WO2019025151A1

WO2019025151A1 - Method for producing a device for determining a density of a medium

Info

Publication number: WO2019025151A1
Application number: PCT/EP2018/068879
Authority: WO
Inventors: Patrick REITH; Fabio SCHRANER; Ragnar VON MÖLLENDORFF
Original assignee: Truedyne Sensors AG
Priority date: 2017-08-02
Filing date: 2018-07-12
Publication date: 2019-02-07
Also published as: DE102017117512A1

Abstract

The invention relates to a method for producing a device for determining a density of a medium, the method comprising at least the following steps: Providing a quartz oscillator (S100) for generating an electric oscillation at a specific frequency; a housing, into which the oscillating quartz is introduced; and an oscillating quartz electronics, which is designed to control the oscillating quartz in order to generate the electric oscillation, and to provide a frequency-dependent output signal; applying the quartz oscillator to a circuit board (S200), which has at least one evaluation unit, and which is designed such that after the quartz oscillator is applied, it is electrically connected to the evaluation unit so that the output signal is delivered to the evaluation unit; puncturing the housing of the quartz oscillator (S300) such that the medium, the density of which is to be determined, can get into contact with the oscillating quartz, and changes the frequency of the oscillating quartz depending on the density, wherein the housing is punctured in such a way that at least one opening is introduced into the housing.

Description

Method for producing a device for determining a density of a

medium

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 for determining a density of a medium

Device with a tuning fork quartz crystal is used. These tuning fork quartz crystals are commonly used as a sensor element without a package, 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 this against

mechanical effects are not protected during the actual measuring 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.

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 oscillator, 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 vacuum, and a quartz crystal electronics, which is adapted to the quartz crystal to generate the electrical oscillation to drive accordingly and to provide a frequency dependent output signal;

Applying, preferably in the form of a soldering step, the quartz oscillator on a printed circuit board, which has at least one evaluation unit, and is formed such that the quartz oscillator after applying electrically with the

Evaluation unit is connected, so that the evaluation unit is supplied with the output signal;

Puncturing 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 alters the frequency of the quartz crystal as a function of density, 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 incorporated in a housing for generating vibrations, which are known as

frequency-determining component includes a in a protective environment, in particular a vacuum having protective environment, located quartz crystal. 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 crystal are converted by an oscillator circuit into square waves of the same frequency.

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 assembly of the quartz oscillator on the circuit board of the quartz oscillator nor by that to this

Time not yet dotted housing is protected. 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 can be obtained inexpensively, 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 other openings are formed so that particles with a geometric equivalent diameter smaller than 35 μιτι, preferably less than 30 μιτι, more preferably less than 25 μιτι not 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 produced 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 by means of the mechanical

Tool introduced at least one opening after the introduction of the other openings by means of the laser is closed again.

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.

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

Oscillating quartz electronic, which is adapted to the quartz crystal for

Correspondingly trigger generation of 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 circuit board and electrically connected to the

Evaluation unit is connected, 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, in contact with the

Occur quartz crystal and can change the frequency of the quartz crystal as a function of density, and the evaluation unit is adapted to use 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 μιτι, preferably less than 30 μιτι, more preferably less than 25 μιτι 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 circuit board has a first region and a second region, wherein the

Quartz oscillator in the first region and the evaluation unit are arranged in the second region, wherein the device further comprises a glass feedthrough, which is provided between the first and second region 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. In terms of use, the task is accomplished through the use of a

Quartz oscillator for determining a density of a medium, wherein the quartz oscillator comprising a quartz crystal, preferably in the form of a quartz watch, for generating an electrical oscillation with a specific frequency, preferably at a frequency of about 32.768 kHz, a housing in which the quartz crystal is introduced and a quartz crystal electronics adapted to

To control vibration quartz for generating the electrical vibration and provide a frequency-dependent output signal, wherein for use of the quartz oscillator for determining the density of the medium, the housing 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 accordingly the output signal.

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

1 shows a schematic sequence of a manufacturing method according to the invention,

2 shows a plan view of a quartz oscillator whose housing is punctured in such a way that the openings form a particle filter, and

3 shows a device according to the invention for determining a density of a medium.

FIG. 1 shows a schematic sequence of the production method according to the invention, which consists essentially of three method steps.

In a first method step S100, a quartz oscillator 3 in the form of a

Standradbauteils provided. The quartz oscillator 3 in this case comprises a quartz oscillator 4, a quartz crystal electronics 6 and a housing 5. The quartz oscillator 4 and the quartz crystal electronics 6 are introduced into the housing 5 and hermetically sealed to the environment. Furthermore, when the quartz oscillator 3 is manufactured, the housing 5 has been vacuumized at least in individual regions, so that at least the quartz oscillator 4 is mounted in the housing 5 in a vacuum. About the quartz oscillator electronics 6, the quartz crystal 4 is driven such that it oscillates electrically at a predetermined frequency or resonance frequency, preferably in the form of a sinusoidal oscillation. Further, the quartz crystal electronics 6 is adapted to convert the generated oscillation into rectangular signals of the same frequency and as a

Output signal Sout to provide an output pin 16 of the quartz oscillator 3. Such quartz oscillators 3 are, as already mentioned above, purchasable as separately formed components in a variety of variants. It is advantageous if as

Quartz oscillator 3 is provided a conventional quartz watch, as this due the high volumes in which it is produced, can be acquired inexpensively.

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 method step S200, the quartz oscillator 3 is applied to a printed circuit board 8. The application can be carried out, for example, by a soldering step in which the quartz oscillator 3 is soldered onto the printed circuit board 8. The circuit board 8 has at least one evaluation unit 7 and is formed such that the soldered

Crystal oscillator 3 is electrically connected via conductor tracks to the evaluation unit 7, so that the generated by the quartz oscillator electronics 6 output signal of

Crystal oscillator Sout the evaluation unit 7 is supplied.

In a third method step S300, the housing 5 of the quartz oscillator 3 is punctured in such a way that the housing 5 has at least one inlet opening 9 for the medium 2. 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

mechanical tool and a non-pulsed laser for puncturing the

Housing 5 exposed. Here, first, the inlet opening 9 is introduced as an initial opening in the housing 9 by a mechanical tool, for example. A punching iron, and then further openings 10 are introduced into the housing 9 by a non-pulsed laser, insofar as further openings in the housing are desired.

In the third method step, it can furthermore be provided that the housing 5 of the quartz oscillator 3 is punctured in such a way that further openings 10 are introduced into the housing 5. The other openings 1 0 and ggfl. the inlet opening serve as a particle filter 1 1, in order not to let particles with a certain diameter into the housing 5 and thus to protect the quartz crystal 4. Accordingly, at least the other openings 1 0 are designed such that no particles with a geometric equivalent diameter smaller than 35 μιτι, preferably less than 30 μιτι, more preferably less than 25 μιτι can penetrate into the housing 5, when the housing 5 is exposed to the medium 2. In the simplest case, the further openings 10 are introduced as essentially circular openings into the housing, which have a diameter of less than 35 μm, preferably less than 30 μm, particularly preferably less than 25 μm. 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 μιτι, preferably less than 30 μιτι, particularly preferably less than 25 μιτι 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. The closing of 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 must be exposed to the medium 2, so that the medium 2 can penetrate into the housing 5 and attenuate the electrical oscillation as a function of its density. On the basis of the damped electrical oscillation can thus be deduced the density of the medium 2. For example, an evaluation unit 7 can be used for this purpose, which is set up to determine a density corresponding to the present medium 2 on the basis of the output signal S out of the quartz oscillator 3. In the first approximation, a linear relationship between the frequency of the electrical oscillation of the quartz crystal 4 and the density of the medium 2 is stored in the evaluation unit 7.

Fig. 2 shows a quartz oscillator 3, the housing 5 is punctured in such a way that the openings form a particle filter 1 1. For this purpose, in the housing 5 a

Inlet opening 9 has been introduced as an initial opening by a punching iron and closed again after the introduction of the other openings 10 by a non-pulsed laser. The particle filter 1 1 is formed in Fig. 2 in the form of a 5 x 1 0 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 mxn matrix. Rather, it has been found that it can be beneficial if one Matrix is used, which is greater than 5 x 1 0. Furthermore, it has been found that it can also be advantageous if the formation of the matrix is distributed over at least one side of the housing 5 substantially completely flat.

FIG. 3 shows a device 1 according to the invention for determining a density of a medium, for example in the form of a gas. In this case, the apparatus comprises a quartz oscillator 3 which is prepared or punctured as described above, a printed circuit board 8 on which is the quartz oscillator 3 and on the other hand an evaluation unit 7, for example in the form of an ASIC or a microprocessor, and a device housing 17 , in which the circuit board 8 is introduced. The quartz oscillator 3 is in a located at a first end of the circuit board 8 first region 12, and the

Evaluation unit 7 arranged in a second region 13 located at a second end of the circuit board, which is opposite to the first end. The electrical connection is in this case realized via conductor tracks of the printed circuit board 8. In the left in Fig. 3

1, the first and second regions 1 2 and 13 merge seamlessly into one another in a middle section 14 between the two regions.

It has proven to be advantageous if in the middle section 14, which lies between the first and second region 12 and 13, a glass bushing 1 5 is arranged, via which the electrical connection or the output signal S out of the quartz oscillator 3 between the two regions 12 and 13 is realized or managed. In Fig. 3, this is indicated by a dashed line. The printed circuit board 8, the glass bushing 1 5 and the device housing 1 7 are in such a way to each other and matched to each other that after inserting the circuit board 8 with the glass duct 15 in the

Device housing 17, the first region 12 is hermetically separated from the second region 13. In this way, the device can be exposed to the medium with the first end of the printed circuit board 8, without the medium being able to get into the second region. In Fig. 3, the medium 2 whose density is to be determined indicated by dots.

Furthermore, the printed circuit board 8 may have a notch in the region of the middle section 14. The notch allows the front part or first area 12 to be separated more easily. In this way, the circuit board for both the variant with glass feedthrough 15 and the variant without glass feedthrough 1 5 can be produced 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 to a printed circuit board or PCB

5300 puncturing 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

5301 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 quartz oscillator

4 quartz crystal

5 housing of the quartz oscillator

6 quartz crystal electronics

7 evaluation unit

8 circuit board

9 opening or initial opening

10 more openings

1 1 particle filter

12 first area of the circuit board

13 second area of the circuit board

14 middle section

15 glass passage

16 output pin

17 device housing

Sout Output signal of the quartz oscillator

Claims

claims

1 . 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

Clock quartz, comprising 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, preferably hermetically introduced in vacuum, and a quartz crystal electronics, which is adapted to correspondingly triggering the quartz oscillator for generating the electrical 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 (S200), 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

Output signal is supplied;

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 alters the frequency of the quartz crystal as a function of the density, wherein the housing is punctured such that at least one opening in the housing is inserted.

2. The method of claim 1, wherein the housing is punctured such that further openings are introduced into the housing (S301).

3. The 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 μιτι, preferably less than 30 μιτι, more preferably less than 25 μιτι not in the housing by the can penetrate further openings, so that at least the other openings serve as a particle filter.

4. The method according to at least one of the preceding claims, wherein the

Housing is dotted in such a way that at least one opening by means of a mechanical tool, in particular a punching iron, is introduced into the housing (S300a).

5. The method according to the preceding claim, wherein the housing is punctured such that the further openings, preferably by means of a laser in the Housing are introduced after the at least one opening has been introduced by means of the mechanical tool (S301).

6. The method according to the preceding claim, wherein the introduced by means of the mechanical tool at least one opening after the introduction of the other

Openings is closed again by means of the laser (S300).

7. The method according to at least one of claims 1 to 3, wherein the housing is punctured in such a way that the at least one opening and / or the further openings by means of a pulsed laser, in particular a picosecond or higher pulsed laser, is introduced into the housing or . (S300b).

8. 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 oscillator (4), preferably in

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), in which the quartz crystal is introduced and a quartz crystal electronics (6), which is adapted to the quartz crystal correspondingly for generating 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 printed circuit board and electrically connected to the

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.

9. Device according to the preceding claim, wherein in the housing further openings (10) are introduced.

10. 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 μιτι, preferably less than 30 μιτι, more preferably less than 25 μιτι can penetrate into the housing through the other openings, so that at least the other openings serve as a particulate filter (1 1).

1 1. Device according to at least one of claims 8 to 10, wherein the at least one opening and / or the further openings are or are formed substantially as circular openings.

12. The device according to at least one of claims 8 to 1 1, wherein the circuit board has a first region (12) and a second region (13), 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 (14) which is provided between the first and second region and the quartz oscillator is electrically connected via the glass feedthrough to the evaluation unit.

13. The device according to at least one of claims 8 to 12, wherein the quartz oscillator as intended serves as a frequency normal and through the 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 misappropriated.

14. Use of a quartz oscillator (3) for determining a density of a medium (2), the quartz oscillator comprising a quartz oscillator (4), preferably in the form of a quartz crystal, for generating an electrical oscillation with a specific frequency, preferably with a frequency of approx 32,768 kHz, a housing (5), in which the quartz crystal is incorporated and a Schwingquarzelektronik (6), which is adapted to control the oscillating quartz for generating 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.