Image position inspecting apparatus, computer-readable medium and image forming apparatus
View Patent ↗An image position inspecting apparatus includes a reading unit, a generating unit and a specifying unit. The reading unit includes light receiving elements arranged with a reading resolution Rs and reads an inspection image. The generating unit generates a profile based on the read inspection image. The specifying unit acquires a position of the center of gravity of the pixels of the inspection image with respect to the light receiving elements from the profile and specifies a position of each of the pixels of the inspection image based on a phase difference which is a deviation of the acquired position of the center of gravity of the pixels with respect to a light receiving center of the light receiving elements. A resolution of the inspection image is Rp. The reading resolution Rs and the resolution Rp satisfy the following equation. And, m is a positive integer. Rp·((m+1)/2)<Rs<Rp·((m+2)/2).
1. An image position inspecting apparatus, comprising:
a reading unit that includes light receiving elements arranged in a main scanning direction crossing a conveying direction of a recording media and that reads an inspection image formed on the recording media one pixel by one pixel at intervals of the same number of pixels along the main scanning direction;
a computer that generates a profile along a main scanning direction of the inspection image based on the inspection image read by the image reading unit; and
a computer that acquires a position of the center of gravity of the pixels of the inspection image with respect to the light receiving elements from the profile and that specifies a position of each of the pixels of the inspection image in the main scanning direction based on a phase difference, the phase difference being a deviation of the acquired position of the center of gravity of the pixels in the inspection image with respect to a light receiving center of the light receiving elements,
wherein, when a reading resolution of the image reading unit along the main scanning direction is Rs and a resolution of the inspection image along the main scanning direction is Rp, the reading resolution of the image reading unit and the resolution of the inspection image satisfy the following equation:
Rp ·(( m+ 1)/2)< Rs<Rp ·(( m+ 2)/2),
m is a positive integer.
2. The image position inspecting apparatus according to claim 1 ,
wherein the computer acquires the position of the center of gravity of the pixels by a parabolic approximation from brightness information of the light receiving elements of three points corresponding to the pixels of the profile.
3. The image position inspecting apparatus according to claim 2 , further comprising:
a correction table that corrects the position of the center of gravity according to the phase difference of the pixels with respect to the light receiving elements.
4. The image position inspecting apparatus according to claim 3 ,
wherein the correction table is generated from the profile.
5. An image forming apparatus, comprising:
the image position inspecting apparatus according to claim 1 ; and
an image forming unit that includes ejection heads in which nozzles ejecting droplets are arranged along the main scanning direction and that forms an image based on image information by droplets ejected from the nozzles of the ejection heads according to the image information.
6. The image forming apparatus according to claim 5 ,
wherein the image position inspecting apparatus includes:
a computer that determines whether the pixel position is suitable based on a position of the main scanning direction of the pixels, the pixels formed on the recording media by the droplets ejected from the nozzles specified by the image position inspecting apparatus; and
a correcting unit that specifies the nozzle corresponding to the pixel which is determined as unsuitable by the determining unit and that corrects the image information so as to complement the pixel corresponding to the specified nozzle with droplets ejected from another nozzle which is adjacent to the specified nozzle.
7. An image position inspecting apparatus, comprising:
a reading unit that includes light receiving elements arranged with a reading resolution Rs in a main scanning direction crossing a conveying direction of a recording media and that reads an inspection image formed on the recording media one pixel by one pixel at intervals of the same number of pixels along the main scanning direction, a resolution of the inspection image being Rp;
a computer that generates a profile along a main scanning direction of the inspection image based on the inspection image read by the image reading unit; and
a computer that acquires a position of the center of gravity of the pixels of the inspection image with respect to the light receiving elements from the profile and that specifies a position of each of the pixels of the inspection image in the main scanning direction based on a phase difference, the phase difference being a deviation of the acquired position of the center of gravity of the pixels in the inspection image with respect to a light receiving center of the light receiving elements,
wherein at least three pixels of the pixels neighboring each other in the main scan direction are opposed to at least three elements of the light receiving elements each of which comprises a sensing area having a predetermined width in the main scan direction, and
the three pixels are opposed to the three elements at different positions within the predetermined widths of the sensing areas, respectively.