The disclosure relates to laser imaging projectors and laser marking systems. More particularly, the disclosure relates to systems and methods for laser projection and marking using a laser beam selectively directed onto and through an aperture in a mask. More particularly still, the disclosure relates to the generation and projection of a randomly selected image along a single axial path.
Conventionally, laser light is projected onto the surface of a material to produce a two dimensional image for applications such as entertainment, printing, semiconductor manufacturing and tissue removal. Three basic techniques are employed to achieve these processes. They are mask generation, raster generation and vector generation. These three techniques are analogous to the differences in the printing industry between type setting, dot matrix printing, and XY plotting.
In type setting a selection of pre-fabricated relief dies, representing individual letters, are aligned in a printing fixture plate to form the desired text image. The dies on the plate are coated with ink and pressed onto the paper, forming the desired text with a single impact of the printing plate. This technique is typically used for high speed, high quality production of fixed images such as newspaper printing.
In a laser mask system, a laser image is projected onto a substrate material, such as paper, by passing the laser light through a mask or stencil having a cutout of the desired text image. The laser image impacts the material to be processed with pulses of laser light, creating the desired text image presented by the mask on the material. For example, the laser beam may cause a visual change to the surface impacted by means of vaporizing surface material (e.g. ink on paperboard), causing a surface change (e.g. glass) and/or causing chemical reaction to the surface material (e.g. some plastics). See FIG. 1.
A character generated by a conventional dot matrix printer is formed by a partially filled matrix of ink dots. A typical implementation contains five vertical columns by seven horizontal rows of dots. A print head for such a device may contain seven pins aligned in a vertical column. Selected pins from the column are engaged to strike a ribbon in front of the paper. This will deposit one column of selected ink dots on the paper, creating the first column of the character. The print head will move horizontally across the paper to the second column of the character and the process is repeated. After a series of five such strikes, the entire five by seven character is generated. Subsequent text is generated by repetition of the process.
Unlike type setting, the next character to be printed can be selected at random. This technique is generally used for medium speed printing of low-resolution images such as computer printouts.
In a conventional multiple laser system, several lasers are aligned to form a vertical column of laser dots. The selected lasers are fired simultaneously to create one vertical column of the image. As the product being processed moves horizontally relative to the lasers' position, sequential columns of laser pulses are generated to form the complete character or desired image. Similarly, a variety of single axis laser scanning systems produce the same effect by deflecting a single laser beam in a vertical axis, while turning the laser beam on and off to produce a vertical column of laser dots.
In a conventional XY plotter, an image or character is generated in a process very similar to handwriting. It positions a pen at the start of the image above the paper, then lowers the pen to the paper and moves the pen the two axis of the image plane, X and Y, to draw a segment of the image. The pen is next lifted off the paper and repositioned to the beginning of the next segment. Subsequent segments are sequentially generated in the same manner to form the entire image over time. This technique can produce type setting quality images with the dynamic image generation of dot matrix printing over a large area. It is typically used for low volume printing processes such as architectural plans.
In a conventional vector laser system, the laser beam can be positioned anywhere on a flat surface within the laser processing area and it can be moved in any desired direction within the X and Y axis of the processing area. In general, the laser is turned off during the positioning function and it is turned on during the controlled motion. These functions permit the sequential generation of the segments of images or characters, creating the entire image over time.
Some current masking systems include the disadvantage that they require high power lasers to illuminate the multiple characters of a mask. Further, the masks of other conventional systems require changing in order to provide for new characters or designs. In such systems, characters on a mask may not be selected at random or upon a command from a computer controlled system. Masks for a particular need must be developed in advance of usage. Masks tend to be a considerable expense in using conventional mask systems. In yet other conventional mask systems, masks may be used in which multiple characters may be included on the mask, in which case the mask must be moved (indexed) to select different characters. In such systems, the exit beam may be configured to exit the system along a single axial path. In yet still other conventional mask systems, the mask may have multiple characters or images and the beam may be moved to select the desired character or image. In such systems, the beam will not remain along a single axial path.
Accordingly, there is a need for a laser projection and/or marking system that may project at random selected characters and/or designs from a mask. Further, there is a need for a laser projection and/or marking system in which a mask does not need to be changed and/or moved (indexed) in order to provide different characters and/or designs. Further, there is a need for a laser projection and/or marking system that utilizes masks and requires lower powers than conventional mask systems. Further still, there is a need for a laser projection and/or marking system that is configured to select chosen characters and/or designs from a mask yet maintain an exit beam along a single axial path.
It would be desirable to provide a system and/or method that provides one or more of these or other advantageous features. Other features and advantages will be made apparent from the present specification. The teachings disclosed extend to those embodiments which fall within the scope of the appended claims, regardless of whether they accomplish one or more of the aforementioned needs.