 in a middle section 14 between the two areas seamlessly into each other.

It has proved to be advantageous if in the middle section 14 that is between the first and second area 12 and 13 lies a glass passage 15 is arranged, via which the electrical connection or the output signal Sout of the quartz oscillator 3 between the two areas 12 and 13 realized or managed. In 3 this is indicated by a dashed line. The circuit board 8th , the glass passage 15 and the device housing 17 are in such a way to each other and coordinated that after inserting the circuit board 8th with the glass passage 15 into the device housing 17 the first area 12 from the second area 13 hermetically separated. In this way, the device with the first end of the circuit board 8th be exposed to the medium without the medium can get into the second area. In 3 is the medium 2 whose density is to be determined by points indicated.

Furthermore, the circuit board 8th a notch in the area of the middle section 14 exhibit. Through the notch, the front part or first area 12 get separated easier. In this way, the circuit board for both the variant with glass feedthrough 15 as well as the variant without glass passage 15 be prepared in the same way. The notch is also in the variant with glass passage 15 the width of the device is not changed substantially.

LIST OF REFERENCE NUMBERS

S100

Providing a quartz oscillator in the form of a standard component

S200

Soldering the quartz oscillator on a PCB or PCB

S300

Dotting of a housing of the quartz oscillator

S300A

Dotting an initial opening in the housing by means of a mechanical tool

S300b

Dotting an initial opening in the housing by means of a pulsed laser

S301

Dotting further openings in the housing by means of a laser

S400

Closing the initial opening

1

Device for determining a density of a medium

2

medium

3

crystal oscillator

4

quartz crystal

5

Housing of the quartz oscillator

6

Quartz crystal electronics

7

evaluation

8th

circuit board

9

Opening or initial opening

10

more openings

11

particulate Filter

12

first area of the circuit board

13

second area of the circuit board

14

mid section

15

Glass bushing

16

output pin

17

device housing

Sout

Output signal of the quartz oscillator

Claims (14)

Method for producing a device for determining a density of a medium, in particular a gas, comprising at least the following steps: - Providing a quartz oscillator (S100), preferably in the form of a quartz watch, comprising a quartz crystal, for generating an electrical oscillation with a certain frequency, preferably with a frequency of about 32.768 kHz, a housing, in which the quartz crystal, preferably hermetically in a vacuum , is introduced and a quartz crystal electronics, which is adapted to control the quartz crystal for generating the electrical oscillation and to provide a frequency-dependent output signal; - Application, preferably in the form of a soldering step, the quartz oscillator on a printed circuit board (S200), which has at least one evaluation unit, and is designed such that the quartz oscillator is electrically connected to the evaluation after application, so that the evaluation unit is supplied with the output signal ; Puncturing the housing of the quartz oscillator (S300), so that the medium whose density is to be determined can come into contact with the quartz crystal and changes the frequency of the quartz crystal in dependence on the density, wherein the housing is punctured such that at least one opening is introduced into the housing. Method according to Claim 1 wherein the housing is punctured such that further openings are introduced into the housing (S301). Method according to the preceding claim, wherein the housing is punctured such that at least the further openings are formed so that particles with a geometric equivalent diameter less than 35 microns, preferably less than 30 microns, more preferably less than 25 microns not into the housing through the other openings can penetrate, so that at least the other openings serve as a particulate filter. Method according to at least one of the preceding claims, wherein the housing is punctured in such a way that at least one opening is introduced into the housing by means of a mechanical tool, in particular a punching iron (S300a). Method according to the preceding claim, wherein the housing is punctured such that the further openings, preferably by means of a laser, are introduced into the housing after the at least one opening has been introduced by means of the mechanical tool (S301). Method according to the preceding claim, wherein the introduced by means of the mechanical tool at least one opening after the introduction of the further openings by means of the laser is closed again (S300). Method according to at least one of Claims 1 to 3 in that the housing is punctured in such a way that the at least one opening and / or the further openings are introduced into the housing by means of a pulsed laser, in particular a picosecond or higher pulsed laser (S300b). Device (1) for determining a density (p) of a medium (2), in particular of a gas, comprising at least: - A quartz oscillator (3), comprising a quartz crystal (4), preferably in the form of a quartz watch, for generating an electrical oscillation with a certain frequency, preferably at a frequency of about 32.768 kHz, a housing (5), in which the quartz crystal is introduced and a quartz oscillator electronics (6), which is adapted to drive the oscillating quartz to generate the electrical oscillation and to provide a frequency-dependent output signal (Sout); - A printed circuit board (8) comprising at least one evaluation unit (7), wherein the quartz oscillator is mounted on the circuit board and is electrically connected to the evaluation unit, so that the evaluation unit is supplied with the output signal of the quartz crystal electronics; wherein in the housing of the quartz oscillator at least one opening (9) is introduced, so that the medium whose density is to be determined, come into contact with the quartz crystal and can change the frequency of the quartz crystal as a function of density, and the evaluation unit is adapted to determine the density based on the output signal representing the changed frequency. Device according to the preceding claim, wherein in the housing further openings (10) are introduced. Device according to the preceding claim, wherein at least the further openings are formed so that no particles with a geometric equivalent diameter smaller than 35 microns, preferably less than 30 microns, more preferably less than 25 microns can penetrate into the housing through the other openings, so that at least the serve further openings as a particulate filter (11). Device according to at least one of Claims 8 to 10 wherein the at least one opening and / or the further openings is or are formed essentially as circular openings. Device according to at least one of Claims 8 to 11 wherein the printed circuit board has a first region (12) and a second region (13), wherein the quartz oscillator is arranged in the first region and the evaluation unit in the second region, wherein the device further comprises a glass feedthrough (14), which between the the first and second region is provided and the quartz oscillator is electrically connected via the glass feedthrough to the evaluation unit. Device according to at least one of Claims 8 to 12 wherein the quartz oscillator is intended to serve as a frequency normal and through which at least one opening (9) in the housing for measuring the density of the medium, which can penetrate through the at least one opening (9), is misused. Use of a quartz oscillator (3) for determining a density of a medium (2), wherein the quartz oscillator comprising a quartz oscillator (4), preferably in the form of a quartz watch, for generating an electrical oscillation with a certain frequency, preferably with a frequency of about 32,768 kHz, a housing (5) into which the quartz crystal is inserted, and a quartz crystal electronics (6) adapted to drive the oscillating crystal to generate the electrical oscillation and to provide a frequency dependent output signal (Sout), for use of the quartz oscillator for determining the density of the medium, the housing is punctured such that at least one opening (9) is introduced into the housing and the quartz oscillator is exposed to the medium, so that the density changes the frequency and, correspondingly, the output signal.

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