EP0770980A2

EP0770980A2 - Device for at choice reproducing a selected representation

Info

Publication number: EP0770980A2
Application number: EP96202905A
Authority: EP
Inventors: Ulbe Jan Lanting
Original assignee: Assembla Lichtreklame BV
Current assignee: Assembla Lichtreklame BV
Priority date: 1995-10-24
Filing date: 1996-10-23
Publication date: 1997-05-02
Anticipated expiration: 2016-10-23
Also published as: ES2175026T3; EP0770980A3; DE69620340D1; EP0770980B1; DE69620340T2; PT770980E; NL1001491C1

Abstract

The invention relates to a publicity board generally having trilateral prisms which are situated with their edges against each other, which position is repeated after each rotation over 120°. To prevent friction and shocking, due to play between the moving parts, the driving member has a coupling member (18), which let the driven member rotate around his axis (3) bringing the driven member in engagement with a segment (17) of the drive member, such that almost no slip between said parts occurs and that a very smooth operation is obtained. By this a self-driving alternating-current motor can be used.

Description

The invention relates to a device for at choice reproducing a selection of two or three representations provided with display panels, each having two respectively three mainly rectangular display faces mounted in a row side by side and which are rotatable around mutually parallel axes, the display faces in two respectively three rotating positions with their edges adjoining the edges of the display faces situated alongside, wherewith a drive is present coupled with each of the display panels by means of a driving member, which has a stabilisation plane for a driven member of the display face and an interrupted circular segment, a coupling member connected to the driving member, which lets the driven member undergo a beginning of a rotation, after which it comes into the path of a recess of the circular segment to be driven till it comes out of the recess of the circular segment by its own rotation.
Such a device is known from the Dutch patent application NL-A-94.00833, in the name of applicant.
Although this known device works satisfactory, it has turned out that the known device could still be improved considerably and specifically with regard to the relative play between the moving parts and also with regard to the friction between these parts.
This is the more important with this known device, because in order to keep the dimensions of the driving unit as small as possible, and the manufacturing costs low, an alternating current driving device is used which needs some starting time and only exerts a low torque. Because such devices can have a considerable number of display panels it is of great importance that the friction for each individual panel is kept as low as possible.
Also the play between the moving parts should be minimized because even the slightest rattling of the display panels due to the wind, which display panels with a normal sized device may have a total weight of several hundred kilos, impose a considerable load on the driving device.
The object of the invention is to improve the known device, that is to lower further the friction and to overcome the play between the moving parts, consequently it is provided by the invention that each driven member has a two-respectively three-tooth rotatable position fixation member, with between the successive teeth a recess, which can protrude with a tooth into the recess of the circular segment and by this is driven and lies in a fixed end position with two teeth against the circular segment.
Herewith the contact surface of the position fixation member, in the fixation position, with the stabilisation plane of the driving member is restricted to small planes at the flanges of respective teeth at respective sides of the recess between the teeth. With the distance between these contact surfaces the stabilization is guaranteed, while the friction between these members in this orientation is reduced to a minimum.
Important herewith is to know that for the greater part of a rotation the fixation member is in contact with the stabilization plane. Specially with applications of the device with which the presentations are changed rather infrequently, for example for traffic control purposes, it is prevented that a much larger initial torque has to be exerted due to the sticking of the moving parts to each other.
It is very important that the cooperation between the coupling member and the driven member passes smoothly and does not lead to a sudden operation in full speed of the driven member.
According to a further elaboration of the invention this is attained by providing that the coupling member in his driven direction is bevelled at his front side which contacts the driven member.
With a flat disk as circular segment it is preferred that the bevel is steeper to the centre of the circular segment. Even more preferably it is provided that this side varies from a flat to a curved side near the centre of the circular segment. Apart from enabling a continuous contact, this also increases considerably the smoothness of the rolling of movement between the coupling member and the driven member.
The part of the driven member contacting the coupling member preferably is two- or three-tooth.
With respect to the shape of the part of the driven member cooperating with the coupling member it appears to be preferable if said part has two respectively three teeth, each having two spherical flanks and between said flanks of the successive teeth a circular-shaped portion. With this shape of the cooperating parts relative small contact zones are realized, which minimizes friction, while at the same time it is realized that these parts remain in engagement constantly during the part of the movement which is operated by these parts. This results in an continuous, noiseless movement without any shocks.
According to a further embodiment it is provided that the coupling member is symmetrical with respect to a line through the rotation axis of the circular segment and that the teeth of the two- or three-tooth member are symmetrical with respect to a line through the axis of said member.
Herewith it is possible to let the device operate in opposite directions. This is important for example when a predetermined position has to be taken directly after a special event, such as the change of a traffic sign to directly the wanted sign, or with sport events for example a goal.
According to a further characteristic of the invention a further improvement in the operation of the driven member is obtained by providing that the position fixation member fixedly connected to the part of the driven member cooperating with the coupling member having two or three teeth with a tapered end with a small rounding off at the top and between the successive teeth a circular-segment-shaped recess.
With the recesses between the teeth, the teeth only have relatively small faces at their tapered ends, which permits for a better fit of the teeth in the opening in the circular segment.
This is further improved by providing that the contact surface of the opening is made up of two planes with an obtuse angle between the planes. The first plane in the opening to contact a tooth being nearer to the centre of the circular segment, than the second plane, and the angles of the planes with respect to the flange of a tooth being such that in the respective positions the rotational movement is transmitted with the least slip between the moving parts.
The recesses between the teeth also have the result that the point of engagement between the circular segment and the position fixation member, can never be closer to the centre of the position fixation member than the intersection line between a tapered teeth end and a respective recess, as a result of which the momentum between the circular segment and the position fixation member remains basically the same during the contact between these parts.
When applying the invention it is always possible to rotate the driving member along a considerable angle without putting it under load. This also means that there is time available to start the motor, and consequently use can be made of a cheaper alternating-current motor in stead of a direct current motor, which are much used at this moment for said purpose.
Although such a motor needs some starting time, there will still be a considerable angle left, so that it is possible with the device according to the invention to start driving the respective panels of a number of display panels one after the other.
The invention in the following is further elucidated on hand of the drawing, in which

fig. 1 shows a front view of the device according to the invention;
fig. 2 shows an upward view of the device of fig.1;
fig. 3 shows a front view of a driven member and the position stabilisation with the driving member in side view;
fig. 4 shows a perspective view on the right hand of the driven member of fig. 3;
fig. 5 shows a view of the disk with cam and recess of the embodiment of fig. 3 and 4, and
fig. 6 shows a top view of the driving member and the driven member.

In fig. 1 a common drive shaft is indicated with 5, with which a number of display panels, rotatable around axes 3, can be driven. The display panels have rectangular display faces adjacent to each other in the position when a representation is shown. Mostly these display faces are the lateral faces of triangular prisms, but naturally the invention is also applicable for constructions with only two display faces, in which case an angle of 180° is necessary in stead of an angle of 120° for switching between representations.
The driving member 6 coupled with the input axis 5 has a circular segment 17 provided with a cam 18 (vide fig. 3 and 4), which is meant to cooperate with a coupling member 27 of the driven member 32, to rotate it so far that a tooth of the driven member comes in engagement with an opening in the circular segment 17.
In fig.2 the driven member is positioned with a tooth in the opening in the circular segment 17, and is exactly in the middle between successive presentations, with a point of the triangle cross-section of the prism pointing upward. For the sake of clarity the axis 5 in this figure is indicated with an interrupted line.
In fig.3 the circular segment 17 is shown with cam 18 with a low steep front surface 20, thereafter an upwardly inclined surface 21 and finally an inclined surface 22 to have again a surface 21 and 20 at the other side. The surface 21, as can be seen from fig.4 and 6, at the side near the centre of the circular segment is concave shaped.
The coupling member 27 has three teeth 28, 29 and 30 (vide fig. 4) with there between circular shaped transitional members 31, the teeth having convex shaped flanges. In the coupling position one of the teeth 28, 29 and 30 in fig. 4 is taken by the cam 18 and by the shape and the inclination thereof and the shape of the teeth a very gradual start of the movement of the coupling member 27 is initiated.
The coupling member 27 is fixedly coupled with the position fixation member 32 having three teeth 33, 34 and 35, which when rotating the combined driving member 27, 32 can protrude in an opening 19 of the circular segment 17 and have such a shaped, that they have virtually no play in said opening. This opening has inclined boundary walls 16,25 with boundary edges 23 and 24, with an obtuse angle between these planes, as can be seen more clearly in fig.3 and 6.
The teeth 33,34 and 35 of the position fixation member 32 have relatively small flatted parts near their ends, which come to rest against the plane of the circular segment 17 in the fixation position. The small surface area in contact with the circular segment means only little friction, while the mutual distance between these parts is sufficient to guarantee a fixation without play.
The circular segment 17, position fixation member 32, coupling member 27 and cam 18 are designed and cooperating in a manner such that during the period in which the position is fixed and during the switching between successive representations, the friction is at a minimum and, equally important, with no play between the moving parts. Important herewith is that during a larger part of the period needed for switching between representations, a tooth of the position fixation member is in engagement with circular segment 17, at the same time that cam 18 is in engagement with coupling member 27.
The result of these measures is that an extremely smooth operation is obtained with particularly little friction. Consequently a relatively low voltage alternating current motor suffices. Moreover in most embodiments only such a small normal capacity is needed, that any accidental hampering will result in a strong increase of the used capacity, which can be observed very easy, clear and unambiguous, and may be used as an input for a switching-out safety system.
Once the moulds are made for the synthetic parts, these driving parts of the device according to the invention can be manufactured at relatively low costs.

Claims

Device for at choice reproducing a selection of two or three representations provided with display panels, each having two respectively three mainly rectangular display faces mounted in a row side by side and which are rotatable around mutually parallel axes, the display faces in two respectively three rotating positions with their edges adjoining the edges of the display faces situated alongside, wherewith a drive is present coupled with each of the display panels by means of a driving member, which has a stabilisation plane for a driven member of the display face and an interrupted circular segment, a coupling member connected to the driving member, which lets the driven member undergo a beginning of a rotation, after which it comes into the path of a recess of the circular segment to be driven till it comes out of the recess of the circular segment by its own rotation, characterized in that each driven member has a two- respectively three-tooth rotatable position fixation member (32), with between the successive teeth a recess, which can protrude with a tooth into the recess (19) of the circular segment (17) and by this is driven and lies in a fixed end position with two teeth against the circular segment (17).
Device according to claims 1, characterized in that the coupling member (18) in his driven direction is bevelled at his front side (21) which contacts the driven member.
Device according to claim 2, characterized in that the bevel is steeper to the centre of the circular segment.
Device according to claim 2 or 3, characterized in that nearer to the centre of the circular segment (17) the front side (21) is concave shaped.
Device according to claim 2-4, characterized in that the coupling member (18) is symmetrical with respect to a line through the rotation axis of the circular segment (17) and that the teeth of the two- or three-tooth member (27) are symmetrical with respect to a line through the axis of said member.
Device according to claims 2-5, characterized in that the position fixation member (32) is provided with a two- or three-tooth member (32) cooperating with the coupling member (18) and the teeth of which each has two spherical flanks and between said flanks of the successive teeth a circular-shaped portion.
Device according to claims 1-6, characterized in that the teeth of the position fixation member (32) have a tapered end with a small rounding off at the top and between the teeth at least one circular segment shaped recess.
Device according to one or more of the preceding claims, characterized in that the driving members are together driven by a self-running alternating-current motor.