Image-forming device

• US 20060285166A1
• Filed: 06/16/2006
• Published: 12/21/2006
• Est. Priority Date: 06/17/2005
• Status: Active Grant

• Current Assignee: Brother Kogyo Kabushiki Kaisha
• Original Assignee: Brother Kogyo Kabushiki Kaisha
• Inventors: Ikeno, Takahiro, Kuno, Takeshi
• Granted Patent: US 7,639,395 B2
• Time in Patent Office: Days
• US Class Current: 358/3.120
• CPC Class Codes: G03G 15/0856 Detection or control means for the developer level
• CPC Class Codes: G03G 15/556 for toner consumption, e.g. pixel counting, toner coverage detection or toner density measurement
• CPC Class Codes: H04N 1/2346 according to a detected condition or state of the reproducing device, e.g. temperature or ink quantity
• CPC Class Codes: H04N 1/295 Circuits or arrangements for the control thereof, e.g. using a programmed control device, according to a measured quantity
• CPC Class Codes: H04N 1/40006 Compensating for the effects of ageing, i.e. changes over time
• CPC Class Codes: H04N 1/40037 the reproducing element being a laser

Abstract

An image-forming device includes: a data conversion unit; an isolated-dot size determining unit; and an image-forming unit. The data conversion unit converts, for each of a plurality of pixels in an image to be formed, original image data indicative of a multilevel density into dot data indicative of whether or not a dot should be formed. The isolated-dot size determining unit determines the size of an isolated dot according to a condition. The image-forming unit forms an image on a recording medium by selectively forming a dot for each pixel based on the dot data, while forming the isolated dot with the determined size.

Claims

1. An image-forming device comprising:

a data conversion unit converting, for each of a plurality of pixels in an image to be formed, original image data indicative of a multilevel density into dot data indicative of whether or not a dot should be formed;

an isolated-dot size determining unit that determines the size of an isolated dot according to a condition; and

an image-forming unit forming an image on a recording medium by selectively forming a dot for each pixel based on the dot data, while forming the isolated dot with the determined size.

2. An image-forming device according to claim 1, wherein the isolated-dot size determining unit determines the size of the isolated dot according to color at which the isolated dot should be formed.

3. An image-forming device according to claim 1, wherein the data conversion unit is capable of converting a first type of original image data indicative of a density among a first number of different density levels into the dot data, and is capable of converting a second type of original image data indicative of a density among a second number of different density levels into the dot data, the second number being smaller than the first number, and

wherein the isolated-dot size determining unit determines the size of the isolated dot obtained from the first type of original image data to be smaller than the size of the isolated dot obtained from the second type of original image data.

4. An image-forming device according to claim 3, wherein the first type of original image data is indicative of a photographic image, and the second type of original image data is indicative of a text image.

5. An image-forming device according to claim 1, further comprising:

a developer-accommodating unit accommodating developer, the image-forming unit forming the image by using the developer accommodated in the developer-accommodating unit; and

a consumption-detecting unit detecting the amount of developer consumed from the developer-accommodating unit,

wherein the isolated-dot size determining unit determines the size of the isolated dot so that the size of the isolated dot that is determined when the amount of consumed developer reaches a reference amount is greater than the size of the isolated dot that is determined when the amount of consumed developer does not reach the reference amount.

6. An image-forming device according to claim 1, further comprising:

a resolution determining unit determining whether a resolution, by which the image-forming unit should form the image, is a first resolution or a second resolution smaller than the first resolution; and

a resolution-dependent-controlling unit that controls, when the resolution is the first resolution, the isolated-dot size determining unit to determine the size of the isolated dot according to the condition, and that controls, when the resolution is the second resolution, the isolated-dot size determining unit to determine the size of the isolated dot to a predetermined value regardless of the condition.

7. An image-forming device according to claim 1, wherein the isolated-dot size determining unit determines the size of an isolated dot as either one of a size that is greater than a size of a non-isolated dot and another size that is equal to the size of the non-isolated dot according to the condition,

wherein the image-forming unit forms the image based on the dot data when the isolated-dot size determining unit determines the size of the isolated dot as the size equal to the size of the non-isolated dot and a ratio of the number of the isolated dots relative to the total number of dots in the image to be formed is smaller than a threshold and when the isolated-dot size determining unit determines the size of the isolated dot as the another size greater than the size of the non-isolated dot,

further comprising a density increasing unit increasing the multilevel density of the original image data when the isolated-dot size determining unit determines the size of the isolated dot as the size equal to the size of the non-isolated dot and the ratio of the isolated dots relative to the total number of dots in the image is greater than or equal to the threshold, the data conversion unit converting, for each pixel, the density-increased original image data into dot data.

8. An image-forming device comprising:

a data conversion unit converting, for each of a plurality of pixels in an image to be formed, original image data indicative of a multilevel density into dot data indicative of whether or not a dot should be formed;

an image-forming unit forming an image on a recording medium by selectively forming a dot for each pixel based on the dot data;

a mode-setting unit setting a mode of the image-forming unit to either one of a first gradation mode in which the data conversion unit converts a first type of image data into dot data, and a second gradation mode in which the data conversion unit converts a second type of image data into dot data, the first type of image data indicating a density level among a first number of density levels, the second type of image data indicating a density level among a second number of density levels, the second number being smaller than the first number; and

a controlling unit controlling the image-forming unit to execute a dot modification process to form images of isolated dots in the first gradation mode with sizes smaller than images of isolated dots formed in the second gradation mode.

9. An image-forming device according to claim 8, wherein the data conversion unit converts image data of photographic images into dot data in the first gradation mode, and converts image data of text images into dot data in the second gradation mode.

10. An image-forming device according to claim 8, wherein the controlling unit controls the image-forming unit to execute the dot modification process when forming images at a first resolution and to fail to execute the dot modification process when forming images at a second resolution lower than the first resolution.

11. An image-forming device according to claim 8, wherein the controlling unit controls the image-forming unit to execute the dot modification process to modify the size of the images of the isolated dots relative to the size of images of non-isolated dots, and

wherein the controlling unit includes:

a density increasing unit increasing the multilevel density of the original image data when the size of the isolated dot modified by the dot modification process is equal to the size of the non-isolated dot and that a ratio of the isolated dots relative to the total number of dots in the image to be formed is greater than or equal to a threshold, the data conversion unit converting, for each pixel, the density-increased original image data into dot data; and

an image-formation controlling unit that controls the image-forming unit to form the image by selectively forming a dot for each pixel based on the dot data determined by the data conversion unit when the size of the isolated dot modified by the dot modification process is greater than the size of the non-isolated dot and when the size of the isolated dot modified by the dot modification process is the same as the size of the non-isolated dots and the ratio of the isolated dots relative to the total number of dots in the image to be formed is smaller than the threshold.

12. An image-forming device according to claim 8, wherein the data conversion unit converts the original image data into the dot data by using an error diffusion method.

13. An image-forming device comprising:

an image-forming unit forming images on a recording medium;

a developer-accommodating unit accommodating developer;

a consumption-detecting unit detecting the amount of developer consumed from the developer-accommodating unit; and

a controlling unit controlling the image-forming unit to execute a dot modification process to form images of isolated dots with a size larger when the amount of consumed developer detected by the consumption-detecting unit reaches a reference amount than when the reference amount has not been reached.

14. An image-forming device according to claim 13, wherein the developer-accommodating unit includes a plurality of different developer-accommodating units accommodating developer of a plurality of different colors;

wherein the consumption-detecting unit detects the amount of consumed developer for each color; and

the controlling unit determines whether the amount of consumed developer for each color has reached the reference amount and controls the image-forming unit to form images of isolated dots with sizes larger for colors whose consumption amount has reached the reference amount than when the amount of consumed developer for the subject color has not reached the reference amount.

15. An image-forming device according to claim 13, further comprising:

a data conversion unit converting, for each of a plurality of pixels in an image to be formed, original image data indicative of a multilevel density into dot data indicative of whether or not a dot should be formed, the image-forming unit forming an image on a recording medium by selectively forming a dot for each pixel based on the dot data; and

a mode-setting unit setting a mode of the image-forming unit to either one of a first gradation mode in which the data conversion unit converts a first type of image data into dot data, and a second gradation mode in which the data conversion unit converts a second type of image data into dot data, the first type of image data indicating a density level among a first number of density levels, the second type of image data indicating a density level among a second number of density levels, the second number being smaller than the first number, and

wherein the controlling unit controls the image-forming unit to form images of isolated dots with sizes smaller in the first gradation mode than in the second gradation mode.

16. An image-forming device according to claim 15, wherein the controlling unit controls, even when the mode-setting unit has set the first gradation mode, the image-forming unit to form images of isolated dots with sizes larger when the amount of consumed developer has reached the reference amount than when the amount of consumed developer has not reached the reference amount.

17. An image-forming device according to claim 15, wherein the controlling unit controls the image-forming unit to execute the dot modification process when forming images at a first resolution and to fail to execute the dot modification process when forming images at a second resolution lower than the first resolution.

18. An image-forming device according to claim 15, wherein the controlling unit controls the image-forming unit to execute the dot modification process to modify the size of the images of the isolated dots relative to the size of images of non-isolated dots, and

wherein the controlling unit includes:

a density increasing unit increasing the multilevel density of the original image data when the size of the isolated dot modified by the dot modification process is equal to the size of the non-isolated dot and that a ratio of the isolated dots relative to the total number of dots in the image to be formed is greater than or equal to a threshold, the data conversion unit converting, for each pixel, the density-increased original image data into dot data; and

an image-formation controlling unit that controls the image-forming unit to form the image by selectively forming a dot for each pixel based on the dot data determined by the data conversion unit when the size of the isolated dot modified by the dot modification process is greater than the size of the non-isolated dot and when the size of the isolated dot modified by the dot modification process is the same as the size of the non-isolated dots and the ratio of the isolated dots relative to the total number of dots in the image to be formed is smaller than the threshold.

19. An image-forming device according to claim 15, wherein the data conversion unit converts the original image data into the dot data by using an error diffusion method.

20. An image-forming device comprising:

an image-forming unit forming images on a recording medium;

a plurality of developer-accommodating units accommodating developer of a plurality of different colors; and

a controlling unit controlling the image-forming unit to execute a dot modification process to form images of isolated dots in developer of at least one color at a different size than the images of isolated dots formed of developer in the other colors.

21. An image-forming device according to claim 20, further comprising:

a data conversion unit converting, for each of a plurality of pixels in an image to be formed in each color, original image data indicative of a multilevel density into dot data indicative of whether or not a dot should be formed, the image-forming unit forming an image in each color on a recording medium by selectively forming a dot for each pixel based on the dot data; and

a mode-setting unit setting a mode of the image-forming unit to either one of a first gradation mode in which the data conversion unit converts a first type of image data into dot data, and a second gradation mode in which the data conversion unit converts a second type of image data into dot data, the first type of image data indicating a density level among a first number of density levels, the second type of image data indicating a density level among a second number of density levels, the second number being smaller than the first number, and

wherein the controlling unit controls the image-forming unit to form images of isolated dots with sizes smaller in the first gradation mode than in the second gradation mode.

22. An image-forming device according to claim 21, wherein the controlling unit controls the image-forming unit to execute the dot modification process when forming images at a first resolution and to fail to execute the dot modification process when forming images at a second resolution lower than the first resolution.

23. An image-forming device according to claim 21, wherein the controlling unit controls the image-forming unit to execute the dot modification process to modify the size of the images of the isolated dots relative to the size of images of non-isolated dots, and

wherein the controlling unit includes:

a density increasing unit increasing the multilevel density of the original image data when the size of the isolated dot modified by the dot modification process is equal to the size of the non-isolated dot and that a ratio of the isolated dots relative to the total number of dots in the image to be formed is greater than or equal to a threshold, the data conversion unit converting, for each pixel, the density-increased original image data into dot data; and

an image-formation controlling unit that controls the image-forming unit to form the image by selectively forming a dot for each pixel based on the dot data determined by the data conversion unit when the size of the isolated dot modified by the dot modification process is greater than the size of the non-isolated dot and when the size of the isolated dot modified by the dot modification process is the same as the size of the non-isolated dots and the ratio of the isolated dots relative to the total number of dots in the image to be formed is smaller than the threshold.

24. An image-forming device according to claim 21, wherein the data conversion unit converts the original image data into the dot data by using an error diffusion method.