WO2017196331A1

WO2017196331A1 - Cooling airflow for a sensor in a lamp assembly

Info

Publication number: WO2017196331A1
Application number: PCT/US2016/032034
Authority: WO
Inventors: Juan Manuel VALERO NAVAZO; Esteve COMAS; Marina Ferran Farres
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2016-05-12
Filing date: 2016-05-12
Publication date: 2017-11-16

Abstract

In some examples, a lamp assembly of a printing system includes a heating lamp to generate heat energy during an operation of the printing system, a sensor, and a first housing defining a sensor chamber in which the sensor is located, the first housing defining an airflow inlet to receive a cooling airflow to cool the sensor, and an exhaust outlet through which a heated exhaust airflow is to exit from the sensor chamber.

Description

COOLING AIRFLOW FOR A SENSOR IN A LAMP ASSEMBLY Background

[0001 ] A three-dimensional (3D) printing system can be used to form 3D objects. A 3D printing system performs a 3D printing process, which is also referred to as an additive manufacturing (AM) process, in which successive layers of material(s) of a 3D object are formed under control of a computer based on a 3D model or other electronic representation of the object. The layers of the object are successively formed until the entire 3D object is formed.

Brief Description Of The Drawings

[0002] Some implementations of the present disclosure are described with respect to the following figures.

[0003] Fig. 1 is a block diagram of a portion of a three-dimensional (3D) printing system, according to some examples.

[0004] Fig. 2 is a schematic sectional view of a lamp assembly that includes a heating lamp and a sensor module according to some examples.

[0005] Fig. 3A is a sectional view of a lamp assembly according to further examples.

[0006] Fig. 3B is an enlarged sectional view of a portion of the lamp assembly of Fig. 3A, according to some examples.

[0007] Fig. 4 is a perspective view showing a cut-away portion of a portion of the lamp assembly according to Fig. 3A, according to some examples.

[0008] Fig. 5 is a block diagram of a printing system according to further examples. [0009] Fig. 6 is a block diagram of a sensor module according to alternative examples.

[0010] Fig. 7 is a flow diagram of forming a lamp assembly, according to some examples.

Detailed Description

[001 1 ] In a 3D printing system, a build material (or multiple different build materials) can be used to form a 3D object, by depositing the build material(s) as successive layers until the final 3D object is formed. In some examples, a build material can include a powdered build material that is composed of particles in the form of fine powder or granules. The powdered build material can include metal particles, plastic particles, polymer particles, or particles of other materials.

[0012] In a 3D printing system, a heating lamp (or multiple heating lamps) can be provided to cause heating of a layer of a build material formed on a build platform of the 3D printing system. A "heating lamp" is interchangeably used with a "heater," and can refer to a heating source that is activatable to generate energy that can be used to cause heating of a target, which in a 3D printing system can be a layer of build material. An example of a heating lamp is a halogen lamp that can generate visible light or near infrared light energy. In other examples, the heating lamp can include light emitting diodes (LEDs), laser diodes, a lamp to generate medium or far infrared light energy, a xenon lamp, or any other type of heater that can produce heat energy (such as a semiconductor plate, e.g. a silicon plate, with a resistor on the semiconductor plate that heats up and produces radiant heat when an electrical current is run through the resistor, or any other type of heat emitter). The heating of the layer build material can be performed to aid in the fusing of a portion of a layer of powdered build material, where powders in such portions are joined together to form a solid. An agent (e.g. a liquid agent or other agent) can also be applied to such portions of the layer of powdered build material for fusing or detailing the heated portions of the layer of powdered build material. In other examples, the heating of a layer of build material can be performed for other purposes. [0013] In some cases, a lamp assembly can include multiple heating lamps. The term "lamp assembly" and "heater assembly" can be interchangeably used, where a "lamp assembly" or "heater assembly" can refer to an assembly that is used to cause heating of a target on a build platform of a 3D printing system. In addition, a sensor can be provided in the lamp assembly, where the sensor is used to detect a temperature of a target (including one or multiple layers of build material) formed on the build platform. Heat from the heating lamps in the lamp assembly can cause the temperature of the sensor to rise above its maximum safe operating temperature. In addition to heat from the heating lamps in the lamp assembly, the sensor can also be subjected to heating that rises from the heated layer of build material on the build platform.

[0014] If the sensor's temperature rises above its maximum safe operating temperature, then the sensor may be damaged. Moreover, the sensor's operation can be variable to temperature— in other words, temperature measurements of a target taken by the sensor can vary based on the temperature of the sensor itself. As a result, if the temperature of the sensor is outside a specified range, then temperature measurements taken by the sensor of a target may not accurately reflect the actual temperatures of the target.

[0015] In accordance with some implementations of the present disclosure, a cooling solution is provided to provide a cooling airflow to the sensor that is arranged inside a lamp assembly. Fig. 1 is a block diagram of a portion of an example three- dimensional (3D) printing system 100. The 3D printing system 100 includes a build platform 102 on which a target can be formed. The target is formed by providing layers of powdered build material onto the surface of the build platform 102. A layer 104 of powdered build material is shown in Fig. 1 .

[0016] The 3D printing system 100 also includes a carriage 106 in which a printhead (not shown) is provided. Although reference is made to just one printhead, it is noted that in other examples, multiple printheads can be carried by the carriage 106. [0017] The carriage 106 and the build platform 102 are moveable with respect to each other along an axis 1 10 during a 3D printing operation. In some examples, the carriage 106 is moveable along an axis 1 10 while the build platform 102 is stationary. In other examples, the carriage 106 is stationary while the build platform 102 is moveable along the axis 1 10. In further examples, both the carriage 106 and the build platform 102 are moveable along the axis 1 10. In additional examples, the carriage 106 and the build platform 102 are moveable with respect to each other along multiple different axes.

[0018] In the 3D printing operation, the printhead 108 is able to deliver an agent (or multiple agents) to the layer 104 of powdered build material, through a print chamber 1 12 of the 3D printing system 100.

[0019] A lamp assembly 1 14 is also attached to, or can be part of, the carriage 106. The lamp assembly 1 14 includes a heating lamp (or multiple heating lamps) to generate heat to radiatively heat the layer 104 of powdered build material. The lamp assembly 1 14 includes a sensor module 1 16 that is used to detect a temperature of a target (including one or multiple layers of build material) has been formed on the build platform 102. In some examples, the sensor module 1 16 can include an infrared sensor, such as an infrared camera, or any other type of sensor that can be used to detect the temperature of a target on the build platform 102.

[0020] The sensor module 1 16 can be placed in the proximity of a number of heating lamps in the lamp assembly 1 14. As a result, heat from the heating lamps in the lamp assembly 1 14 as well as heat from the print chamber 1 12 can cause the temperature of the sensor module 1 16 to rise outside a specified temperature range of the sensor in the sensor module 1 16.

[0021 ] In accordance with some implementations of the present disclosure, the sensor module 1 16 is provided with a cooling subsystem to cool the sensor module 1 16, such that the operating temperature of the sensor module 1 16 can be kept within the specified temperature range. The specified temperature range can include a minimum temperature and a maximum temperature. If the sensor module's temperature were to rise above the maximum temperature, then potential damage can occur to the sensor module 1 16. Moreover, if the sensor module 1 16 were to be below the minimum temperature or above the maximum temperature, then temperature measurements made by the sensor module 1 16 may be inaccurate.

[0022] The 3D printing system 100 also includes an airflow generator 1 18 to produce an airflow that is directed towards the lamp assembly 1 14 through an air duct 120. In some examples, the airflow generator 1 18 can be a fan, or multiple fans. The airflow produced by the airflow generator 1 18 is used to cool the sensor module 1 16. An "airflow" can refer to a flow of a gas, such as air or another type of gas (e.g. an inert gas).

[0023] The airflow generator 1 18 can be mounted to the carriage 106. The airflow generator 1 18 can be selectively activated and deactivated. For example, the airflow generator 1 18 can be activated to produce a cooling airflow in response to a detection that the temperature of the sensor module 1 16 has risen to an elevated level (i.e. above a specified upper temperature threshold). Moreover, the airflow generator 1 18 can be deactivated to remove the cooling airflow in response to a detection that the temperature of the sensor module 1 16 has dropped below a specified lower temperature threshold. Additionally, the rate of cooling airflow can also be controlled by adjusting a speed of the airflow generator 1 18, such as by adjusting the rotational rates of the fan(s) of the airflow generator 1 18. Thus, the airflow generator 1 18 can be caused to increase its speed with rising temperature of the sensor module 1 16.

[0024] The intake air to the airflow generator 1 18 can be from an environment outside the 3D printing system. In such examples, one or multiple filters can be provided to filter incoming air before respective airflow is directed into the sensor module 1 16. The filter(s) can be used to remove or reduce the amount of

particulates in the environment, such that the particulates are reduced or removed in the cooling airflow to the sensor module 1 16. [0025] In other examples, the cooling airflow to the sensor module 1 16 can be from the airflow generator that is used to also cool the lamp assembly 1 14. In such latter examples, the airflow generator 1 18 can be used to produce cooling airflows directed towards the heating lamps in the lamp assembly 1 14 and directed towards the sensor module 1 16.

[0026] Fig. 2 is a schematic sectional side view of the lamp assembly 1 14 according to some implementations. The heating lamp assembly 1 14 includes a heating lamp 202 provided in a lamp chamber 203 of a housing of the lamp assembly 1 14. The heating lamp 202 is to generate heat that is radiatively directed towards the build platform 102. Although just one heating lamp 202 is shown in Fig. 2, it is noted that the lamp chamber 203 of the lamp assembly 1 14 can include multiple heating lamps, which can be provided on both sides of the sensor module 1 16. More specifically, in some examples, if the lamp assembly 1 14 includes an array of heating lamps 202, the sensor module 1 16 can be provided generally in a central location within the array of heating lamps 202. A "central location" within an array of heating lamps can refer to a location in the array where substantially the same number of heating lamps is provided on either side of the sensor module 1 16. "Substantially the same number" of heating lamps can refer to a first number of heating lamps that is within one or two of a second number of heating lamps. For example, X number of heating lamps can be provided on a first side of the sensor module 1 16, and Y number of heating lamps can be provided on a second, different side of the sensor module 1 16. X and Y are substantially the same number if X and Y differ by one or less, or by two or less, or by any other specified difference.

[0027] Although Fig. 2 shows the lamp assembly 1 14 with just one sensor module 1 16, it is noted that in other examples, the lamp assembly 1 14 can include multiple sensor modules 1 16, with each arranged and configured as discussed herein.

[0028] The sensor module 1 16 includes a sensor module housing 204 that is provided within the lamp assembly 1 14. The sensor module housing 204 defines a sensor chamber 206 in which a sensor 208 (or multiple sensors) is provided. A "housing" can refer to a single integral housing section, or to multiple housing sections that are attached together. In some examples, the sensor module housing 204 can be formed of a metal that is able to reflect radiative heating produced by the heating lamp(s) 202, to reflect radiative heat from the heating lamps 202 in the lamp chamber 203 of the lamp assembly 1 14 away from the sensor chamber 206 of the sensor module 1 16. In addition, the sensor module housing 204 also isolates the inner components of the sensor module 1 16 from the heat inside the lamp assembly 1 14. An example of a metal that can be used to form the sensor module housing 204 is aluminum, although other metals can be used in other examples. In further examples, the sensor module housing 204 can be implemented with another material that is able to provide heat insulation between the sensor chamber 206 of the sensor module 1 16 and the lamp chamber 203 of the lamp assembly 1 14.

[0029] As shown in Fig. 2, an upper opening (or multiple upper openings) 210 is provided in the sensor module housing 204. An airflow inlet is provided by the upper opening(s) 210 of the sensor module housing 204. The airflow inlet receives a cooling airflow 212, which is produced by the airflow generator 1 18 (Fig. 1 ).

[0030] In other examples, instead of or in addition to the upper opening(s) 210 on the top side of the sensor module housing 204, the airflow inlet can of the sensor module 1 16 can include an opening on a different side of the sensor module housing 204.

[0031 ] As further shown in Fig. 2, an exhaust outlet 214, which can include one opening or multiple openings, is also provided in the sensor module housing 204 to allow a heated exhaust airflow 216, produced by heating of the cooling airflow 212 by the sensor 208, to exit the sensor chamber 206 of the sensor module 1 16. In examples according to Fig. 2, the exhaust outlet 214 allows the heated exhaust airflow 216 to exit to the lamp chamber 203 of the lamp assembly 1 14. In other examples, the exhaust outlet 214 can be provided at a different part of the sensor module housing 204, so that the heated exhaust airflow does not flow into the lamp chamber 203 but instead is directed elsewhere. [0032] Fig. 3A is a longitudinal cross-sectional view of the lamp assembly 1 14, according to further examples. Fig. 3B is an enlarged view of a portion of the lamp assembly 1 14 of Fig. 3A. Fig. 4 is a perspective view of a portion of the lamp assembly 1 14, with a section of the lamp assembly 1 14 cut away to show half the lamp assembly 1 14. The following refers to Figs. 3A, 3B, and 4.

[0033] The lamp assembly 1 14 includes multiple heating lamps 202, which are located in a lamp chamber 203 that is defined between two horizontal plates 306 and 308, in the orientation of the lamp assembly 1 14 shown in Fig. 3A. More generally, the lamp chamber 203 is defined between two plates, or more than two plates. The plates 306 and 308 can be considered to be a lamp housing that contains the heating lamps 302.

[0034] In some examples, the upper plate 306 can be formed of a metal, such as aluminum or some other metal. In further examples, the upper plate 306 can be formed of a different rigid material.

[0035] The lower plate 308 can be formed of a substrate that is transmissive to energy produced by the heating lamps 202 to cause heating of a target on the build platform 102. In some examples, the lower plate 308 can be a glass plate that allows for heat produced by the heating lamps 202 to pass through the glass plate towards the build platform 102 below the lamp assembly 1 14. In some examples, the glass plate can be formed of quartz glass, borosilicate glass, aluminosilicate glass, or other type glass. In further examples, the lower plate 308 can be formed of a different material that is transmissive to energy produced by the heating lamps to cause heating of a target on the build platform 102, where such examples of other materials can include ceramics, or a non-transparent plate such as a silicium plate, germanium plate, and so forth.

[0036] In implementations according to Fig. 3A, the sensor module 1 16 is located generally in a central location within the array of heating lamps 202. More generally, the sensor module 1 16 is located in a space between at least two heating lamps 202 of an array of heating lamps that are part of the lamp assembly 1 14. [0037] In examples according to Figs. 3A-3B, the exhaust outlet 214 is provided that includes an orifice (or multiple orifices) in the sensor module housing 204. The exhaust outlet 214 allows the heated exhaust airflow 216 to pass from the sensor chamber 206 of the sensor module 1 16 to the lamp chamber 203. Thus, the incoming cooling airflow 212 flows into the sensor chamber 206 of the sensor module housing 204. The cooling airflow 212 cools the sensor 208, which causes the airflow to be heated to produce the heated exhaust airflow 216. This heated exhaust airflow 216 exits through the exhaust outlet 214 into the lamp chamber 203.

[0038] In implementations where the exhaust outlet 214 leads to the lamp chamber 203, the heated exhaust airflow 216 that exits through the exhaust outlet 214 can also be used to cool at least some of the heating lamps 202 in the lamp chamber 203. Note that the heated exhaust airflow 216 from the sensor module 1 16 can still be cooler than the temperature of the lamp chamber 203.

[0039] In other examples, an exhaust outlet from the sensor module 1 16 can be located at a different location, with another example depicted in Fig. 6 discussed further below.

[0040] As further shown in the enlarged view of Fig. 3B, the sensor 208 is located within a sensor holder housing 320 that holds the sensor 208. The sensor holder housing 320 is an inner housing of the sensor module 1 16 that is within the sensor module housing 204, which is considered the outer housing of the sensor module 1 16.

[0041 ] The sensor holder housing 320 can be used to provide heat insulation for the sensor 208 contained inside the sensor holder housing 320. The sensor holder housing 320 can be formed of a material that can reflect radiative heating produced inside the inner chamber of the sensor module housing 204. For example, the sensor holder housing 320 can be formed of aluminum or other suitable material. Any radiative heating directed towards the sensor 208 would be reflected by the sensor holder housing 320 away from the sensor 208. In addition, if the sensor holder housing 320 is formed of a heat conductive material, such as aluminum or other suitable metal, the sensor holder housing 320 can provide a uniform temperature along at least a portion of the outside of the sensor 208. The

temperature of the sensor holder housing 320 is kept at a lower level by the cooling airflow 212.

[0042] An opening is formed at the bottom portion of the sensor holder housing 320, where a lens 322 can be provided. The sensor 208 can detect radiated heat of a target on the build platform 102 (Fig. 1 ) to allow for the sensor 208 to sense the temperature of the target. As shown in Figs. 3A and 3B, an opening is formed in the lower plate 308 underneath the sensor 208 so that the lower plate 308 does not interfere with the temperature measurement by the sensor 208 of the target on the build platform 102.

[0043] In some examples, a heat insulator 324 is provided between the sensor holder housing 320 and the sensor module housing 204, to prevent heat conduction between the sensor module housing 204 and the sensor holder housing 320. Note that the sensor module housing 204 has an outer surface 326 that is exposed to the lamp chamber 203, such that the sensor module housing 204 is heated by the heat in the lamp chamber 203. The heat insulator 324 reduces the amount of such heat from being conductively transferred to the sensor 208.

[0044] In some examples, the heat insulator 324 can be generally ring-shaped to fit around an outer surface 328 of the sensor holder housing 320. The heat insulator 324 can be formed of a plastic, a polymer, or any other heat insulating material.

[0045] In addition, as further shown in Figs. 3A and 3B, a seal 330 is provided between the lower plate 308 and the sensor module housing 204, to prevent communication of heated air inside the lamp chamber 203 from leaking or flowing out to a region 332 that is underneath the sensor 208. This is to prevent the temperature inside the region 332 from being raised due to the heated air inside the lamp chamber 203, which can interfere with accurate measurement, through the lens 322, by the sensor 208 of the surface temperature of a target on the build platform [0046] The seal 330 can be generally ring-shaped, and can be formed of a silicon foam or other compressible material that can prevent leakage of air or other gas inside the lamp chamber 203 from reaching the region 332.

[0047] As further shown in Fig. 3A, the same airflow generator 1 18 can produce cooling airflows that can be directed both into the lamp chamber 203, as indicated by arrow 335, and the sensor module 1 16, as indicated by arrow 212. The conduits between the airflow generator 1 18 and the lamp chamber 203 and the sensor module 1 16 are not shown in Fig. 3A.

[0048] In other examples, separate airflow generators can be used to

respectively produce the cooling airflow to the lamp chamber 203, and the cooling airflow to the sensor module 1 16.

[0049] In further examples, a sensor 334 can also be attached to the sensor holder housing 320, to measure a temperature of the sensor holder housing 320. The measurement of the temperature of the sensor holder housing 320 can be provided to a controller of the 3D printing system such that the controller can take action to address the temperature of the sensor 208. For example, if the

temperature from the sensor 334 indicates that the sensor holder housing 320 is elevated (e.g. greater than a specified threshold), the controller of the 3D printing system can increase the flow rate of the cooling airflow 212 that is directed into the sensor chamber 206 of the sensor module 1 16, such as by increasing the speed of the airflow generator 1 18.

[0050] In alternative examples, as shown in Fig. 3B, slots 350 can be formed through the heat insulator 324 and a lower portion 352 of the sensor module housing 204. These slots 350 allow the airflow that flows inside the sensor chamber 206 of the sensor module 1 16 to flow through the heat insulator 324 and the lower portion 352 of the sensor module housing 204, into the region 332 adjacent the lens 322 associated with the sensor 208. This airflow can be used for cleaning the lower surface of the lens 322. In some cases, powdered build material particles or other particles can coat at least a portion of the lens 322, which can interfere with the temperature measurement being made by the sensor 208. The airflow that is passed through the slots 350 can be used to clean the lower surface of the lens 322. In implementations where the slots 350 are provided through the heat insulator 324 and the lower portion 352 of the sensor module housing 204, the cooling airflow 212 directed into the sensor chamber 206 of the sensor module 1 16 can be turned off during times when the sensor 208 is making a measurement of the target on the build platform 102, to avoid interference with the temperature measurement being taken by the sensor 208 caused by the airflow from inside the sensor chamber 206 passing through the slots 350 to the region 332.

[0051 ] Fig. 5 is a block diagram of an example arrangement of a portion of a 3D printing system. In Fig. 5, a controller 502 of the 3D printing system is shown. The controller 502 can be implemented as a microprocessor, a core of a multi-core microprocessor, a microcontroller, a programmable integrated circuit device, a programmable gate array, or another hardware processing circuit. The controller 502 can also in some examples include machine-readable instructions executable on the hardware processing circuit.

[0052] The controller 502 receives a temperature output 504 from the sensor 208, which provides an indication of the temperature of a target on the build platform 102. The controller 502 can use the temperature of the target as measured by the sensor 208 to control the heating lamps 202 of the lamp assembly 1 14, to adjust the temperature of the target on the build platform 102 based on the feedback provided by the sensor 208.

[0053] The controller 502 also receives a temperature output 506 from the sensor 334, which indicates a temperature of the sensor holder housing 320 (Figs. 3A-3B and 4) that holds the sensor 208. In response to the temperature output 506, the controller 502 can adjust the airflow generator 1 18 to cause a change in the rate of the cooling airflow 212 provided into the sensor chamber 206 of the sensor module 1 16. For example, if the sensor 334 indicates an elevated temperature, then the controller 502 can increase the rate of the cooling airflow 212. On the other hand, if the sensor 334 indicates a lower temperature, then the controller 502 can reduce the rate of the cooling airflow 212.

[0054] In some examples discussed above, the heated exhaust airflow 216 exits through the exhaust outlet 214 (Figs. 3A-3B) to the lamp chamber 203. In alternative examples, as shown in Fig. 6, an exhaust outlet 602 can be provided at a different location of the sensor module 1 16. In Fig. 6, the exhaust outlet 602 is formed at the upper portion of the sensor module 1 16, in the form of an annular opening around the upper opening 210.

[0055] A cylindrical inner housing 606 can be provided inside the sensor module housing 204, to define an annular space 610 between the inner housing 606 and the sensor module housing 204. The cooling airflow 212 enters through the upper opening 210 to cool the sensor 208. The cooling airflow 212 is heated by the sensor 208, which produces a heated exhaust airflow 604 that passes from the sensor chamber 206 where the sensor 208 is located through an opening 608 (or multiple openings) formed in the inner housing 606 to the annular space 610. The heated exhaust airflow 604 continues upwardly through the annular space 610 to exit through the exhaust outlet 602.

[0056] Thus, according to the arrangement shown in Fig. 6, the airflow inlet includes a first opening (e.g. upper opening 210) on a first side (e.g. the top side) of the sensor module housing 204, and the exhaust outlet 602 includes a second opening (e.g. exhaust outlet 602) on the first side of the sensor module housing 204.

[0057] Fig. 7 is a flow diagram of a process of forming a lamp assembly for a printing system. The process of Fig. 7 includes arranging (at 704) an array of heating lamps inside a lamp chamber of the lamp assembly. The process further includes arranging (at 704) a sensor module among the heating lamps, and providing (at 706) an airflow inlet in a housing of the sensor module to receive a cooling airflow to cool a sensor in the sensor module. The process additionally includes providing (at 708) an exhaust outlet in the housing through which heated exhaust airflow is to exit from the sensor module. [0058] Machine-readable instructions that can be executed on the controller 502 of Fig. 5 can be stored on a non-transitory machine-readable or computer-readable storage medium. The storage medium can include one or multiple different forms of memory including semiconductor memory devices such as dynamic or static random access memories (DRAMs or SRAMs), erasable and programmable read-only memories (EPROMs), electrically erasable and programmable read-only memories (EEPROMs) and flash memories; magnetic disks such as fixed, floppy and removable disks; other magnetic media including tape; optical media such as compact disks (CDs) or digital video disks (DVDs); or other types of storage devices. Note that the instructions discussed above can be provided on one computer- readable or machine-readable storage medium, or alternatively, can be provided on multiple computer-readable or machine-readable storage media distributed in a large system having possibly plural nodes. Such computer-readable or machine-readable storage medium or media is (are) considered to be part of an article (or article of manufacture). An article or article of manufacture can refer to any manufactured single component or multiple components. The storage medium or media can be located either in the machine running the machine-readable instructions, or located at a remote site from which machine-readable instructions can be downloaded over a network for execution.

[0059] In the foregoing description, numerous details are set forth to provide an understanding of the subject disclosed herein. However, implementations may be practiced without some of these details. Other implementations may include modifications and variations from the details discussed above. It is intended that the appended claims cover such modifications and variations.

Claims

What is claimed is: 1 . A lamp assembly of a printing system, comprising:

a heating lamp to generate heat energy during an operation of the printing system;

a sensor; and

a first housing defining a sensor chamber in which the sensor is located, the first housing defining an airflow inlet to receive a cooling airflow to cool the sensor, and an exhaust outlet through which a heated exhaust airflow is to exit from the sensor chamber.

2. The lamp assembly of claim 1 , comprising an array of heating lamps, wherein the first housing is located in a space between at least two heating lamps of the array of heating lamps.

3. The lamp assembly of claim 2, wherein the space is in a central location within the array of heating lamps.

4. The lamp assembly of claim 1 , further comprising a lamp housing defining a lamp chamber in which the heating lamp is located, wherein the first housing defines the sensor chamber that is separate from the lamp chamber.

5. The lamp assembly of claim 4, wherein the exhaust outlet is to pass the heated exhaust airflow from the sensor chamber to the lamp chamber.

6. The lamp assembly of claim 1 , wherein the airflow inlet includes a first opening on a first side of the first housing, and the exhaust outlet includes a second opening on the first side of the first housing.

7. The lamp assembly of claim 1 , further comprising a plate through which energy produced by the heating lamp is transmitted.

8. The lamp assembly of claim 7, wherein the plate includes an opening through which the sensor is to measure a temperature of a target on a build platform of the printing system.

9. A printing system comprising:

a carriage;

an airflow generator; and

a lamp assembly attached to the carriage and comprising:

a heating lamp to generate energy to heat a layer of build material on a build platform;

a sensor to detect a temperature of the layer of build material; and a first housing defining a sensor chamber in which the sensor is located, the first housing comprising an airflow inlet to receive a cooling airflow generated by the airflow generator and received through a duct to cool the sensor.

10. The printing system of claim 9, further comprising a second housing inside the first housing, the second housing to hold the sensor and to reflect radiative heat away from the sensor, the second housing to provide a uniform temperature along at least a portion of the sensor, and the first housing to reflect radiative heat generated by the heating lamp and to isolate the sensor from heat inside a chamber containing the heating lamp.

1 1 . The printing system of claim 10, further comprising a heat insulator between the first housing and the second housing.

12. The printing system of claim 10, further comprising a slot to allow airflow in the sensor chamber to flow to a region adjacent a surface of a lens associated with the sensor, the airflow to clean particles from the lens.

13. The printing system of claim 9, wherein the sensor is a first sensor, the printing system further comprising:

a controller; and

a second sensor to measure a temperature of the first sensor and to provide a temperature measurement to the controller,

wherein the controller is to control speed of the airflow generator in response to the temperature measurement.

14. A method of forming a lamp assembly for a printing system, comprising:

arranging an array of heating lamps inside a lamp chamber of the lamp assembly;

arranging a sensor module among the heating lamps;

providing an airflow inlet in a housing of the sensor module to receive a cooling airflow to cool a sensor in the sensor module; and

providing an exhaust outlet in the housing through which heated exhaust airflow is to exit from the sensor module.

15. The method of claim 14, further comprising providing an airflow generator to generate the cooling airflow, wherein the airflow generator is to further communicate another cooling airflow to cool the array of heating lamps.