Patent Application
20100110137
1. The Field of the Invention
The present invention relates to a semiconductor laser. More specifically, the present invention relates to a vertical cavity surface emitting laser (VCSEL) for use in a printer.
2. The Relevant Technology
As people have become increasingly dependent on electronics and computers for performing their day-to-day tasks, the need to accurately and quickly produce a permanent or hard copy of the information stored in electronic form has increased. One method of converting electronic information into a hard copy is by using a printer or other recording medium. As advancements have been made in computers and related electronic devices, corresponding advancements have been required in printers. For example, as digital cameras have been developed with increasingly high resolution, there has been an increased need for a printer which is capable of printing at a correspondingly high resolution. Thus, there is an increased need for a more accurate printer.
One reason why the accuracy of a printing operation is currently limited is due to difficulties in accurately detecting the location or speed of the paper or other printing medium. Currently, light-emitting diodes or LEDs are used to detect the location or speed of the printing medium as it is transported through the printer. One problem with using LEDs to detect the paper, however, is that LEDs typically have difficulties detecting the edge of a paper when a printing operation requires more than one piece of paper and consecutive pages are fed through the printer. Similarly, printers equipped with LED detection systems often have difficulties detecting the properties of transparent printing mediums.
In some instances, the inability to accurately detect the traveling speed or edge of a printing medium may result in errors or wasted ink. For instance, when a photo is being printed, it is important to accurately detect the location of the edge of the photo paper so that the amount of overspray or ink ejected to the area beyond the edge of the printing medium may be reduced. Thus, there is a need for a printer with an improved detection system that is capable of improving print quality and efficiency.
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary technology area where some embodiments described herein may be practiced.
These and other limitations are overcome by embodiments of the invention which relate to systems and methods for detecting paper in printers using a vertical cavity surface emitting laser (VCSEL) or other laser including edge emitters.
One aspect of the invention is a printing apparatus capable of detecting the properties of a printing target which uses a vertical cavity surface emitting laser disposed in the printing apparatus. A method comprises transporting the printing target through the printing apparatus, emitting a wavelength modulated optical signal toward the printing target using the vertical cavity surface emitting laser, receiving a reflection of the wavelength modulated optical signal, and analyzing the reflected optical signal to identify a property of the printing target.
Another aspect of the invention is a printing apparatus capable of detecting the properties of a printing target. The printing apparatus comprises a transport system capable of transporting the printing target through the printing apparatus, a vertical cavity surface emitting laser capable of emitting a wavelength modulated optical signal onto the printing target, a detector capable of receiving a reflection of the wavelength modulated optical signal and converting the received reflected signal into an electrical signal, and an analyzing unit capable of analyzing the electrical signal to identify a property of the printing target.
Another aspect of the invention is a method of locating an edge of a printing target in a printing apparatus capable of performing a recording process on the printing target. The method comprises emitting a wavelength modulated optical signal towards a first surface within the printing apparatus using a vertical cavity surface emitting laser disposed in the printing apparatus, receiving a first reflection of the wavelength modulated optical signal when the wavelength modulated optical signal emitted toward the first surface is reflected from the first surface within the printing apparatus, transporting the printing target through the printing apparatus such that a portion of the printing target covers the first surface within the printing apparatus, receiving a second reflection of the wavelength modulated optical signal when the wavelength modulated optical signal emitted toward the first surface is reflected from a surface of the printing target, analyzing the first and second reflected optical signals to identify difference(s) between the first reflection and the second reflection, and determining the location of the edge of the printing target when a difference is identified between the first reflection and the second reflection.
As described more fully below, one advantage of the system described herein is the ability to more accurately detect the properties of a printing target (such as paper or other media) then in systems currently known in the art. More specifically, by using a light source capable of generating a more intense signal in a smaller area, the systems described herein are able to detect smaller variations in the reflected signal, and hence are capable of more accurately determining the properties of the printing target.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential characteristics of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The features and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.
To further clarify the above and other advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
Embodiments of the invention relate to printing apparatuses and to methods for a printing apparatus to detect a property of a printing target such as paper. More specifically, embodiments of the invention relate to systems and techniques for measuring and detecting the properties of a paper or other printing medium as it is transported through a printer. Embodiments of the invention utilize vertical cavity surface emitting lasers (VCSELs), which are a type of light source that are typically used in communication systems. VCSELS are popular in the communication industry in part because they can be manufactured in large quantities, due to their relatively small size. Another advantage of VCSELS is that they can be manufactured relatively efficiently due to their ability to be tested while still in wafer form.
In the frame 2, a guide member 5 is provided to be parallel with the platen 3. A carriage 6 is inserted in the frame 2 and is supported by the guide member 5 so as to move along the guide member 5. In addition, a carriage motor 7 is attached to the frame 2. The carriage 6 is in drivable connection with the carriage motor 7 via a timing belt 8, which is stretched between a pair of pulleys P1 and P2. When the carriage motor 7 is driven, its driving force is transferred to the carriage 6 through the timing belt 8. The carriage 6 receives the driving force and is guided by the guide member 5 to reciprocate in a main scanning direction (+x direction and −x direction) in parallel with the platen 3. One of skill in the art can appreciate that the mechanisms for moving a carriage or a printing head can vary depending on the specific printer. In some instances, it may be the media that is moved relative to a print head.
As shown in
As shown in
In the printer 1, the region where ink droplets are discharged onto the recording paper P while the carriage 6 reciprocates is referred to as a printing region or ejecting region. In addition to the printing region, the printer 1 also includes a non-printing region where the nozzles are capped when the printer is not performing a printing operation. A maintenance unit 11 is provided in the non-printing region. The maintenance unit 11 periodically performs maintenance operations on the recording head 9 in order to ensure that the nozzles are able to properly discharge the liquid during the printing process.
In this embodiment, the printer 1 is capable of performing edgeless printing, wherein the carriage 6 is capable of traveling to the area beyond the edge of the paper P so that nozzles 9 of the recording head 9 may eject ink onto the entire area of the paper P without leaving a margin on the edges of the paper P without a printed image. As previously mentioned, one problem with printers currently known in the art is that it is difficult to perform edgeless printing without overspraying the ink beyond the edge of the paper and onto the platen 3 because it is often difficult to locate the exact location of the edge of the paper. Unfortunately, this overspray can result in ink transfer from one printing process to a subsequent process as the ink sprayed onto the platen 3 is transferred onto a subsequent piece of paper. Moreover, the overspray can result in smeared images and wasted ink.
In this example, the VCSEL 200 is a laser which emits a signal 205 towards a target . In this case, the target area R is on the surface of the platen 3 opposite to the emitting surface of the VCSEL 200. When a piece of paper P is traveling through the printer 1 and a portion of the piece of paper S is located between the emitting surface of the VCSEL 200 and the surface of the platen 3, the portion of paper S will act as a target area. When the paper is located between the emitting surface of the VCSEL 200 and the target area R, the light 205 emitted from the VCSEL 200 will be reflected from the portion of paper S as a reflected signal 210. The reflected signal 210 is then captured by a signal detector 225.
In other instances, when there is no paper P traveling through the printer 1, or when the edges of two subsequent sheets of paper P form a space therebetween, which space is located above the target area R, the light emitted 205 from the surface of the VCSEL 200 will reflect off the surface of the platen 3. When the paper P is not located between the VSCEL 200 and the target area R, the signal 205 emitted from the VCSEL 200 is reflected from the target area R. The reflected signal 212 (shown in
As described more fully below, using the difference between the two reflected signals 210, 212, it is possible to accurately detect where the edge of the paper P is located.
As may be understood by one of ordinary skill in the art, the VCSEL 200 may be located any number of places within the printer 1 and/or at various orientations within the printer 1. For example, the paper P may be fed horizontally (shown in
The structure and characteristics of the VCSEL will now be described. One benefit of using a VCSEL in the printer 1 is that VCSELs are capable of creating a powerful circular beam of light in a small area, which increases the laser's ability to detect minor changes in the surface of the printing medium. This provides various advantages over the configurations currently known in the art. For example, the method and system described herein is capable of detecting the edge of the printing medium, so that overspray may be minimized.
As previously mentioned, embodiments of the invention utilize a VCSEL in a detection system. At a basic level, semiconductor lasers are essentially p-n-junctions that convert electrical energy into light energy. Typically, a gain medium or active region is formed at the p-n-junction between the p-type material and the n-type material. Often the active region includes a gain medium such as quantum wells. As light passes through the active region or gain medium, the light is amplified by stimulated emissions. At certain frequencies or wavelengths, the semiconductor lasers lase and generate output light.
In VCSELs, minors are usually formed both above and below the active region. The mirrors reflect light back and forth through the active region. Within the VCSEL cavity that is effectively bounded by the minors or by this mirror system, the light resonates vertically or perpendicularly to the p-n-junction and some light emerges from a surface of the VCSEL. Because the light is resonating vertically, the cavity length of a VCSEL is often very short with respect to the direction of light travel and the length of the cavity thus has an effect on the ability of a proton to produce additional photons through stimulated emission, particularly at low carrier densities. The minors increase the likelihood of a photon stimulating the emission of an additional photon. As previously mentioned, the light emitted by VCSELs typically has multiple transverse modes or wavelengths.
As shown in
In the integrated VCSEL-Photodiode chip 208 shown in
In this embodiment, the VCSEL-Photodiode chip 208 may determine the characteristics of the paper P by calculating the period of time between the time when the signal is emitted and the time when the reflected signal 215 or 217 is received. Because the signal reflected from the target R travels a greater distance than the signal reflected from the paper P disposed above the target R, the signal reflected from the target R will take a greater period of time to be reflected than the signal reflected from the area S of the paper P.
In either configuration described herein, the captured signal is analyzed in order to detect the properties of the target that reflects the light. For example, in addition to using the delay between the time when the signal is emitted to the time when the reflected signal is received, the frequency and amplitude of the reflected light may be analyzed in order to determine the speed that the target surface is moving. Moreover, the reflected light may be used to detect the presence or absence of a printing medium.
In some embodiments, the VCSEL 200 or 208 may generate an infrared light. One advantage of using an infrared light is that infrared light is agnostic to all colors of ink except for black. Thus, the light reflected by a paper or other printing medium P would be unchanged for a printing medium P which has a variety of images printed on its surface, including yellow, magenta, and cyan. Thus, the system would be capable of detecting properties of the paper, regardless of whether or not there is an image printed on its surface.
In other situations, the infrared beam's ability to recognize black ink would enable the detection system of the printer 1 to more accurately align the paper for more accurate printing. For example, a series of small black demarcations could be printed on the printing medium, in order to act as a series of guides for more accurately placing the printing images. In some embodiments, these demarcations may even be imperceptible to the human eye. Using the detection system described more fully below, the system may accurately determine the position of the printing head 6 in relation to the printing medium P. In other embodiments, the black demarcations may be covered by recording an image over the demarcations.
As previously described, the optical signal 205 or 214 is emitted toward a surface R within the printer 1. When the paper P is not in the path of the optical signal 205, the signal is continuously reflected from the surface R, resulting in a relatively constant signal 212 or 217 being received by the system. However, as the paper P gradually moves along the transport path in the printer 1, a portion of the paper S eventually enters the area where the VCSEL 200 is emitting the optical signal 205. Because the portion of the paper S covers the surface R where the signal 205 is directed, the signal 205 or 214 is reflected from the portion of paper S instead of the surface R. Then, the signal reflected 210 or 215 from the piece of paper S is captured and analyzed 425 in order to identify the properties of the paper P.
In one embodiment, the system may be used to detect the presence or absence of paper P in the transport path. Because the paper P has different reflective properties than the surface R within the printer 1, the reflected signal 210 or 215 captured by the system when the signal is reflected from the paper P will differ from the reflected signal 212 or 217 that occurs when there is no paper in the path of the signal. For example,
As previously described, one advantage of the system described herein is the ability to more accurately detect the properties of the paper than in systems currently known in the art. For example,
As previously described, the captured signal is analyzed to detect properties of the paper moving through the printer. As may be understood by one of ordinary skill in the art, the analysis may include identifying changes in the signal, including a change in noise, or analyzing the strength, frequency, or other properties of the captured signal in order to determine other properties of the paper. For example, the detected signal may have variations that are due to the light emitted from the laser impinging on demarcations on the paper or other medium. These demarcations can thus be used to quickly identify a paper jam, paper speed and paper position. The demarcations themselves may be configured to generate specific changes in the laser light such that certain conditions can be detected. For example, one demarcation can be used to identify the closeness of an edge of paper. The demarcations, or the paper alone in some instances, can be used to determine paper speed or printing speed while printing on a particular page.
In another embodiment, the location of the edge of the paper may be precisely located. In some instances, a particular type of paper may be identified to set printer settings, for instance, the reflection may be different on different types of paper. The laser can be used in combination with characteristics of the paper itself (e.g., demarcations) to identify paper type, paper speed, paper motion, printer problems such as paper jams, and the like. In some instances, multiple lasers or a single VCSEL that can split and redirect a laser beam in different directions can be used can be used to determine paper alignment by detecting positions of adjacent sides of the paper.
In other embodiments, the signal may be analyzed to identify other properties of the paper, including the speed that the paper is traveling through the printer and the like. Embodiments may also be used to identify any paper jams or errors in the paper feeding process. Furthermore, and as may be understood by one of ordinary skill in the art, the system may output any number of various signals based on the analysis of the captured signal. For example, the system may output a digital signal, an analog voltage signal, a threshold signal, or a simple yes/no indication of whether the paper is present or is moving. This determination may also be output to a digital interface where a user may review the information.
The embodiments described herein may include the use of a special purpose or general-purpose computer including various computer hardware or software modules, as discussed in greater detail below.
Embodiments within the scope of the present invention also include computer-readable media for carrying or having computer-executable instructions or data structures stored thereon. Such computer-readable media can be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code means in the form of computer-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a computer, the computer properly views the connection as a computer-readable medium. Thus, any such connection is properly termed a computer-readable medium. Combinations of the above should also be included within the scope of computer-readable media.
Computer-executable instructions comprise, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing device to perform a certain function or group of functions. Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.
As used herein, the term “module” or “component” can refer to software objects or routines that execute on the computing system. The different components, modules, engines, and services described herein may be implemented as objects or processes that execute on the computing system (e.g., as separate threads). While the system and methods described herein are preferably implemented in software, implementations in hardware or a combination of software and hardware are also possible and contemplated. In this description, a “computing entity” may be any computing system as previously defined herein, or any module or combination of modulates running on a computing system.
The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.
This application claims the benefit of U.S. Provisional Application Ser. No. 61/110,464, filed Oct. 31, 2008, entitled “USE OF VCSEL TO DETECT PAPER IN A PRINTER,” which application is incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61110464 | Oct 2008 | US |
