DE102019124697A1 - Device for projecting images onto a projection surface - Google Patents

Abstract

A device (10, 50, 60, 70, 90) for projecting at least two images onto a projection surface (12), with a light source (14, 62) for generating illuminating light (82), with an image-generating element (20) which has at least two areas (38) which can be transilluminated by the illuminating light (82) emitted by the light source (14, 62) and which are each assigned to at least one of the two images, and with imaging optics (22) which the two areas ( 38) of the image generation element (20) s for generating the two images on the projection surface (12). The light source (14, 62) has at least two individually controllable light source elements (66) which are designed to illuminate one of the two areas (38). Alternatively, the device (10, 50, 70, 90) comprises a diaphragm unit (18) with at least two individually switchable segments which can be transilluminated by the illuminating light (82) emitted by the light source (14) and are arranged in such a way that one of the two segments of the diaphragm unit (18) each a region (38) of the image-generating element (20) is transilluminated.

Description

The invention relates to a device for projecting at least two images onto a projection surface. The device comprises a light source for generating illuminating light, an image generating element which has at least two areas which can be transilluminated by the illuminating light emitted by the light source and which are each assigned to at least one of the two images, and imaging optics which the two areas of the image generating element to generate the two images on the projection surface.

In the automotive sector, so-called logo lights are used, which can project several static, i.e. still images or a sequence of images to generate a short animation onto an area to the side of a vehicle, for example in front of a vehicle door. The functionality of these logo lights corresponds to that of a film projector. In order to be able to produce such logo lights particularly inexpensively and compactly, an LCD unit is used to generate images. The LCD unit has several individually switchable segments that are illuminated by a light source such as a mask and are imaged onto a projection surface by imaging optics for generating images.

With current production methods for LCD units, structures of the transparently switchable segments can be produced precisely down to a minimum size of approx. 50 μm. Image optics commonly used in logo lights have a resolution of approx. 15 µm. In other words: the imaging optics resolve much smaller structures than can be formed in the segments used as a mask for image generation. This limits the maximum contrast of the image and thus impairs the quality of the images projected onto the projection surface. Colored images or gray gradients are also difficult to achieve with LCD units.

It is the object of the invention to specify a device which is suitable for projecting at least two images with a high image quality onto a projection surface.

The object is achieved by a device with the features of claim 1. Advantageous further developments are given in the dependent claims.

In the device according to claim 1, the light source has at least two individually controllable light source elements which are designed to illuminate one of the two areas in each case. Alternatively, the device has a diaphragm unit with at least two individually switchable segments which can be transilluminated by the illuminating light emitted by the light source and which are arranged in such a way that one area of the imaging element is transilluminated by switching one of the two segments of the diaphragm unit transparent.

The design of the light source according to the invention and the diaphragm unit each realize a means by which the two areas of the image-generating element can be illuminated individually and independently of one another. In this case, only the image assigned to the area of the image generation element that is illuminated in each case is generated on the projection surface.

In the device according to claim 1, the image generation and the selection of the image to be projected are carried out by different structurally separate units. In particular, these units are arranged at different distances along the optical axis of the imaging optics. Since the image to be projected is not selected by the image generation element, it is not necessary to control it. This means in particular that the image-generating element does not have to include a conductor track. These conductor tracks would have to have a certain minimum thickness for safe current conduction. This would take up an area of the imaging element that would not be available for imaging. In the device according to the invention, on the one hand, more area is available for the areas of the image generating element. On the other hand, the individual areas can be closer together, which leads to a more homogeneous overall impression of the projected images. In particular, however, the two areas can thereby be assigned to a single overall image in which the two images each represent a part of the overall image. By optionally illuminating the two areas, the impression of a dynamically illuminated overall picture is created.

In the device according to claim 1, the conductor tracks required to control the light source and the diaphragm unit are not arranged in the same plane along the optical axis of the imaging optics as the areas of the imaging element that are transilluminated for imaging. Correspondingly, these conductor tracks are only imaged in a blurred manner on the projection surface by the imaging optics. The conductor tracks are thus concealed, as it were, and have no or a negligible effect on the projected images. The inventive separation of the units for image generation and the units for selecting the images to be projected thus achieves a high image quality.

The device according to claim 1 can in particular be installed in a vehicle in order to project a short animation composed of the images onto an area in front of a door or tailgate of the vehicle. As an alternative or in addition to the animation composed of the images, the images can also be projected individually. The imaging optics can be designed in one piece or as an assembly with several elements.

It is advantageous if the imaging element has a light-absorbing layer which is preferably a negative of the two images. In this advantageous embodiment, those parts of the image-generating element which are not intended to be imaged as one of the images on the projection surface are covered with the light-absorbing layer. The light-absorbing layer thus represents a non-transparent masking, which increases the contrast of the device and enables a better representation of the individual images. For this purpose, the imaging optics are preferably focused on the light-absorbing layer of the imaging element. The light-absorbing layer is preferably a chromium layer.

It is also advantageous if the light-absorbing layer comprises at least one region in which it forms a point pattern, the diameter of the points of the point pattern each having a value between 0.1 μm and the optical resolution of the imaging optics. Such a point pattern creates gray gradients in the individual images. By varying the point density of the point pattern, different gray levels can be generated. The creation of gray gradients by means of the dot pattern is comparable to the dithering known from computer graphics.

In a preferred embodiment, the imaging element comprises a slide of the two images. In the present application, the term slide means a translucent positive of an image. The slide can be produced, for example, by a screen printing process or a semiconductor process on a transparent plate, in particular a pane of glass. With semiconductor processes, layers of paint can be applied particularly precisely. For this purpose, paint is applied over the entire surface of the transparent plate, photolithographically masked and then partially removed again so that the color only remains in the desired areas. Alternatively, the slide can be formed by a foil or a photographic film applied to the transparent plate.

In a particularly preferred embodiment, the panel unit has a passive LCD element which has at least two individually controllable liquid crystal elements which each form one of the two segments of the panel unit.

The two liquid crystal elements can be individually and independently switched to be transparent. The two liquid crystal elements thus in each case produce a screen which either blocks the illuminating light or allows it to pass through one of the two areas of the image-generating element in order to illuminate it. Since the structural size of the two liquid crystal elements is insignificant for the contrast of the two images projected onto the projection surface, in particular more cost-effective passive LCD elements can be used. This particularly preferred embodiment can thus be produced inexpensively.

It is advantageous if the screen unit has two transparent plates, that a first of the two transparent plates is arranged on a side of the two liquid crystal elements facing the imaging optics, that a second of the two transparent plates is arranged on a side of the two liquid crystal elements facing away from the imaging optics, and that the first transparent plate has one or the light-absorbing layer which forms the two areas of the imaging element. The two liquid crystal elements are held by the two transparent plates. The glass plate of the diaphragm unit arranged on the side of the two liquid crystal elements facing the imaging optics also serves as a carrier for the light-absorbing layer of the imaging element. As a result, an additional component can be dispensed with and the device can be made more compact.

In an advantageous embodiment, the device has a condenser optics for directing the illuminating light onto the diaphragm unit or the image generating element. The condenser optics are preferably designed in such a way that as much of the illuminating light as possible reaches the image generating element. As a result, the light source is optimally used.

It is advantageous if the condenser optics are made of plastic. It is also advantageous if the imaging optics are made of plastic. Optical elements that are made of a plastic are weather-resistant and therefore particularly suitable for use in a vehicle or an outdoor area.

In a preferred embodiment, the device has a control unit for controlling the light source and the diaphragm unit. The control unit is preferably designed such that, when an operating voltage is applied, it controls the device in such a way that the two images alternate on the Projection surface are generated. As a result, the device is independent of the existing control units of the vehicle and can therefore be easily retrofitted.

In a preferred embodiment, the device can be connected to a LIN bus or CAN bus. Both LIN buses and CAN buses are widespread field buses in the automotive sector that connect various sensors and actuators of a vehicle to a central control unit. The device can thus be controlled by means of the central control unit of the vehicle.

The invention also relates to an assembly for a vehicle, in particular a motor vehicle, with a device according to the aforementioned type. The assembly is designed in particular such that it can be installed in a door of the vehicle, a side mirror, a side sill of the vehicle or in an installation space that is suitable for a reversing camera is provided, can be arranged.

Alternatively, the assembly is designed in such a way that it can be arranged in an installation space that is provided for a light of the vehicle. In this alternative embodiment, the device is designed in particular to project at least one image onto the projection surface that represents an approved signal light function or is part of an approved signal light function, for example a tail light or a direction indicator.

However, the use of the assembly is not restricted to the exterior of the vehicle. For example, the assembly can also be arranged as dynamic reading or room lighting in the interior of the vehicle.

Further features and advantages emerge from the following description, which explains an exemplary embodiment in connection with the accompanying figures.

• 1 eine schematische Darstellung einer Vorrichtung zum Projizieren eines Bildes auf eine Projektionsfläche nach dem Stand der Technik;
• 2 eine schematische Darstellung einer Vorrichtung zum Projizieren von Bildern auf die Projektionsfläche nach dem Stand der Technik;
• 3 eine schematische Darstellung einer erfindungsgemäßen Vorrichtung zum Projizieren von mindestens zwei Bildern auf eine Projektionsfläche gemäß einem ersten Ausführungsbeispiel;
• 4 eine schematische Darstellung der erfindungsgemäßen Vorrichtung zum Projizieren der zwei Bilder auf die Projektionsfläche gemäß einem zweiten Ausführungsbeispiel;
• 5 eine schematische Darstellung der erfindungsgemäßen Vorrichtung zum Projizieren der zwei Bilder auf die Projektionsfläche gemäß einem dritten Ausführungsbeispiel;
• 6 eine schematische Darstellung der erfindungsgemäßen Vorrichtung zum Projizieren der zwei Bilder auf die Projektionsfläche gemäß einem Ausführungsbeispiel; und
• 7 eine Explosionsdarstellung der erfindungsgemäßen Vorrichtung zum Projizieren der zwei Bilder auf die Projektionsfläche gemäß einem Ausführungsbeispiel.

Show it:

• 1 a schematic representation of a device for projecting an image onto a projection surface according to the prior art;
• 2 a schematic representation of a device for projecting images onto the projection surface according to the prior art;
• 3 a schematic representation of a device according to the invention for projecting at least two images onto a projection surface according to a first embodiment;
• 4th a schematic representation of the device according to the invention for projecting the two images onto the projection surface according to a second embodiment;
• 5 a schematic representation of the device according to the invention for projecting the two images onto the projection surface according to a third embodiment;
• 6th a schematic representation of the device according to the invention for projecting the two images onto the projection surface according to an embodiment; and
• 7th an exploded view of the device according to the invention for projecting the two images onto the projection surface according to an embodiment.

1 shows a schematic representation of a device 100 for projecting an image onto a projection surface 102 according to the prior art. The projection surface 102 is in 1 indicated by a dashed line. The known device 100 has a light source 104, a condenser optics 106, a glass plate 108 and an imaging optics 110.

The light source 104 generates illuminating light which is directed onto the glass plate 108 by a condenser lens 112 of the condenser optics 106. A chrome layer 114 is applied to the glass plate 108. A mask is formed by the chrome layer 114, which mask blocks part of the illuminating light that has passed through the glass plate 108. The chrome layer 114 is, as it were, a negative of the image to be projected. The imaging optics 110 have an imaging lens 116 which is focused on the chrome layer 114 and images this chrome layer 114 onto the projection surface 102 in order to generate the image.

The chrome layer 114 can be applied very precisely to the glass plate 108, so that this known device 100 can be used to project high-resolution images with high contrast onto the projection surface 102. In particular, the chromium layer 114 can also have one or more regions in which the chromium layer 114 forms a point pattern, the points of which have a diameter that is less than the resolution limit of the imaging lens 116. Such regions result in gray levels in the image projected onto the projection surface 102 generated. It is also possible to apply paint to the glass plate 108 in a targeted manner and with high precision in order to generate colored areas in the image projected onto the projection surface 102.

The known device 100 can be used to project a high-resolution image onto the projection surface 102, but only this one image. The following is based on the 2 another known device 200 described, by means of which several images are shown on the projection surface 12th let project.

2 shows a schematic representation of the known device 200 for projecting images onto the projection surface 102 according to the prior art. The known device 200 according to 2 differs from the known device 100 according to 1 essentially in that the device 200 according to 2 has a passive LCD element 202 instead of the glass plate 108 with the chrome layer 114. Identical or equivalent elements are in the 1 and 2 denoted by the same reference numerals.

The LCD element 202 comprises two or more liquid crystal elements 204 which are arranged between two glass plates 206, 208. The liquid crystal elements 204 can be switched to be transparent individually and independently of one another and are each assigned to one of the images. The liquid crystal element 204, which is switched to be transparent in each case, is illuminated by the light source 104 and forms a mask of the image assigned to the liquid crystal element 204. In order to generate the image which is assigned to the liquid crystal element 204 which is switched to be transparent, the liquid crystal element 204 is imaged onto the projection surface 102 through the imaging lens 116. By means of the known device 200, on the one hand, several images can be projected onto the projection surface 102. On the other hand, by successively switching the liquid crystal elements 204 transparent, a short animation composed of the images can be projected onto the projection surface 102.

The disadvantage of the known device 200 after 2 consists in the fact that the contrast that can be achieved when an image is generated by means of the passive LCD element 202 is limited. With current manufacturing methods for LCD elements, structures down to a minimum size of approximately 50 μm can be produced precisely. However, the imaging lens 116 has a resolution size of about 15 µm. This has the consequence that it is with the device 200 after 2 it is not possible to generate gray gradients in the images that are projected onto the projection surface 102, as is the case with the device 100 according to FIG 1 is possible with the help of the dot pattern.

3 shows a schematic representation of a device according to the invention 10 for projecting at least two images onto a projection surface 12th according to a first embodiment. The projection surface 12th is in 3 indicated by a dashed line. The device 10 has a light source 14th , a condenser optic 16 , an aperture unit 18th , an imaging element 20th and imaging optics 22nd .

The light source 14th generates illuminating light that passes through a condenser lens 24 the condenser optics 16 on the bezel unit 18th is steered. The aperture unit 18th includes a passive LCD element 26th , the at least two individually controllable liquid crystal elements 28 Has. The two liquid crystal elements 28 are between two glass plates 30th , 32 arranged and can be switched transparently individually and independently of each other. Each of the two liquid crystal elements 28 of the passive LCD element 26th forms a segment of the diaphragm unit 18th that can be switched to be transparent to the illumination light through the diaphragm unit 18th to pass through.

The imaging element 20th includes a glass plate 34 on top of which an opaque layer 36 is upset. The opaque layer 36 has two areas 38 which are each assigned to one of the images to be projected onto the projection surface. Each of the areas 38 of the imaging element 20th is also a segment of the diaphragm unit 18th assigned. The areas assigned to one another 38 of the imaging element 20th and the shutter unit 18th are arranged such that one of the areas 38 of the imaging element 20th is shone through by the illuminating light when the segment of the diaphragm unit assigned to it 18th is switched transparent. The two areas 38 of the imaging element 20th form, as it were, a slide or a mask of the area 38 respectively assigned image. In particular, these images can also each represent a part of an overall image, that is to say the areas 38 together form a slide or a mask of the overall picture. By optionally x-raying the areas 38 a dynamic light effect is thus generated in the overall picture. The overall image can be, for example, the logo of a car manufacturer.

The imaging optics 22nd includes an imaging lens 40 held by a retaining element 42 with the glass plate 34 of the imaging element 20th is mechanically connected. Through the holding element 42 is a distance between the imaging lens 40 and the opaque layer 36 of the imaging element 20th along the optical axis O of the imaging lens 40 Are defined. The distance defined in this way is chosen such that the opaque layer 36 sharp, ie with maximum contrast on the projection surface 12th is mapped. The imaging lens 40 thus forms the two areas 38 of the imaging element 20th with maximum contrast on the projection surface 20th from. This causes the two images to appear on the projection surface 12th generated. About gray gradients in the two on the projection surface 12th The opaque layer can produce projected images 36 of the imaging element 20th Have areas in which this forms a dot pattern. The diameter of the points of this point pattern is smaller than the resolution size of the imaging optics 40 . By combining the opaque layer 36 Colored images can also be generated with a layer of paint.

4th shows a schematic representation of the device according to the invention 50 to project the two images onto the projection surface 12th according to a second embodiment. The projection surface 12th is in 4th indicated by a dashed line. The device 50 according to the second embodiment 4th differs from the device 10 according to the first embodiment 3 essentially through the design of the imaging element 52 . Identical and equivalent elements are in the 3 and 4th denoted by the same reference numerals.

In the embodiment shown, the light-absorbing layer is 36 of the imaging element 52 not as in the device 10 to 3 on a specially designed glass plate 34 upset. Instead it is the light absorbing layer 36 of the imaging element 52 on a glass plate 30th of the two glass plates 30th , 32 the aperture unit 18th applied that on the imaging optics 22nd facing side of the passive LCD element 26th the aperture unit 18th is arranged. As a result, an additional component and the device can be dispensed with 50 be made more compact overall.

5 shows a schematic representation of the device according to the invention 60 to project the two images onto the projection surface 12th according to a third embodiment. The device 60 according to the third embodiment 5 exhibits in contrast to the device 10 according to the first embodiment 3 no aperture unit 18th on. Identical and equivalent elements are used in the 3 , 4th and 5 denoted by the same reference numerals.

In the embodiment shown, the light source comprises 62 a circuit carrier 64 on the two light source elements 66 are arranged, which are designed as LED elements in the embodiment shown. These light source elements 66 can be controlled individually and are arranged in such a way that each one area 38 of the imaging element 20th by exactly one of the light source elements 66 is x-rayed. With the two controllable light source elements 66 is thus a means for selective x-raying of the two areas 38 of the imaging element 20th given. Alternative to the light source elements 66 It is also possible to use other components which permit such a spatially resolved fluoroscopy of the image-generating element 20th allow, for example, matrix headlights or self-illuminating displays, as they are known from data glasses. Through this spatially resolved fluoroscopy of the imaging element 20th can on the condenser optics 16 be waived.

6th shows a schematic representation of the device according to the invention 70 to project the two images onto the projection surface 12th according to an embodiment. Identical or equivalent elements are in the 3 to 6th denoted by the same reference numerals.

The device 70 includes a housing 72 and an interface located on the side of the housing 74 . the interface 74 allows the device 70 to connect to an electrical connection of a vehicle. In addition, the device 70 by means of the interface 74 can also be connected to a field bus, such as a LIN or CAN bus. The case 72 includes the light source 14th , a cooling element 76 to cool the light source 14th , the condenser optics 16 , the aperture unit 18th , the imaging element 20th and the imaging optics 22nd .

The light source 14th comprises a circuit carrier 78 on which an LED element 80 is arranged. The LED element 80 emits the illuminating light that is in 6th with the reference number 82 is designated. After passing through the condenser optics 16 falls the illuminating light 82 on the bezel unit 18th . By means of the individual controllable segments of the panel unit 18th can now be determined which areas 38 of the imaging element 20th from that through the aperture unit 18th stepped illumination light 82 be x-rayed. The imaging optics 22nd forms the areas 38 of the imaging element 20th for generating the images through a light exit surface 84 of the housing 72 onto the projection surface 12th from.

7th shows an exploded view of the device according to the invention 90 to project the two images onto the projection surface 12th according to an embodiment. Identical or equivalent elements are in the 3 to 7th denoted by the same reference numerals.

The device 90 includes the housing 72 that in the embodiment according to 7th is designed as a two-part assembly, for example. The housing consists of a first housing part 72a and a second housing part 72b and is used to fix and adjust the remaining units of the device 90 . The case 72 is light-absorbing and thus shields stray light. The first housing part 72a has one to the light source 14th directed is the light inlet opening 92 . The second housing part 72b has the light exit surface 84 through which the imaging optics 22nd the areas 38 of the imaging element 20th to generate the images on the projection surface 12th maps.

Below the first housing part 72a is the light source 14th arranged. The light source includes the circuit carrier 78 on which the LED element 80 is arranged.

The passive LCD element 26th the aperture unit 18th is via signal lines 94 with an LCD control unit 96 connected. Alternatively, the passive LCD element 26th also via a flexboard with the LCD control unit 96 be connected. The LCD control unit 96 controls the liquid crystal elements by means of voltage levels 28 of the passive LCD element 26th individually. The voltage levels are preferably constant. Alternatively, the voltage levels can be modulated over time. In an alternative embodiment, the LCD control unit comprises 96 a multiplex unit that is formed, a plurality of liquid crystal elements 28 of the passive LCD element 26th via a single signal line 94 head for.

The LCD control unit 96 and the circuit carrier 78 the light source 14th together form a control unit of the device 90 . This control unit is designed to be the light source 14th and the shutter unit 18th to control. In the embodiment according to 7th are the LCD control unit 96 and the circuit carrier 78 the light source each arranged on its own circuit board. In an alternative embodiment, the LCD control unit 96 and the circuit carrier 78 the light source 14th be arranged on a common circuit board.

In the embodiment according to 7th includes the imaging optics 22nd three optical elements 22a, 22b, 22c. On the one directly on the imaging element 20th arranged optical element 22a are the holding elements 42 formed, each fixed to a support surface with the glass plate 30th of the imaging element 20th are firmly connected.

List of reference symbols

10

contraption

12th

Projection surface

14th

Light source

16

Condenser optics

18th

Aperture unit

20th

Imaging element

22nd

Imaging optics

24

Condenser lens

26th

Passive LCD element

28

Liquid crystal element

30, 32, 34

Glass plate

36

layer

38

Area

40

Imaging lens

42

Retaining element

50

contraption

52

Imaging element

60

contraption

62

Light source

64

Circuit carrier

66

Light source element

70

contraption

72

casing

72a, 72b

Housing part

74

interface

76

Cooling element

78

Circuit carrier

80

LED element

82

Illuminating light

90

contraption

92

Light entry opening

94

Signal line

96

LCD control unit

98

Retaining element

Claims (11)

Device (10, 50, 60, 70, 90) for projecting at least two images onto a projection surface (12), with a light source (14, 62) for generating illuminating light (82), with an image-generating element (20) which has at least has two areas (38) which can be transilluminated by the illuminating light (82) emitted by the light source (14, 62) and which are each assigned to at least one of the two images, and with imaging optics (22) which enclose the two areas (38 ) depicts the image generation element (20) for generating the two images on the projection surface (12), characterized in that the light source (14, 62) has at least two individually controllable light source elements (66) which are designed to each have one of the two areas ( 38) to be x-rayed, or that the device (10, 50, 70, 90) has a diaphragm unit (18) with at least two individually switchable segments that can be transilluminated by the illuminating light (82) emitted by the light source (14) and are arranged in such a way that one each of the two segments of the diaphragm unit (18) each a region (38) of the image-generating element (20) is transilluminated. Device (10, 50, 60, 70, 90) according to Claim 1 , characterized in that the imaging element (20) has a light absorbing layer (36) which is preferably a negative of the two images. Device (10, 50, 60, 70, 90) according to Claim 2 , characterized in that the light-absorbing layer (36) comprises at least one area in which it forms a point pattern, the diameter of the points of the point pattern each having a value between 0.1 µm and the optical resolution of the imaging optics (22). Device (10, 50, 60, 70, 90) according to Claim 2 or 3 , characterized in that the imaging optics (22) are focused on the light-absorbing layer (36) of the imaging element (20). Device (10, 50, 60, 70, 90) according to one of the preceding claims, characterized in that the image-generating element (20) comprises a slide of the two images and that the imaging optics (22) is focused on the slide. Device (10, 50, 70, 90) according to one of the preceding claims, characterized in that the panel unit (18) has a passive LCD element (26), and that the passive LCD element (26) has at least two individually has controllable liquid crystal elements (28) which each form one of the two segments of the diaphragm unit (18). Device (10, 50, 70, 90) according to Claim 6 , characterized in that the screen unit (18) has two transparent plates (30, 32), that a first of the two transparent plates (30, 32) is arranged on a side of the two liquid crystal elements facing the imaging optics (22), that a second of the two transparent plates (30, 32) is arranged on a side of the two liquid crystal elements (28) facing away from the imaging optics (22), and that the first transparent plate (30) has the light-absorbing layer (36) which covers the two areas (38 ) of the imaging element (20). Device (10, 50, 70, 90) according to one of the preceding claims, characterized by condenser optics (16) for directing the illuminating light (82) onto the diaphragm unit (18) or the image generating element (20). Device (10, 50, 60, 70, 90) according to one of the preceding claims, characterized by a control unit for controlling the light source (14, 62) and the diaphragm unit (18). Device (10, 50, 60, 70, 90) according to one of the preceding claims, characterized in that the device (10, 50, 60, 70, 90) can be connected to an LIN bus or CAN bus. Assembly for a vehicle, in particular a motor vehicle, with a device (10, 50, 60, 70, 90) according to one of the preceding claims.

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