Printing apparatus and printing method

A printing apparatus prints by making a printing head do printing scan for a unit area of the print medium by 2M+1 times (M is an integer larger than 1) comprising:

• dividing unit which divides image data that should be printed in the unit area into 2M+1 pieces of image data for the 2M+1 times printing scan (Pass 1 to Pass 2M+1) by using a mask:
• the mask setting printable areas included in the unit area for each of the 2M+1 times printing scan respectively, so that plural dots of the same color may be printed at the same area at least by two printing scan;
• and
• printing unit which prints dots in the printable areas by each of the 2M+1 times printing scan (Pass 1 to Pass 2M+1) according to the divided image data;
• wherein the mask is configured so that
• i) a ratio of the printable areas in which printing is permitted both bypasses performed before Pass (M+1) and by passes performed after Pass M and a ratio of the printable areas in which printing is permitted both by passes performed before Pass (M+2) and by passes performed after Pass (M+1) are larger than a ratio of the printable areas in which printing is permitted both by passes performed before Pass (N+1) (N is an integer differing from M or M+1 and smaller than 2M) and by passes performed after Pass N,
• ii) as for a combination of S and T (S and T are different and positive integer smaller than 2M), a difference between a ratio of the printable areas in which printing is permitted both by passes performed before Pass (S+1) and by passes performed after Pass S and a ratio of the printable areas in which printing is permitted both by passes performed before Pass (S+2) and by passes performed after Pass (S+1), is different from a difference between a ratio of the areas in which printing is permitted both by passes performed before Pass (T+1) and by passes performed after Pass T and a ratio of the printable areas in which printing is permitted both by passes performed before Pass (T+2) and by passes performed after Pass (T+1).

A printing method for printing by making a printing head do printing scan for a unit area of the print medium by 2M times (M is an integer larger than 1) comprising:

• dividing step to divide image data that should be printed in the unit area into 2M pieces of image data for the 2M times printing scan (Pass 1 to Pass 2M) by using a mask:
• the mask setting printable areas included in the unit area for each of the 2M times printing scan respectively, so that plural dots of the same type of color may be printed at the same area at least by two printing scan;
• and
• printing step to print dots in the printable areas by each of the 2M times printing scan (Pass 1 to Pass 2M) according to the divided image data;
• wherein the mask is configured so that
• i) a ratio of the printable areas in which printing is permitted both by passes performed before Pass (M+1) and by passes performed after Pass M is larger than a ratio of the printable areas in which printing is permitted both by passes performed before Pass (N+1) (N is an integer differing from M and smaller than 2M) and by passes performed after Pass N,
• ii) a ratio of the printable areas in which printing is permitted both by passes performed before Pass (M−L+1) (L is a positive integer smaller than M) and by passes performed after Pass (M−L) is smaller than a ratio of the printable areas in which printing is permitted both by passes performed before Pass (M−L+2) and by passes performed after Pass (M−L+1), and a ratio of the printable areas in which printing is permitted both by passes performed before Pass (M+L+1) and by passes performed after Pass (M+L) is larger than a ratio of the printable areas in which printing is permitted both by passes performed before Pass (M+L+2) and by passes performed after Pass (M+L+1),
• iii) as for at least one combination of S and T (S and T are different and positive integer smaller than 2M), a difference between a ratio of the printable areas in which printing is permitted both by passes performed before Pass (S+1) and by passes performed after Pass S and a ratio of the printable areas in which printing is permitted both by passes performed before Pass (S+2) and by passes performed after Pass (S+1), is different from a difference between a ratio of the printable areas in which printing is permitted both by passes performed before Pass (T+1) and by passes performed after Pass T and a ratio of the printable areas in which printing is permitted both by passes performed before Pass (T+2) and by passes performed after Pass (T+1).

A printing method for printing by making a printing head do printing scan for a unit area of the print medium by 2M+1 times (M is an integer larger than 1) comprising:

• dividing step to divide image data that should be printed in the unit area into 2M+1 pieces of image data for the 2M+1 times printing scan (Pass 1 to Pass 2M+1) by using a mask:
• the mask setting printable areas included in the unit area for each of the 2M+1 times printing scan respectively, so that plural dots of the same type of color may be printed at the same area at least by two printing scan;
• and
• printing step which prints dots in the printable areas by each of the 2M+1 times printing scan (Pass 1 to Pass 2M+1) according to the divided image data;
• wherein the mask is configured so that
• i) a ratio of the printable areas in which printing is permitted both by passes performed before Pass (M+1) and by passes performed after Pass M and a ratio of the printable areas in which printing is permitted both by passes performed before Pass (M+2) and by passes performed after Pass (M+1) are larger than a ratio of the printable areas in which printing is permitted both by passes performed before Pass (N+1) (N is an integer differing from M or M+1 and smaller than 2M) and by passes performed after Pass N,
• ii) as for a combination of S and T (S and T are different and positive integer smaller than 2M), a difference between a ratio of the printable areas in which printing is permitted both by passes performed before Pass (S+1) and by passes performed after Pass S and a ratio of the printable areas in which printing is permitted both by passes performed before Pass (S+2) and by passes performed after Pass (S+1), is different from a difference between a ratio of the printable areas in which printing is permitted both by passes performed before Pass (T+1) and by passes performed after Pass T and a ratio of the printable areas in which printing is permitted both by passes performed before Pass (T+2) and by passes performed after Pass (T+1).