EP0357942A1 - Rotating device for the display of an image through an angle of 360 degrees - Google Patents

Abstract

The invention relates to a rotating device for the display of an image (14) through an angle of 360 DEG . In order to avoid transmission of vibrations of the image carrying drum (10) and to relieve stress on the motor, the latter can be brought into engagement with the image carrying drum (10) merely via a drive element (4). The drive element may be for example a drive wheel (4a) or a rubber-metal coupling (4c). Expediently, the motor (3) is connected to an electrical torque control system (11), by which the torque can be increased during start-up. It is also possible to provide a braking device (15) for the rapid stopping of the drum (10), in that preferably the motor (3c) can be switched into the generator drive onto a load resistor (16). <IMAGE>

Description

The invention relates to a rotatable device according to the preamble of claim 1 or 2. Such a device is known from EP-A-208283. This European patent application as well as PCT / CH88 / 00098 and the patent application "Light source for a device for all-round display of a flat image over an angle of 360 °" from the same filing date as the present patent application are considered to be disclosed within the scope of this description.

EP-A-208283 describes the principle of the device, while PCT / CH88 / 00098 specifies the second-mentioned improvements and specifications of the grid. The patent application on the light source is concerned with improvements in light for such a device.

The few previously known devices according to the preamble of claim 1 work quite well with regard to the technical improvements already made in accordance with the patent applications mentioned at the beginning. However, problems arise when driving the image carrier drum.

Due to the relatively high speed and the associated vibrations of the rotating image carrier drum, damage to the bearing parts of the motor can occur, especially in continuous operation. The balancing of the image carrier drums is difficult in certain cases because the material (e.g. plexiglass) is subject to a certain deformation at speeds of over 1500 revolutions per minute and the vibrations cannot be completely eliminated by conventional balancing measures. In part, such problems can be reduced by off-center mounting of the drive motor, as described in DE-A-2949419.

In addition, however, it was shown that the starting inertia, especially with larger drums, meant that the motors had to be designed much larger than would actually be necessary for ongoing operation. Only a low power is then required during operation, since the image carrier drum is usually well-supported and therefore only relatively low bearing resistances occur.

The aim of the invention is to provide a rotatable device with a motor in which the transmission of the vibrations of the image carrier drum to the motor is reduced or switched off and in which the motor can be better designed for continuous operation, so that it is essentially based on the Rated speed is coordinated and does not have to be particularly oversized for startup.

The stated object is achieved in a satisfactory manner by the characterizing part of claim 1. Just a little jerk at the start of the start helps to overcome the inertia that is greatest from the zero speed position. As a drive member in the sense of the invention, all those rotatable components are to be understood that prevent, complicate or at least dampen direct vibration transmission between the motor and image carrier drum and at least allow a small relative movement between the motor and the mel. For example, it can be an elastic coupling, gears, gears, drive wheels or the like. act.

Various additional improvements result from further configurations and variants, which are described in the characteristics of the subclaims.

The features of claim 2 allow particularly well the separation of the radial forces acting radially to the axis of rotation from the motor, the transverse design of the same also saves in height, whereby the device can be made relatively flat.

The variant according to claim 3 is characterized by a simple design, which to a certain extent has integrated a slip clutch. This slip clutch is created between the friction surface and the drive wheel by allowing a certain amount of slippage there. In addition, the variation of the radial width of the shaft extension together with the variation of the drive wheel diameter enables the optimal adaptation to the engine characteristic.

If the drive wheel, as proposed in claim 4, is provided with a friction-increasing coating, then a separate slip clutch between the motor shaft of the drive motor and the drive wheel is advantageous, the coating being noise-damping and reducing the operating noise. In this case, various types of clutch known per se can be considered as a slip clutch, such as e.g. Viscose, magnetic or simple friction lining clutches, possibly also cone clutches or multi-plate clutches.

The design according to claim 5 has proven to be advantageous in tests, the actual speed of the motor being irrelevant. For example, DC motors run much faster than asynchronous AC motors in many cases, but their design may be smaller so that they are better used. The dividend rpm specified in the formula of claim 5 can be, for example in the case of a device with a corresponding number of revolutions of the image carrier drum, about 2000 to 3000 revolutions per minute, which is the optimal number of revolutions for an apparently stationary image reproduction. Of course, here lower values - correspondingly lower revolutions of the image carrier drum - can also be used, which, however, can lead to a flashing effect for a single image. When mounting two images back to back and a reflected light construction, the dividend can be halved despite the static image.

Smaller motors, which may be overloaded for a short time, are advantageously switched according to the variant of claim 6, with DC motors with the properties according to claim 7 proving to be particularly advantageous for this. E.g. an increase in the motor supply voltage increases the torque. In addition, this is the easiest way to implement countercurrent braking and / or speed control. Because of its small, and therefore easier to control, mass, a direct current motor with a bell armature will prove its worth, at least if the device is not too large.

In previous devices, the motor always served as a bearing part for the image carrier drum, which is disadvantageous in the sense of this invention. However, there was also less frictional force or loss as a result.

However, a bearing according to the features of claim 8 is particularly friction-free according to the invention, an embodiment according to claim 9 additionally giving the advantage of thermal separation between the rotary drive and the light source. The mutual heating of these two important elements of the device is thereby prevented. By mounting the motor according to the feature of claim 8, however, the area of light access to the image carrier drum is also large enough. It can be further increased by the following measures:

In the case of a plate which is transparent on all sides, this is mirrored on its peripheral edge and on its upper side facing the grid. The total area of the underside of the plate thus serves as the light entry area. Due to the total reflection on the mirrored sides, a large part of the light of the plate half mirrored on its top is reflected in the part of the plate that is not mirrored, as a result of which this light is also directed into the space behind the picture and thus through the picture.

The variant according to claim 10 enables the individual setting of an image flashing frequency, which can be further amplified by the additional effect of an interference beat by a light intensity fluctuation of the light source lying at a frequency in the region of the rotational frequency of the image carrier drum. If the position in which the light from the light source is weakened or darkened (dark phase) appears to move around the axis of rotation of the image carrier drum, this leads to an additional light threshold effect, which is particularly suggestive and long-term when a picture is viewed for a long time and the intensity of the light fluctuation is low can be haunting, which is often welcomed by advertisers.

Training with a braking device is particularly advantageous for those devices in which the picture is to be changed frequently. Because of the rotating masses of the drum, it may take up to a minute or two for the image carrier drum to come to a standstill without a braking device. Here one can fall back on constructions as they are known for the single image switching of heavier cameras (eg 16mm).

• Fig.1 einen Schnitt durch eine Einrichtung etwa im Bereich der Bildebene;
• Fig.2 einen Schnitt durch eine auf die Schnittebene gemäss Fig.1 senkrechte Ebene,und zwar durch eine Einrichtung mit einer ausserhalb der Bildträgertrommel angeordneten Lichtquelle;
• Fig.3 ein Detail des Antriebes der Variante nach Fig.2, und
• Fig.4 ein Detail einer Einrichtung mit einer elastischen Wel­lenkupplung.

Further features, advantages and variants result from the following description of the drawing. The invention is explained in more detail by way of example, but is not limited to them. They show

• 1 shows a section through a device approximately in the area of the image plane;
• 2 shows a section through a plane perpendicular to the section plane according to FIG. 1, namely through a device with a light source arranged outside the image carrier drum;
• 3 shows a detail of the drive of the variant according to Figure 2, and
• 4 shows a detail of a device with an elastic shaft coupling.

The figures are described together. The same parts have the same reference numbers, similar parts have the same reference numbers and different indices.

The essence of the invention is the load-related separation between an image carrier drum 10 and a motor 3. The motor 3 is only intended to produce the rotary movement of the image carrier drum 10; however, it should be separated from the weight and from any vibrations of the image carrier drum 10.

According to the design according to FIG. 1, this is done by mounting the image carrier drum 10 on a needle 12a which engages in a bearing pit 21 of a plate 1a of the image carrier drum 10. The bearing pit 21 is tapered - with its center in the axis of rotation 22 of the image carrier drum 10. The needle 12a is shown cranked to the axis of rotation 22, but can also lie entirely in the axis of rotation 22. The area of the needle 12a facing away from the plate 1a is fixed to the housing. The outer housing 28, like the image carrier drum 10, is transparent and is provided with a lower and an upper end plate 29a and b, respectively.

The counter bearing to the needle 12a is provided by a journal arrangement 31 between the two upper plates 1b and 21b. Alternatively, as can be seen from FIG. 2, a further needle 12b could also function as a counter bearing.

2 is formed by a ball 12c which lies in a bearing socket 30 which is fixed relative to the outer housing 28. An opposite pan 30a is mounted on the lower plate 1d of the image carrier drum 10. A variant could at best be that the drum 10, instead of running on a ball, runs on the plurality of balls, which can be rolled in a circumferential groove on the underside of the plate 1d and roll in an opposite stationary groove. Such constructions are known from the rotary mounting of slewing cranes, ship unloading systems or the like.

The variant according to FIG. 4 is mounted on a magnetic levitation bearing 27 which is fastened on the one hand to the periphery of the lower plate 1e and on the other hand to a bearing ring 26 which is fixed opposite the outer housing 28. The bearing forces in the vertical and radial directions are absorbed by the magnetic forces that are generated by magnets of the magnetic levitation bearing 27. The opposing surfaces 25a, b are magnetically polarized equally, so that they repel each other.

The variant of FIG. 1 is driven by the motor 3a via its motor shaft onto a drive wheel 4a which is in frictional connection with the friction surface 17 of a tubular shaft extension 18 via a friction-increasing lining 5a. The shaft extension 18 is rigidly connected to the lower plate 1a or is formed in one piece with it. Slip rings 24 electrically insulated from one another are mounted on its outer circumference, with carbon brushes 23 being juxtaposed.

The carbon brushes 23 are spring-loaded and electrically insulated from one another in a known manner (not shown) and are held firmly with respect to the outer housing 28. They are connected to power sources (not shown) for the light source 2a via supply lines (not shown). The light source 2a is socketed in the plate 1a and connected to the slip rings 24 via current paths (not shown).

The motor 3a is connected via electric lines 32 to a torque control 11, to which a braking device 15 is assigned. The torque control can be regulated automatically or via a handwheel 33. It causes an increase in the power of the motor 3a when starting off or a power reduction or variation in the nominal operation, in which, as already mentioned, only bearing forces on the needle 12a or on the bearing journal arrangement 31 have to be overcome. Friction losses on the slip rings 24 are negligible and can be selected by the choice of material, e.g. by increasing the amount of silver added.

The variant according to FIG. 2 is driven by a transverse motor 3b which is fastened in the upper end plate 29c. The end plate 29c is accordingly recessed and also has a slot 34 through which a drive wheel, which is rigidly connected to the motor 3b, accesses the top of the plate 1c. Frictional slip can occur between the drive wheel 4b and the plate 1c, as a result of which the motor can reach its rotational speed much faster when starting and the starting torque of the image carrier drum 10 does not lead to a thermal overload of the motor. Such an embodiment is used in particular where the device is frequently switched on and off. The motor 3b is against the plate by a spring 35 1c held down. The slip behavior can be varied by means of this spring 35 or its spring force, which is preferably adjustable. The spring 35 is supported on the inside of a sheet metal roof 36 of the outer housing 28.

The needle 12b already mentioned, like the motor 3b, is fastened in the upper end plate 29c.

The distance a of the drive wheel 4b from the axis 22 of the image carrier drum 10 is determined by the product of the nominal speed of the motor ⁿ m times the radius r of the drive wheel 4b divided by the desired number of revolutions rpm of the image carrier drum 10 - in the most common case 2000 to 3000 revolutions per minute .

The power supply to the motor 3b and to the light source 2b is not specified and is known to a person skilled in the art depending on the particular design. A DC motor is particularly suitable as a motor 3b with a transverse position.

The light source 2b according to FIG. 2 is located outside the image carrier drum 10 and is mounted as a circular lamp concentrically around the bearing pan 30 in a manner fixed to the outer housing. Their light rays 13 penetrate through the at least half-sided transparent plate 1d into the space behind the image 14. This space is mirrored on the side walls 37. If the plate 1d is completely transparent, it is mirrored on its upper side 39 facing a grid 38 and on its peripheral peripheral edges 40. This results in total reflection and optimal use of light by the light source 2b.

The frontally visible space behind the light source 2a in FIG. 1 is also mirrored on its side walls 37 in order to increase the light output and to prevent the light from penetrating outward in the direction facing away from the image.

The drive according to Figure 3 corresponds to that of Figure 2. A slip clutch 8 is also provided between the motor shaft 7 and the drive wheel 4b, which allows slippage in the starting operation, as a result of which the lining 5b wears less on the drive wheel 4b.

The motor 3c is fed via a speed control element 41 and is connected to a braking device 15, which has a load resistor 16 connected externally. When the motor 3c is switched off, the braking device 15 automatically switches the motor to the braking resistor 16 in generator mode, so that it is braked electrically. The electrical structure of the speed control element 41 and the braking device 15 is known to a person skilled in the art and is therefore not described in detail, but it can be designed as a countercurrent brake known per se, in which the motor is operated until a minimum speed, e.g. until standstill, a counter torque is given. Such circuits have been proposed variously in cinema technology, for example for stopping a shutter in a precise position.

Centrically to the axis of rotation 22, a siren plate 19 with openings 20 is indicated in FIG. 3, which is capable of causing air to vibrate at higher speeds and thereby generating tones. The openings 20 are provided with tongues 9 which generate suitable air vortices. The speed control element 41 can be equipped in such a way that it automatically varies the speed so that the sounds produced by the plate 19 result in a melody. The plate 19 is preferably rotatably connected directly below the plate 1, not shown, with the image carrier drum. Your shaft 42 is used as storage for the image carrier drum. On the other hand, could the rotation of such a plate can also be used to generate cooling air for dissipating the heat emitted by the light source or motor by providing 9 ventilation blades instead of the tongues.

The variant according to FIG. 4 is driven by a motor 3d arranged below the image carrier drum 10 with the axis of rotation 22 centrally, the motor shaft 7a of which is connected to the plate 1e of the image carrier drum 10 via an elastic coupling 4c. The elastic coupling 4c is, for example, a rubber-metal coupling. The side of the coupling 4c facing the plate is either attached directly to the plate 1e or connected to the latter via an intermediate piece (not shown).

Vibrations of the image carrier drum 10 are swallowed or damped by the clutch 4c. As already explained above, the weight of the drum 10 is carried by the magnetic levitation bearing 27. Instead of the magnetic levitation bearing 27, a ball or slide bearing could also be provided. Likewise, a mechanical filter in the form of a flywheel could be provided on the drive side, in front of the clutch, to filter out vibrations, which is uncoupled accordingly for stopping. Another possibility is electronic filtering with the aid of a speed control circuit, which has a tachometer generator connected to the image carrier drum.

Reference symbol list

• 1 a, d, e lower end plate of the image carrier drum 10
• 1 b, c upper end plate of the image carrier drum 10
• 2 a, b light source
• 3 a, b, c, d drive motor
• 4 a, b, c driving wheel, clutch
• 5 a, b topping
• 6 surface
• 7, 7a motor shaft
• 8 slip clutch
• 9 slats
• 10 a image carrier drum
• 11 Torque control
• 12 a, b needle or ball
• 13 rays of light
• 14 picture
• 15 braking device
• 16 load resistance
• 17 friction surface
• 18 wave extension
• 19 siren plate
• 20 openings
• 21 storage pit
• 22 axis of rotation
• 23 carbon brushes
• 24 slip rings
• 25 a, b areas
• 26 bearing ring
• 27 magnetic levitation bearings
• 28 outer housing
• 29 a, b, c end plate of the housing 28
• 30 a bearing pan
• 31 journal arrangement
• 32 lines
• 33 handwheel
• 34 slot
• 35 spring
• 36 roof
• 37 side walls of the drum
• 38 grid
• 39 top
• 40 peripheral side walls
• 41 speed actuator
• 42 wave of the siren plate 19

Claims (11)

1. Rotatable device for making an image visible over an angle of 360 degrees with an image carrier drum (10) bounded at least at one end by an end plate (1) and carrying an image (14), with a light source (2) and with a drive motor (3), the shaft (7) of the drive motor (3) being engageable with the end plate (1) via a drive wheel (4b), characterized in that the motor (3b) is arranged transversely and the end plate (1a) can be acted upon directly by the driving wheel (4b). (Fig.2; 3) 1. Rotatable device for making an image visible over an angle of 360 degrees with an image carrier drum (10) bounded at least at one end by an end plate (1) and carrying an image (14), with a light source (2) and with a drive motor (3), the shaft (7) of the drive motor (3) being axially connected to the end plate (1), characterized in that a rubber-elastic coupling (4b) is provided between the shaft (7) and the end plate (1). (Fig 4) 3. Device according to claim 1, characterized in that the drive wheel (4b) has a friction-increasing - preferably soft and noise-damping - coating (5b) and is in direct engagement with the surface (6) of the plate, optionally between the motor shaft (7 ) of the drive motor (3c) and the drive wheel (4b) a slip clutch (8) is provided. 4. Device according to claim 3, characterized in that the drive wheel (4b) touches the plate (1c) at a distance (a) from the axis (22) of the image carrier drum (10), the distance (a) being from the radius of the drive wheel (r) according to the formula ⁿ mr / rpm, where rpm is the desired speed of the image carrier drum (10) and ⁿ m is the nominal speed of the motor, and preferably the distance (a) corresponds to the radius (r) of the drive wheel . 5. Device according to one of the preceding claims, characterized in that the motor (3) is connected to an electrical torque control (11) through which the torque can be increased during start-up operation, and / or that a braking device (15) for the rapid stopping the drum (10) is provided in that the motor (3c) can preferably be switched to a load resistor (16) in the generator drive. 6. Device according to claim 5, characterized in that the motor (3) is a DC motor, the nominal voltage (Um) and nominal speed ( ⁿ m) by the torque control (11) after starting can be reduced to about half, half Nominal speed ( ⁿ m: 2) is preferably 2000 to 3000 revolutions per minute. 7. Device according to one of the preceding claims, characterized in that the image carrier drum (10m) at one end is mounted centrally on a needle (12a) or ball (12b), and that the motor (3a, b) is mounted at the other end. 8. Device according to one of the preceding claims, characterized in that a light source (2b) is provided on the end of the drum (10) facing away from the motor (3), the plate (1d) facing the light source (2b) being transparent at least on one side is carried out so that the light rays (13) preferably illuminate the image (14). 9. Device according to one of the preceding claims, characterized in that the speed ( ⁿ m) of the motor (3) can be regulated by hand and / or program-controlled, and that optionally on a rotating siren plate (19) devices (20) for generating Tones are provided. 10. Device according to one of the preceding claims, characterized in that the motor (3) can be put into operation via a control which can be controlled by a proximity switch. 11. The device according to claim 1 or 2, characterized in that the image carrier drum (25a, b) is mounted independently of the motor (3) - preferably on a magnetic bearing.

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