JP2022055005A - Optical information reading device and optical information reading method - Google Patents

Abstract

To expand a range that can be imaged.SOLUTION: An optical information reading device 100 comprises: a first imaging unit 10 that includes a fixed focus optical system 12; a second imaging unit 20 that includes a variable focus optical system 22, a second image pick-up device 21, and a focus driving unit 23; and a control unit 40 that can read information on a symbol based on first image data generated by the first imaging unit 10 and second image data generated by the second imaging unit 20. The control unit 40 analyzes the first image data generated by the first imaging unit 10, calculates a focal position of the variable focus optical system 22 necessary for the second imaging unit 20 to pick up an image focused on the symbol when determining that imaging performed by the first imaging unit is not suitable for reading of the symbol, controls the focus driving unit 23 to match the focal position of the variable focus optical system 22 with the calculated focal position, and reads the information on the symbol based on the second image data generated by the second imaging unit 20 and focused on the symbol.SELECTED DRAWING: Figure 2

Description

The present invention relates to an optical information reading device and an optical information reading method for reading symbols such as barcodes and two-dimensional codes.

Light from a symbol such as a barcode or QR code to be read is received by a camera called an image sensor such as a CCD camera to acquire image data of the symbol, and the image data is analyzed to correspond to the symbol. A hand-held optical information reader called a bar code reader, a handy scanner, a handy terminal, or the like that reads information is known (for example, Patent Document 1). In such an optical information reader, generally, image data of a symbol is acquired by one fixed focus type camera.

However, for symbols such as barcodes and QR codes, it is required to acquire clear image data in focus, but with a fixed-focus camera, image data of sufficient quality can be obtained depending on the conditions. There was something that wasn't there.

On the other hand, it is conceivable to use a variable focus camera. However, variable focus cameras have a mechanical drive part such as a voice coil motor (VCM) to adjust the focus, so the life of the camera that can be used stably with high reliability is limited. There was a problem. In addition, since the mechanism for adjusting the focus is mechanically driven, the power consumption is increased, and in the hand-held optical information reader driven by the battery, there is a problem that the battery life becomes poor. .. Furthermore, when performing autofocus processing with a variable focus camera, it is necessary to capture several frames of images in order to acquire in-focus image data, which increases the time required for imaging and reduces responsiveness. There was also the problem of doing.

Japanese Unexamined Patent Publication No. 2019-101555 U.S. Pat. No. 7,195,164 Special Table 2003-532944 Gazette

One of an object of the present invention is to provide an optical information reading device and an optical information reading method in which an image pickup range is expanded.

Means for Solving Problems and Effects of Invention

According to the optical information reader according to the first aspect of the present invention, the optical information reader is an optical information reader that captures an image of a symbol to be read and reads the information of the symbol, and is incident on the symbol to read the symbol. A first image pickup element including a fixed focus optical system that collects the reflected light reflected in the above and a first image pickup element that converts the light collected by the fixed focus optical system into an electric signal to generate first image data. The image pickup unit, the variable focus optical system that receives the reflected light incident on the symbol and reflected by the symbol, and the light focused by the variable focus optical system are converted into electrical signals to generate second image data. A second image pickup unit including a second image pickup element for changing the focal position of the variable focus optical system, a first image data generated by the first image pickup unit, and the second image pickup unit. The control unit is provided with a control unit capable of reading symbol information based on the second image data generated by the first image pickup unit, and the control unit analyzes the first image data generated by the first image pickup unit. When it is determined that the image pickup by the image pickup unit is inappropriate for reading the symbol, the focal position of the variable focus optical system required for the second image pickup unit to image an image in focus on the symbol is calculated. , The focus driving unit is controlled so as to match the focal position of the variable focus optical system with the focal position, and the symbol is based on the second image data focused on the symbol generated by the second imaging unit. Can be configured to read information. With the above configuration, priority is given to imaging by the first imaging unit, and only the symbols that cannot be read by this first imaging unit are switched to the second imaging unit for imaging, thereby reducing the frequency of use of the variable focus optical system. As a result, it is possible to realize an optical information reader with improved reading speed and product life by avoiding an increase in imaging time due to focus adjustment and a shortening of life due to mechanically driving a variable focus.

Further, according to the optical information reader according to the second aspect of the present invention, in addition to the above configuration, whether or not the second image pickup element is suitable for reading a symbol by the image pickup by the first image pickup unit. The optical image of the object with the symbol can be captured regardless of the determination of the control unit, and the optical image of the object is stored in association with the information of the symbol read by the control unit. Can be configured as With the above configuration, it is possible to leave, for example, a photograph of a symbol or a photograph of evidence showing the situation at the time of reading with the second image sensor. In addition, when reading the symbol information, by acquiring the optical image of the object with this symbol and saving it in association with it, there is an advantage that the work of confirming the state of the product with the symbol at a later date can be easily performed. can get.

Further, according to the optical information reader according to the third aspect of the present invention, in addition to any of the above configurations, when the second image pickup element captures an optical image of an object with a symbol. , The focus drive unit can be configured to be configurable so as not to move the variable focus optical system. With the above configuration, when an optical image of a symbol is captured by the second image pickup element, the variable focus optical system is driven by driving the variable focus optical system by keeping the focal position fixed at a predetermined position in advance and not moving the variable focus optical system. It prevents the generation of time and prevents deterioration due to wear of the mechanical drive part, simplifying the processing and extending the life of the product.

Furthermore, according to the optical information reader according to the fourth aspect of the present invention, in addition to any of the above configurations, aiming light irradiation for irradiating aiming light adjacent to the fixed focus optical system is further performed. The control unit can be configured to estimate the distance to the symbol based on the aimer image captured by the first imaging unit from the image including the aiming light irradiated by the aiming light irradiation unit. With the above configuration, the focal position can be estimated based on the Aimer image by capturing the Aimer image including the aiming light with the first imaging unit.

Furthermore, according to the optical information reader according to the fifth aspect of the present invention, in addition to any of the above configurations, the control unit makes it inappropriate to read the symbol using the first image pickup unit. When determined, the focus drive unit can be configured to drive the focal length so that the focal length of the variable focal length optical system matches the distance to the symbol calculated based on the aimer image. With the above configuration, the second image data adjusted to the focal position estimated from the Aimer image can be acquired, and the reading accuracy can be improved.

Furthermore, according to the optical information reader according to the sixth aspect of the present invention, in addition to any of the above configurations, the control unit has a focal length D of the second image pickup unit stored in advance and the said. It can be configured to control the focus drive unit according to the relational expression I = F (D) of the drive current I that drives the focus drive unit.

Furthermore, according to the optical information reader according to the seventh aspect of the present invention, in addition to any of the above configurations, the control unit analyzes the Aimer image using the Aimer image as the first image data. Based on the calculated distance to the symbol, it can be configured to determine whether or not the symbol can be properly read by the image pickup by the first image pickup unit. With the above configuration, by capturing an Aimer image containing aiming light as the first image data in the first imaging unit, the focal position can be estimated based on this Aimer image, and it is further determined whether or not the first imaging unit can capture the image. Then, it becomes possible to determine whether or not switching to the second image pickup unit is necessary.

Furthermore, according to the optical information reader according to the eighth aspect of the present invention, in addition to any of the above configurations, the control unit is aiming imaged by the first imaging unit after acquiring the aimer image. The present image pickup data containing no light can be used as the first image data, and it can be configured to determine whether or not the symbol can be appropriately read by the image pickup by the first image pickup unit based on the present image pickup data. With the above configuration, the main image pickup data that does not include the aiming light is imaged by the first image pickup unit as the first image data, and based on this image pickup data, it is determined whether or not the image pickup is possible by the first image pickup unit. It is possible to determine whether or not switching to the imaging unit is necessary.

Furthermore, according to the optical information reader according to the ninth aspect of the present invention, in addition to any of the above configurations, the first illumination unit for the fixed focus optical system and the variable focus optical system are further provided. The first illumination unit, the fixed focus optical system, the variable focus optical system, and the second illumination unit can be arranged in a straight line.

Furthermore, according to the optical information reader according to the tenth aspect of the present invention, in addition to any of the above configurations, the resolution of the first image pickup unit is made lower than the resolution of the second image pickup unit. be able to.

Furthermore, according to the optical information reader according to the eleventh aspect of the present invention, in addition to any of the above configurations, the imaging field of view of the first imaging unit is larger than the imaging field of view of the second imaging unit. Can be narrowed.

Furthermore, according to the optical information reader according to the twelfth aspect of the present invention, in addition to any of the above configurations, the first image sensor is an image sensor that captures a monochrome image, and the second image pickup is performed. The element is an image sensor that captures a color image, and can be configured to be readable by using color difference information.

Furthermore, according to the optical information reader according to the thirteenth aspect of the present invention, in addition to any of the above configurations, whether the control unit analyzes the first image data and is unsuitable for reading the symbol. Any one of the resolution, the visual field range, and the contrast of the first image data can be included in the criterion for determining whether or not.

Furthermore, according to the optical information reader according to the fourteenth aspect of the present invention, in addition to any of the above configurations, the control unit reads from the image data generated by the first image pickup unit. When the resolution of the target symbol is calculated and the resolution calculated by the control unit is equal to or less than a predetermined threshold value, the first image data generated by the first image pickup unit is inappropriate for reading the symbol. It can be configured to determine that.

Furthermore, according to the optical information reader according to the fifteenth aspect of the present invention, in addition to any of the above configurations, the control unit is based on the first image data generated by the first image pickup unit. , The required visual field of the symbol to be read is calculated, and when the required visual field calculated by the control unit is equal to or higher than a predetermined threshold value, the first image data generated by the first imaging unit is the symbol. It can be configured to determine that it is unsuitable for reading.

Furthermore, according to the optical information reader according to the sixteenth aspect of the present invention, in addition to any of the above configurations, the control unit is based on the first image data generated by the first image pickup unit. , The contrast of the symbol to be read is calculated, and when the contrast calculated by the control unit is equal to or less than a predetermined threshold value, the first image data generated by the first image pickup unit is used for reading the symbol. It can be configured to be determined to be inappropriate.

Furthermore, according to the optical information reader according to the seventeenth aspect of the present invention, in addition to any of the above configurations, the control unit has the first image data generated by the first image pickup unit and the first image data. A reading control unit capable of reading symbol information based on the second image data generated by the second image pickup unit and a focus control unit for controlling the focus drive unit of the second image pickup unit may be provided. can.

Furthermore, according to the optical information reader according to the eighteenth aspect of the present invention, in addition to any of the above configurations, a first main surface and a second main surface facing the first main surface are further provided. A housing extended in one direction having a projecting portion partially projecting toward the second main surface side, and the second housing provided on the first main surface side of the housing. A display unit for displaying the second image data generated by the image pickup unit can be provided.

Furthermore, according to the optical information reader according to the nineteenth aspect of the present invention, in addition to any of the above configurations, the protruding portion has an inclined surface inclined with respect to the second main surface. It has an optical window adjacent to the inclined surface, and the first image sensor and the second image sensor are arranged side by side in a posture facing the optical window inside the protrusion. The optical axes of the one image sensor and the second image sensor can be tilted in a direction along the inclined surface with respect to the longitudinal direction of the housing through the optical window.

Furthermore, according to the optical information reading method according to the twentieth aspect of the present invention, it is an optical information reading method that captures an image of a symbol to be read and reads the information of the symbol, and is incident on the symbol. A fixed-focus optical system that collects the reflected light reflected by the symbol and a first image pickup element that converts the light collected by the fixed-focus optical system into an electric signal to generate first image data. As a result of the step of capturing the first image data including the symbol by the including first imaging unit, the step of analyzing the first image data by the control unit, and the analysis by the control unit, the first image data is obtained. Based on the result of the analysis, when it is determined that the symbol is unsuitable for reading, the variable focus optical system that receives the reflected light incident on the symbol and reflected by the symbol, and the variable focus optical system The variable focus optics required to capture an image focused on a symbol in a second imaging unit that includes a second imaging element that converts the focused light into an electrical signal and generates second image data. A step of calculating the focal position of the system and a step of matching the focal position of the variable focus optical system with the focal position by the focus drive unit that changes the focal position of the variable focus optical system according to the calculation result by the control unit. And, based on the second image data focused on the symbol generated by the second image pickup unit, the control unit may include a step of reading the information of the symbol. As a result, priority is given to imaging by the first imaging unit, and only the symbols that cannot be read by the first imaging unit are switched to the second imaging unit for imaging, thereby reducing the frequency of use of the variable focus optical system. Therefore, it is possible to realize an optical information reader with improved reading speed and product life by avoiding an increase in imaging time due to focus adjustment and a shortening of life due to mechanically driving a variable focus.

It is external perspective view of the optical information reading apparatus which concerns on Embodiment 1. FIG. It is a block diagram of the optical information reader of FIG. 3A is a schematic side view of the optical information reader of FIG. 1, and FIG. 3B is a schematic front view showing an image pickup module of the optical information reader of FIG. 1. It is a schematic diagram which shows the field of view range of the 1st image pickup element and the 2nd image pickup element. It is a schematic diagram which shows the visual field range at the time of reading a plurality of symbols by a 1st image pickup element and a 2nd image pickup element. It is a schematic cross-sectional view which shows an example of the 2nd image pickup part. It is a flowchart which shows the image pickup procedure of the 1st image pickup unit in the optical information reading method which concerns on Embodiment 1. FIG. It is a graph which shows the relationship between the Aimer center position and the distance obtained by the calibration of the 1st imaging unit. It is a flowchart which shows the procedure which determines the necessity of the image pickup by the 2nd image pickup unit. It is a schematic diagram which shows the range when only a part of a symbol can be read. It is a schematic diagram which shows an example of the field of view of the 1st image pickup part and the field of view of a 2nd image pickup part. It is a graph which set the 1st image pickup distance range in the graph which shows the distance range which can be imaged by the 1st image pickup part, the 2nd image pickup part, and the cell size of a symbol. It is a graph which shows the state which set the first imaging distance range narrower than FIG. It is a flowchart which shows the procedure which performs the image pickup setting in the 2nd image pickup unit. It is a graph which shows the relationship between the current value I of VCM, and the focus position D. It is a graph which shows the relationship of the brightness of the 1st image pickup part and the 2nd image pickup part. It is a flowchart which shows the image pickup procedure of the 1st image pickup unit in the optical information reading method which concerns on a modification. It is a flowchart which shows the operation procedure seen from the 2nd image pickup unit.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiments shown below exemplify an optical information reading device and an optical information reading method for embodying the technical idea of the present invention, and the present invention is an optical information reading device and optics. The formula information reading method is not specified as follows. Further, the present specification does not specify the members shown in the claims as the members of the embodiment. In particular, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments are not intended to limit the scope of the present invention to the specific description, but are merely described. It's just an example. The size and positional relationship of the members shown in each drawing may be exaggerated for the sake of clarity. Further, in the following description, members of the same or the same quality are shown with the same name and reference numeral, and detailed description thereof will be omitted as appropriate. Further, each element constituting the present invention may be configured such that a plurality of elements are composed of the same member and the plurality of elements are combined with one member, or conversely, the function of one member is performed by the plurality of members. It can also be shared and realized.
[Embodiment 1]

The optical information reader is a terminal device for reading symbols such as barcodes and two-dimensional codes. The optical information reader is used in the sense that it includes a handy scanner that reads and outputs a symbol, a handy terminal that performs arbitrary data processing such as registering the read information and collating data, a PDA for business use, and the like.

The symbol to be read includes a standardized code such as a bar code and a two-dimensional code, a code of an original standard, and a character string composed of characters and numbers. These symbols are printed directly on the surface of a work or shelf such as a product to be read, or on a label affixed to the surface of the work. Further, reading a symbol generally means decoding (decoding) the information encoded (encoded) into the symbol. However, as described above, when the symbol is a character string, it means optical reading (OCR) of characters and numbers.

The optical information reader 100 according to the first embodiment of the present invention is shown in FIGS. 1 to 3B. In these figures, FIG. 1 is an external perspective view of the optical information reader 100, FIG. 2 is a block diagram, FIG. 3A is a schematic side view of the optical information reader 100 of FIG. 1, and FIG. 3B is a schematic view of the image pickup module 1. The front view is shown respectively. The optical information reader 100 shown in these figures is a handy terminal. The optical information reader 100 of FIG. 1 has a plate shape in which the outer shape of the housing 2 which is a substantially square shape is extended in one direction. An image pickup module 1 for optically reading a symbol to be read is provided at the front end portion or the back surface portion of the housing 2. The image pickup module 1 is composed of a camera module that reads symbols such as barcodes, two-dimensional codes, and character strings, a scan module that scans barcodes, and the like.

A display unit 3 and a key arrangement unit 30 are provided on the upper surface of the housing 2. A display unit 3 is provided on one end side of the housing 2, and a key arrangement unit 30 is provided on the other end side opposite to the display unit 3.

The housing 2 is composed of a display portion DA including the display unit 3 and a grip portion HA including the key arrangement portion 30, and the user grips the grip portion HA by hand and is provided on the display portion DA. While referring to the display content of the display unit 3, each operation key of the key arrangement unit 30 arranged on the surface side of the grip portion HA is operated. In the housing 2, the display portion DA is wide and the grip portion HA is narrow in the plan view, while the grip portion HA is thick in the side view. This makes it easier to hold the grip portion HA.

The display unit 3 is provided on one side of the housing 2, and displays various information such as an image obtained by capturing the symbol to be read by the camera unit, information obtained by decoding the symbol, and other setting information. The display unit 3 is composed of, for example, a liquid crystal display (LCD), an organic EL, or the like. Further, the display unit 3 may be configured as a touch panel. The display unit 3 composed of the touch panel also functions as a key input unit.

A plurality of operation keys such as a numeric keypad, a power key, and a function key for performing various operations are arranged in the key arrangement unit 30. Each input device arranged in the key arrangement unit 30 constitutes a key input unit that accepts various input operations. Further, the key arrangement unit 30 is provided with a trigger key 31. By operating the trigger key 31, the data collection timing for collecting symbol information is defined. That is, the image pickup unit 10 (details will be described later) detects that the trigger key 31 has been operated, is incident on a symbol to be read, converts the reflected light reflected by this symbol into an electric signal, and performs image data. The imaging process for generating the image is started. In this way, the trigger key 31 defines the trigger signal. In the present invention, the trigger key is not limited to the physical key, and may be, for example, a virtual key displayed on the user interface.

The optical information reading device 100 includes a battery for supplying driving power in order to ensure portability. Further, the aiming light irradiation unit 15 that specifies the position to be imaged, that is, irradiates the aiming light indicating the reading position, and the image pickup module 1 are provided on the back surface side of the housing 2.

The housing 2 has an elongated shape extended in one direction. As shown in FIG. 3A, the housing 2 includes a first main surface and a second main surface facing the first main surface. A partially protruding protrusion is provided on the second main surface side. A display unit is provided on the first main surface side of the housing.

The protrusion has an inclined surface inclined with respect to the second main surface and an optical window adjacent to the inclined surface. The image pickup module 1 including the first image pickup element and the second image pickup element is arranged side by side in a posture facing the optical window inside the protrusion. The optical window is made of a translucent member, for example, resin, glass, or the like, and each member constituting the image pickup module 1, such as the first image pickup element and the second image pickup element, is moved from the housing 2 to the outside through the optical window. appear.

Further, the optical axes of the first image sensor and the second image sensor are inclined as shown by a broken line with respect to the longitudinal direction of the housing 2 shown by the alternate long and short dash line in FIG. 3A. The inclination direction is a direction along the inclined surface, that is, a direction away from the longitudinal direction of the housing 2 as the distance from the tip of the optical information reading device 100 increases. In the example of FIG. 3A, the optical axes of the first image sensor and the second image sensor are inclined at an angle θ with respect to the longitudinal direction of the housing 2. As a result, when the symbol is read by the optical information reading device 100, the user can easily adjust the posture of the optical information reading device 100, and an environment that is easy to grasp and handle without difficulty is realized.

FIG. 2 is a block diagram of the optical information reading device 100 according to the first embodiment. As shown in this figure, the optical information reading device 100 includes a control unit 40, a RAM 51, a storage unit 52, a display unit 3, an operation unit (key layout unit) 30, and a communication interface that execute at least a control program for controlling the operation. 50, the image pickup module 1 is provided.

The control unit 40 is connected to each of the above-mentioned hardware parts of the optical information reading device 100 via an internal bus or the like, controls the operation of each of the above-mentioned hardware parts, and is stored in the storage unit 52. Performs various software functions according to the computer program. Such a control unit 40 can be suitably realized by a CPU, MPU, SoC, ASIC, or the like. The RAM 51 is composed of volatile memories such as SRAM and SDRAM, and a load module is expanded when the computer program is executed to store temporary data and the like generated when the computer program is executed.

Further, the control unit 40 realizes the functions of the read control unit 42 and the focus control unit 49. The reading control unit 42 reads the symbol information based on the first image data generated by the first image pickup unit 10 and the second image data generated by the second image pickup unit 20. Further, the focus control unit 49 controls the focus drive unit 23 of the second image pickup unit 20. Specifically, the focus control unit 49 sets the focus drive unit 23 according to the relational expression I = F (D) of the focal length D of the second image pickup unit 20 and the drive current I for driving the focus drive unit 23, which are stored in advance. Control (details below).

The storage unit 52 also stores the firmware 211, the decoder 212, and the character recognition dictionary 213. The firmware 211 is a group of programs such as driver software that controls the operation of each connected hardware. The decoder 212 decodes, for example, a QR code (registered trademark) or a barcode. The character recognition dictionary 213 is a dictionary for converting an captured image into text data. The storage unit 52 can be configured by a non-volatile memory such as a ROM.

The communication interface 50 is connected to an internal bus, and by being connected to an external network such as the Internet, LAN, WAN, etc., it is possible to transmit / receive data to / from an external computer or the like. The operation unit (key arrangement unit 30) 40 functions as a key input unit that accepts various input operations, and accepts input for operation by key input.

The aiming light irradiation unit 15 irradiates the aiming light adjacent to the fixed focus optical system 12. The image captured by the first imaging unit 10 after irradiating the aiming light with the aiming light irradiation unit 15 is called an aimer image. The focus control unit 49 can estimate the distance to the symbol based on this Aimer image (details will be described later). If the reading control unit 42 determines that the reading of the symbol using the first imaging unit 10 is inappropriate, the reading using the second imaging unit 20 is executed. Specifically, the focus drive unit 23 is driven so that the focal length of the variable focal length optical system 22 matches the distance to the symbol calculated based on the Amer image.
(Imaging module 1)

As shown in FIG. 3B, the image pickup module 1 includes a first illumination unit 14, a first image pickup unit 10, an aiming light irradiation unit 15, a second image pickup unit 20, and a second illumination unit 24. In this way, the first image sensor 11 and the second image sensor 21 are arranged side by side in a straight line. Further, the second image sensor 21 is configured to be able to capture an optical image of the symbol even when the first image data captured by the first image sensor 11 can be read.

In particular, the second image sensor 21 is provided at a position different from the back surface side of the display unit 3 in the housing 2. With such an arrangement, by arranging the second image sensor on the back side of the display unit, which is a viewfinder for a general digital camera, the image on the optical axis seen by the user is displayed in real time. Since an optical information reader captures a symbol such as a bar code, it is sufficient if the symbol that is the subject can be directly visually recognized. In addition, by providing the second image sensor 21 at a position different from that of the first image sensor 21, it is not necessary to change the optical information reading device, and the image is taken in the same posture as the first image data reading by the first image sensor 21. The advantage of being able to image is obtained.

That is, the second image sensor 20 can be used as a digital camera function, and the second image sensor 21 can leave a photograph of the symbol, a proof photograph showing the situation at the time of reading, and the like. In addition, conventionally, an optical information reader having a digital camera function has a digital camera installed at a position different from that of a camera for reading symbols. Where it was necessary to move, according to this configuration, since the first image sensor 11 and the second image sensor 21 are arranged side by side, the second image sensor 11 keeps the image data imaging posture. The image sensor 21 can capture an optical image of the symbol, which can improve usability.

Further, in the second image sensor 21, the focus drive unit 23 moves the variable focus optical system 22 when the first image sensor 11 captures the first image data and also captures the optical image of the symbol as described above. It can also be set not to let. With such a configuration, when the second image pickup element 21 captures an optical image of a symbol like a digital camera, the variable focus optical system 22 is not moved while the focal position is fixed in advance at a predetermined position, so that the variable focus position is variable. It is possible to prevent the occurrence of waiting time due to driving the focal optical system 22 and prevent deterioration due to wear of the mechanical driving portion, thereby simplifying the processing and extending the life of the product.

The first illumination unit 14 irradiates the first illumination light for the fixed focus optical system. The second illumination unit 24 irradiates the second illumination light for the variable focus optical system. The first illumination unit 14 and the second illumination unit 24 respond to the imaging field so as to emit the first illumination light and the second illumination light suitable for imaging by the fixed focus optical system 12 and the variable focus optical system 22, respectively. It is adjusted to the light distribution and the amount of light. It is preferable that the second lighting unit 24 has a wider light distribution range than the first lighting unit 14. Further, it is preferable that the second lighting unit 24 has a larger amount of light than the first lighting unit 14. Semiconductor light emitting elements such as LEDs and organic ELs can be suitably used for the first lighting unit 14 and the second lighting unit 24.

The first image pickup unit 10 is composed of a fixed focus optical system 12 and a first image pickup element 11. The fixed focus optical system 12 is a member that collects the reflected light incident on the symbol and reflected by the symbol, and is preferably composed of one or more first optical lenses. The first image sensor 11 is a member for converting the light focused by the fixed focus optical system 12 into an electric signal and generating the first image data. As the first image sensor 11, an image sensor such as CMOS or CCD can be used.

The second image pickup unit 20 includes a variable focus optical system 22, a second image pickup element 21, and a focus drive system. The variable focus optical system 22 is a member that receives the reflected light incident on the symbol and reflected by the symbol, and is preferably composed of one or more second optical lenses. The second image sensor 21 is a member for converting the light focused by the variable focus optical system 22 into an electric signal and generating the second image data. As the second image sensor 21, an image sensor such as CMOS or CCD can be used.

The second image sensor 21 preferably has a higher resolution than the first image sensor 11. As a result, even if the image captured by the first image sensor 11 fails to be read, the probability that the image captured by the second image sensor 21 will be successfully read can be improved. Further, it is preferable that the imaging field of view of the second imaging unit 20 is wider than the imaging field of view of the first imaging unit 10. Similarly, even if the image captured by the first image sensor 11 cannot be read due to insufficient field of view, it can be expected that the field of view of the image captured by the second image sensor 21 will be sufficient and the probability of successful reading will be increased.

Here, an image sensor that captures a monochrome image is used as the first image sensor 11. On the other hand, the second image sensor 21 is an image sensor that captures a color image. By using a color camera, the color difference information of the captured image data can also be used for decoding. Further, in the example of FIG. 3B, the first image sensor 11 has a pixel number of 1 Mbyte, the shutter method is a global shutter, and the gray scale image sensor is used as CMOS. Further, the second image sensor 21 uses an image sensor of 8 Mbytes and a color of a rolling shutter. As a result, the field of view as shown in FIG. 4 is realized by the first image sensor 11 and the second image sensor 21. In this figure, a thin line indicates the field of view of the first image sensor 11, and a thick line indicates the field of view of the second image sensor 21. Further, the second image sensor 21 may be capable of switching a plurality of image pickup fields. For example, in the example of FIG. 4, the number of pixels of the second image sensor 21 can be switched to either 8 Mbytes or 13 Mbytes, and the thick line indicates 8 Mbytes and the broken line indicates 13 Mbytes. By making the field of view switchable in this way, it is possible to capture a wider range with a single imaging. For example, as shown in FIG. 5, the number of symbols SB to be read is set to eight, but even if only four are in the field of view in the first imaging unit 10, eight are activated by activating the second imaging unit 20. It becomes possible to read the symbol of.
(Modification example)

Further, a polarizing filter may be added to the second imaging unit 20. The polarizing filter is formed, for example, in the form of a film, and is further attached to the surface of the second imaging unit 20 as a seal with glue applied to one surface. Further, as a second operation mode for driving determination of the second image pickup unit 20, which will be described later, an operation mode for adding a polarizing filter film to the second image pickup unit 20 may be added. In this case, when determining the drive of the second image pickup unit 20, it is possible to add a step of determining the presence or absence of halation of the image captured by the first image pickup unit 10. When halation is detected, the second image pickup unit 20 to which the polarizing filter film is attached is driven.
(Focus drive unit 23)

The focus drive unit 23 is a member for changing the focal position of the variable focus optical system 22. The focus drive unit 23 extends the focal range of the variable focus optical system 22 to be larger than that of the fixed focus optical system 12. The fixed focus optical system 12 and the variable focus optical system 22 are composed of one or more optical lenses as described above. In the fixed focal length optical system 12, the first optical lens is fixed and the focal length is substantially constant. On the other hand, the variable focus optical system 22 has a movable second optical lens, and the focus drive unit 23 moves the second optical lens along the optical axis of the second image pickup element 21 to move the second optical lens to the second image pickup element 21. The focal position in is adjustable. The focus drive unit 23 is driven by the focus control unit 49.

The focus drive unit 23 includes a voice coil motor (VCM) as a movable mechanism for mechanically moving the optical lens. FIG. 6 shows an example of the second imaging unit 20 using the VCM. The second image pickup unit 20 shown in this figure includes a second image pickup unit housing 25, a spring 26, a lens unit 27, a coil 28, a magnet 29, a second image pickup element 21, and a substrate 25B. The VCM shown in this figure uses a movable coil type motor in which only the coil 28 moves in the magnetic field generated by the magnet 29.
(Aiming light irradiation unit 15)

Further, the aiming light irradiation unit 15 is a member for irradiating a work or a symbol with aiming light (aiming light). The aiming light irradiation unit 15 scans the surface of a work or the like to be imaged with light into a predetermined scanning pattern so that the reading position can be visually recognized, and draws a predetermined pattern on the locus. In the present specification, this pattern is referred to as aiming light or aiming light. As the aiming light, any pattern can be used, such as a linear light extended in the horizontal direction of the imaging field and the captured image, and light forming a cross in the horizontal direction and the vertical direction. Here, the aiming light is used as a cross-shaped pattern. The aiming light irradiation unit 15 is preferably composed of a laser light source and a scanner capable of scanning the laser light from the laser light source.

The first illumination unit 14, the first image pickup unit 10, the aiming light irradiation unit 15, the second image pickup unit 20, and the second illumination unit 24 are arranged in a straight line. In this way, by arranging the cameras and lights side by side in a row instead of arranging them in two stages, the hardware necessary for reading the symbol is put together as the image pickup module 1 on the tip side of the housing 2, and the image pickup module 1 is arranged. Making it thinner can contribute to making the optical information reader 100 thinner, lighter, and smaller.

In the example of FIG. 3B, the first image sensor 11 and the fixed focus optical system 12 constituting the first image pickup unit 10 are arranged so as to be overlapped with each other. That is, in front view, the fixed focus optical system 12 is arranged in front of the first image sensor 11. Similarly, the second image sensor 21 and the fixed focus optical system 12 constituting the second image pickup unit 20 are also arranged so as to be overlapped with each other. That is, in front view, the fixed focus optical system 12 is arranged in front of the second image sensor 21. Therefore, in the example of FIG. 3B, the first illumination unit 14, the fixed focus optical system 12, the aiming light irradiation unit 15, the variable focus optical system 22, and the second illumination unit 24 are arranged in a straight line. .. The image sensor may be arranged so as to be displaced from the optical system. For example, the image sensor may be arranged at a position where it does not overlap with the optical system in front view by bending the optical axis of the optical system by interposing a mirror or the like.
(Optical information reading method)

An optical information reading method of capturing a symbol to be read by using the optical information reading device 100 and reading the information of the symbol will be described. First, the first image pickup unit 10 captures the first image data including the symbol. Next, the read control unit 42 analyzes the first image data. When, as a result of the analysis by the reading control unit 42, it is determined that the first image data is inappropriate for reading the symbol, the second imaging unit 20 uses the analysis result to determine that the image is focused on the symbol. The focal position of the variable focal point optical system 22 required for imaging the image is calculated. Then, the focus drive unit 23 controls so that the focal position of the variable focus optical system 22 matches this focal position according to the calculation result of the focus control unit 49. Further, the reading control unit 42 reads the symbol information based on the second image data focused on the symbol generated by the second image pickup unit 20. As a result, the variable focus optical system 22 is used by giving priority to imaging by the first imaging unit 10 and switching to the second imaging unit 20 to image only the symbols that cannot be read by the first imaging unit 10. It is possible to realize an optical information reader 100 with improved reading speed and product life by reducing the frequency and avoiding an increase in imaging time due to focus adjustment and a shortening of life due to mechanically driving a variable focus. ..

The read control unit 42 first analyzes the first image data generated by the first image pickup unit 10. Then, when it is determined that the first image data is not suitable for reading the symbol, the second image pickup unit 20 captures the second image data. At this time, based on the result of the analysis of the first image data, the focal position of the variable focus optical system 22 required for the second imaging unit 20 to capture an image in which the symbol is focused is calculated. Then, the focus driving unit 23 is controlled so as to match the focal position of the variable focus optical system 22 with the calculated focal position, and the second image pickup unit 20 generates the second image data focused on the symbol. This makes it possible to read the information even if the symbol cannot be read by the first imaging unit 10.

In this way, by giving priority to imaging by the first imaging unit 10 and switching to the second imaging unit 20 to image only the symbols that cannot be read by the first imaging unit 10, the variable focus optical system 22 It is possible to reduce the frequency of use. As a result, it is possible to realize an optical information reading device 100 in which the reading speed and the product life are improved by avoiding the increase in the imaging time due to the adjustment of the focus and the shortening of the life due to mechanically driving the variable focus.

Even in the conventional optical information reader, there is a barcode reader equipped with a plurality of image sensors such as a color camera. However, the added image sensor has been used for applications such as capturing an optical image of a product with a symbol. In other words, an image sensor such as an additional color camera was not used for reading the symbol, and an image sensor dedicated to reading the symbol was used for reading the symbol. The additional image sensor was positioned like a digital camera to capture an optical image of a product with a symbol, and was only used for the purpose of leaving a proof photograph showing the condition of the product. Further, there is no one that performs switching control such as switching between such a plurality of image sensors according to the distance to the symbol.

On the other hand, in the optical information reader 100 according to the first embodiment, the second image pickup unit 20 of the variable focus optical system 22 is added in addition to the first image pickup unit 10 of the fixed focus optical system 12. Even if the symbol cannot be read by the first image pickup unit 10, it is possible to increase the possibility of reading the symbol by switching to the second image pickup unit 20 and taking an image, and it is possible to improve the reading stability. By giving priority to imaging by the first imaging unit 10 and reducing the frequency of use of the variable focus optical system 22 in this way, deterioration of the variable focus optical system 22 having a mechanically movable part and shortening of the life due to the deterioration can be achieved. It can be avoided. In addition, it is possible to avoid a decrease in reading speed caused by adjusting the focus and a battery consumption due to an increase in power consumption for driving the VCM.

In addition, many optical information readers to which a conventional color camera has been added have a color camera arranged on the back side of the housing. This is to realize the same usability as a digital camera by arranging a color camera on the back side of the display provided on the front side of the housing and making the display function as a view finder that displays the contents captured in real time. it is conceivable that. However, in this configuration, when the user wants to capture an optical image of a symbol with a color camera, the housing is changed from the posture of reading the symbol, that is, the posture in which the tip end side of the housing provided with the symbol reading camera is directed toward the symbol. It was necessary to change the housing so that the back side of the body faces the symbol, and then take an image with a color camera.

On the other hand, in the optical information reader 100 according to the first embodiment, since the second image sensor 21 capable of capturing an optical image is arranged side by side with the first image sensor 11, the posture is the same as the posture for reading the symbol. The optical image can be captured by the second image sensor 20 without changing the housing 2. In particular, since the optical image of the symbol is captured for the purpose of confirming the state of the product with the symbol, it is sufficient if the work is shown, and it is not necessary to check the field of view one by one using the display unit 3 as a view finder. In other words, it is not necessary to arrange the second image pickup unit 20 on the back surface side of the display unit 3.

Further, since this optical image is not intended to read a symbol, it is not necessary to make a clear image in focus. For this reason, it is more convenient for the optical information reader to be able to acquire an optical photograph while keeping the posture of reading the symbol. When capturing an optical image, the variable focus optical system 22 may be driven to focus and image, or the variable focus optical system 22 may not be driven and the second image pickup element 21 captures the optical image. You may. As mentioned above, since the optical image is not intended for reading symbols, it is not necessary to focus neatly, and it is necessary to drive the variable focus optical system 22 in order to focus, which takes time and increases power consumption. Further, there is a problem such as shortening the life of the VCM constituting the variable focus optical system 22, and there is a merit that such a problem can be avoided by not intentionally adjusting the focus.

The first image data analyzed by the reading control unit 42 for reading the symbol may be an Aimer image, or may be the main imaging data captured in high definition by the first imaging unit 10 after the Aimer image is captured. Generally, it is sufficient to acquire only the coordinate position of the aiming light, so that the aimer image is easily captured in a short time. In other words, a normal Aimer image is an image with a lower resolution than this captured data. However, a high-definition Aimer image may be captured by the first imaging unit 10 from the beginning, and the high-definition Aimer image may be used for reading a symbol. The high-definition Aimer image captured in this way serves both for measuring the distance and for decoding.

Further, in the case where the first image data is an Aimer image, the case where the reading control unit 42 determines that the reading of the symbol is inappropriate is the case where the main image pickup data taken by the first image pickup unit 10 after the acquisition of the Aimer image is performed. There are cases where the reading is inappropriate, for example, the distance to the symbol is determined to be out of range. On the other hand, when the first image data is used as the main imaging data, the case where the reading control unit 42 determines that the reading of the symbol is inappropriate is determined based on the present imaging data that the reading of the main imaging data fails. In some cases, reading using the first image pickup unit 10 is inappropriate, for example, it is determined that the resolution is insufficient. Further, in the case where the first image data is a high-definition Aimer image, the case where the reading control unit 42 determines that the reading of the symbol is inappropriate is taken by the high-definition Aimer image and subsequently by the first imaging unit 10. There are cases where it is determined that reading with this imaged data is inappropriate.

Parameters such as image resolution, visual field, and contrast can be used as a criterion for the reading control unit 42 to analyze the image and determine whether or not it is inappropriate for reading the symbol. For example, the reading control unit 42 calculates the resolution of the symbol to be read from the image data generated by the first imaging unit 10. When the resolution calculated by the reading control unit 42 is equal to or less than a predetermined threshold value, the first image data generated by the first imaging unit 10 is inappropriate for reading the symbol, in other words, the second. It is determined that it is preferable that the image pickup unit 20 captures and reads the second image data.

Further, the reading control unit 42 may calculate the required field of view of the symbol to be read from the first image data generated by the first imaging unit 10. In this case, if the required visual field calculated by the reading control unit 42 is equal to or greater than a predetermined threshold value, the first image data generated by the first imaging unit 10 is inappropriate for reading the symbol. It is determined that it is preferable that the second image pickup unit 20 captures and reads the second image data.

Further, the reading control unit 42 may calculate the contrast of the symbol to be read from the first image data generated by the first imaging unit 10. In this case, if the contrast calculated by the reading control unit 42 is equal to or less than a predetermined threshold value, the first image data generated by the first imaging unit 10 is inappropriate for reading the symbol. It is determined that it is preferable that the second image pickup unit 20 captures and reads the second image data.

For the second image pickup unit 20, a general-purpose camera module for taking a picture used in a digital camera, a smartphone, or the like can be used. By using the general-purpose camera module as the second image pickup unit 20, the manufacturing cost of the optical information reader can be reduced. A general-purpose camera module generally employs a contrast focus process that determines a focus position based on contrast. Further, the optical lens used in the general-purpose camera module generally has a large lens F value and a shallow focus position. When a symbol is imaged and used for reading by using such a general-purpose camera module, it is necessary to always acquire the second image data in focus. However, when the conventional autofocus process based on contrast is applied, it is necessary to take several frames to acquire the second image data in focus. As a result, the driving time becomes long, and the reading speed, that is, the camera imaging speed decreases. In addition, the power consumption required to drive the VCM increases, and the battery life for driving the optical information reader also decreases. In addition, the drive life is shortened due to the increase in the amount of spring displacement of the VCM.

On the other hand, in the optical information reader 100 according to the present embodiment, the first image pickup unit 10 of the fixed focus optical system 12 is combined with the second image pickup unit 20 of the variable focus optical system 22 at a higher resolution, and further calculation is performed. By controlling the focus of the second image pickup unit 20 based on the estimated distance, the drive time of the focus drive unit 23 is shortened, and the above-mentioned problems are solved. Hereinafter, the details will be described based on the flowchart of FIG. 7.
(Optical information reading method)

The flowchart of FIG. 7 shows a procedure for performing an image pickup by the first image pickup unit 10 in the optical information reading method according to the first embodiment. First, in step S701, a trigger start operation is performed. Specifically, the trigger key 31 is pressed. Next, in step S702, the work is irradiated with aiming light. Then, in step S703, the aiming light irradiation unit 15 captures an aimer image of the symbol irradiated with the aiming light. The captured Aimer image contains a cross-shaped pattern of aiming light.

Further, in step S704, the distance (working distance) from the optical information reader 100 to the symbol is measured based on this Aimer image. The position of the aiming light contained in the Aimer image varies depending on the distance. This is because the optical axis of the aiming light emitted by the aiming light irradiation unit 15 and the optical axis of the reflected light received by the first image sensor 11 that captures the Aimer image do not match. Generally, the farther the distance is, the closer the cross-shaped aiming light AL is to the center of the Aimer image as shown in FIG. 8, and conversely, the closer it is, the more the cross-shaped aiming light AL deviates from the center. Therefore, the distance can be estimated by measuring the position of the aiming light AL in the Aimer image.

In order to estimate the distance from the Aimer image, as a preliminary calibration, the Aimer center position (x) in the imaging field of the first imaging unit 10 and the work to be imaged are captured in advance in the manufacturing process of the optical information reader 100. The relationship of the distance (D) to is inspected and retained. As a result of this calibration, a distance estimation formula of D = F (x) is obtained as shown in FIG. This distance estimation formula is used when calculating the distance. Specifically, the symbol is irradiated with aiming light, an Aimer image is imaged by the first imaging unit 10, and the center coordinates of the aiming light are calculated. The calculated Aimer center coordinates are calculated by the focus control unit 49 or the like using the equation of D = F (x) in FIG. 8 obtained by calibration to calculate the estimated distance from the optical information reader 100 to the work. The distance calculated in this way is held in the storage unit 52 or the like of the optical information reading device 100.

Then, in step S705, the first imaging unit 10 performs the main imaging process. Specifically, the symbol is illuminated by irradiating the illumination light from the first illumination unit 14, and the first image data is acquired. Note that steps S704 and S705 do not necessarily have to be performed in this order, but may be performed in the reverse order or at the same time. The processing time can be shortened by simultaneously performing the imaging of the first image data by the first imaging unit 10 and the calculation of the distance from the Aimer image.

Next, in step S706, the brightness is calculated from the image obtained by the first imaging unit 10. Brightness is calculated as brightness, for example, by image processing according to a known algorithm. The calculated brightness of the first imaging unit 10 is also held in the storage unit 52 or the like of the optical information reading device 100. Here, it is preferable to calculate the brightness using the first image data (main image pickup data) captured by the first image pickup unit 10 rather than the Aimer image. When taking an Aimer image, in general, it is often taken in a dark state such as turning off the illumination light so that the aiming light becomes clear. This is because image data is preferable.

Then, in step S707, the reading control unit 42 performs the decoding process of the first image data. Further, in step S708, it is determined whether or not decoding is possible. That is, if the reading control unit 42 can decode, the reading is successful (step S709), and the process ends.

On the other hand, if it is determined in step S708 that the reading control unit 42 cannot read, the process proceeds to step S710 to determine whether or not imaging by the second imaging unit 20 is necessary. A specific procedure for determining the necessity of imaging by the second imaging unit 20 will be described later with reference to FIG. If the image pickup by the second image pickup unit 20 is unnecessary, the process returns to step S702 and the process is repeated. On the other hand, when the image pickup by the second image pickup unit 20 is required, the image pickup by the second image pickup unit 20 is performed. Specifically, the procedure proceeds to the procedure for setting the image pickup by the second image pickup unit 20 shown in FIG. 14, which will be described later.
(Drive determination of the second image pickup unit 20)

Here, the procedure for driving the second image pickup unit 20, that is, driving the variable focus optical system 22 with the focus drive unit 23 and determining whether or not to capture the second image data with the second image pickup element 21 is shown in the figure. This will be described based on the flowchart of 9. First, in step S901, the distance to the symbol is measured, and the preset distance range is read. In this example, the set distance range is set as the range in which the first imaging unit 10 performs imaging. Next, in step S902, it is determined whether or not the measured distance is within the set distance range. If it is within the set distance range, the second imaging unit 20 does not need to be driven, and the process ends (details will be described later).

On the other hand, if it is determined that the distance is not within the set distance range, the process proceeds to step S903, and the estimated resolution is calculated from the image captured by the first imaging unit 10. Next, in step S904, the preset resolution threshold value is read. The resolution threshold is a threshold that serves as a reference for whether or not the resolution required for accurate reading is guaranteed by the captured image, and is used prior to the use of the optical information reading device 100 or for reading optical information. It is set in advance at the time of shipment from the factory of the device 100. Then, in step S905, it is determined whether or not the resolution of the image captured by the first imaging unit 10 is sufficient.

For example, only part of the symbol may be readable. For example, when the symbol is a bar code, in the bar code BC shown in FIG. 10, the bar code BC in the portion surrounded by the thick frame may be partially read. When the symbol is a QR code, there are cases where a part of the QR code can be read but the cell size is small and cannot be completely decoded, or a finder pattern is found but the cell size is small and cannot be decoded. In the case of such a symbol, it is determined that the condition cannot be resolved by the first imaging unit 10, and the second imaging unit 20 is driven. Specifically, it is determined whether or not the entire symbol can be decoded by the first imaging unit 10 by looking at the size and resolution of the read region. Since the second image sensor 21 has a higher resolution than the first image sensor 11, if it is determined that reading by the first image sensor 10 is difficult due to insufficient resolution, the second image sensor 20 is activated.

As described above, when the resolution is lower than the resolution threshold value in step S905, the process proceeds to A to drive the second imaging unit 20 (details will be described later based on FIG. 14). On the other hand, if the resolution is sufficient, the process proceeds to step S906, and the estimated required visual field is calculated from the result of the first imaging unit 10. Then, in step S907, the visual field threshold value is read. As shown in FIG. 11, the visual field threshold is that the entire symbol SB cannot be imaged due to insufficient imaging field of view that can be imaged by the first imaging unit 10, but if it is the imaging field of the second imaging unit 20, the entire symbol can be captured. It is a threshold value of the image field of view of the first image pickup unit 10 set in advance so that the image pickup is performed by the second image pickup unit 20 when the image can be imaged. Further, in step S908, it is determined whether or not the field of view of the image is insufficient. Here, the estimated required visual field calculated for the first image data of the first imaging unit 10 is compared with a preset visual field threshold value, and if it is determined that the visual field is insufficient, the process proceeds to A. (2) Drives the image pickup unit 20. These steps S906 to S908 are also performed in substantially the same procedure as the steps S903 to S905 described above. That is, since the second image pickup unit 20 has a wider field of view that can be imaged than the first image pickup unit 10, if it is determined that the first image pickup unit 10 is difficult to read due to insufficient field of view, the second image pickup unit 20 is second. (Ii) The imaging unit 20 is activated.
(Judgment of insufficient contrast)

On the other hand, if the field of view is sufficient, the process proceeds to step S909, and the estimated contrast is acquired from the result of the first imaging unit 10. Here, the contrast value of the first image data is calculated by image processing. For example, the contrast value is calculated based on the contrast difference in the region included in the image data generated by the first image pickup unit, the gain which is the ratio of the received light amount to the total light emission amount, and the like. Further, it may be the entire area included in the image data, or may be a part of the area when it is partially decoded. Further, in step S910, the contrast threshold value is read. The contrast threshold value is a preset value as a contrast value required for reading the symbol. Then, in step S911, it is determined whether or not the contrast is insufficient. Specifically, the estimated contrast and the contrast threshold value are compared to determine the lack of contrast. If the contrast is insufficient, the process proceeds to A to drive the second imaging unit 20. On the other hand, when the contrast is sufficient, it is determined that the driving of the second imaging unit 20 is unnecessary, and the process is terminated.

For example, when a part of a barcode is decoded, the size of the field of view of the entire barcode is estimated. Since the second image pickup unit 20 has a larger field of view than the first image pickup unit 10, if it is determined that decoding by the first image pickup unit 10 is difficult due to insufficient field of view, the second image pickup unit 20 is activated. Then, the maximum luminance difference of the partially decoded barcode edge pattern is calculated. For example, when a barcode printed in red is illuminated with red illumination light, or when a barcode is printed in red on a red background, the difference in brightness between the barcode bar and the space is small, and the first imaging is performed. If it is estimated that the contrast is insufficient in the unit 10, the second imaging unit 20 is activated.

In the drive determination of the second imaging unit 20, some determinations may be omitted. For example, steps S909 to S911 for determining the excess or deficiency of contrast are omitted, and when it is determined in step S98 that the field of view is sufficient, it is determined that the drive determination of the second imaging unit 20 is unnecessary and the process is terminated. You can also do it. As a result, the drive determination of the second imaging unit 20 can be performed more quickly.

Further, when it is determined that the second image pickup unit 20 is driven by analyzing the image captured by the first image pickup unit 10, the second image pickup unit 20 may be given priority to read the symbol. For example, by pressing the mode switching button for switching the shooting mode displayed on the display unit, the second image pickup unit 20 is driven until the mode switching button is pressed again, and the second image pickup unit 20 is used. The symbol information is read based on the captured image. By doing so, when it is known in advance that it is appropriate to use the second image pickup unit 20 due to the influence of ambient light or the like, the second image pickup unit 20 can be used without analyzing the image captured by the first image pickup unit 10. Since it is driven, the time required for reading the symbol information can be shortened.

Here, an example of a reference for switching from the first imaging unit 10 to the second imaging unit 20 in steps S901 to S902 of FIG. 9 will be described with reference to FIGS. 12 and 13. These figures show the relationship between the distance that can be decoded (read) by the first imaging unit 10 and the second imaging unit 20 and the cell size of the symbol when the symbol is composed of cells as the smallest unit such as a two-dimensional code. ing. Although the cell size of the two-dimensional code is taken as an example here, when the symbol is a one-dimensional code, it may be the width of the narrow bar. In addition, the cell size and narrow bar width may be referred to as the minimum module size or resolution. Further, the straight line in the figure indicates the boundary line of the range readable by the first imaging unit 10, and the alternate long and short dash line indicates the boundary line of the range readable by the second imaging unit 20. As shown in these figures, the range that can be imaged by the second image pickup unit 20 is generally wider than the range that can be imaged by the first image pickup unit 10. The range that can be imaged by the first image pickup unit 10 overlaps with a part of the range that can be imaged by the second image pickup unit 20, for example, the intermediate portion. Under such conditions, the distance range for switching from the first imaging unit 10 to the second imaging unit 20 is set.

Here, the first imaging distance range DR1 is set as the set distance range. When the distance measured during operation exists in the first imaging distance range DR1, imaging is performed by the first imaging unit 10. Further, in a range other than the first imaging distance range DR1, the first imaging unit 10 and the second imaging unit 20 are switched to perform imaging according to the procedure and conditions described with reference to FIGS. 7 and 9. The first region shown by cross-hatching in FIGS. 12 and 13 is a region in which the symbol is read by using the first imaging unit 10. Further, the second region shown by the diagonal line is a region where the symbol is read by switching between the first imaging unit 10 and the second imaging unit 20 according to the conditions.

This first imaging distance range DR1 can be variable. For example, as shown by the thick arrow in FIG. 13, the first imaging distance range DR1 may be set narrower than that shown in FIG. By narrowing the first imaging distance range DR1, the region where the first imaging unit 10 and the second imaging unit 20 are switched according to the conditions to perform imaging increases, and the reading accuracy can be improved. That is, the narrower the range of the first imaging distance range DR1, the higher the probability of decoding. On the other hand, since the focus drive unit 23 of the second image pickup unit 20 is used more frequently, which leads to an increase in power consumption and a decrease in life, it is preferable to set it according to the application.

In this way, the first imaging distance range DR1 is set, and the conditions for switching to imaging by the second imaging unit 20 are defined. Conversely, it can be said that the wider the first imaging distance range DR1 is set, the narrower the range for switching to the second imaging unit 20. Here, when the image is farther or closer than the first image pickup distance range DR1, the second image pickup unit 20 performs image pickup. That is, if the distance measured in step S901 of FIG. 9 is within the first imaging distance range DR1 indicated by the bold arrow in FIGS. 12 and 13 (step S902), the first imaging unit 10 performs imaging. In other words, it does not switch to the second imaging unit 20. If the measured distance is not within the first imaging distance range DR1, the second imaging unit 20 is not necessarily switched to imaging by the second imaging unit 20, but is activated through steps S903 to S911 in FIG. It will be judged whether or not it is possible.

The set distance range is, for example, directly specified by the user by directly inputting a distance or a numerical value for the first imaging distance range DR1 (for example, Acm to Bcm). Alternatively, a group of candidates for a distance range prepared in advance (for example, "first imaging unit priority" in which the first imaging distance range DR1 is widened, "second imaging unit priority" in which the first imaging distance range DR1 is narrowed ", the same. You may choose from the middle "balance" etc.). Further, as a method for setting the set distance range, a range for imaging by the second imaging unit 20 (for example, C cm or less, D cm or more) may be defined.

As described above, when the measured distance from the optical information reader 100 to the symbol is the first imaging distance range DR1 indicated by the bold arrow in FIGS. 12 and 13, the first imaging unit 10 is used. It will be an image. In these figures, the region indicated by cross-hatching is the region to be imaged using the first imaging unit 10, and the region indicated by the diagonal line is the region indicated by the diagonal line, and the first imaging unit 10 and the second imaging unit 20 are switched according to the conditions to perform imaging. Area Indicates the area. The alternate long and short dash line indicates the boundary of the region that can be imaged by the second image pickup unit 20, and the area PA between the alternate long and second dash line and the cross-hatched area can be read by the second image pickup unit 20 but not by the first image pickup unit 10. It becomes an area. Therefore, if the region PA includes the measured distance (indicated by ● in FIG. 12) and the position determined by the cell size of the symbol, the symbol can be read by switching to the second imaging unit 20. Therefore, as shown in FIG. 13, it is possible to reduce the reading error by setting the first imaging distance range DR1 to be narrow. However, since the area PA is narrow, in the setting of FIG. 12, in the first imaging distance range DR1 indicated by the bold arrow, it is specified to be read by the first imaging unit 10 without determining whether the second imaging unit 20 can be driven. are doing.

On the other hand, in FIG. 13, the first imaging distance range DR1 is set narrow. In this case, when the distance range for imaging by the first imaging unit 10 is narrow, for example, when the measured distance is the position indicated by ● in FIG. 13, a step of determining whether or not the second imaging unit 20 can be driven is performed. (Step S902 in FIG. 9), the possibility of reading is increased. With this setting, if the second imaging unit 20 is more suitable for reading, the possibility of using the second imaging unit 20 is high, and the reading probability is improved. However, as the frequency of use of the second image pickup unit 20 increases, the life of the optical information reading device 100 is relatively shortened. In other words, the smaller the width of the first imaging distance range DR1 indicated by the bold arrow, the higher the possibility of operating the second imaging unit 20, and conversely, the larger the width, the lower the possibility of operating the second imaging unit 20. Become. Therefore, it is preferable to set the first imaging distance range DR1 according to the user's usage environment. For example, it is desirable for a user who wants to keep the possibility of using the second imaging unit 20 as much as possible to reduce the width of the first imaging distance range DR1. Further, the width of the first imaging distance range DR1 can be set to zero. In this case, since the determination in step S902 of FIG. 9 described above always proceeds to YES, the second imaging unit 20 operates (imaging setting of the second imaging unit 20).

Next, a procedure for setting the imaging conditions for imaging in the second imaging unit 20 when driving the second imaging unit 20 will be described with reference to FIG. First, in step S1401, the calibration value set in advance by pre-calibration is read. In the pre-calibration, the relationship between the current value (I) and the focus position (D) of the VCM constituting the focus drive unit 23 is measured and stored in advance in the manufacturing process of the optical information reader 100. As a result, the equation I = F (D) as shown in FIG. 15 is obtained.

Next, in step S1402, the estimated distance is read. Here, the distance estimated from the aiming light described in step S704 of FIG. 7 described above is used. Next, in step S1403, the estimated current value of the drive current that drives the variable focus optical system 22 is calculated. Here, the drive current I of the VCM, which is the focus drive unit 23 for driving the variable focus optical system 22, and the relational expression I = F (D) of the distance D are calibrated and acquired in advance. Then, the current value required to move the estimated distance is estimated from the equation I = F (D) obtained by the pre-calibration.

Further, in step S1404, the brightness of the first imaging unit 10 is read. The brightness of the first imaging unit 10 is read from the brightness estimation value of the first imaging unit 10 calculated and stored in step S706 described above. Then, in step S1405, the brightness estimation value of the second imaging unit 20 is calculated from the brightness estimation value of the first imaging unit 10. Here, as shown in FIG. 16, the brightness of the first imaging unit 10 and the second imaging unit 20 are in a proportional relationship if the imaging conditions are the same, and the first imaging unit 10 obtained in step S1404 is used. The brightness estimation value of the second imaging unit 20 is estimated from the brightness estimation value of. Then, the focus position is adjusted in step S1406. Specifically, the variable focus optical system 22 is driven by the estimated current value calculated in step S1403 to adjust the focal position. Here, the current value I for VCM control is calculated using the distance D to be focused and the I = F (D) in FIG. 15 obtained by pre-calibration, and the VCM is calculated using this current value. It is driven and the variable focus optical system 22 is controlled so as to be in focus at the estimated distance.

Finally, in step S1407, the brightness setting is reflected in the second imaging unit 20. Specifically, the exposure time and gain of the second image sensor 21 are adjusted, and the amount of light of the second illumination unit 24 is adjusted so as to be the brightness estimated value of the second image pickup unit 20 estimated in step S1405. do. Further, in the initial brightness setting of the second imaging unit 20, the initial brightness value of the second imaging unit 20 and the presence / absence of illumination may be determined based on the exposure time and gain imaged by the first imaging unit 10. This makes it possible to reduce the number of trial imagings for adjusting the brightness. After setting the imaging conditions of the second image pickup unit 20 in this way, the second image pickup unit 20 performs image pickup and acquires the second image data.

The order of the above-mentioned settings is an example, and the order of each process may be changed. For example, the brightness of steps S1401 to S144 to S1405 may be set prior to the setting of the focal position in steps S1401 to S1403, or the focal position setting and the brightness setting may be set at the same time or in parallel. You may go there.
[Modification example]

The procedure for taking an image in the first imaging unit 10 is not limited to the above-mentioned procedure. For example, it was found that the timing for determining whether or not imaging by the second imaging unit 20 is necessary cannot be decoded with respect to the first image data subjected to the main imaging process by the first imaging unit 10 as shown in FIG. It may be done before this instead of when it is done. Such an example will be described with reference to the flowchart of FIG. 17 as an optical information reading method according to a modified example. Here, too, the procedure for performing imaging by the first imaging unit 10 is shown.

First, in step S1701, a trigger start operation is performed. Next, in step S1702, the work is irradiated with aiming light. Then, in step S1703, an Aimer image is taken. Further, in step S1704, the distance is estimated based on the Aimer image. The procedure up to this point is the same as in steps S701 to S704 of FIG. 7 described above.

Next, in step S1705, it is determined whether or not imaging by the second imaging unit 20 is necessary. The specific procedure for determining the necessity of imaging by the second imaging unit 20 is as shown in FIG. Then, if imaging by the second imaging unit 20 is required, the procedure proceeds to the procedure shown in FIG. On the other hand, if imaging by the second imaging unit 20 is unnecessary, the process proceeds to step S1706, and the first imaging unit 10 performs the main imaging process. Then, in step S1707, the decoding process of the first image data is performed. Further, in step S1708, it is determined whether or not decoding is possible. If the decoding is successful, the reading is successful (step S1709), and the process ends. On the other hand, if it is determined in step S1708 that decoding is not possible, the process returns to step S170 and the process is repeated.
(Procedure in the second imaging unit 20)

Next, the procedure seen from the second imaging unit 20 will be described with reference to the flowchart of FIG. First, in step S1801, it is determined whether or not there is a command to drive the second imaging unit 20. If there is no instruction, the process ends. If there is a command, the process proceeds to step S1802 to set the image pickup of the second image pickup unit 20. Here, the imaging conditions for capturing the second image data by the second imaging unit 20, for example, the focal position of the variable focus optical system 22, the shutter speed of the second imaging element 21, the brightness of the second lighting unit 24, and the like are set. do.

Next, in step S1803, the second imaging unit 20 performs an imaging process. That is, the second image data is imaged by the second image pickup unit 20 according to the set image pickup conditions. Then, the reading control unit 42 executes the decoding process of the second image data captured by the second image pickup unit 20 (step S1804), and determines whether or not the symbol can be decoded (step S1805). If decoding cannot be performed, the process returns to step S1802 and the above process is repeated. On the other hand, if the decoding is successful, the reading is successful (step S1806), and the process is terminated.

The optical information reading device and the optical information reading method of the present invention are handy scanners used in warehouses, factories, stores, hospitals, etc. that read symbols such as barcodes and two-dimensional codes to register and collate data. It can be suitably used for handy terminals, commercial PDA, etc.

100 ... Optical information reader 1 ... Image pickup module 2 ... Housing 3 ... Display unit 4 ... Inclined surface 5 ... Optical window 10 ... First image pickup unit 11 ... First image pickup element 12 ... Fixed focus optical system 14 ... First illumination Unit 15 ... Aiming light irradiation unit 20 ... Second image pickup unit 21 ... Second image pickup element 22 ... Variable focus optical system 23 ... Focus drive unit 24 ... Second illumination unit 25 ... Second image pickup unit housing 25B ... Substrate 26 ... Spring 27 ... Lens unit 28 ... Coil 29 ... Magnet 30 ... Key arrangement unit 40 ... Control unit 42 ... Read control unit 49 ... Focus control unit 50 ... Communication interface 51 ... RAM
52 ... Storage unit DA ... Display part; HA ... Grip part SB ... Symbol BC ... Bar code AL ... Aiming light PA ... Area between the alternate long and short dash line and the cross-hatched area DR1 ... First imaging distance range

Claims (20)

An optical information reader that captures a symbol to be read and reads the information of the symbol.
A fixed-focus optical system that collects the reflected light that is incident on the symbol and reflected by the symbol,
A first image pickup unit including a first image pickup element that converts light focused by the fixed focus optical system into an electric signal and generates first image data.
A variable focus optical system that receives the reflected light that is incident on the symbol and reflected by the symbol,
A second image sensor that converts the light focused by the variable focus optical system into an electrical signal and generates second image data.
A focus drive unit that changes the focal position of the variable focal optical system,
The second imaging unit including
A control unit capable of reading symbol information based on the first image data generated by the first image pickup unit and the second image data generated by the second image pickup unit is provided.
The control unit analyzes the first image data generated by the first imaging unit, and when it is determined that the imaging by the first imaging unit is inappropriate for reading the symbol, the second imaging unit The focal position of the variable focus optical system required to capture an image in which the symbol is focused is calculated, and the focus drive unit is controlled so as to match the focal position of the variable focus optical system with the focal position. An optical information reader configured to read the symbol information based on the second image data focused on the symbol generated by the second imaging unit. The optical information reader according to claim 1.
The second image sensor is configured to be capable of capturing an optical image of an object with a symbol, regardless of whether or not the control unit determines whether or not the second image pickup device is suitable for reading the symbol in the image pickup by the first image pickup unit. Ori,
An optical information reading device configured to store an optical image of the object in association with the symbol information read by the control unit. The optical information reader according to claim 2.
An optical information reader configured such that the second image sensor can be set so that the focus driving unit does not move the variable focus optical system when an optical image of an object with a symbol is imaged. The optical information reader according to any one of claims 1 to 3, further comprising.
It is provided with an aiming light irradiation unit that irradiates aiming light adjacent to the fixed focus optical system.
The control unit is an optical information reading device configured to estimate the distance to the symbol based on the Aimer image captured by the first imaging unit from the image including the aiming light irradiated by the aiming light irradiation unit. .. The optical information reading device according to claim 4.
When the control unit determines that the reading of the symbol using the first imaging unit is inappropriate, the focal length of the variable focus optical system is matched with the distance to the symbol calculated based on the aimer image. An optical information reader configured to drive the focal length drive unit. The optical information reader according to claim 5.
The control unit is configured to control the focus drive unit according to the relational expression I = F (D) of the focal length D of the second image pickup unit and the drive current I for driving the focus drive unit, which is stored in advance. Optical information reader. The optical information reader according to any one of claims 4 to 6.
Whether the control unit can appropriately read the symbol by the image pickup by the first image pickup unit based on the distance to the symbol calculated by analyzing the aimer image using the aimer image as the first image data. An optical information reader configured to determine whether or not. The optical information reader according to any one of claims 4 to 6.
The control unit uses the main image pickup data not including the aiming light captured by the first image pickup unit after the acquisition of the aimer image as the first image data, and uses the main image pickup data as the first image image to symbolize the image pickup by the first image pickup unit. An optical information reader configured to determine whether or not the image can be read properly. The optical information reader according to any one of claims 1 to 8, further comprising:
The first illumination unit for the fixed focus optical system and
It is provided with a second illumination unit for the variable focus optical system.
An optical information reader in which the first illumination unit, the fixed focus optical system, the variable focus optical system, and the second illumination unit are arranged in a straight line. The optical information reader according to any one of claims 1 to 9.
An optical information reader whose resolution of the first image pickup unit is lower than that of the second image pickup unit. The optical information reader according to any one of claims 1 to 10.
An optical information reading device in which the imaging field of view of the first imaging unit is narrower than the imaging field of view of the second imaging unit. The optical information reader according to any one of claims 1 to 11.
The first image sensor is an image sensor that captures a monochrome image.
The second image sensor is an image sensor that captures a color image.
An optical information reader configured to be able to read symbols using color difference information. The optical information reader according to any one of claims 1 to 12.
An optical information reader that includes any of the resolution, visual field range, and contrast of the first image data as a criterion for the control unit to analyze the first image data and determine whether or not it is inappropriate for reading the symbol. .. The optical information reader according to any one of claims 1 to 13.
The control unit calculates the resolution of the symbol to be read from the image data generated by the first image pickup unit.
When the resolution calculated by the control unit is equal to or less than a predetermined threshold value, the first image data generated by the first image pickup unit is configured to be determined to be unsuitable for reading the symbol. Optical information reader. The optical information reader according to any one of claims 1 to 14.
The control unit calculates the required field of view of the symbol to be read from the first image data generated by the first image pickup unit.
When the required visual field calculated by the control unit is equal to or higher than a predetermined threshold value, it is configured to determine that the first image data generated by the first imaging unit is inappropriate for reading the symbol. Optical information reader. The optical information reader according to any one of claims 1 to 15.
The control unit calculates the contrast of the symbol to be read from the first image data generated by the first image pickup unit.
When the contrast calculated by the control unit is equal to or less than a predetermined threshold value, the first image data generated by the first image pickup unit is configured to be determined to be unsuitable for reading the symbol. Optical information reader. The optical information reader according to any one of claims 1 to 16.
The control unit
A reading control unit capable of reading symbol information based on the first image data generated by the first image pickup unit and the second image data generated by the second image pickup unit.
An optical information reading device including a focus control unit for controlling the focus drive unit of the second image pickup unit. The optical information reader according to any one of claims 1 to 17, further comprising.
A unidirectionally extended housing comprising a first main surface and a second main surface facing the first main surface and having a partially projecting portion on the second main surface side.
A display unit provided on the first main surface side of the housing for displaying the second image data generated by the second image pickup unit, and a display unit.
An optical information reader equipped with. The optical information reading device according to claim 18.
The protrusion
An inclined surface inclined with respect to the second main surface,
It has an optical window adjacent to the inclined surface and has an optical window.
The first image sensor and the second image sensor are arranged side by side in a posture facing the optical window inside the protrusion.
An optical information reader in which the optical axes of the first image sensor and the second image sensor are inclined in a direction along the inclined surface with respect to the longitudinal direction of the housing through the optical window. It is an optical information reading method that captures a symbol to be read and reads the information of the symbol.
A fixed-focus optical system that collects the reflected light that is incident on the symbol and reflected by the symbol,
A step of capturing the first image data including a symbol by a first image pickup unit including a first image pickup element that converts the light focused by the fixed focus optical system into an electric signal and generates the first image data. When,
The process of analyzing the first image data in the control unit,
As a result of the analysis by the control unit, when it is determined that the first image data is inappropriate for reading the symbol, based on the result of the analysis,
A variable focus optical system that receives the reflected light that is incident on the symbol and reflected by the symbol,
In order to capture an image in focus on a symbol in a second image pickup unit including a second image pickup element that converts the light focused by the variable focus optical system into an electric signal and generates a second image data. The step of calculating the required focal position of the variable focal point optical system and
A step in which the focus driving unit that changes the focal position of the variable focus optical system matches the focal position of the variable focus optical system with the focal position according to the calculation result by the control unit.
A step of reading the symbol information by the control unit based on the second image data focused on the symbol generated by the second image pickup unit.
Optical information reading method including.

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