CN111988542B - Scanning system and method for controlling aiming light source - Google Patents
Scanning system and method for controlling aiming light source Download PDFInfo
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- CN111988542B CN111988542B CN202010684228.2A CN202010684228A CN111988542B CN 111988542 B CN111988542 B CN 111988542B CN 202010684228 A CN202010684228 A CN 202010684228A CN 111988542 B CN111988542 B CN 111988542B
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- 238000000034 method Methods 0.000 title claims abstract description 21
- 238000003384 imaging method Methods 0.000 claims abstract description 73
- 238000005096 rolling process Methods 0.000 claims abstract description 21
- 238000005286 illumination Methods 0.000 claims description 11
- 206010070834 Sensitisation Diseases 0.000 claims description 7
- 230000008313 sensitization Effects 0.000 claims description 7
- 238000009432 framing Methods 0.000 claims description 3
- 238000007781 pre-processing Methods 0.000 claims description 3
- 238000010586 diagram Methods 0.000 description 9
- 230000000694 effects Effects 0.000 description 5
- 230000001360 synchronised effect Effects 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000000295 complement effect Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 235000015110 jellies Nutrition 0.000 description 2
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- 229910044991 metal oxide Inorganic materials 0.000 description 2
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- 238000004364 calculation method Methods 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/50—Control of the SSIS exposure
- H04N25/53—Control of the integration time
- H04N25/531—Control of the integration time by controlling rolling shutters in CMOS SSIS
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/70—Circuitry for compensating brightness variation in the scene
- H04N23/73—Circuitry for compensating brightness variation in the scene by influencing the exposure time
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/40—Extracting pixel data from image sensors by controlling scanning circuits, e.g. by modifying the number of pixels sampled or to be sampled
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/50—Control of the SSIS exposure
- H04N25/53—Control of the integration time
- H04N25/533—Control of the integration time by using differing integration times for different sensor regions
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection
Abstract
The application provides a scanning system and a method for controlling an aiming light source, which are characterized by comprising an image sensor, wherein a pixel array is sequentially exposed through a rolling shutter to acquire a target image, the pixel array comprises effective pixels and non-imaging pixels, the effective pixels are pixels which are actually used for image decoding, and the non-imaging pixels are pixels which are not actually used for image decoding; a sighting light source for projecting a sighting pattern sighting target; a control unit to control the image sensor and the aiming light source such that the aiming light source is in an off state during an exposure time of the active pixel and the aiming light source is in an on state during at least a portion of the exposure time of the non-imaging pixel.
Description
Technical Field
The application relates to a scanning system and a method for controlling an aiming light source.
The background technology is as follows:
the existing image reader is divided into two exposure modes, namely global exposure and rolling shutter exposure, wherein the global exposure generally refers to simultaneous exposure of all pixels, the rolling shutter exposure refers to sequential exposure of a pixel array, the global exposure mode can avoid jelly effect, clear images can be generated for objects moving at high speed, and the rolling shutter exposure can not generate clear images for moving objects due to the time difference of the pixel exposure and can generate jelly effect. Usually, the ccd (Charge Coupled Device charge coupled device) and part of the cmos (Complementary Metal Oxide Semiconductor complementary metal oxide semiconductor) are global exposure, and part of the cmos is rolling shutter exposure, so that the rolling shutter exposure cmos has price advantages over the global exposure ccd and cmos, has fewer noise points and clearer imaging, and is widely applied.
In the field of optical image reading, an aiming light source is generally required to project an aiming pattern to indicate the reading range of an image reader, and the brightness of the aiming pattern is higher than that of the surrounding environment, so that local overexposure of the image is often caused, and the reading efficiency is affected. The global exposure image reader can stagger the starting time of the aiming light source and the exposure time of all pixels through a blanking technology because the exposure of all pixels is synchronous, so that aiming patterns can not appear in the acquired image, and local overexposure is avoided; since the pixel is sequentially exposed, the exposure time of the pixel is not synchronous, and the same blanking technique as the global exposure cannot be adopted.
The present application addresses the above problems by providing a new scanning system and method for controlling an aiming light source, which employs new methods and techniques to solve these problems.
Disclosure of Invention
In view of the problems faced by the background art, an object of the present application is to provide a scanning system and method for controlling an aiming light source, which can avoid overexposure of an image caused by an aiming pattern projected by the aiming light source.
In order to achieve the above purpose, the application adopts the following technical means:
the application provides a scanning system for controlling an aiming light source, which is characterized by comprising:
the image sensor sequentially exposes a pixel array through a rolling shutter to acquire a target image, wherein the pixel array comprises effective pixels and non-imaging pixels, the effective pixels are pixels which are actually used for image decoding, and the non-imaging pixels are pixels which are not actually used for image decoding;
a sighting light source for projecting a sighting pattern sighting target;
a control unit to control the image sensor and the aiming light source such that the aiming light source is in an off state during an exposure time of the active pixel and the aiming light source is in an on state during at least a portion of the exposure time of the non-imaging pixel.
Optionally, the image sensor is sequentially exposed in pixel row units, defining a pixel row with the effective pixels in a row, and the aiming light source is in an off state during the exposure time of the effective pixel row.
Optionally, defining the entire row as a non-imaging pixel row of the non-imaging pixel rows, and the aiming light source is in an on state for at least a portion of an exposure time of the non-imaging pixel row.
Optionally, the exposure time of the non-imaging pixel row partially coincides with the exposure time of the active pixel row, and the aiming light source is in an on state during the exposure time of the non-imaging pixel row alone and in an off state when the two exposure times coincide.
Optionally, the effective pixels are pixels actually participating in the sensitization, and the non-imaging pixels are pixels not actually participating in the sensitization.
Optionally, the imaging of the active pixels is used to extract characters for decoding, and the imaging of the non-imaging pixels is removed during image preprocessing.
Optionally, the aiming pattern comprises an aiming frame for framing the target, the image of the aiming frame on the pixel array substantially frames all of the active pixels.
Optionally, an illumination source is included for providing illumination light, and the control unit controls the illumination source to be in an on state during an exposure time of the effective pixels of the image sensor and to be in an off state during an exposure time of the non-imaging pixels.
The application provides a method for controlling an aiming light source, which is characterized by comprising the following steps:
projecting a aiming pattern through an aiming light source to aim at a target;
the pixel array of the image sensor is sequentially exposed, and the aiming light source is turned off when the pixel is an effective pixel, and is turned on according to a preset program when the pixel is a non-imaging pixel.
Optionally, the preset program includes turning on the aiming light source only during the exposure time of the non-imaging pixels alone and turning off the aiming light source when the exposure time of the non-imaging pixels coincides with the exposure time of the effective pixels.
The application provides a scanning system for controlling an aiming light source, which is characterized by comprising:
the camera comprises a lens and an image sensor, wherein the lens is used for collecting a target image, and the image sensor sequentially exposes the pixel array through the rolling shutter to convert the target image into an electric signal;
a sighting light source to project a sighting pattern that aims at a target, the sighting pattern comprising a spot located in a field of view of the lens, the spot remaining relatively fixed in position relative to the field of view of the lens over a depth of field of the lens such that an image of the sighting pattern on the pixel array via the lens remains relatively fixed in position;
the control unit is used for controlling the camera and the aiming light source to be in a closed state in the exposure time of the pixel corresponding to the image of the light spot on the pixel array.
Optionally, the pixel array is sequentially exposed in pixel row units, and the aiming light source is in an off state during an exposure time of a corresponding pixel row of the light spot.
Optionally, the pixel array is sequentially exposed in pixel row units, and the aiming light source is in an on state during an exposure time of the pixel row staggered from an image of the aiming pattern.
Optionally, the aiming light source periodically projects the aiming pattern.
Optionally, the control unit controls the automatic exposure of the camera to adjust the exposure time of the next frame of image according to the quality of the previous frame of image, and adjusts the on time of the aiming light source according to the exposure time of the next frame of image.
Optionally, the aiming pattern includes an aiming frame for framing a target, the aiming frame indicating a field of view range of the lens.
The application provides a method for controlling an aiming light source, which is characterized by comprising the following steps:
projecting a aiming pattern through an aiming light source, the aiming pattern comprising light spots located in the field of view of the lens;
sequentially exposing a pixel array of the image sensor;
and turning off the aiming light source in the exposure time of the pixel corresponding to the image of the aiming pattern on the pixel array.
Optionally, the pixel array is sequentially exposed in pixel row units, and the aiming light source is turned off during the exposure time of the corresponding pixel row of the light spot.
Optionally, the pixel array is sequentially exposed in pixel row units, and the aiming light source is turned on during an exposure time of a pixel row on the pixel array, which is staggered from the image of the light spot.
Optionally, the aiming light source periodically projects the aiming pattern.
The application provides a scanning system for controlling an aiming light source, which is characterized by comprising:
the camera is used for collecting a target image;
a sighting light source for projecting a sighting pattern sighting target;
the control unit is used for controlling the camera and the aiming light source, so that the aiming light source is started only in partial frames in multi-frame images continuously collected by the camera.
Optionally, the control unit decodes only images acquired by the camera when the aiming light source is turned off.
Optionally, the camera transmits only the image acquired when the aiming light source is turned off to the control unit.
Optionally, the camera comprises an image sensor that sequentially exposes the pixel array through a rolling shutter to convert the target image into an electrical signal; defining that the control unit controls the aiming light source to be turned on to a first mode only for a part of the frame; defining that the control unit controls the aiming light source to be in a second mode when the aiming light source is in a closed state within the exposure time of a pixel row corresponding to an image of the aiming pattern in the pixel array; the control unit activates a first mode when the exposure time of the pixel row is greater than a threshold value and activates a second mode when the exposure time of the pixel row is lower than the threshold value.
Optionally, the control unit controls the automatic exposure of the camera to adjust the exposure time of the next frame image according to the quality of the previous frame image, and selects to start the first mode or the second mode according to the exposure time of the next frame image.
The application provides a method for controlling an aiming light source, which is characterized by comprising the following steps:
projecting a aiming pattern through an aiming light source to aim at a target;
and acquiring a target image through a camera, and starting the aiming light source only in partial frames in multi-frame images continuously acquired by the camera.
Optionally, the control unit decodes only images acquired by the camera when the aiming light source is turned off.
Optionally, the camera transmits only the image acquired when the aiming light source is turned off to the control unit.
Optionally, the camera comprises an image sensor that sequentially exposes the pixel array through a rolling shutter to convert the target image into an electrical signal; defining that the control unit controls the aiming light source to be turned on to a first mode only for a part of the frame; defining that the control unit controls the aiming light source to be in a second mode when the aiming light source is in a closed state within the exposure time of a pixel row corresponding to an image of the aiming pattern in the pixel array; the control unit activates a first mode when the exposure time of the pixel row is greater than a threshold value and activates a second mode when the exposure time of the pixel row is lower than the threshold value.
Optionally, the control unit controls the automatic exposure of the camera to adjust the exposure time of the next frame image according to the quality of the previous frame image, and selects to start the first mode or the second mode according to the exposure time of the next frame image.
Compared with the prior art, the application has the following beneficial effects:
the image sensor sequentially exposes the pixel array through the rolling shutter to acquire a target image, the pixel array comprises effective pixels and non-imaging pixels, the effective pixels are pixels which are actually used for image decoding, the non-imaging pixels are pixels which are not actually used for image decoding, the control unit controls the image sensor and the aiming light source, so that the aiming light source is in a closed state during the exposure time of the effective pixels, the aiming light source is in an open state during at least part of the exposure time of the non-imaging pixels, the opening time of the aiming light source is staggered with the exposure time of the effective pixels, and the partial overexposure of the image acquired by the exposure of the effective pixels is avoided.
The image sensor sequentially exposes the pixel array through the rolling shutter to convert a target image into an electric signal, and the control unit controls the camera and the aiming light source to be in a closing state within the exposure time of the pixel corresponding to the image of the light spot on the pixel array, so that the light spot cannot be acquired by the image sensor, and the local overexposure of the image caused by the light spot is avoided.
The control unit controls the camera and the aiming light source, so that in multi-frame images continuously collected by the camera, the aiming light source is started only in partial frames, aiming effect is achieved by projecting aiming patterns through the aiming light source, meanwhile, the aiming light source is not started in other frames, and the collected images cannot be overexposed due to the aiming patterns.
Drawings
FIG. 1 is a schematic diagram of a handheld terminal of the present application;
FIG. 2 is an enlarged schematic view of the scan head of FIG. 1;
FIG. 3 is a block diagram of a scanning system of the present application;
FIG. 4 is a schematic diagram of an image sensor according to the present application;
FIG. 5 is a schematic diagram of another image sensor according to the present application;
FIG. 6 is a timing diagram of a control unit controlling an image sensor and an aiming light source according to one embodiment of the present application;
FIG. 7 is a timing diagram of a control unit controlling an image sensor and an aiming light source according to another embodiment of the present application;
FIG. 8 is a timing diagram of a control unit controlling an image sensor and an aiming light source according to another embodiment of the present application;
FIG. 9 is a timing diagram of a control unit controlling an image sensor and an aiming light source according to another embodiment of the present application;
FIG. 10 is a flow chart of a method of controlling an aiming light source according to one embodiment of the present application;
FIG. 11 is a flow chart of a method of controlling an aiming light source according to another embodiment of the present application;
fig. 12 is a flow chart of a method of controlling an aiming light source according to another embodiment of the present application.
Reference numerals of the specific embodiments illustrate:
| hand-held terminal 1 | Scanning head 2 | Camera 3 | Image sensor 4 | Effective pixel 5 |
| Effective pixel row 50 | Non-imaging pixels 6 | Non-imaging pixel rows 60 | Aiming light source 7 | Aiming pattern 8 |
| Spot 9 | Aiming frame 10 | Image 11 | Control unit 12 | Illumination source 13 |
| Memory 14 | Imaging range 15 |
Detailed Description
For a better understanding of the application with objects, structures, features, and effects, the application will be described further with reference to the drawings and to the detailed description.
The scanning system for controlling the aiming light source 7 is mainly applied to a scanning system of a rolling shutter and is used for avoiding or reducing local overexposure of an image caused by an aiming pattern 8 projected by the aiming light source 7. The scanning system may be used in a variety of scan engines, scan guns, finger ring scanners, hand held terminals 1 (PDAs), stationary scanners, image recognition robots, and the like. The structure, function and control method of the scanning system of the present application will be described in detail with reference to the handheld terminal 1.
As shown in fig. 1, 2 and 3, the scanning system according to the embodiment of the present application is applied to the handheld terminal 1, and the handheld terminal 1 mainly includes: a camera 3, an aiming light source 7 and a control unit 12.
The camera 3 includes a lens for capturing a target image and an image sensor 4 for photoelectrically converting the target image, the field of view of the lens is known in advance, and the image sensor 4 sequentially exposes the pixel array through the rolling shutter to capture the target image in cooperation with the lens and converts the target image into an electric signal. The rolling shutter is usually exposed in pixel line unit order, but there are also exposure in pixel line unit order of a plurality of lines, exposure in pixel division area, or the like, and the rolling shutter of the present application is preferably exposed line by line. With additional reference to the image sensor 4 shown in fig. 4, the pixel array (which is only shown as an illustration and does not represent the size and number of actual pixels) includes effective pixels 5 and non-imaging pixels 6, wherein the effective pixels 5 are pixels actually used for image decoding, and the non-imaging pixels 6 are pixels not actually used for image decoding, and the effective pixels 5 and the non-imaging pixels 6 will be further explained with reference to the two embodiments in fig. 4 and 5.
The aiming light source 7 is used to project an aiming pattern 8 to direct a user to aim at a target. The aiming light source 7 may typically employ a laser-coupled Diffractive Optical Element (DOE) or LED-coupled lens to generate the aiming pattern 8 such that the aiming pattern 8 has a clear shape or profile and is also significantly brighter than the surrounding ambient brightness. The aiming pattern 8 comprises a centrally located spot 9 (typically cross-shaped, also in-line or circular form, etc.) and an edge-located aiming block 10, some of the aiming pattern 8 having no aiming block 10 and only the spot 9. The spot 9 is arranged to be centered in the field of view of the lens so as to remain in a fixed position relative to the field of view of the lens, within the depth of field of the lens, since, although the field of view of the lens varies proportionally with distance, the size of the spot 9 varies in substantially the same proportion with distance, so that the position occupied by the spot 9 in the field of view of the lens remains substantially unchanged. The image 11 of the spot 9 imaged on the pixel array of the image sensor 4 via the lens then remains relatively fixed, which is also known in advance, as a rule the image 11 of the spot 9 falls on several rows of pixels in the centre of the pixel array.
Turning back to the image sensor 4 in the embodiment shown in fig. 4, the imaging range 15 of the lens is shown as a circular dashed line, which covers a part of the pixel array, these pixels actually used for photosensitive imaging being the effective pixels 5; pixels outside the imaging range 15 of the lens are not actually used for sensitization, so that photoelectric conversion cannot be performed to generate an image, but are not used for image decoding, the pixels are the non-imaging pixels 6, the non-imaging pixels 6 can be used for calculating dark current generated in the pixels, and therefore dark current in the effective pixels 5 can be removed through an algorithm, the magnitude of current generated by the effective pixels 5 through photoelectric conversion is obtained, and the effect of noise reduction is achieved. When the pixel array is sequentially exposed in pixel row units, the whole row is defined as a pixel row non-imaging pixel row 60 of the non-imaging pixels 6, and the pixel row effective pixel row 50 of the effective pixels 5 is defined, so that the non-imaging pixel row 60 is actually a pixel row which does not participate in the sensitization, and the effective pixel row 50 is a pixel row at least some or all of which actually participate in the sensitization. The image 11 of the light spot 9 is located at the center of the molding range of the lens and also located at the center of the pixel array, and the relative position of the image is fixed relative to the pixel array, and the aiming frame 10 is slightly larger than the field of view range of the lens and is not collected by the camera 3, so that the image overexposure is not caused.
As with the image sensor 4 of the other embodiment shown in fig. 5, the imaging range 15 of the lens is shown as a circular dashed line, which covers substantially the entire pixel array, so that the entire pixel array is photosensitive. The aiming pattern 8 projected by the aiming light source 7 also comprises a light spot 9 (usually in a cross shape, or in a straight shape, a round shape or the like) and an aiming frame 10, wherein the light spot 9 and the aiming frame 10 are both positioned in the field of view of the camera 3, unlike the previous embodiment, the positions of the images 11 of the aiming frame 10 on the pixel array are known in advance, the images 11 of the aiming frame 10 imaged on the pixel array are preset to substantially frame all the effective pixels 5, other pixels on the pixel array are defined as non-imaging pixels 6, and the images 11 of the aiming frame 10 are actually positioned on the non-imaging pixels 6, so that the image overexposure is not caused even if the aiming frame 10 is positioned in the field of view of the camera. The image signals collected by the pixel array are firstly subjected to image preprocessing, and the image signals collected by the non-imaging pixels 6 are cut off and are not used for image decoding; the image signal acquired by the active pixel 5 will be used for extracting characters and for image decoding.
In some embodiments (not shown, the same applies below), the imaging range of the lens is not necessarily circular, and the imaging range 15 of some shaped lenses may be elliptical or even square.
The control unit 12 is configured to control the image sensor 4 and the aiming light source 7, specifically, to control an exposure process of the pixel array of the image sensor 4 according to a preset program stored in a memory, and to control an on state and an off state of the aiming light source 7 during the exposure process.
The control unit 12 controls the frame rate of the camera 3 according to a preset program stored in the memory, and controls the exposure time of the pixel row of the image sensor 4 by automatic exposure, so as to adjust the exposure time of the pixel row when the next frame image is acquired according to the quality of the previous frame image.
The control unit 12 may control the timing of the aiming light source 7 and the image sensor 4 by various schemes, all for the purpose of eliminating or reducing local overexposure of the target pattern caused by the aiming pattern 8 (mainly the spot 9).
Scheme one: referring to fig. 4 and 5, since the image 11 of the spot 9 is located on the effective pixel row 50, when the on-time of the aiming light source 7 is synchronized with the exposure time of the effective pixel row 50, local overexposure of the image is caused. Referring to the timing diagram of fig. 6, the aiming light source 7 is turned on to aim at a target first, then the image sensor 4 of the camera 3 sequentially exposes the pixel array through the rolling shutter to acquire an image of the target, first, a plurality of non-imaging pixel rows 60 located at the edge of the pixel array are exposed, the individual exposure time of the non-imaging pixel rows 60 lasts for a preset time t, and then the effective pixel rows 50 start to be exposed. After the non-imaging pixel row 60 is continuously exposed for a preset time t, the aiming light source 7 is turned off, and then the effective pixel row 50 is sequentially exposed, wherein the effective pixel row 50 and the non-imaging pixel row 60 are simultaneously exposed, and the exposure time of the two is coincident, so that the aiming light source 7 is in a turned-off state, and the image overexposure is not caused. After all the active pixel rows 50 in a frame have been exposed, the aiming light source 7 is turned on to project the aiming pattern 8 and the remaining non-imaging pixel rows 60 are sequentially exposed, at which time the image sensor 4 may have started the exposure acquisition of the next frame image, and the next frame image is still at the exposure time of the first several non-imaging pixel rows 60, without starting the exposure time of the active pixel rows 50, and turning on the aiming light source 7 during this time will not cause image overexposure. Typically, the control unit 12 controls the exposure time of the pixel rows of the image sensor 4 by automatic exposure, so as to adjust the exposure time of the pixel rows when the next frame image is acquired according to the quality of the previous frame image, the frame rate of the image sensor 4 is preset, and the start time interval of sequential exposure between the pixel rows is also preset, after the control unit 12 sets the exposure time of the next frame image, the on-time of the aiming light source 7 is set according to the exposure time of the non-imaging pixel row 60 and the effective pixel row 50, so that the aiming light source 7 is always in the off state during the exposure time of the effective pixel 5 and is in the on state during at least part of the exposure time of the non-imaging pixel 6.
Of course, instead of controlling the image sensor 4 by automatic exposure, the control unit 12 may set a fixed exposure time such that the exposure time of the pixel rows remains a fixed length, the pixel array periodically exposes the non-imaging pixel rows 60 and the active pixel rows 50 in sequence, the aiming light source 7 is also arranged to periodically project the aiming pattern 8, the aiming light source 7 is turned on at the individual exposure time of the non-imaging pixel rows 60, and the aiming light source 7 is turned off during the exposure time of the active pixel rows 50.
Scheme II: referring to fig. 4 and 5, since the image 11 of the spot 9 is located on the effective pixel row 50, when the on-time of the aiming light source 7 is synchronized with the exposure time of the effective pixel row 50, local overexposure of the image is caused. Note that the position of the image 11 of the spot 9 on the pixel array remains substantially fixed, so long as the aiming light source 7 is in the off state during the exposure time of the pixel rows where the image 11 of the spot 9 is located, the spot 9 will not cause image overexposure, and the pixel rows of the image 11 of the spot 9 corresponding to the pixel rows are known in advance. Referring to the timing chart of fig. 7, the aiming light source 7 is turned on first, then the pixel array is sequentially exposed, the aiming light source 7 is turned off when the exposure of the pixel row corresponding to the image 11 of the light spot 9 is started, and the aiming light source 7 is turned on again when the exposure of the pixel row corresponding to the image 11 of the light spot 9 is completed. Because the proportion of the pixel row corresponding to the image 11 of the light spot 9 to the total pixel array is smaller, the control on the on and off time of the aiming light source 7 is achieved through the accurate control on the space (the pixel row corresponding to the image 11 of the light spot 9 and other pixel rows) in the scheme II, and compared with the scheme I, the time of the on of the aiming light source 7 is longer, and the aiming pattern 8 can be clearer; of course, it is also possible to switch off the aiming light source 7 during the exposure time of the row of pixels corresponding to the image 11 of the spot 9, and to switch on the aiming light source 7 during some, but not all, of the other times.
Scheme III: referring to the timing chart shown in fig. 8, in the multi-frame images continuously collected by the camera 3, the aiming light source 7 is turned on only in a partial frame, so that the aiming pattern 8 is not collected in other multi-frame images, the camera 3 only transmits the image collected when the aiming light source 7 is turned off to the control unit 12, and the control unit 12 only decodes the image collected by the camera 3 when the aiming light source 7 is turned off, thereby improving decoding efficiency. Of course, the camera 3 may also transmit all acquired images to the control unit 12, but the control unit 12 only decodes images acquired by the camera 3 when the aiming light source 7 is turned off. The third scheme is not only applicable to rolling shutters, but also to global shutters. But scheme three sacrifices decoding speed as only partial images are decoded relative to scheme one and scheme two.
Scheme IV: referring to the timing chart shown in fig. 9, when the control unit 12 adjusts the exposure time of the pixel array by automatic exposure so that the exposure time of the pixel rows is long, as in the case of the exposure time of the effective pixel rows 50 of the first two frames of images in fig. 9 being linked together, there is no separate exposure time of the non-imaging pixel rows 60 in the middle, resulting in the failure to adopt the first and second schemes, and only the third scheme; the exposure time of the third frame image is shorter, the second frame image and the third frame image directly have the separate exposure time of the non-imaging pixel row 60, and the aiming light source 7 can be turned on to project the aiming pattern 8, so that the first scheme or the second scheme can be adopted. Defining a scheme III as a first mode, defining a scheme I or a scheme II as a second mode, enabling the control unit 12 to start the first mode when the control unit 12 judges that the exposure time of the pixel row is greater than a threshold value, and enabling the control unit 12 to start the second mode when the exposure time of the pixel row is lower than the threshold value; the threshold value may be set to an appropriate value after passing through calculation or a plurality of tests in advance.
Typically, an illumination source 13 is further included for providing illumination light to illuminate a target, the control unit 12 controls the illumination source 13 to be in an on state during an exposure time of the active pixels 5 of the image sensor 4 and to be in an off state during an individual exposure time of the non-imaging pixels 6 to reduce the power consumption of the illumination source 13.
The camera 3, the aiming light source 7 and the illumination source 13 are integrated together to form a scanning head 2, and then the scanning head 2 is controlled by the control unit 12 on the main board of the handheld terminal 1 to collect the target image. In some embodiments (not shown, the same applies below), the camera 3, the aiming light source 7, the illumination source 13, the control unit 12 and other elements are integrated together to form the scan engine, and then the integrated control switch is used to collect the target image through the scan engine, so that the finger ring scanner adopts a similar structure. In some embodiments, a decoding chip dedicated may be additionally provided to decode the target image, and not by the control unit 12.
The scanning system and the method for controlling the aiming light source have the following beneficial effects:
the image sensor 4 sequentially exposes the pixel array through the rolling shutter to acquire the target image, the pixel array comprises an effective pixel 5 and a non-imaging pixel 6, the effective pixel 5 is a pixel actually used for image decoding, the non-imaging pixel 6 is a pixel not actually used for image decoding, the control unit 12 controls the image sensor 4 and the aiming light source 7, so that the aiming light source 7 is in a closed state during the exposure time of the effective pixel 5, the aiming light source 7 is in an open state during at least part of the exposure time of the non-imaging pixel 6, the opening time of the aiming light source 7 is staggered with the exposure time of the effective pixel 5, and the local overexposure of the image acquired by the exposure of the effective pixel 5 is avoided.
The image sensor 4 sequentially exposes the pixel array through the rolling shutter to convert the target image into an electric signal, and the control unit 12 controls the camera 3 and the aiming light source 7 so that the aiming light source 7 is in a closed state within the exposure time of the pixel corresponding to the image 11 of the light spot 9 on the pixel array, so that the light spot 9 cannot be collected by the image sensor 4, and the local overexposure of the image caused by the light spot 9 is avoided.
The control unit 12 controls the camera 3 and the aiming light source 7 so that in a plurality of frames of images continuously acquired by the camera 3, the aiming light source 7 is only started in partial frames, the aiming light source 7 projects aiming patterns 8 to play a role in aiming, and meanwhile, the aiming light source 7 is not started in other frames, so that the acquired images cannot be overexposed due to the aiming patterns 8.
The above detailed description is merely illustrative of the preferred embodiments of the application and is not intended to limit the scope of the application, so that all equivalent technical changes that can be made by the present specification and illustrations are included in the scope of the application.
Claims (6)
1. A scanning system for controlling an aiming light source, comprising:
the image sensor sequentially exposes a pixel array through a rolling shutter to acquire a target image, wherein the pixel array comprises effective pixels and non-imaging pixels, the effective pixels are pixels which are actually used for image decoding, the non-imaging pixels are pixels which are not actually used for image decoding, the image sensor sequentially exposes the pixels in pixel row units, defines a pixel row with the effective pixels in a row, and defines a pixel row with the effective pixels in a whole row as the non-imaging pixels;
a sighting light source for projecting a sighting pattern sighting target;
a control unit for controlling the image sensor and the aiming light source such that the aiming light source is in an off state during an exposure time of the active pixel row and in an on state during at least a portion of an exposure time of the non-imaging pixel row, wherein the exposure time of the non-imaging pixel row partially coincides with the exposure time of the active pixel row, and the aiming light source is in an on state during an exposure time of the non-imaging pixel row alone and in an off state when the two exposure times coincide.
2. The scanning system of claim 1, wherein: the effective pixels are pixels which actually participate in the sensitization, and the non-imaging pixels are pixels which do not actually participate in the sensitization.
3. The scanning system of claim 1, wherein: the image of the active pixels is used to extract characters for decoding, and the image of the non-imaging pixels is removed during image preprocessing.
4. The scanning system of claim 1, wherein: the aiming pattern includes an aiming frame for framing a target, the aiming frame imaging on the pixel array substantially frames all of the active pixels.
5. The scanning system of claim 1, wherein: the control unit controls the illumination source to be in an on state during the exposure time of the effective pixels of the image sensor and to be in an off state during the exposure time of the non-imaging pixels.
6. A method of controlling an aiming light source, comprising the steps of:
projecting a aiming pattern through an aiming light source to aim at a target;
the method comprises the steps of sequentially exposing a pixel array of an image sensor, turning off the aiming light source when a pixel is an effective pixel, and turning on the aiming light source according to a preset program when the pixel is a non-imaging pixel, wherein the effective pixel is a pixel actually used for image decoding, and the non-imaging pixel is a pixel not actually used for image decoding, and the preset program comprises the steps of turning on the aiming light source only in a single exposure time of the non-imaging pixel and turning off the aiming light source when the exposure time of the non-imaging pixel and the effective pixel coincide.
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| CN201117008Y (en) * | 2005-06-27 | 2008-09-17 | 手持产品公司 | Bar code reading device, marking reading device and data acquisition device |
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