DE102016014247A1 - Video endoscope and method for operating a video endoscope - Google Patents

Abstract

A video endoscope according to the invention, in particular a cable-free video endoscope (1) comprising at least one internal heat source, has a latent heat accumulator (12) for receiving at least part of the heat generated by the at least one internal heat source via one between the at least one internal heat source and the latent heat accumulator (12) formed on the heat transport path, wherein a thermal resistance element is arranged to increase a thermal resistance in the heat transport path. In this way, it can be achieved, in particular, that the video endoscope (1) can be operated over a relatively long period of time without a surface of a housing (4) of the video endoscope (1) exceeding a predetermined maximum temperature T _max . The invention also relates to a method for operating a video endoscope.

Description

The present invention relates to a video endoscope according to the preamble of claim 1, in particular a cable-free video endoscope, and a method for operating a video endoscope.

Video endoscopes for medical or non-medical applications include optical and / or electronic components for capturing an image of a scene in a cavity, wherein the captured image is typically routed via a cable to an external display or viewing device. In order to adequately illuminate the endoscopic scene to be recorded, it is known to direct illumination light generated by an external illumination device to the endoscope via a light guide cable or to arrange one or more light sources, for example light emitting diodes (LEDs) within the endoscope. In this way, as well as by electronic components, however, heat loss occurs during operation, which leads to heating of the endoscope. This heating is undesirable. In particular, heating the surface of the endoscope beyond a maximum temperature of 41 ° C may result in damage to body tissue with which the endoscope comes into contact in a medical application. Similarly, heating a handle can interfere with the operation of the endoscope.

Out EP 2 756 791 A2 an endoscopic device is known, which comprises an endoscope, wherein in the endoscope at least one heat-generating component is arranged and a head piece of the endoscope has a heat exchange surface for delivering the heat generated by the at least one heat-generating component to the outside of the endoscope. The endoscopic device further comprises a cooling neck which can be connected to the endoscope and which is designed to absorb heat from the heat exchange surface of the head piece and to dissipate heat through a cooling fluid flowing through the cooling neck. The fluid lines for supply and discharge of the cooling fluid are guided in a supply line.

Such a supply line and electrical and optical cables can limit the freedom of movement of a user and the usability of the endoscope. Furthermore, such lines and cables are subject to wear, and finally, a sterile preparation of an endoscope and connected thereto or connectable cables and cables with a considerable overhead.

There are also known wireless endoscopes that work without such supply lines in operation. Here are system components that are housed in wired endoscopes in external utilities, integrated into the endoscope, which includes, for example, a light source, an image sensor, an image-processing electronics and a transmission module for wireless image transmission. The fact that these system components are arranged within the endoscope, a particularly high thermal power loss is generated within the endoscope during operation of the endoscope.

In WO 2012/075989 A1 discloses a hand-operated endoscope for medical purposes, wherein a power supply by means of a rechargeable battery, which is part of a structural unit, which includes a camera system with associated optics, a light source and a transmission system and which can be used as an unsterilized unit in a sterilized housing. In this case, a data transmission can be done by radio. This creates a wireless, handy system. Measures for heat dissipation are not disclosed.

According to EP 0 917 438 B1 For example, a portable endoscopic hand-held camera has a light source capable of illuminating an endoscope but at the same time having a low wattage so as not to rely on fans or heat sinks to prevent overheating. The wattage of the light source means is in the range of 0.5 to 5 watts.

It is an object of the present invention to provide a video endoscope, in particular a cable-bound video endoscope, in which a heating of the surface during operation is as low as possible or the temperature of the surface remains at least for a longest possible time below a maximum allowable temperature, the functionality as possible largely corresponds to a wired video endoscope. It is another object of the invention to provide a corresponding method for operating a video endoscope.

This object is achieved by a video endoscope according to claim 1 and by a method according to claim 16.

Advantageous developments of the invention will become apparent from the dependent claims.

A video endoscope according to the invention is designed in particular as a cable-free video endoscope, ie it can be operated for at least a limited period of time without a cable-bound or line-connected connection to an external supply device and can therefore also be referred to as a wireless video endoscope. During operation of the video endoscope, a wireless connection to an external receiving device may be provided. Such a cable-bound video endoscope can be designed as a self-sufficient video endoscope. The video endoscope according to the invention is designed in particular for medical applications, but may also be intended for non-medical applications. The video endoscope according to the invention can, especially if it is intended for medical applications, be hermetically sealed and sterilizable or autoclavable.

The video endoscope comprises at least one heat source, which is arranged within the video endoscope and emits heat during operation of the video endoscope. The heat source is formed for example by electrical, electronic and / or optoelectronic components that generate heat during operation. This heat, which develops inside the video endoscope and can lead to unwanted heating of the video endoscope, is also referred to as waste heat or waste heat. The heat source is therefore also referred to here as a heat loss source.

In particular, the video endoscope comprises an image sensor for receiving an endoscopic image of an object field, which can also be referred to as a video sensor, and video electronics. The video electronics may comprise one or more electronic assemblies for processing and transmission of the image captured by the image sensor, in particular a transmission electronics for a wireless transmission of the image to an external receiving device, where it for further processing, storage and / or display on a display device, such as a monitor, may be available. Furthermore, the video endoscope can comprise one or more light sources for illuminating the object field, for example one or more light-emitting diodes (LEDs). The light source can be arranged for direct illumination of the object field. However, the video endoscope can also comprise illumination optics for relaying the illumination light generated by the light source to the object field. The at least one heat loss source of the video endoscope is thus preferably formed by the image sensor, the video electronics and the one or more light sources.

The video endoscope may comprise further components, for example observation optics for generating an image of the observed object field on the image sensor. By way of example, the observation optics can have an objective and, if appropriate, an image relay, which can comprise one or more relay lens systems and which is arranged to forward the image of the object field designed by the objective to the image sensor. The video endoscope may include electrical cables, optical cables and / or other supply lines or connections for the connection of such cables or supply lines; however, preferably, the video-endoscope may be operated without such cables for at least a limited period of time and may provide an endoscopic image of the object-field.

According to the invention, the video endoscope has a latent heat accumulator, which is designed to receive at least part of the heat emitted by the at least one internal heat source, in particular the heat loss generated by the at least one light source, the image sensor and / or the video electronics, and for this purpose via a between at least one internal heat source and the latent heat storage formed heat transport path is in thermal communication with the at least one internal heat source. Via this thermal connection, i. over the heat transport path, thus at least a portion of the heat loss of the heat source can be dissipated to the latent heat storage and absorbed by this. The latent heat storage device can be arranged, for example, within the video endoscope or be connected to it in such a way that it forms a compact and easily manageable unit with it.

In particular, the latent heat store comprises a phase change material (phase change material, phase change material, PCM). When using a PCM as a heat storage agent at least a portion of the heat loss can be stored on the latent enthalpy of fusion of the PCM. Preferably, the PCM has a phase transition temperature, such as a melting point, which is above a room temperature and below a maximum allowable temperature of the surface of the video-endoscope, more preferably below about 41 ° C, for example between about 25 ° C and about 35 ° C. It is advantageous if the PCM has a high specific heat absorption capacity, for example more than 50 J / g. As a result, a small amount of the PCM is sufficient to operate the video endoscope for a long period of time, in particular for a typical duration of an endoscopic procedure, without exceeding the maximum permissible surface temperature. Suitable phase-change materials have been, for example, low-melting metals, such as gallium, or eutectic alloys. In principle, for example, organic materials or salt solutions can be used. In this case, low-melting metals have the additional advantage of higher thermal conductivity. This allows a particularly efficient absorption of the heat loss in the latent heat storage and thus a particularly compact design of the video endoscope.

According to the invention, the video endoscope further comprises a thermal resistance element arranged to increase a thermal resistance of the heat transport path in the heat transport path, i. in the thermal connection between the at least one internal heat source and the latent heat storage is arranged. By the interposition of the thermal resistance element in the heat transport path, the thermal resistance of the heat transport path is increased from the at least one internal heat source to the latent heat storage. The thermal resistance element has in particular a defined thermal resistance. The thermal resistance element can also be arranged spatially between the at least one inner heat source and the latent heat storage.

Characterized in that the video endoscope has a latent heat storage, which can absorb at least a portion of the generated during operation of the video endoscope of the optical and / or electronic components contained loss heat, the loss heat generated by the heat source can be recorded at least for a limited period of latent heat storage, without a significant increase in temperature occurs. Characterized in that a thermal resistance element is arranged in the thermal connection between the heat source and the latent heat storage, the size of a heat flow from the heat source to the latent heat storage can be selectively influenced and so the latent heat storage can be used particularly effectively. Surprisingly, it has been shown that this makes it possible to operate the video endoscope for an especially long time without exceeding a maximum permissible surface temperature. In particular, it can thereby be made possible, at least for a limited period of time, for example for a predefinable operating time, to avoid exceeding a maximum permissible surface temperature of, for example, 41 ° C. At the same time, the video endoscope can be configured in a compact design, in particular as a cable-bound, particularly handy video endoscope, and have largely the same functionality as a wired video endoscope.

Preferably, the video endoscope has an elongated shaft suitable for insertion into a cavity. In a medical video endoscope, the shaft is designed for insertion into a body-internal cavity of a human or animal body. In a video endoscope intended for non-medical applications, for example, the shaft is suitable for insertion into a cavity of a technical object. The shaft is particularly rigid, but may also be semi-rigid or flexible.

More preferably, the videoendoscope has a head disposed at a proximal (i.e., near-to-the-user) end of the shaft that may be flared in a transverse dimension from the shaft and may include a housing. The latent heat storage is associated with the head according to this embodiment. In particular, the latent heat storage is arranged in the head, i. accommodated within a housing of the head, so that the space in the head usually available space for the accommodation of the latent heat storage can be used. But it can also be provided that the latent heat storage is arranged at the head and is connected, for example, with a housing of the head. As a result, a suitable for medical or non-medical applications video endoscope is created, which allows the recording of an endoscopic image of a cavity arranged in an object field, has a compact design and is operable for a longer period without a maximum allowable surface temperature is exceeded.

According to a preferred embodiment of the invention, the video endoscope has a housing, which is in thermal communication with the at least one internal heat source, ie for example with the light source, the image sensor and / or the video electronics, and for dispensing another part of the at least an internal heat source generated heat is formed, for example, over a surface of the housing to an environment of the video endoscope. For this purpose, the housing may have approximately one or more heat-emitting surfaces, which are formed on an outer side of the housing and may be arranged such that they are not touched or embraced by a user when using the video-endoscope in the rule. The housing is in particular a housing of the head of the endoscope or comprises a housing of the head of the endoscope. The housing may, for example, be in direct thermal contact with the light source, the image sensor and / or the video electronics, or may be connected to it via a heat conductor, for example a heat-conducting structure or, for example, a heat pipe (heat pipe). As a result, an advantageous distribution of the heat loss generated by the at least one internal heat source can be achieved in a simple manner, wherein only a portion of the heat loss is absorbed by the latent heat storage and another part is released to the environment. This can make it possible, with an equal heat capacity of the Latent heat storage to operate the video endoscope for a long period without exceeding the maximum allowable surface temperature.

Most preferably, a thermal resistance of the thermal resistive element to maximize a service life of the video-endoscope, during which a surface of the housing does not exceed a predetermined maximum temperature, dimensioned. By dimensioning the thermal resistance of the thermal resistance element, a distribution of the heat loss between the latent heat storage and the housing surface can be determined, so that a first portion of the heat loss is absorbed by the latent heat storage and a second portion of the heat loss is directed to the housing and from this over the surface of the Housing is delivered to the environment. By increasing the thermal resistance of the thermal resistive element, the surface temperature of the housing can be increased, causing increased heat dissipation through the housing to the environment. On the other hand, a reduction of the thermal resistance causes an increased heat absorption by the latent heat storage. According to this embodiment of the invention, the thermal resistance of the thermal resistance element is determined such that a possible operating time is maximum without exceeding the maximum permissible surface temperature. This means that such a proportion of the heat loss arrives at the latent heat accumulator and such a proportion to the housing that the housing surface does not exceed a predefinable maximum permissible temperature of, for example, 41 ° C. for as long as possible, at least for a predefinable operating period; The housing surface preferably has a temperature which corresponds to the maximum allowable temperature or is only slightly lower, for example in the range of 35 ° C to 40 ° C.

The thermal resistance of the thermal resistive element is advantageously determined as a function of the phase transition temperature of the latent heat accumulator and furthermore on the total heat absorption capacity of the latent heat accumulator and the efficiency of the heat dissipation over the surface of the housing. The achievable thereby duration, during which the video endoscope can be operated without the housing surface exceeds the maximum allowable temperature, may also be dependent on the ambient temperature and the operation of the video endoscope, for example, the power with which the light source is operated. The adaptation of the thermal resistance of the thermal resistance element can be related to an average or a maximum ambient temperature as well as to an average or a maximum heat loss output of the at least one heat source of the video endoscope. Characterized in that the thermal resistance of the thermal resistance element is dimensioned so that a first portion of the video endoscope resulting heat loss arrives at the latent heat storage and a second proportion to the housing of the head, wherein the first and the second portion in particular depending on the heat absorption by the latent heat storage and the heat output are determined over the surface of the housing, it can be achieved that the video endoscope can be operated for a particularly long period of time without the housing surface exceeds a predetermined maximum temperature, for example 41 ° C.

According to a preferred embodiment of the invention, substantially the entire surface of the housing, in particular substantially the entire surface of the head of the video endoscope, is in thermal contact with the at least one heat source. As a result, a maximum surface and thus a particularly efficient heat dissipation is possible, so that a particularly long service life of the video endoscope is reached without exceeding the predetermined maximum surface temperature.

In a particularly advantageous manner, the video endoscope has at least one thermal tooth for forwarding at least part of the heat loss generated by the heat source, in particular the light source, the image sensor and / or the video electronics, to the latent heat accumulator. The thermal track is disposed between the at least one internal heat source and the latent heat storage and connected in series with the thermal resistance element. The heat transport path from the heat source to the latent heat accumulator can thus be formed by or comprise the thermal path and the thermal resistance element, so that the part of the heat loss discharged from the heat source to the latent heat accumulator flows through the thermal path and through the thermal resistance element. For example, if the light source is located in the distal (remote) end portion of the shaft, a thermal path may be used to propagate the heat loss of the light source into the head of the video endoscope and at least in part to the latent heat storage. Likewise, for example, the image sensor may be arranged in the distal end region of the shaft and a thermal track, which may be the same as that associated with the light source, may be provided for forwarding the waste heat generated by the image sensor to the head. However, one or more heat sources and one or more corresponding heat paths may also be arranged within the head for the purpose of transmitting at least part of the heat loss generated to the latent heat store, in particular for the transmission of the part of the heat loss to the thermal resistance element, via which this passes to the latent heat storage. Such thermal paths can be formed for example by heat pipes (heat pipes), Peltier elements and / or thermally conductive materials, such as silver. Such a heat pipe can, for example, as in EP 2 394 567 A1 be described, which document is incorporated herein by reference in the present application. Due to the fact that the video endoscope has at least one thermal track for forwarding at least part of the heat loss of the at least one heat source to the latent heat accumulator, dissipating the heat loss for recording by the latent heat accumulator can also be largely independent of the arrangement of the at least one heat source within the video endoscope and thus improved overheating of the video endoscope can be prevented.

The thermal path can also be designed with a defined thermal resistance in order to specifically influence, together with the thermal resistance of the thermal resistance element, the portion of the heat loss reaching the housing and the latent heat accumulator. In particular, the sum of the thermal resistances of the at least one thermal track and the thermal resistive element may be dimensioned as previously described for the thermal resistance of the thermal resistive element.

Advantageously, the thermal resistance element may be formed such that the thermal resistance of the thermal resistance element is adjustable. This allows a particularly accurate adaptation to the properties of the video endoscope and a particularly favorable distribution of the heat loss of the at least one heat source to the housing and the latent heat storage, so that the video endoscope over a particularly long period without exceeding a maximum surface temperature can be operated. Alternatively, the thermal resistance of the thermal resistive element may be predetermined and sized in a predetermined manner as previously described.

Preferably, the thermal resistance element comprises two heat exchange surfaces in contact with each other, wherein the thermal resistance of the thermal resistance element is determined by a contact region of the heat exchange surfaces. In particular, the size of the surface of the contact region can be selected accordingly to determine the latent heat storage reaching first portion of the heat loss and reaching the housing of the head second portion of the heat loss so that the longest possible operating time is exceeded without exceeding the predetermined maximum allowable temperature ,

Alternatively or additionally, the thermal resistance element may comprise a gap which is formed, for example, between two heat exchange surfaces arranged at a distance from one another and via which the dissipated heat loss flows by means of a medium arranged within the gap or between the heat exchange surfaces. In this case, the thermal resistance of the thermal resistance element can be determined by the gap width and / or the heat transfer properties of the medium filling the gap. The medium may be, for example, air or a liquid or a thermopad. Characterized in that the thermal resistance of the thermal resistance element is determined by the gap, a maximization of the possible without exceeding the maximum surface temperature permissible operating time of the video endoscope is possible in a particularly simple and effective manner.

Further alternatively or additionally, a bimetallic element may be provided which, depending on a temperature, establishes a thermal contact between two sections of the thermal resistance element and thereby determines its thermal resistance. According to further alternative or additional possibilities for adjusting the thermal resistance of the thermal resistance element, this may comprise a condenser or a heat pipe (heat pipe) and / or a Peltier element, via which the heat loss is passed on and which determines the thermal resistance as a function of temperature. This allows the best possible adaptation of the thermal resistance to achieve the longest possible operating time without exceeding the predetermined maximum allowable temperature.

Preferably, the latent heat storage is partially thermally insulated. In particular, the latent heat accumulator is insulated in this way and can be surrounded by an insulating material in such a way that, as far as possible, no heat flow to the latent heat accumulator can occur, except via the heat transport path or via the thermal resistance element. In particular, the latent heat accumulator can be thermally insulated from the housing. In this way it can be prevented that the housing emits a part of the heat loss to the latent heat storage, and it can be ensured that the heat absorption is limited by the latent heat storage to a correspondingly determined proportion of the heat loss. In addition, the isolation of the influence of hand warmth of a user who holds the video endoscope can be reduced, for example, to a faster melting of the PCM could lead. As a result, the possible operating time of the video endoscope can be further optimized without exceeding the maximum permissible surface temperature.

Preferably, the latent heat storage is at least partially surrounded by an elastically deformable or compressible material, which is also preferably also thermally insulating. The compressible material can absorb a change in volume of the latent heat accumulator, for example a volume jump during freezing or melting of a PCM of the latent heat accumulator, and thus avoids a mechanical stress on the housing due to the expansion. Furthermore, it can thereby be achieved that the latent heat accumulator is biased by the elastically deformable material to improve the thermal conduction of the thermal resistance element against a thermal contact surface. Furthermore, the latent heat storage can be protected thereby against heating by the hand heat of a user or by the warmer housing parts.

According to a particularly preferred embodiment of the invention, the latent heat storage device is exchangeable and is in particular arranged interchangeably in or at the head of the video endoscope. Preferably, the latent heat storage device according to this embodiment is designed as an insertable or attachable to the housing of the head module. The latent heat storage is thermally connected by inserting or applying for heat absorption of the at least one heat source with this. In particular, the thermal resistance element is formed when setting in or preparing, for example, via mutually associated contact surfaces and a heat transport path between one or more heat loss sources and the latent heat storage is closed by way of this. The module can be removed from the housing again or be removable from this. In this way, a rapid reuse of the video endoscope after a successful use as well as an extended operating time can be made possible by exchanging the latent heat storage. Furthermore, the cleaning and / or sterilization of the video endoscope can thereby be facilitated by being prepared separately from the latent heat store or a module which comprises the latent heat store. In a particularly advantageous manner, the latent heat storage can be arranged in a replaceable handle of the video endoscope. In this way, an advantageous mass distribution can be achieved, thereby improving the handling of the video endoscope.

Preferably, the latent heat storage is designed to be interchangeable with an electrical energy storage, which serves to power the video endoscope. The electrical energy storage device may be, for example, an accumulator. In particular, the latent heat storage and the electrical energy storage can be accommodated together in a replaceable energy module. In addition to a contact surface or a heat exchange surface over which the heat transfer can take place, this module can have a plurality of resilient contact pins via which an electrical connection between the electrical energy store and electrical consumers of the video endoscope, for example the light source and / or the video electronics, can be produced. In this way, a rapid reuse of the video endoscope after a successful use and a prolonged operating time of the video endoscope, in particular if this is designed as a cable-bound video endoscope, are made possible in a particularly simple manner by replacing the power module. The energy module itself, like the video endoscope without the energy module, can be made hermetically sealed and sterilizable or autoclavable. In a further advantageous manner, the energy module can be designed as a replaceable handle of the video endoscope, whereby a particularly advantageous mass distribution can be achieved and the manageability of the video endoscope can be further improved.

In a particularly preferred manner, a heat absorption capacity of the latent heat accumulator and an energy content of an electrical energy accumulator of the video endoscope are matched to one another. In a video endoscope, in which the latent heat storage is interchangeable with an electrical energy storage and both are included, for example, in a removable power module, it is particularly advantageous if the heat absorption capacity of the latent heat storage and the energy content of the electrical energy storage are matched. In particular, the heat absorption capacity of the latent heat storage and the energy content of the electrical energy storage can be coordinated such that exceeding the maximum surface temperature is prevented even with a substantial or complete depletion of the energy content of the electrical energy storage during operation of the video endoscope. This can be achieved, for example, by virtue of the fact that the heat absorption capacity of a latent heat accumulator formed with a PCM, in particular the latent heat absorption capacity in the phase transition, is greater than or approximately equal to the energy content of the electrical energy accumulator. The latent heat absorption capacity of the latent heat storage can also be much lower than the energy content of the electrical energy storage, as in a typical or a maximum expected ambient temperature during operation of the video endoscope to heat loss can be discharged through the housing surface. If the electrical energy storage is an accumulator, the corresponding, matched to the heat absorption capacity of the latent heat storage energy content by a limited charge of the accumulator or by a suitably tuned capacity, ie the maximum storable charge amount of the accumulator can be guaranteed. In this way, a video endoscope can be created, which is compact and lightweight and in which overheating is reliably avoided.

Alternatively or additionally, it may be provided in an advantageous manner that a heat absorption by the latent heat storage and thus consumption of the heat absorption capacity of the latent heat storage is monitored. For this purpose, the video endoscope may comprise an electronic control device which is designed to monitor the heat absorption of the latent heat accumulator and for this purpose may have a processor device and one or more suitable sensors. The control device may in particular be designed to monitor the heat absorption by the latent heat storage by monitoring the operating time and the consumed electrical power, which can be considered approximately as a measure of the generated heat loss. As a result, the total heat generated during operation of the video endoscope can be determined. In order to determine the part of the heat loss of the at least one heat source picked up by the latent heat accumulator, it can also be assumed, for example, that a predetermined or measured proportion of the heat loss due to a measured or average ambient temperature is transported to the latent heat accumulator and is absorbed by it. Alternatively or additionally, it can be provided that a temperature increase of the PCM is detected by means of a temperature sensor, from which the consumption of the latent heat absorption capacity, i. on a complete phase transition of the PCM, can be concluded. The control device may further be configured such that when the part of the generated heat loss transferred to the latent heat storage device reaches or almost reaches a predetermined heat absorption capacity of the latent heat storage, a user-detectable warning signal is generated, and / or when the heat absorption capacity of the heat transfer device is reached Latent heat storage a further operation of the heat loss sources and thus further use of the video endoscope is prevented. The warning signal may be, for example, an acoustic or an optical signal which, in a graduated form, for example by different acoustic signals or by different colors of LED displays, first indicates an advance warning and then a shutdown of the heat sources. In a simple embodiment, a monitoring of the duration of use and a warning signal or a shutdown of the video endoscope shortly before or when reaching a maximum period of use, which corresponds to the maximum heat capacity of the latent heat storage at a maximum or average electrical power of the loss heat sources may be provided. In this way, it can also be made possible to avoid further use of the video endoscope after the heat absorption capacity of the latent heat accumulator has been consumed and the maximum permissible surface temperature has been exceeded; the heat absorption capacity of the latent heat storage and the energy content of the electrical energy storage must not be coordinated.

According to a method according to the invention for operating a video endoscope which has at least one internal heat source, a first portion of the heat generated by the at least one internal heat source is transmitted to and absorbed by a latent heat accumulator via a heat transport path comprising a thermal resistance element with a thermal resistance , A second portion of the heat generated by the heat source is forwarded to a housing of the video endoscope and delivered there, for example, to the environment. By the thermal resistance element switched into the heat transport path from the heat source to the latent heat accumulator, the thermal resistance of the heat transport path is increased. The thermal resistance of the thermal resistance element is dimensioned in particular as a function of a power loss of at least one internal heat source and a heat absorption of the latent heat storage such that a surface of the housing for a longest possible period, for example, does not exceed a predetermined operating temperature, a predetermined maximum temperature. The video endoscope is designed in particular as described above.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

• 1 ein Ausführungsbeispiel eines erfindungsgemäßen Videoendoskops in einer vereinfachten schematischen Darstellung;
• 2a bis 2e unterschiedliche Varianten zur Ausführung des thermischen Widerstandselements eines erfindungsgemäßen Videoendoskops in schematischer Darstellung;
• 3 exemplarisch den Verlauf der Oberflächentemperatur des Gehäuses eines Videoendoskops mit unterschiedlichen Auslegungen des Wärmemanagementsystems;
• 4a und 4b zwei Varianten zur Ausführung eines wechselbaren Latentwärmespeichers;
• 5a und 5b eine Ausführungsform eines Energiemoduls mit einem Latentwärmespeicher und einem elektrischem Energiespeicher für ein erfindungsgemäßes Videoendoskop;
• 6a und 6b zwei weitere Ausführungsbeispiele eines erfindungsgemäßen Videoendoskops in vereinfachter schematischer Darstellung.

Other aspects of the invention will become apparent from the following description of preferred embodiments and the accompanying drawings. Show it:

• 1 an embodiment of a video endoscope according to the invention in a simplified schematic representation;
• 2a to 2e different variants for the execution of the thermal resistance element of a video endoscope according to the invention in a schematic representation;
• 3 exemplarily the course of the surface temperature of the housing of a video endoscope with different interpretations of the thermal management system;
• 4a and 4b two variants for the execution of a removable latent heat storage;
• 5a and 5b an embodiment of an energy module with a latent heat storage and an electrical energy storage for a video endoscope according to the invention;
• 6a and 6b two further embodiments of a video endoscope according to the invention in a simplified schematic representation.

In 1 are shown in schematic form by way of example the heat-emitting system components and the thermal management system of a video endoscope according to the invention. The video endoscope 1 is a cordless, self-sufficient, compact video endoscope. The video endoscope 1 includes an elongate shaft 2 which is dimensioned, for example, for introduction into a body-internal cavity of a human or animal body, and one opposite to the shaft 2 extended head 3 , The head 3 has one with the shaft 2 tightly connected housing 4 on. The housing 4 can be together with the shaft 2 form a hermetically closed unit. The video endoscope 1 can have operating and display elements that are in 1 are not shown.

Inside the case 4 of the head 3 are arranged electronic and optoelectronic components, in the embodiment shown, an LED light source 5 for illuminating an object field, an image sensor 6 for receiving an endoscopic image of the object field, a signal conditioning electronics 7 to supply the image sensor 6 and for the preparation of the image taken by this and a radio transmission electronics 8th for a wireless image transmission to an external receiving device, not shown. The video endoscope 1 further includes an illumination optic, which is that of the LED light source 5 generated illumination light through the shaft 2 in the direction of the object field, and observation optics, the light returning from the object field through the shaft 2 for recording by the image sensor 6 passes; these are in 1 not shown. Furthermore, in 1 through narrow lines electrical lines 9 indicated that serve to power the electronic components and signal transmission.

When operating the video endoscope 1 generate said electronic components heat loss, which leads to heating of the video endoscope and in particular of the housing 4. Over the surface of the housing 4 heat can be released to the environment (in 1 through arrows 10 indicated). The surface of the housing 4 can this special heat transfer surfaces 11 exhibit. As a rule, the electronic components of the video endoscope generate 1 but more heat loss than on the case 4 can be delivered to the environment for example by Freiluftkonvektion. For receiving a portion of the heat loss is therefore a latent heat storage 12 provided that contains a PCM.

To distribute the heat loss, the video endoscope includes heating elements 13 , which are formed for example by highly thermally conductive materials or by heat pipes and in 1 are indicated by wide lines. Additionally is in 1 a heat pipe 14 as part of a heat pipe 13 shown, which allows a particularly efficient heat transfer. The thermal trains 13 conduct the heat loss generated by the electronic components to the housing 4 or to the heat delivery surfaces 11 and a thermal resistance element passing through a pair of opposed heat exchange surfaces 15 . 15 ' is formed, via the indicated by arrows heat transfer to the latent heat storage 12 he follows.

In the embodiment shown, the video endoscope 1 an accumulator 16 as an electrical energy storage, via the electrical lines 9 the electronic components supplied with electrical energy. The accumulator 16 is together with the latent heat storage 12 in a replaceable power module 17 added. By coupling the energy module 17 to the housing 4 will both be an electrical connection to the power supply of the video endoscope 1 through the accumulator 16 as well as a thermal connection for transmitting a part of the heat loss of the video endoscope 1 to the latent heat storage 12 produced. To overheat the video endoscope 1 can safely prevent the energy content of the accumulator 16 and the latent heat absorption capacity of the PCM be coordinated so that the electrical energy of the accumulator 16 then used up when the PCM has just melted. Provided an additional heat transfer through the housing 4 takes place, a longer operating time can be achieved, and a correspondingly higher electrical Energy content of the accumulator 16 to be provided. The video endoscope 1 may comprise a control device, not shown, which is adapted to monitor the consumed or still available latent heat absorption capacity of the PCM and to generate a warning signal or to switch off the heat loss sources, regardless of the energy content of the accumulator 16 , Also in this case can by an additional heat release over the housing 4 an extension of the operating time can be achieved.

To achieve the longest possible operating life without overheating the video endoscope 1 occurs, both part of the generated heat loss through the housing 4 or the heat release surfaces 11 dissipated to the environment as well as a part of the heat loss in the form of latent heat through the latent heat storage 12 or included in this PCM included. For this it is favorable, if the surface of the housing 4 so far warmed up that a maximum amount of waste heat from the housing 4 can be delivered to the environment. The remaining heat loss, which does not have the housing 4 is discharged flows into the latent heat storage 12 or the PCM.

The distribution of heat loss to the housing 4 and the latent heat storage 12 can be based on the thermal resistance of the thermal paths 13 and the thermal resistance element passing through the heat exchange surfaces 15 . 15 ' is set to be set. In particular, the thermal resistance in the heat transfer between the heat exchange surfaces can be 15 . 15 ' set specifically. By adjusting this thermal resistance of the heat flow to the latent heat storage 12 be controlled, which in turn the proportion of heat loss, which over the housing 4 is released to the environment is determined. This also leaves the temperature of the surface of the housing 4 to adjust. It has been shown that an optimum temperature of the surface of the housing 4 typically between about 35 ° C and 40 ° C. A maximum temperature of 41 ° C should not be exceeded. The design of the thermal resistances, in particular the resistance during the heat transfer to the latent heat storage 12 , is performed such that at a given loss of heat output of the internal heat sources of the video endoscope 1 ie, said optoelectronic and electronic components, and given heat dissipation efficiency across the surface of the housing 4 the said temperature of the housing 4 is not exceeded for as long a period as possible, in particular for a desired operating period.

Different variants for the design of the heat exchange surfaces 15 . 15 ' for adjusting the thermal resistance are exemplified in the 2a to 2e shown. Here are the heat loss sources, the in 1 shown embodiment by the LED light source 5 , the image sensor 6 , the signal conditioning electronics 7 and the radio transmission electronics 8th be formed, as a loss of heat source 18 summarized.

As in 2a shown, according to a first variant by an adjusting screw 19 the width w of a gap 20 between the heat exchange surface 15 of the housing 4 and the heat exchange surface 15 ' the latent heat storage 12 to be adjusted. A narrower gap 20 allows a better heat transfer, ie a lower thermal resistance. The gap width w is adjusted so that the surface of the housing 4 the maximum permissible temperature does not exceed.

According to 2 B can be a heat exchange surface 15 through a material 21 are formed, which expands when heated; This can also serve a bimetallic element. As a result, a surface contact between the housing 4 and the latent heat storage 12 allows. In addition, it can be achieved that the contact surface when heating the material 21 increases; Thus, as the temperature increases, the heat flux to the latent heat storage increases, which in turn decreases or limits the surface temperature of the housing 4 leads.

As in 2c shown, according to another variant, the heat flow into the PCM on the basis of the size of the contact area of the heat exchange surfaces 15 . 15 ' be determined. The size of the contacting surface areas of the heat exchange surfaces 15 . 15 ' can for example by means of a screw 22 to be controlled.

At the in 2d shown variant is by applying a voltage to a Peltier element 23 a temperature gradient between the heat exchange surfaces 15 . 15 ' generated. This temperature gradient can be determined by means of the applied voltage so that the housing 4 does not exceed a maximum permissible surface temperature and the remainder of the heat loss in the PCM of the latent heat accumulator 12 flows.

As in 2e symbolically represented, according to a further variant, a heat pipe 24 between the heat loss source 18 and the latent heat storage 12 or the PCM serve as a regulating thermal resistance element. Only when the heat loss source 18 or the housing 4 has reached a temperature threshold, the transport liquid evaporates in the heat pipe 24 , As a result, the two-phase circuit in the heat pipe 24 in Gear set and the heat to the latent heat storage 12 dissipated.

In 3 is exemplified for different interpretations of the thermal management system, the course of the temperature T of the housing surface of a video endoscope shown as in 1 is shown constructed. The housing surface is the surface of the housing 4 of the head 3 of the video endoscope 1 ; because the shaft 2 firmly with the head 3 is connected, the temperature of the surface of the shaft 2 usually approximately the same as the surface of the housing 4 , In the following it is assumed that at the time t = 0 all components of the video endoscope 1 approximately the starting temperature of, for example, T ₀ = 24 ° C have. At time t = 0, the video endoscope is put into operation. From this point on, the internal heat sources of the video endoscope, in particular the LED light source, generate 5 , the image sensor 6 , the signal conditioning electronics 7 and the radio transmission electronics 8th , a substantially constant power dissipation over time. This leads to a heating of the housing surface. To damage the tissue with which the video endoscope 1 comes to avoid, the surface temperature T must not exceed a maximum temperature T _max , which in this case is 41 ° C. This limits the maximum possible operating time.

The curve A shows the temperature profile without the latent heat storage 12 , Due to the power loss released in the housing, the housing temperature T rises relatively quickly and exceeds the maximum permissible value T _max at time t ₁ . t ₁ is a measure of the maximum operating time without latent heat storage 12 , In the example mentioned, with a power loss of 4.5 W, this time t _{1 is} already reached after about 15 to 20 minutes. In the course of the temperature T of the housing would rise above 45 ° C.

The curve B sets the temperature profile with latent heat storage 12 but without any between the heat loss source 18 which at the in 1 shown embodiment by the LED light source 5 , the image sensor 6 , the signal conditioning electronics 7 and the radio transmission electronics 8th is formed, and the latent heat storage 12 arranged thermal resistance element. The generated heat loss flows through the thermal paths 13 , which have a low thermal resistance, directly into the PCM of the latent heat storage 12 , This leaves the case 4 relatively cool during the melt phase of the PCM. However, the PCM is melted quickly. Thereafter, the housing temperature T increases relatively quickly and exceeds the maximum allowable temperature T _max at time t ₂ . In the example shown, this time t ₂ is about 80 min. This is the maximum operating time reached.

The curve C shows the temperature profile with the latent heat storage 12 in the case that between the heat loss source 18 and the latent heat storage 12 specifically a thermal resistance has been introduced. The thermal resistance is in the example shown through the air gap between the heat exchange surfaces 15 . 15 ' certainly. Due to the higher thermal resistance, less heat flows into the PCM of the latent heat accumulator 12 from; this causes a higher case temperature T during melting of the PCM than at the curve B , Due to the higher housing temperature T in this phase, a larger amount of heat is released to the environment. As a result, the melting phase of the PCM is significantly extended, and only at time t ₃ , which is reached after about 95 min, the maximum allowable temperature of 41 ° C is exceeded. By introducing a suitably selected thermal resistance, for example by means of an appropriately set gap, thus a longer operating time can be achieved, in the illustrated example, an extension of about 15 min.

In the example shown, the thermal resistance is as in 2a represented by adjusting the width of the air gap between the heat exchange surfaces 15 . 15 ' has been varied. However, other options for setting a suitable thermal resistance can be selected, such as in the 2 B to 2e shown.

For a most efficient heat dissipation to the environment should the housing 4 of the head 3 of the video endoscope 1 have as large a surface as possible. On the other hand, the usable surface is limited by the handling of the video endoscope, where it is convenient to head 3 form as a compact handle. To the entire surface of the head 3 for the heat to be used to the environment, it may be provided, for example, that the power module 17 in a recess 25 of the housing 4 can be used and largely from the housing 4 is enclosed. This is exemplary in 4a shown. This is the latent heat storage 12 by an insulation 28 relative to the housing 4 largely thermally insulated, so that the heat flow into the PCM takes place almost exclusively via a heat transport path with the intended thermal resistance, ie on the thermal paths 13 and the heat exchange surfaces 15, 15 'and the gap formed between them.

On the other hand, as in the 1 to 2e indicated, the power module can also be connected to the housing 4 be attachable, as in 4b is shown. Here are the coupling in the Surface of the housing 4 and the outer surface 26 of the energy module 17 in thermal contact with each other. As a result, virtually the entire surface can also be used for dissipating heat to the environment. Again, heat flow into the PCM proceeds as previously described.

In 5a is an embodiment of an energy module in a partially transparent view seen obliquely from the proximal direction 17 shown. On the distal side, the energy module points 17 a cavity 27 for the in 5a PCM not shown, while on the proximal side of the accumulator 16 located. The cavity 27 has an insulation 28 for the PCM. The cavity 27 can be hermetically closed, for example welded airtight. The outer surface 26 is thermal with the housing 4 connectable. Proximalseitig are pins 29 for a charge of the accumulator 16 intended. The total stored electrical energy of the accumulator 16 in this example, is not greater than the total amount of heat energy that can be released into the environment and into the PCM within the intended operating time. As a result, overheating of the system can be safely excluded.

As in 5b is shown in a view obliquely seen from the proximal direction, find when coupling the power module 17 to the housing 4 of the head 3 of the video endoscope 1 both a thermal contact between the housing 4 and the outer surface 26 of the energy module 17 as well as an electrical contact for the electrical power supply of the video endoscope 1 through the accumulator 16 of the power module 17 instead. This is a plug connection with pins 30 that are vapor-tight in an insulating element 31 are potted, and corresponding sockets of the power module 17 intended. Furthermore, when coupling the energy module 17 a thermal connection over in 5b unrecognizable heat exchange surfaces 15 . 15 ' (S. 1 ) for the heat flow to the PCM. The housing 4 of the video endoscope 1 together with the shaft 2 as well as the energy module 17 can each be designed as hermetically sealed units.

In the embodiments described above, the head is used 3 of the video endoscope 1, on or in the power module 17 is applied, even as a handle for holding the video endoscope 1 , In the 6a and 6b show two embodiments of a video endoscope, wherein the power module is designed as an angled removable handle.

In the embodiment according to 6a is a handle 32 provided in the form of a pistol handle. Inside the handle 32 is the latent heat storage 12 absorbed, the thermal with a heat exchange surface 15 ' is connected, wherein the heat exchange surface 15 ' of the handle 32 for absorbing heat from the heat exchange surface 15 of the head 3 interacts with this. Furthermore, inside the handle 32 the accumulator 16 arranged, via a non-illustrated connector with the head 3 of the video endoscope 1 electrically connected. The handle 32 is via a non-illustrated releasable mechanical connection, which may be formed as described above and in particular a gap 20 between the heat exchange surfaces 15 . 15 ' guaranteed, with your head 3 of the video endoscope 3 coupled. As the latent heat storage 12 and the accumulator 16 are relatively heavy, the handling of the video endoscope 1 This improves that these components within the handle 32 are arranged. Incidentally, the video endoscope 1 formed as described above.

At the in 6b embodiment shown is the handle 33 in a slightly angled or nearly stretched arrangement on a proximal end surface 34 of the head 3 of the video endoscope 1 stated. The proximal end surface 34 has a heat exchange surface 15 on that over a gap 20 with the heat exchange surface 15 ' of the handle 33 cooperates for heat transfer. Furthermore, the proximal end face 34 a connector, not shown, via which an electrical contact with the handle 32 arranged accumulator 16 is taught. Incidentally, the video endoscope 1 formed as described above.

For clarity, not all figures are shown in all figures. Reference numerals not explained to a figure have the same meaning as in the other figures.

LIST OF REFERENCE NUMBERS

1

Videoscope

2

shaft

3

head

4

casing

5

LED light source

6

image sensor

7

Signal conditioning electronics

8th

Radio transmission Electronics

9

Electrical line

10

arrow

11

Heat transfer surface

12

Latent heat storage

13

heat Bahn

14

Heatpipe

15, 15 '

Heat exchange surface

16

accumulator

17

power module

18

Waste heat source

19

screw

20

gap

21

material

22

screw

23

Peltier element

24

Heatpipe

25

recess

26

outer surface

27

cavity

28

insulation

29

contact pins

30

contact pins

31

Insulating element

32

handle

33

handle

34

Proximal endface

A

Curve

B

Curve

C

Curve

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 2756791 A2 [0003]
• WO 2012/075989 A1 [0006]
• EP 0917438 B1 [0007]
• EP 2394567 A1 [0025]

Claims (16)

Video endoscope, in particular cable-free video endoscope, with at least one internal heat source, characterized in that the video endoscope (1) a latent heat accumulator (12) for receiving at least a portion of the heat generated by the at least one internal heat source via a between the at least one internal heat source and the Latent heat accumulator (12) formed Wärmetransportweg, wherein a thermal resistance element is arranged to increase a thermal resistance in the heat transport path. Video endoscope after Claim 1 characterized in that the video endoscope (1) comprises a housing (4) in thermal communication with the at least one internal heat source and for delivering a further portion of the heat generated by the at least one internal heat source to an environment of the video endoscope (10). 1) is formed. Video endoscope after Claim 2 , characterized in that a thermal resistance of the thermal resistance element for maximizing an operating time of the video endoscope (1) during which a surface of the housing (4) does not exceed a predetermined maximum temperature T _max is dimensioned. Video endoscope after Claim 2 or 3 , characterized in that substantially an entire surface of the housing (4) is in thermal communication with the at least one heat source. Video endoscope according to one of the preceding claims, characterized in that the heat transport path between the at least one internal heat source and the latent heat accumulator (12) comprises at least one in series with the thermal resistance element connected to the heat path (13). Video endoscope according to one of the preceding claims, characterized in that the thermal resistance element has an adjustable thermal resistance. Video endoscope according to one of the preceding claims, characterized in that the thermal resistance element comprises two heat exchange surfaces (15, 15 ') in contact with each other, the thermal resistance of the thermal resistance element being determined by the size of a contact region of the heat exchange surfaces (15, 15'). Video endoscope according to one of the preceding claims, characterized in that the thermal resistance element comprises a gap (20), wherein the thermal resistance of the thermal resistance element by a gap width and / or a medium which is arranged in the gap (20) is determined. Video endoscope according to one of the preceding claims, characterized in that the thermal resistance element comprises a bimetallic element, a Peltier element (23) and / or a heat pipe (24). Video endoscope according to one of the preceding claims, characterized in that the latent heat accumulator (12) is partially thermally insulated. Video endoscope according to one of the preceding claims, characterized in that the latent heat accumulator (12) is at least partially surrounded by an elastically deformable material. Video endoscope according to one of the preceding claims, characterized in that the latent heat store (12) is exchangeable. Video endoscope after Claim 12 , characterized in that the latent heat accumulator (12) together with an electrical energy store (16) of the video endoscope (1) is interchangeable. Video endoscope according to one of the preceding claims, characterized in that a heat absorption capacity of the latent heat accumulator (12) and an electrical energy content of an electrical energy store (16) of the video endoscope (1) are matched to one another. Video endoscope according to one of the preceding claims, characterized in that the video endoscope (1) is arranged for monitoring a heat absorption of the latent heat accumulator (12). Method for operating a video endoscope (1) having at least one internal heat source, wherein a first part of the heat generated by the at least one internal heat source via a heat transport path to a latent heat storage (12) forwarded and received by this and a second part of the heat generated at least one internal heat source to a housing (4) of the video endoscope (1) is forwarded, wherein in the heat transport path to increase a thermal resistance, a thermal resistance element is arranged.

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