Device and method for determining the concentration of a vapor

Abstract

A device for determining the partial pressure or the concentration of a steam in a volume, includes a sensor body that can be oscillated. The temperature of the sensor body can be controlled to a temperature below the condensation temperature of the steam, and the oscillation frequency of the sensor body is influenced by a mass accumulation of the condensed steam on a surface of the sensor body. Means are provided for generating a gas flow from the sensor surface in the direction of the volume through a steam transport channel that adjoins a window to the volume. In order to increase the maximum service life of the sensor body, the means for generating a gas flow has a slit nozzle designed as an annular channel.

Claims

1. A device for determining a partial pressure or a concentration of a vapor in a volume (2), the device comprising: a sensor body (5) configured to be brought into oscillation, the sensor body having a temperature that is controllable to a temperature below the condensation temperature of the vapor, and an oscillation frequency that is influenced by an accumulated mass formed by the vapor condensing on a sensor surface (6) of the sensor body (5), wherein a vapor transport channel (20) adjoins a window (3) to the volume (2), through which the vapor diffuses in a direction of transport (T) towards the sensor surface (6); and an annular channel (16) that forms a wide slit nozzle through which a gas flow is generated, the gas flow flowing from the sensor surface (6) towards the vapor transport channel (20) in a direction counter to the direction of transport (T) of the diffusion of the vapor.

2. The device of claim 1, wherein the annular channel (16) is provided in an immediate vicinity of the sensor body (5).

3. Device A for determining a partial pressure or a concentration of a vapor in a volume (2), the device comprising: a sensor body (5) that is configured to be brought into oscillation, sensor body (5) having a temperature that is controllable to a temperature below a condensation temperature of the vapor, and an oscillation frequency that is influenced by an accumulated mass formed by the vapor condensing on a sensor surface (6) of the sensor body (5); a pipe stub (17) surrounding a vapor transport channel (20), wherein at a first end of the pipe stub (17), the pipe stub (17) adjoins a window (3) to the volume (2) and at a second end of the pipe stub (17), the pipe stub (17) is spaced apart from the sensor surface (6) by a gap; and flow generating means configured to generate a gas flow that is fed through the gap and into the vapor transport channel (20).

4. The device of claim 1, wherein the volume (2) is formed by a vapor transport line (1) through which the vapor is transported by means of a carrier gas.

5. The device of claim 1, wherein the volume (2) is formed by a process chamber of a coating device.

6. A method for determining a partial pressure or a concentration of a vapor in a volume (2), the method comprising: oscillating a sensor body (5) at an oscillation frequency; controlling a temperature of the sensor body (5) to a temperature below a condensation temperature of the vapor; diffusing, in a direction of transport (T), the vapor through a vapor transport channel (20) to reach a sensor surface (6) of the sensor body (5) condensing the vapor on the sensor surface (6); as a result of the vapor condensing on the sensor surface (6), forming an accumulated mass on the sensor surface, the accumulated mass influencing the oscillation frequency of the sensor body (5); feeding a gas flow in from an edge of the sensor surface (6) in a direction towards a center of the sensor surface (6); and flowing the gas flow counter to the direction of transport (T) through the vapor transport channel (20) and into the volume (2).

7. The method of claim 6, wherein the gas flow is fed through a gap between an edge of a pipe stub (17) bounding the vapor transport channel (20), and the edge of the sensor surface (6).

8. The method of claim 6, wherein the volume (2) is formed by a vapor transport line (1), through which the vapor is transported by means of a carrier gas.

9. The method of claim 6, wherein an average transport velocity of the vapor through the vapor transport channel (20) towards the sensor surface (6) is adjusted by adjusting a flow velocity of the gas flow.

10. The device of claim 2, wherein the volume (2) is formed by a vapor transport line (1) through which the vapor is transported by means of a carrier gas.

11. The device of claim 2, wherein the volume (2) is formed by a process chamber of a coating device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In what follows the invention is described in detail with the aid of an example embodiment. Here:

(2) FIG. 1 shows a cross-section along the line I-I in FIG. 2 of a gas transport line 1, with which the vapor of an organic source material is transported from a vapor source to a gas inlet device of an OLED coating device, wherein the line of cut I-I is positioned centrally through a window 3 in the wall 4 of the vapor transport line 1;

(3) FIG. 2 shows the cross-section along the line II-II in FIG. 1;

(4) FIG. 3 shows at an enlarged scale the detail III in FIG. 1; and

(5) FIG. 4 shows a cross-section along the line IV-IV in FIG. 3.

DETAILED DESCRIPTION

(6) The vapor transport line 1 forms a volume 2, through which passes a vapor of an organic source material, transported by an inert gas. The wall 4 of the vapor transport line is heated to a temperature above the condensation temperature of the vapor, for example to 350° C.

(7) The volume 2 of the vapor transport line 1 is connected to a sensor surface 6 of a sensor body 5 by way of a window 3, and an adjoining vapor transport channel 20. The diameter of the vapor transport channel 20 corresponds approximately to the diameter of the window 3. In one embodiment, the vapor transport channel 20 is surrounded by a pipe stub 17, which forms a funnel-shaped apron, which forms a free edge on its side facing away from the window 3.

(8) The edge of the pipe stub 17 is spaced apart from the sensor surface 6 by a gap. This gap forms an annular flow channel 16, such that a flat nozzle is formed, through which a gas flow G can flow.

(9) The vapor of the organic source material contained in the volume 2 is transported, in particular by diffusion, in a direction of transport T through the window 3 and the vapor transport channel 20 towards the sensor surface 6 of the sensor body 5. Here the vapor is transported counter to the gas flow G, which flows against the direction of transport T through the vapor transport channel 20 and the window 3. The transport rate of the vapor in the direction of transport T towards the sensor surface 6 can thus be adjusted by the mass flow rate or the volumetric flow rate of the gas flow G.

(10) A cooling element 11 is provided, which is connected in terms of heat conduction to the rear face 7 of the sensor body 5 by way of a heat transfer body. With the cooling element 11 the sensor surface 6 is cooled down to a temperature of, for example 220° C., at which temperature the vapor condenses on the sensor surface 6.

(11) The sensor body 5 is formed by a QCM, which is set into oscillation with suitable means known from the prior art. In particular, the QCM is part of a resonant circuit. The resonance frequency of the QCM is influenced by the accumulated mass of condensed vapor formed on the sensor surface 6. From the alteration of the resonance frequency, conclusions can be drawn about the vapor concentration or the partial pressure of the vapor in the volume 2. The rate of mass accumulation on the sensor surface 6 can be reduced by increasing the gas flow G. This allows the cycle duration of the sensor body 5 to be extended.

(12) According to one aspect of the invention, the heat transfer body is a heating element 8. The heating element 8 has a heat transfer surface 9, which is in heat conductive contact with the rear face 7 of the sensor body 5. A heat dissipation surface 18, which differs from the heat transfer surface 9 and in one embodiment is located opposite the heat transfer surface 9, is connected in terms of heat conduction to a cooling surface 19 of the cooling element 11, such that the heating element 8 has the function of a heat transfer body if no electrical heat output is fed into the heating element 8.

(13) In one embodiment, provision is also made for an insulation element 10 to be arranged between the heat dissipation surface 18 of the heating element 8 and the cooling surface 19 of the cooling element 11. The insulation element 10 has a lower thermal conductivity than that of the heating element 8. The thermal conductivity property of the insulation element 10 is selected such that, if the cooling capacity of the cooling element 11 is not switched off, the sensor surface 6 can, by feeding electrical heating power into the heating element 8, be heated up to a temperature at which the condensate accumulated on the sensor surface 6 can sublimate. The heat transfer surface 9 thus has the function on the one hand of dissipating heat from the sensor body 5 during normal operation, and on the other hand of supplying heat to the sensor body 5 during the cleaning operation.

(14) If the heat supply to the heating element 8 is terminated, heat is extracted from the heating element 8 through the insulation element 10. The heating element 8 cools down and also extracts heat from the sensor body 5, such that the sensor surface 6 is brought down to a temperature below the condensation temperature of the vapor.

(15) The heating element 8, the insulation element 10 and the cooling element 11 form a sensor body support, which is inserted in a housing 14, into which a gas supply line 15 opens, through which the gas flow, which flows as a purge gas flow G, is fed through the annular gap-shaped opening between the edge of the pipe stub 17 surrounding the vapor transport channel 20 and the sensor surface 6, and into the vapor transport channel 20. The gas flow G preferably consists of an inert gas. This can be nitrogen, an inert gas or hydrogen. The gas flow G preferably consists of the same substance as the carrier gas flow, with which the vapor is transported through the volume 2 formed by a gas line.

(16) A contact element 12 is provided, which has an annular shape and surrounds a central region of the sensor surface 6. The sensor body 5 is preferably excited so as to oscillate such that the contact line of the contact element runs along a node line. The rear face of the sensor body 5 forms a counter contact to the contact element 12. The contact element 12 and the counter contact are connected to an electronic circuit for purposes of executing the oscillation.

(17) A plurality of spring elements 13 are preferably provided, with which the contact element 12 is supported on a hot part of the housing. The spring elements 12 thus offer a heat transfer resistance in the form of a heat insulation element, so that the temperature of the sensor body 5 can be set essentially independently of the temperature of the wall 4 of the volume 2, or the temperature of the pipe stub 17.

(18) The above statements serve to explain the inventions recorded by the application as a whole, which develop the prior art at least by means of the following combinations of features, and in each case also independently, wherein two, a plurality, or all, of these combinations of features can also be combined, namely:

(19) A device, which is characterized in that means are provided for generating a gas flow from the sensor surface 6 in the direction of the volume 2.

(20) A device, which is characterized in that the means for generating the gas flow are provided in the immediate vicinity of the sensor body 5.

(21) A device, which is characterized in that the means for generating a gas flow are formed by a wide slit nozzle.

(22) A device, which is characterized in that the wide slit nozzle is formed by an annular channel 16.

(23) A device, which is characterized by a vapor transport channel 20 adjoining a window 3 to the volume 2.

(24) A device, which is characterized in that the vapor transport channel 20 is surrounded by a pipe stub 17, which adjoins the window 3 at one end, and at its other end is spaced apart from the sensor surface 6 by a gap, wherein the gap forms a flow channel 16 for feeding the gas flow into the vapor transport channel 20.

(25) A device, which is characterized in that the volume 2 is formed by a vapor transport line 1, through which a carrier gas transporting the vapor can flow.

(26) A device, which is characterized in that the volume 2 is formed by a process chamber of a coating device.

(27) A method, which is characterized in that a gas flow is generated in a direction counter to the direction of transport T.

(28) A method, which is characterized in that the gas flow is fed from the edge of the sensor surface 6 in a direction towards the center of the sensor surface 6, and enters into the volume 2 through a window 3.

(29) A method, which is characterized in that the gas flow flows through a vapor transport channel 20 towards the window 3.

(30) A method, which is characterized in that the gas flow is fed in through a gap between an edge of a pipe stub 17, bounding the vapor transport channel 20, and the edge of the sensor surface 6.

(31) A method or a device, which is characterized in that the sensor body 5 rests on a heating element 8, which is connected in terms of heat conduction to a cooling element 11, in particular by way of an insulating element 10.

(32) A method, which is characterized in that the volume 2 is formed by a vapor transport line 1, through which the vapor is transported by means of a carrier gas.

(33) All disclosed features are essential to the invention (both individually, and also in combination with one another). In the disclosure of the application, the disclosure content of the associated/attached priority documents (copy of the prior application) is hereby also incorporated in full, also for the purpose of incorporating features of these documents in the claims of the present application. The subsidiary claims characterize, even without the features of a claimed claim, with their features independent inventive developments of the prior art, in particular in order to make divisional applications on the basis of these claims. The invention specified in each claim can additionally comprise one or a plurality of the features described in the above description, in particular with features provided with reference symbols and/or specified in the list of reference symbols. The invention also relates to forms in which individual of the features mentioned in the above description are not implemented, in particular insofar as they are recognizably dispensable for the respective purpose, or can be replaced by other technically equivalent means.

LIST OF REFERENCE SYMBOLS

(34) 1 Vapor transport line 2 Volume 3 Window 4 Wall 5 Sensor body 6 Sensor surface 7 Rear face 8 Heating element 9 Heat transfer surface 10 Insulation element 11 Cooling element 12 Contact element 13 Spring element 14 Housing 15 Gas supply line 16 Flow channel 17 Pipe stub 18 Heat dissipation surface 19 Cooling surface 20 Vapor transport channel G Purge gas flow T Direction of transport