Patent Publication Number: US-2022219601-A1

Title: Light signal device for a driverless transport system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This continuation application claims priority to PCT/EP2020/078103 filed on Oct. 7, 2020 which has published as WO 2021/069485 A1 and also the German application number 10 2019 215 332.1 filed on Oct. 7, 2019, the entire contents of which are fully incorporated herein with these references. 
    
    
     DESCRIPTION 
     Field of the Invention 
     The invention relates to a light signal device for a driverless transport system, to a light signal arrangement for a driverless transport system and to a driverless transport system. The invention also relates to the use of a light signal device and to an operating method for a driverless transport system. 
     Background of the Invention 
     Driverless transport systems are widely used to transport loads in manufacturing and logistics. 
     It is known to illuminate driverless transport systems by means of LED strips arranged around the periphery or by means of LED matrices. In practice, this has often required many LEDs with a correspondingly high-power consumption, which is disadvantageous with regard to the limited battery capacity of the driverless transport system. Static illumination often takes place with constant illumination brightness and color, by means of which substantially only the position or contour of the driverless transport system can be highlighted. 
     US 2012/0280528 A1 describes a light strip for an outer surface of a vehicle with a light guide into which light from LEDs is coupled at several points. A rear face of the light guide is treated such that light is reflected out to the front face of the light guide. The light strip has a one-way mirror on the front, which can be masked in regions so that, for example, illuminated letters appear. 
     DE 10 2012 211 052 A1 discloses motor vehicle interior lighting with a plurality of light sources and a plurality of light guides, the light sources and light guides being designed and arranged relative to one another in such a way that light from different light sources is coupled into different light guides. The light guides each have a plurality of decoupling regions spaced apart in the main light propagation direction. The light guides can be arranged so as to extend one next to the other. The light guides can be held on a substantially transparent diffuser. At the location of a recess in a vehicle door interior lining, the diffuser can have a diffusion plate or a printed foil by means of which the light guided through the diffuser and coupled out at the recess is homogenized. 
     SUMMARY OF THE INVENTION 
     Object of the Invention 
     It is the object of the invention to improve the perceptibility of driverless transport systems. 
     Description of the Invention 
     This object is achieved according to the invention by a light signal device according to claim  1 , a light signal arrangement according to claim  5 , a driverless transport system according to claim  9 , a use according to claim  15  and an operating method according to claim  16 . 
     Light Signal Device According to the Invention: 
     According to the invention, a light signal device is provided for a driverless transport system. The light signal device is used to optically highlight the driverless transport system, in particular an operating state of the driverless transport system. As a result, the actions of the driverless transport system can be better assessed by people, for example production workers. This can help to increase acceptance of driverless transport systems and prevent accidents. 
     The light signal device comprises a front element having a plurality of optically transparent light exit openings. Light can exit through the light exit openings during operation of the light signal device. Apart from the light exit openings, the front element is fundamentally opaque, i.e., not translucent. In other words, the light exit openings are designed as optically transparent regions in the otherwise opaque front element. The light exit openings can be formed as physical openings, i.e., through-holes in the front element. The front element can preferably have a (physically) closed surface, the front element being partially transparent (to form the light exit openings) and (otherwise) opaque. Overall, the front element can have a flat, in particular smooth, surface. Alternatively, the light exit openings can be recessed or raised on the surface of the front element. By means of the distribution, size, arrangement and/or design of the light exit openings on the front element, the optical effect of the light signal device during operation can be designed in a way that is suitable for the relevant application. When the light signal device does not emit any light, the light exit openings are typically not visible to the naked eye. The front element can be black, at least on its visible surface. This can contribute to the improved visibility of lighting effects and to concealing the light exit openings in the non-backlit state. 
     The light signal device also has at least one light generating unit. The light generating unit comprises a light guide and two light sources arranged at opposite ends of the light guide. The light sources are used to introduce light into the light guide at the ends thereof. In particular, the light sources can be designed and arranged for introducing light in end faces of the light guide. The light guide can consist of PMMA (polymethyl methacrylate). The light guide is typically elongate. A length of the light guide between the two light sources can be at least five times, typically at least 10 times, preferably at least 20 times, as great as a width or height of the light guide measured perpendicularly to the longitudinal extension. 
     The light guide has a plurality of light decoupling elements in order to emit light through the light exit openings. The light decoupling elements make it possible to direct the light from the two light sources to the plurality of light exit openings and to emit it through the plurality of light exit openings. The light decoupling elements can be introduced into the light guide by mechanical processing, for example milling, or by printing, for example pad, digital or screen printing. A processed or printed part of the light guide typically forms a light decoupling element. The front element can act as a diffuser medium for light decoupled from the light guides. 
     Typically, light is supplied to a plurality of light exit openings by a single light decoupling element of the light guide. The light guide can have light decoupling elements that are not assigned to any light exit openings. This can make it possible to use structurally identical light guides with different front elements, where different light decoupling elements interact with light exit openings depending on the particular front element. 
     The light guide can extend in a straight line. The light exit openings are typically arranged so as to extend parallel to the light guide. A straight light signal device of this kind can advantageously be used to highlight the longitudinal or transverse contours of a driverless transport system. 
     The light exit openings are advantageously arranged on the front element in a plurality of rows. This allows another dimension to be added to the light signal device. This allows further refined optical effects for highlighting the driverless transport system. A separate light generating unit is provided for each of the rows. In this way, the rows can be actuated or illuminated independently of one another. Each of the rows can have a plurality of light exit openings in height direction. In other words, the light exit openings can be arranged closer together within one of the rows than between two adjacent rows. 
     The light sources are preferably in the form of LEDs, in particular RGB LEDs. Light-emitting diodes have a particularly low energy consumption. By means of RGB LEDs (typically each comprising a green, a red and a blue LED element), any light colors can be emitted by suitable actuation. In particular, RGB LEDs allow the light color to be adapted to an operating state of the driverless transport system that is to be highlighted, for example braking, driving forward or a change of direction. Advantageously, RGB LEDs can be formed as RGBW LEDs with an additional white LED element, or more preferably as RGBWW LEDs for emitting white light of different color temperatures, in particular by mixing warm white and cool white light (typically obtainable from a warm white and a cool white LED element of RGBWW-LED). 
     A plurality of the light exit openings may form a common light spot. In particular, a plurality of light spots can each be formed by a plurality of the light exit openings. The visibility of the illumination can be further improved by light spots enlarged in this way. The shape and size of the light spot can be defined in a suitable manner by the positioning of the light exit openings. The light spots can be, for example, round, oval, rectangular, linear, triangular and/or arrow-shaped. One light decoupling element is typically assigned to exactly one light spot. The light exit openings forming one light spot are typically arranged so close together that they cannot be distinguished from one another with the naked eye (in particular, in the illuminated state). 
     Alternatively, the light exit openings may be designed and arranged in the front element for virtually continuous emission of light. This can give the impression of uniform illumination of the front element. 
     The light decoupling elements are particularly preferably designed and/or arranged for homogeneous light emission over the length of the light guide. As a result, the attenuation of the light fed into the light guide by the light sources can be counteracted in the light guide as the distance from the particular light source increases. In order to achieve this, the size, type and/or distribution of the light decoupling elements can be suitably selected. 
     Light Signal Arrangement According to the Invention: 
     A light signal arrangement for a driverless transport system comprising a plurality, preferably four or eight, of light signal devices according to the invention as described above also falls within the scope of the present invention. Additional optical effects can be achieved by the plurality of light signal arrangements. In particular, different sides or edges of the driverless transport system can each be highlighted by means of a light signal device of the light signal arrangement. 
     The light signal devices can form a preferably rectangular frame. The frame can be arranged around the periphery of the driverless transport system. Two or more light signal devices are preferably arranged in succession along one side of the frame. This allows the two portions of the side to be illuminated independently of one another using the relevant light signal device. In addition, this can improve the uniformity of illumination along the side of the frame. 
     The light signal arrangement can also have a display, in particular a matrix display. The display can be used to display symbols and/or characters. Additional information can be shown by means of the display. Information shown by means of the display can be aimed directly at a viewer of the driverless transport system comprising the light signal arrangement. 
     Driverless Transport System According to the Invention: 
     A driverless transport system comprising a light signal device according to the invention as described above also falls within the scope of the present invention. The driverless transport system preferably comprises a light signal arrangement according to the invention as described above having a plurality of light signal devices according to the invention as described above. The driverless transport system also comprises a controller for actuating the light signal device or the light signal arrangement depending on an operating state of the driverless transport system. The driverless transport system is thus able to visualize its operating state by means of the light signal device or light signal arrangement. 
     The light signal device or the light signal arrangement (preferably all the light signal devices of the light signal arrangement) can be oriented for an, in particular directed, emission of light obliquely upward. This can advantageously allow the light signal device or light signal arrangement to be arranged for emitting light toward the eyes of a viewer (who is in a typical position relative to the driverless transport system, for example standing a few meters next to the driverless transport system). In particular, the front element of the light signal device(s) can enclose an angle of between 30° and 75°, preferably between 50° and 70°, with the horizontal. 
     In principle, the driverless transport system has a power drive for automatically moving the driverless transport system and a load-bearing device for carrying loads (cargo) to be transported. The controller can also be designed to actuate the power drive. 
     The control unit is preferably set up to carry out an operating method according to the invention described below. 
     The light signal device or the light signal arrangement is preferably arranged adjacent to the load-bearing device of the driverless transport system. This allows the optical highlighting of the load-bearing device or a load (cargo) that is being handled. The load-bearing device is typically arranged at the top of the driverless transport system. 
     The controller can be set up to visualize a movement (planned and/or already being in execution) of the driverless transport system by means of the light signal device or the light signal arrangement. This can make it possible for a viewer to foresee a movement of the driverless transport system before this movement is (completely) executed. In particular, it can be provided that light effects, preferably green-colored brightness maxima, propagate in the direction of travel when driving forward or backward along side edges of the driverless transport system. Braking can be indicated by an illumination, in particular, in red, on a rear side of the driverless transport system. A change of direction can be indicated by light effects propagating in the direction of the new direction of travel, in particular by orange-colored brightness maxima, on the rear side and/or a front side of the driverless transport system. 
     The controller is preferably set up to provide information regarding a loading state of the driverless transport system by means of the light signal device or the light signal arrangement. The information can relate, for example, to maintaining or exceeding a permissible load. Alternatively or additionally, the information can relate to the positioning, in particular a shifting, of a load on the driverless transport system. This can make the operation of the driverless transport system safer. 
     It is possible for the controller to be set up to indicate an imminent collision of the driverless transport system with an obstacle by means of the light signal device or the light signal arrangement. In particular, a person located in the planned route of the driverless transport system can be informed by suitable light signals that they are blocking this route. A person can also be informed by suitable light signals that an object is located as an obstacle in the planned route, so that said person can remove the object. The controller is particularly preferably set up to stop the driverless transport system before it collides with the obstacle. 
     Use According to the Invention of a Light Signal Device: 
     The scope of the present invention also includes the use of a light signal device according to the invention as described above, in particular a light signal arrangement according to the invention as described above having a plurality of light signal devices, for visualizing an operating state of a driverless transport system. The light signal device or the light signal arrangement is typically an on-board light signal device or light signal arrangement of the driverless transport system. The driverless transport system can be a driverless transport system according to the invention as described above. The operating state can describe a movement state of the driverless transport system, for example a driving speed and/or a driving direction and/or a change in either of these. Alternatively or additionally, the operating state can describe a loading state, for example with regard to maintaining a permissible loading and/or a position of a load (cargo). Furthermore, the operating state can describe a charging process and/or a state of charge of a battery of the driverless transport system. 
     Operating Method According to the Invention: 
     Finally, the scope of the present invention includes an operating method for a light signal device according to the invention as described above, in particular for a driverless transport system according to the invention as described above comprising a light signal device. In the operating method, simultaneously, a luminous flux emitted by one light source of the light generating unit is reduced and a luminous flux emitted by the other light source of the light generating unit is increased, so that a brightness maximum, migrating along the front element, of emitted light is generated. This operating method advantageously allows an operating state of the driverless transport system, in particular a movement state or a change therein, to be visualized. If a plurality of light-generating units arranged one above the other in rows are provided, additional effects can be generated by a time offset in the actuation of the light sources of the light generating units of the different rows. In particular, the optical impression of an arrow (moving in the direction of travel, for example) can be generated by slightly earlier actuation of the light sources of the central light-generating unit(s). 
     Further features and advantages of the invention can be found in the description and the drawings. The aforementioned features and those which are to be explained below can each be used individually for themselves or for a plurality of expedient combinations of any kind. The embodiments shown and described are not to be understood as an exhaustive enumeration but rather have exemplary character for the description of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is represented in the drawings and is explained in more detail using embodiments. In which: 
         FIG. 1  is a schematic perspective view of a driverless transport system according to the invention comprising a light signal arrangement according to the invention having a plurality of light signal devices according to the invention; 
         FIG. 2  is a schematic plan view of a light signal arrangement according to the invention having a plurality of light signal devices according to the invention, which form a rectangular frame, and having a matrix display; 
         FIG. 3  is a schematic exploded view of the light signal arrangement of  FIG. 2 ; 
         FIG. 4  is a schematic exploded view of two light signal devices according to the invention arranged in succession; 
         FIG. 5  is a schematic cross-sectional view of a light signal device according to the invention; 
         FIG. 6  is a schematic illustration of an operating method for a light signal arrangement for generating a moving brightness maximum. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a driverless transport system  10 . The driverless transport system  10  has a load-bearing device  12  for carrying loads (not shown in more detail). The driverless transport system  10  also has a power drive (not shown in detail) with wheels  14 . The driverless transport system  10  can move automatically by means of the power drive. 
     The driverless transport system  10  has a light signal arrangement  16 . Here, the light signal arrangement  16  is designed in the form of a rectangular frame  17 ; see also  FIG. 2 . The light signal arrangement  16  can be provided directly adjacently to the load-bearing device  12  on the driverless transport system  10 . Here, the light signal arrangement  16  surrounds the load-bearing device  12  over the entire periphery thereof. 
     The driverless transport system  10  has a controller  18 . The controller  18  is used to actuate the light signal arrangement  16  depending on an operating state of the driverless transport system  10 . Furthermore, the controller  18  can be set up to actuate the power drive, i.e., to automatically move the driverless transport system  10  by means of the wheels  14 . 
       FIG. 2  shows the light signal arrangement  16  of the driverless transport system  10  from  FIG. 1  in isolation.  FIG. 3  shows the light signal arrangement  16  in an exploded view. Here, the light signal arrangement  16  comprises four side elements  20 , four corner connectors  22  and a display  24 . The display  24  is designed as a matrix display in this case. The display  24  can be used, in particular, to display symbols and/or characters. The display  24  can be arranged on one of the side elements  20 , preferably in the middle. The display  24  can be a TFT display. The display  24  can have additional LEDs on the side. The LEDs on the side can be used, for example in the form of information or warning lights, to display predefined states. The display  24  in the middle can be used, for example, to simulate a mimic expression of the driverless transport system  10  and/or to display more detailed status information (e.g., relating to a load of the driverless transport system  10 ). 
       FIG. 4  shows a side element  20  in a schematic exploded view. Here, each of the side elements  20  has two light signal devices  26 . The two light signal devices  26  in one of the side elements  20  are arranged in succession in the longitudinal direction of the particular side element  20 . 
     The light signal devices  26  each have a plurality of light generating units  28 . Here, each light signal device  26  comprises three light-generating units  28  arranged one above the other in rows. Each of the light generating units  28  comprises an elongate light guide  30 . Here, the light guides  30  are straight and extend parallel to one another. Each of the light generating units  28  also comprises two light sources  32  for each of the light guides  30 . The light sources  32  can be designed as LEDs. Here, the light sources  32  are each designed as an RGB LED. The light sources  32  are each arranged at opposite ends  34 ,  36  of the light guides  30 . The light sources  32  can be designed and arranged for introducing light into the light guides  30  at end faces thereof. 
     Here, the light sources  32  for one of the ends  34 ,  36  of the three light guides  30  of one of the light signal devices  26  are each arranged on a common circuit board  38 . The circuit boards  38  can each have electronic components for actuating the light sources  32 . Here, four plug-in contacts  40   a ,  40   b ,  40   c ,  40   d  are provided on each of the circuit boards  38  in order to supply the light sources  32  with electrical energy and control signals from the controller  18 . In the embodiment shown, only the plug-in contacts  40   a ,  40   b  are used. The plug-in contacts  40   c  and  40   d  could be omitted. The plug-in contacts  40   a  and  40   b  of the two circuit boards  38  of one of the light signal devices  26  can be connected by means of a cable  42 . The plug-in contacts  40   a  and  40   b  of the adjacent circuit boards  38  of the two light signal devices  26  of the side element  20  can be plugged directly into one another. 
     Here, the light guides  30  of the two light signal devices  26  of the side element  20  are held in a common light guide mount  44 . Alternatively, a separate light guide mount (not shown) could also be provided for each of the light signal devices  26 . 
     The light signal devices  26  have a front element  46 . Here, a common front element  46  for the two light signal devices  26  of the side element  20  is provided. Alternatively, a separate front element (not shown) could also be provided for each of the light signal devices  26 . 
     The front element  46  has a plurality of optically transparent light exit openings. Apart from the light exit openings, the front element  46  is opaque (not translucent). The light exit openings are not visible in the drawings due to their small size. A plurality of light exit openings can be grouped in such a way that they form a common light spot  48 ; cf.  FIG. 3 . Here, the light exit openings or the light spots  48  are arranged on the front element  46  in three rows  50  arranged one above the other. The rows  50  on the front element  46  correspond to the three light guides  30  of the light signal devices  26 . In  FIG. 3 , four light spots  48  of each of the rows  50  are shown illuminated by way of example. 
     In order to be able to emit light from the light sources  32  through the light exit openings of the front element  46 , the light guides  30  each have a plurality of light decoupling elements (not shown in detail). The light decoupling elements can each be obtained by mechanically changing the surfaces of the light guides  30  facing the front element  46 . In particular, the surface of the light guides  30  can be mechanically processed to form the light decoupling elements, for example by milling. Alternatively, the light decoupling elements can be printed onto the light guides  30 . 
     The light decoupling elements can be distributed over the length of the light guides  30  or formed differently over the length such that when light is introduced through one or both of the light sources  32  at the ends  34 ,  36 , the light is emitted uniformly (homogeneously) toward the front element  46 . As a result, the perceptible brightness of the light exiting through the light exit openings of the front element  46  is at least approximately constant over the length of the light signal device  26 . The determination of a suitable design, in particular size, and/or distribution (arrangement) of the light decoupling elements can preferably be carried out by calculation, in particular by simulation, or experimentally. 
       FIG. 5  shows a cross section through one of the light signal devices  26  according to  FIG. 4  in the assembled state. The circuit board  38  and the light sources  32 , the light guides  30 , the light guide mount  44  and the front element  46  are accommodated in a main body  52  of the light signal device  26 . Here, the main body  52  is designed to accommodate the two light signal devices  26  of the side element  20 . Alternatively, a separate main body could be provided for each light signal device  26 . 
     Here, the front element  46  encloses an angle  53  of 60° with the horizontal (the plane of movement of the driverless transport system  10 ; cf.  FIG. 1 ). This results in directed emission of light obliquely upward through the light exit openings. In this way, the emitted light can be directed specifically into the eyes of a viewer standing at a typical distance of a few meters from the driverless transport system  10 . The light signal devices  26  therefore appear particularly bright to the viewer. 
       FIG. 6  shows, in schematic form, an operating method for a light signal device  26 . In the operating method, a luminous flux F 1  emitted by the one light source  32  on the left in  FIG. 6  of the light signal device  26  is reduced over the time t. Simultaneously with the reduction in the luminous flux F 1 , a luminous flux F 2  emitted by the second light source  32 , on the right in  FIG. 6 , of the light signal device  26  is increased over the time t. The two luminous fluxes F 1  and F 2  are superimposed in the light guide (not shown in more detail) of the light signal device  26 . As a result, a local brightness maximum  54  is emitted via the light exit openings of the front element  46 . Due to the simultaneous dimming down and up of the first and second light sources  32 , the brightness maximum  54  moves along the front element  46 , here from left to right; cf. arrow direction  56 .  FIG. 6  shows the position of the brightness maximum  54  at a point in time t 1 . 
     This operating method can be used, in particular, to display a movement, for example a direction of travel or a (planned) change in the direction of travel of a driverless transport system  10 ; cf.  FIG. 1 . The controller  18  can be set up to carry out the operating method. 
     The operating method for the driverless transport system  10  can also include that a loading state of the load-bearing device  12  is displayed by means of one or more of the light signal devices  26  and/or the display  24 . Furthermore, the operating method for the driverless transport system  10  can include that an imminent collision of the driverless transport system  10  with an obstacle is indicated by means of one or more of the light signal devices  26  and/or the display  24 . The controller  18  can be set up to correspondingly actuate the light signal devices  26  or the display  24 . 
     LIST OF REFERENCE SIGNS 
     
         
         Driverless transport system  10   
         Load-bearing device  12   
         Wheels  14   
         Light signal arrangement  16   
         Frame  17   
         Controller  18   
         Side elements  20   
         Corner connector  22   
         Display  24   
         Light signal devices  26   
         Light generating unit  28   
         Light guide  30   
         Light sources  32   
         Opposite ends  34 ,  36   
         Circuit board  38   
         Plug-in contacts  40   a ,  40   b ,  40   c ,  40   d    
         Cable  42   
         Light guide mount  44   
         Front element  46   
         Light spot  48   
         Rows  50   
         Main body  52   
         Angle  53   
         Luminous flux F 1 , F 2    
         Time t 
         Point in time t 1    
         Brightness maximum  54   
         Arrow direction  56