Patent Application
20090001163
The present invention relates to a controlled imaging scanner and more specifically, an imaging scanner having controlled illumination and exposure modes for capturing target objects.
Various electro-optical systems have been developed for reading optical indicia, such as bar codes. A bar code is a coded pattern of graphical indicia comprised of a series of bars and spaces of varying widths, the bars and spaces having differing light reflecting characteristics. Some of the more popular bar code symbologies include: Uniform Product Code (UPC), typically used in retail stores sales; Code 39, primarily used in inventory tracking; and Postnet, which is used for encoding zip codes for U.S. mail. Systems that read and decode bar codes employing charged coupled device (CCD) or complementary metal oxide semiconductor (CMOS) based imaging systems are typically referred to hereinafter as imaging systems, imaging-based bar code readers, or imaging scanners.
Imaging systems electro-optically transform the graphic indicia into electrical signals, which are decoded into alphanumerical characters that are intended to be descriptive of the article or some characteristic thereof. The characters are then typically represented in digital form and utilized as an input to a data processing system for various end-user applications such as point-of-sale processing, inventory control and the like.
Imaging systems that include CCD, CMOS, or other imaging configurations comprise a plurality of photosensitive elements (photosensors) or pixels typically aligned in an array pattern that could include a number of arrays. The imaging-based bar code reader systems employ light emitting diodes (LEDs) or other light sources for illuminating a target object, e.g., a target bar code. Light reflected from the target bar code is focused through a lens of the imaging system onto the pixel array. As a result, the focusing lens generates an image from its field of view (FOV) that is projected onto the pixel array. Periodically, the pixels of the array are sequentially read out creating an analog signal representative of a captured image frame. The analog signal is amplified by a gain factor, by for example, an operational amplifier. The amplified analog signal is digitized by an analog-to-digital converter. Decoding circuitry of the imaging system processes the digitized signals representative of the captured image frame and attempts to decode the imaged bar code.
As mentioned above, imaging scanners typically employ an illumination system to flood a target object with illumination from a light source such as an LED in the reader. Light from the light source or LED is reflected from the target object. The reflected light is then focused through a lens of the imaging system onto the pixel array, the target object being within a field of view of the lens. It is not uncommon for a single imaging scanner to employ as an illumination source multiple LEDs or cluster of LEDs for producing illumination that is reflected from the target object. Such configurations undesirably demand a significant amount of power, reducing the battery life on portable or remote imaging scanners. A fixed amount of illumination is not always necessary based on environmental or imaging application changes. In order to conserve battery life or reduce power requirements, the following changes to conventional imaging scanner technology is proposed.
The present invention relates to an imager for imaging target objects comprising an illumination source for providing illumination directed toward a target object, an intensity of the illumination being a function of a magnitude of current provided to the illumination source and photosensitive circuitry located within the imager for capturing an image from the target object while the imager is activated during an exposure period. The imager further comprises a selectively adjustable imaging mode for selecting either of: the magnitude of current provided to the illumination source or the exposure period of the imager such that the other of the magnitude of current or the exposure period is automatically adjusted as a result of the selection.
The present invention also relates to a method for imaging target objects comprising illuminating a target object with an illumination source to produce a reflected image of the target object, an intensity of the illumination being a function of a magnitude of current provided to the illumination source and capturing the reflected image of the target object on photosensitive circuitry located within the imager while the imager is activated during an exposure period. The method further comprises selecting an adjustable imaging mode for selecting either of: the magnitude of current provided to the illumination source or exposure period of the imager and automatically adjusting the other of the magnitude of current provided to the illumination source or exposure period of the imager as a result of the selection of the adjustable imaging mode.
The present invention further relates to an imager for imaging target objects comprising an illumination means for providing illumination that is reflected from the target object, an intensity of the illumination means being a function of a magnitude of current provided to the illumination means and capturing means located within the imager for capturing the image reflected from a target object to the imager while the imager is activated during an exposure period. The imager further comprises a selectively adjustable imaging mode for selecting either of: the magnitude of the current provided to the illumination source or exposure period of the imager such that the other of the magnitude of current or exposure period of the imager is automatically adjusted as a result of the selection.
The present invention yet further relates to an imaging-based reader for imaging target objects comprising an imager for imaging a target object. The imager is energized by a power source and an illumination source is provided for illumination that is directed toward the target object, an intensity of the illumination being a function of a magnitude of current provided to the illumination source. Photosensitive circuitry is located within the imager for capturing an image from the target object while the imager is activated during an exposure period. The imaging-based reader further comprises a selectively adjustable imaging mode for selecting either of: the magnitude of the current provided to the illumination source or the exposure period of the imager such that the other of the magnitude of current or exposure period of the imager is automatically adjusted as a result of the selection. A check routine is provided for determining the type of power source used to energize the imager. The adjustable imaging mode is disabled when the determined type of power source is an in-line power and the adjustable imaging mode is enabled when the determined type of power source is a remote power source.
The foregoing and other features and advantages of the present invention will become apparent to those skilled in the art to which the present invention relates upon reading the following description with reference to the accompanying drawings, in which:
An imaging system 10 includes an imaging scanner 12 in communication 14 either through hard-wire or over-the-air (remote communication) to a host computer 16 as shown schematically in
However, it should be recognized that the imaging system 10 of the present invention, to be explained below, may be advantageously used in connection with any type of scanner or imaging device, be it portable or stationary. It is the intent of the present invention to encompass all such scanners and imagers.
Internal to the imaging scanner 12 is a scan engine 20. The scan engine 20 includes an illumination source 22 such as a light emitting diode (LED) or bank of LEDs for projecting light 24 at a target object 26 such as a bar code. The imaging scanner 12 can be automatically enabled, continuously enabled, or enabled by engaging a trigger 28, which initiates the projection of the light 24 in the hand-held system 10 as it is directed by a user toward the target object 26.
A bus connection 42 provides a communication link between the imager element 38 and a decoder 44. The bus connection 42 is a high-speed (8) bit parallel interface for providing a digital signal to the decoder 44 representative of the captured image frame. The decoder 44 processes the digitized signals and attempts to decode the target object 26 into decoded information 46. The decoded information 46 can be stored locally by the scan engine 20 in memory 48 and/or communicated to a peripheral device (not shown) such as a monitor or remote computer through an output port 50.
The amount of power consumed by imaging scanner is an important issue, especially for portable scanners powered by their own remote (non-lined) power supply, such as a battery. The more power used during the scanning operation the greater the operating costs, and for portable scanners, the greater the power consumption, the greater the reduction in power or battery life. One of the largest sources of power and operating costs in the imaging scanners is the illumination source, which can include a single or multiple LEDs for capturing images of the target objects. Conventional imaging scanners typically provide a fixed amount of illumination, independent of the application or surrounding conditions.
In an exemplary embodiment, the imaging system 10 of
In the illustrated exemplary embodiment of
The imaging mode 120 controls in the scan engine 20 the amount of illumination provided by the illumination source 22 by controlling the amount of current used at 130. The adjustment of the illumination current 130 can be incremental, having two or more incremental values or settings at 132, or alternatively, could be any value selected on a continuous scale at 134.
Once the adjustment to the illumination current is made at 130, the illumination source 22 illuminates the target object 26 at 140. Substantially simultaneously, the exposure time of the scan engine 20 is automatically adjusted at 150 to compensate for the selected illumination current at 130. The automatic adjustment of scan engine 20 exposure time at 150 is achieved, for example, by a look-up table programmed into the scan engine 20, host computer 16, or related circuitry, in which the amount of exposure time is set for the amount of current provided to the illumination source 22. The automatic exposure time adjustment changes the total amount of light that the scan engine 20 allows on the photosensitive sensor, such as the pixel, CMOS, or CCD array 36. If the current selection 130 is relatively low, then the exposure time is longer, providing more light to the array 36. Alternatively, if the current selection is relatively high, then the exposure time is shorter, providing less light to the array 36.
The imaging mode 120 controlling the scan engine 20 is achieved through the electronics in the scan engine, an application specific integrated circuit (ASIC) coupled to the scan engine, computer readable programming read by the scan engine, or any combination thereof. Once the target object 26 is illuminated and the exposure time of the scan engine 20 is adjusted, the target object is imaged by the scan engine at 160.
The imaging mode 220 controls in the scan engine 20 the amount of exposure time provided by the scan engine 20 to the pixel array 36 at 230. The exposure time adjustment 230 can be incremental, having two or more incremental values or settings at 232, or alternatively, could be any value selected on a continuous scale at 234.
Once the adjustment to the exposure time is made at 230, an automatic adjustment is made to the amount of current that is provided to the illumination source 22 at 240. The automatic adjustment of the current at 240 provided to the illumination source 22 is achieved, for example, by a look-up table programmed into the scan engine 20, host computer 16, or related circuitry, in which the amount of current is set for the amount of exposure selectively controlled at 230. Selection of the imaging mode 220 adjusts the amount of light and duration that the scan engine 20 allows on the photosensitive sensor, such as the pixel, CMOS, or CCD array 36. If the selected exposure is relatively slow, then the exposure time is longer, requiring less current to the illumination source 22 in order to provide the necessary illumination to the array 36. Alternatively, if the exposure is relatively fast, then the exposure time is shorter, requiring more current to the illumination source 22 in order to provide the necessary illumination to the array 36.
The imaging mode 220 controlling the scan engine 20 is achieved through the electronics in the scan engine, an (ASIC) coupled to the scan engine, computer readable programming read by the scan engine, or any combination thereof. Once the auto-adjustment to the illumination current 240 occurs, the target object 26 is illuminated at 250 and imaging of the target object 26 commences by the scan engine 20 at 260.
The imaging mode 320 controls in the scan engine 20 the amount of illumination provided by the illumination source 22 by controlling the amount of current used at 330. The adjustment of the illumination current 330 can be incremental, having two or more incremental values or settings at 332, or alternatively, could be any value selected on a continuous scale at 334.
Once the adjustment to the illumination current is made at 330, the exposure time of the scan engine 20 is automatically adjusted at 340 to compensate for the selected illumination current at 330. Illumination is then provided to the target object 26 at 350. A determination is then made at 360 as to whether the amount of exposure time was sufficient, by for example, algorithms or heuristic techniques programmed within the scan engine 20 or host computer 16. If the determination at 360 finds that the amount of illumination is insufficient, the exposure time is adjusted appropriately at 365, by for example, an incremental increase in the exposure time. An attempt to illuminate the target object 26 is again made at 350. If the determination at 360 is in the affirmative, the target object 26 is imaged at 370.
The imaging mode 420 controls in the scan engine 20 the amount of exposure time provided by the scan engine 20 to the pixel array 36 at 430. The exposure time adjustment 430 can be incremental, having two or more incremental values or settings at 432, or alternatively, could be any value selected on a continuous scale at 434.
Once the adjustment to the exposure time is made at 430, an automatic adjustment is made to the amount of current that is provided to the illumination source 22 at 440. Illumination is then provided to the target object 26 at 450. A determination is then made at 460 as to whether the amount of illumination provided at 450 was sufficient, by for example, algorithms or heuristic techniques programmed within the scan engine 20 or host computer 16. If the determination at 460 finds that the amount of illumination is insufficient, the amount of current is adjusted appropriately at 465, by for example, an incremental increase to the current supplied to the illumination source 22. An attempt to illuminate the target object 26 is again made at 450. If the determination at 460 is in the affirmative, the target object 26 is imaged at 470.
While the present invention has been described with a degree of particularity, it is the intent that the invention includes all modifications and alterations from the disclosed design falling within the spirit or scope of the appended claims.
