Patent Application
20110015861
The present invention relates in general to collision detection between objects wherein at least one of the objects moves relative to the other object, and in particular to maintaining a relative distance between a moving imaging head and an imaging drum.
Electro-mechanical machinery is comprised of plurality of elements, often some of the elements may be configured to move within the machine. An example for such machinery is a computer-to-plate (CTP) imaging device. The imaging device includes a rotating drum adapted to carry a printing plate to be imaged by an imaging head, which is part of the CTP imaging device. The imaging head includes a laser source, configured to emit radiation on the printing plate. In addition, the imaging head will include an optical focus system, capable of focusing on regions of the plate surface and subsurface. When engraving a printing plate, the imaging head is required to move towards the rotating drum to enable the focus system to focus deeper into the printing plate. The movement of the imaging head towards the rotating drum must be controlled in order to avoid hazardous situations in the CTP imaging device. The invention described hereunder suggests an apparatus and methods to prevent collisions between the elements inside such devices.
Briefly, according to one aspect of the present invention, a collision detection system is provided for objects moving relative to each other. In one embodiment, a collision detection unit is attached to the first object and includes an air flow source element for applying an air stream to the first and second object, a pressure sensitive unit for sensing air pressure between the first object and the second object, a pressure data analysis module for analyzing air pressure levels, and an alert unit configured to alert when an abnormal distance is detected between the first object and the second object.
These and other objects, features, and advantages of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings wherein there is shown and described an illustrative embodiment of the invention.
The subject matter regarded as the invention will become more clearly understood in light of the ensuing description of embodiments herein, given by way of example and for purposes of illustrative discussion of the present invention only, with reference to the accompanying drawings, wherein:
In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the disclosure. However, it will be understood by those skilled in the art that the teachings of the present disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the teachings of the present disclosure.
The present invention describes a collision detector method and apparatus integrated in an auxiliary device. The device is comprised of at least two objects which move relative to each other. The collision detector is adapted to sense a possible collision between the objects and produce an alert signal. The invention helps avoid collisions between moving objects.
In operation, air flow source 156 applies air flow 116. Air flow 116 propagates via air flow channel 112 to the possible collision area 160. While objects are far from each other, exhausted air has no obstacles on its way, and therefore the pressure in the possible collision area 160 is practically equal to atmosphere pressure. When objects approaching each other, the distance X between them becomes smaller, thus forcing the air to flow through the gap between the objects. The thickness of the gap X determines the resistance level to the air flow Rg. In this case pressure P in the possible collision area may be defined as follows: P=F×Rg (1) where F represents the air flow value. The resistance to air flow is inversely proportional to the distance between the objects and it can be represented as Rg=k/X (2), wherein k is a constant dependent on the gap geometry.
After substitution of equation (2) into (1) yields the following equation (3):
P=F×k/X (3)
Equation (3) shows that pressure in possible collision area 160 will grow as much as the distance between the objects becomes smaller.
Pressure sensor 120 senses the levels of the air pressure and sends a pressure signal 136 to controller 124, which detects the pressure level sensed in the possible collision area 160. Controller 124 comprises a signal analyzer 140 and motor control logic 148, the signal analyzer 140 also includes an alert element 164.
Pressure signal 136 is analyzed by signal analyzer 140. If signal analyzer 140 detects increasing pressure, which represents a possible collision between the first and second protected objects 104 and 108, an collision alert signal 144 is sent to motor control logic 148. The motor control logic 148 implementation may be based, for example, on a controller described in U.S. Pat. No. 7,505,847. Motor control logic 148 produces a motor control signal 152 to motor 128, which causes first protected object 104 to stop or move away from second protected object 108, thus preventing a collision between the objects.
In an another embodiment of this invention, controller 124 will be set so that first protected object 104 and second protected object 108 are always within a specific range 504 between each other. A collision alert signal 144 will be produced in the case when first protected object 104 is a distance less than minimum the distance 512 from second protected object 108. The collision alert signal 144 will be also produced when the distance between first and second protected objects 104 and 108 is more than the maximum distance 508.
While the invention has been described with respect to a limited number of embodiments, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of some of the preferred embodiments. Other possible variations, modifications, and applications are also within the scope of the invention. Accordingly, the scope of the invention should not be limited by what has thus far been described, but by the appended claims and their legal equivalents.
The invention has been described in detail with particular reference to certain preferred embodiments thereof but it will be understood that variations and modifications can be effected within the scope of the invention.
