News Column

Patent Issued for Optical Detection Device for Detecting the Position of an Object by Using Emission Current Control Information

June 25, 2014



By a News Reporter-Staff News Editor at Journal of Engineering -- Seiko Epson Corporation (JP) has been issued patent number 8748858, according to news reporting originating out of Alexandria, Virginia, by VerticalNews editors.

The patent's inventor is Nakanishi, Daisuke (Matsumoto, JP).

This patent was filed on June 3, 2011 and was published online on June 10, 2014.

From the background information supplied by the inventors, news correspondents obtained the following quote: "The present invention relates to a processing device, an optical detection device, a display device, and so on.

"In the electronic devices such as a cellular phone a personal computer, a car navigation device, a ticket-vending machine, or a banking terminal, there is used in recent years a display device provided with a position detection function having a touch panel disposed on the front surface of the display section. According to the display device, it becomes possible for the user to point an icon or the like in a display image or input information while referring to the image displayed on the display section. As a position detection method using such a touch panel, there are known a resistive film type and a capacitance type, for example.

"On the other hand, the display devices for projection display devices (projectors) and digital signage have a larger display area compared to the display devices for cellular phones and personal computers. Therefore, in these display devices, it is difficult to realize the position detection using the resistive touch panels and the capacitance touch panels described above.

"Further, as the related art of the position detection device for the projection display devices, there are known the technologies disclosed in, for example, JP-A-11-345085 and JP-A-2001-142643. However, in the position detection devices, there arise the problems that the scale of the system becomes large and that the position detection is affected by the reflectance of the object."

Supplementing the background information on this patent, VerticalNews reporters also obtained the inventor's summary information for this patent: "An advantage of some aspects of the invention is to provide a processing device, an optical detection device, a display device, an electronic apparatus, and so on capable of reducing, for example, the influence of the reflectance of the object to thereby perform detection with high accuracy.

"An aspect of the invention relates to a processing device including a control section adapted to perform emission control of a first light source section and a second light source section based on a light reception result of a light receiving section adapted to receive a reflected light beam caused by an object reflecting irradiation light beams from the first light source section and the second light source section, and a determination section adapted to determine a positional relationship of the object with respect to the first light source section and the second light source section based on emission current control information for performing the emission control, wherein the determination section determines the positional relationship between the first and second light source sections and the object based on first period emission current control information as the emission current control information in a first period in which the object fails to exist in a detection area as an area where the object is detected and second period emission current control information as the emission current control information in a second period in which the object exists in the detection area.

"According to this aspect of the invention, since the determination section can determine the positional relationship of the object based on the emission current control information in the first period and the emission current control information in the second period, it becomes possible to reduce the influence of the outside light (the environment light) such as the sunlight, the influence of the initial path of the irradiation light beam, and so on. As a result, improvement of the position detection accuracy becomes possible.

"Further, according to the aspect of the invention, it is also possible that the light receiving section further receives an irradiation light beam from a reference light source section, the control section performs the emission control of the first light source section, the second light source section, and the reference light source section based on the light reception result in the light receiving section, and the determination section determines the positional relationship between the first and second light source sections and the object based on the first period emission current control information and the second period emission current control information for performing the emission control of the first light source section, the second light source section, and the reference light source section.

"According to this configuration, since the determination section can determine the positional relationship of the object based on the emission current control information of not only the first and second light source sections but also the reference light source section, it becomes possible to reduce the influence of the reflectance varying between the objects. As a result, it becomes possible to, for example, improve the position detection accuracy without being affected by the reflectance of the object.

"Further, according to the aspect of the invention, it is also possible that the control section performs, in the first period, the emission control of the first light source section and the reference light source section so that the light reception result of the light receiving section when the first light source section emits the light beam and the light reception result of the light receiving section when the reference light source section emits the light beam become equal to each other, and the emission control of the second light source section and the reference light source section so that the light reception result of the light receiving section when the second light source section emits the light beam and the light reception result of the light receiving section when the reference light source section emits the light beam become equal to each other, and the control section performs, in the second period, the emission control of the first light source section and the reference light source section so that the light reception result of the light receiving section when the first light source section emits the light beam and the light reception result of the light receiving section when the reference light source section emits the light beam become equal to each other, and the emission control of the second light source section and the reference light source section so that the light reception result of the light receiving section when the second light source section emits the light beam and the light reception result of the light receiving section when the reference light source section emits the light beam become equal to each other.

"According to this configuration, since it is possible for the control section to compare the light reception result when the first light source section emits the light beam and the light reception result when the reference light source section emits the light beam with each other to thereby perform the emission control so that the both results become equal to each other, it becomes possible to perform the stable emission control using, for example, a comparator circuit.

"Further, according to the aspect of the invention, it is also possible that the control section outputs, in the first period, primary first period emission current control information for setting currents respectively flow through the first light source section and the reference light source section to the determination section so that the light reception result of the light receiving section when the first light source section emits the light beam and the light reception result of the light receiving section when the reference light source section emits the light beam become equal to each other, and secondary first period emission current control information for setting currents respectively flow through the second light source section and the reference light source section to the determination section so that the light reception result of the light receiving section when the second light source section emits the light beam and the light reception result of the light receiving section when the reference light source section emits the light beam become equal to each other, and the control section outputs, in the second period, primary second period emission current control information for setting currents respectively flow through the first light source section and the reference light source section to the determination section so that the light reception result of the light receiving section when the first light source section emits the light beam and the light reception result of the light receiving section when the reference light source section emits the light beam become equal to each other, and secondary second period emission current control information for setting currents respectively flow through the second light source section and the reference light source section to the determination section so that the light reception result of the light receiving section when the second light source section emits the light beam and the light reception result of the light receiving section when the reference light source section emits the light beam become equal to each other, and the determination section determines the positional relationship of the object with respect to the first light source section and the second light source section based on the primary first period emission current control information, the secondary first period emission current control information, the primary second period emission current control information, and secondary second period emission current control information.

"According to this configuration, since the determination section can determine the positional relationship of the object based on the primary and secondary first period emission current control information and the primary and secondary second period emission current control information, it becomes possible to reduce the influence of the outside light (the environment light) such as the sunlight, the influence of the initial path of the irradiation light beam, the influence of the reflectance varying between the objects, and so on. As a result, it becomes possible to improve the position detection accuracy and to detect the objects with the reflectance different from each other.

"Further, according to the aspect of the invention, it is also possible that, assuming that current setting values of the currents respectively flowing through the first light source section and the reference light source section, which correspond to the primary first period emission current control information, are IA1 and IB1, current setting values of the currents respectively flowing through the second light source section and the reference light source section, which correspond to the secondary first period emission current control information, are IA2 and IB2, current setting values of the currents respectively flowing through the first light source section and the reference light source section, which correspond to the primary second period emission current control information, are IA1d and IB1d, current setting values of the currents respectively flowing through the second light source section and the reference light source section, which correspond to the secondary second period emission current control information, are IA2d and IB2d, a value of a first function representing the positional relationship of the object with respect to the first light source section is FA1, a value of a second function representing the positional relationship of the object with respect to the second light source section is FA2, and a ratio between the value FA1 of the first function and the value FA2 of the second function is FR, the determination section determines the positional relationship of the object with respect to the first light source section and the second light source section by obtaining the ratio FR between the value FA1 of the first function and the value FA2 of the second function using the following relational expression. FR=(IB2.times.IA1.times.IB1d/IA1d-IB1.times.IB2)/(IB1.times.IA2.times.IB2- d/IA2d-IB1.times.IB2)

"According to this configuration, since the determination section can determine the positional relationship of the object with respect to the first and second light source sections based on the current setting values of the respective light source sections as the emission current control information.

"Further, according to the aspect of the invention, it is also possible that the control section performs, in the first period, the emission control of the first light source section and the second light source section so that the light reception result of the light receiving section when the first light source section emits the light beam and the light reception result of the light receiving section when the second light source section emits the light beam become equal to each other, and the control section performs, in the second period, the emission control of the first light source section and the second light source section so that the light reception result of the light receiving section when the first light source section emits the light beam and the light reception result of the light receiving section when the second light source section emits the light beam become equal to each other.

"According to this configuration, since the control section can perform the emission control without using the reference light source section, it becomes possible to perform the efficient position detection with a simple configuration.

"Further, according to the aspect of the invention, it is also possible that the control section outputs, in the first period, the first period emission current control information for setting currents respectively flow through the first light source section and the second light source section to the determination section so that the light reception result of the light receiving section when the first light source section emits the light beam and the light reception result of the light receiving section when the second light source section emits the light beam become equal to each other, and the control section outputs, in the second period, the second period emission current control information for setting currents respectively flow through the first light source section and the second light source section to the determination section so that the light reception result of the light receiving section when the first light source section emits the light beam and the light reception result of the light receiving section when the second light source section emits the light beam become equal to each other, and the determination section determines the positional relationship of the object with respect to the first light source section and the second light source section based on the first period emission current control information and the second period emission current control information.

"According to this configuration, since it is possible for the control section to compare the light reception result when the first light source section emits the light beam and the light reception result when the second light source section emits the light beam with each other to thereby perform the emission control so that the both results become equal to each other, it becomes possible to perform the stable emission control using, for example, a comparator circuit.

"Further, according to the aspect of the invention, it is also possible that, assuming that current setting values of the currents respectively flowing through the first light source section and the second light source section, which correspond to the first period emission current control information, are IA1 and IA2, current setting values of the currents respectively flowing through the first light source section and the second light source section, which correspond to the second period emission current control information, are IA1d and IA2d, a value of a first function representing the positional relationship of the object with respect to the first light source section is FA1, a value of a second function representing the positional relationship of the object with respect to the second light source section is FA2, and a ratio between the value FA1 of the first function and the value FA2 of the second function is FR, the determination section determines the positional relationship of the object with respect to the first light source section and the second light source section by obtaining the ratio FR between the value FA1 of the first function and the value FA2 of the second function using the following relational expression. FR=(IA1.times.IA2d)/(IA2.times.IA1d)

"According to this configuration, since the determination section can determine the positional relationship of the object with respect to the first and second light source sections based on the current setting values of the respective light source sections as the emission current control information.

"Another aspect of the invention relates to an optical detection device including any one of the processing devices described above.

"Further, according to this aspect of the invention, it is possible to include an irradiation section including the first light source section and the second light source section, and the light receiving section adapted to receive the reflected light beam caused by the object reflecting the irradiation light beam from the irradiation section.

"According to this configuration, it is possible that the control section performs the emission control based on the light reception result of the light receiving section adapted to receive the reflected light caused by the object reflecting the irradiation light beams from the first and second light source sections of the irradiation section, and the determination section determines the positional relationship of the object based on the emission current control information.

"Further, according to this aspect of the invention, it is possible that the irradiation section includes a light guide having a curved shape and adapted to guide a first source light beam from the first light source section and a second source light beam from the second light source section along a curved light guide path, and an irradiation direction setting section adapted to receive the first source light beam and the second source light beam emitted from an outer circumferential side of the light guide and set the irradiation direction of the irradiation light beam to a direction from an inner circumferential side toward the outer circumferential side of the light guide having the curved shape.

"According to this configuration, since it is possible to form two irradiation light intensity distributions by making the first and second light source sections alternately emit light beams, it becomes possible to reduce the influence of the outside light such as the sunlight to thereby improve the position detection accuracy.

"Still another aspect of the invention relates to a display device and an electronic apparatus including any one of the optical detection devices described above."

For the URL and additional information on this patent, see: Nakanishi, Daisuke. Optical Detection Device for Detecting the Position of an Object by Using Emission Current Control Information. U.S. Patent Number 8748858, filed June 3, 2011, and published online on June 10, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8748858.PN.&OS=PN/8748858RS=PN/8748858

Keywords for this news article include: Seiko Epson Corporation.

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Source: Journal of Engineering


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