KR20080056625A - Image forming apparatus and control method thereof - Google Patents

Abstract

An image forming apparatus and a control method thereof are provided to adjust an image forming part to form a test image determined by a position error of a transfer belt and to adjust the feature of the image forming part based on the concentration of the test image so as to minimize the consumption of the toner. An image forming apparatus(100) comprises a transfer part(110), an image forming part(120), a concentration evaluating part(130), and a control part. The transfer part has a belt for transferring a printing medium. The image forming part forms a color image. The concentration evaluating part, arranged on a moving path of the belt, evaluates the image concentration formed by the image forming part. The control part controls the image forming part to form a test image determined by a position error of the belt, adjusts features of the image forming part based on the concentration of the test image, and controls the transfer part to maintain the moving speed of the belt slower than a predetermined speed.

Description

Image forming apparatus and control method thereof {IMAGE FORMING APPARATUS AND CONTROL METHOD THEREOF}

The present invention relates to an image forming apparatus and a control method thereof. More specifically, the present invention relates to an image forming apparatus for adjusting image forming characteristics using a test image and a control method thereof.

An image forming apparatus such as a laser printer exposes a photosensitive member to develop a toner, and then transfers and fuses the toner on a printing medium such as paper to form an image.

In general, an image forming apparatus capable of forming a color image includes an LSU (Laser Scanning Unit) provided corresponding to a plurality of colors, and an image forming unit including a plurality of photosensitive members, a transfer roller, and the like. For example, the plurality of photosensitive members and the like are arranged along the conveying path of the printing medium conveyed by a conveying means such as conveying belt.

Such an image forming apparatus may form an image (hereinafter referred to as a "test image") for adjustment rather than actual image formation in order to adjust image forming characteristics of the image forming unit such as determination of development conditions, color registration, and the like. Can be.

1 is a view for explaining formation of a test image by a conventional image forming apparatus. Reference numeral 1 denotes a conveyance belt, and reference numeral 2 denotes a formed test image corresponding to a plurality of colors (hereinafter, referred to as a "density mark").

The image forming apparatus forms the density mark 2 by transferring the toner to a predetermined position on the surface of the conveyance belt 1 according to the test data provided for adjusting the image forming characteristics. The image forming apparatus forms the density mark 2 while moving the conveyance belt 1 like the actual printing operation. In FIG. 1, reference numeral A denotes a moving direction of the conveyance belt 1.

As shown in Fig. 1, the image forming apparatus forms four density marks 2 corresponding to the colors C, M, Y, and K, respectively. Each density mark 2 has a substantially rectangular shape.

The image forming apparatus includes a sensing unit 3 for sensing the density mark 2. The detector 3 detects the light reflected by the density mark 2 by irradiating light with a predetermined driving voltage. The image forming apparatus evaluates the density of the density mark 2 using the detection result obtained by the sensing unit 3. The image forming apparatus determines the image forming characteristics of the image forming portion, i.e., the developing conditions or performs color alignment, based on the density of the density mark 2 evaluated.

The sensing unit 3 may perform sensing a plurality of times for one density mark 2 in order to obtain a reliable sensing result. In addition, the plurality of sensing units 3 may be disposed across the moving direction A of the transport belt 2 to sequentially perform sensing. In this case, the size W of each density mark 2 for each color in the moving direction A of the conveying belt 2 may be determined by the following equation (1).

[Equation 1]

W (mm) = moving speed of feed belt (2) (mm / s) * sensing time (sec) * number of sensing * number of sensing section (3)

Here, the sensing time means a time taken by the sensing unit 3 to perform one sensing.

In addition, the image forming apparatus may repeatedly adjust the image forming characteristics while changing the level of the driving voltage of the sensing unit 3 to obtain a more reliable sensing result. In this case, as shown in Fig. 1, the conveyance belt 1 needs to be formed with a plurality of density marks 2.

In this way, when the image forming characteristics are adjusted using the test image, the amount of toner consumed for forming the test image depends on the characteristics of the image forming apparatus. That is, the faster the moving speed of the conveyance belt 1, the higher the reliability of performing the image forming characteristic, the more the amount of toner consumed becomes a problem.

In addition, since the toner transferred to the transfer belt 1 to form the test image becomes waste toner, it becomes a problem to increase the waste toner capacity. Even if the toner transferred to the transfer belt 1 is recovered using reverse transfer or the like, there is a problem such as a long reverse transfer time.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an image forming apparatus and a control method thereof that can minimize the consumption of toner in adjusting image forming characteristics using a test image.

In order to achieve the above object, the present invention provides an image forming apparatus, comprising: a conveying unit having a conveying belt for conveying a printing medium, and an image forming unit for transferring a toner to the printing medium to form a color image; A density evaluator provided on the movement path of the conveyance belt to evaluate the density of the image formed by the image forming unit; Controlling the image forming unit to form a test image whose size in the conveying direction is determined by the positional deviation of the conveying belt, adjusting the characteristics of the image forming unit based on the density of the transferred test image, and evaluating the density And a control unit which controls the transfer unit such that a moving speed of the transfer belt is equal to or less than a predetermined value when evaluating the density of the test image by the unit.

The size in the conveying direction of the test image can be determined by the following equation.

[Equation 2]

Size of test image in the feed direction = Position deviation of the feed belt in the feed direction + Sensing light size + margin

The controller may control the transfer unit to stop the movement of the transfer belt.

The test image may be formed on the conveyance belt.

The image forming unit may include a plurality of sub image forming units provided corresponding to a plurality of colors and arranged along a conveying direction of the printing medium, and the control unit may include a plurality of concentrations of the test images corresponding to the plurality of sub image forming units. The transfer unit can be controlled to sequentially evaluate.

The concentration evaluator may include at least one detector configured to detect light reflected from the test image.

The concentration evaluation unit may evaluate the concentration of the test image while changing the level of the driving voltage of the detection unit.

The adjustment of the characteristics of the image forming unit may include at least one of determination of a developing condition and color alignment.

The above object of the present invention includes a transfer unit having a transfer belt for transferring a printing medium, and a plurality of image forming units for transferring a toner to the printing medium to form a color image; A control method of an image forming apparatus, comprising a density evaluating unit provided on a moving path of the conveying belt and evaluating a density of an image formed by the image forming unit, wherein the size in the conveying direction is determined by the positional deviation of the conveying belt. Controlling the image forming unit to form a determined test image; Controlling the transfer unit such that the moving speed of the transfer belt is equal to or less than a predetermined value when the concentration of the test image is evaluated by the concentration evaluation unit; It can also be achieved by a control method of the image forming apparatus, characterized in that it comprises the step of adjusting the characteristics of the image forming unit based on the density of the transferred test image.

As described above, according to the present invention, it is possible to provide an image forming apparatus and a control method thereof which can minimize the consumption of toner in adjusting the image forming characteristics using a test image.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. 2 is a block diagram showing the configuration of an image forming apparatus 100 according to an embodiment of the present invention. The image forming apparatus 100 may be implemented as a laser printer.

As shown in FIG. 2, the image forming apparatus 100 includes a transfer unit 110, an image forming unit 120, a density evaluator 130, and a controller 140.

The transfer unit 110 transfers a printing medium such as paper under the control of the controller 140. 3 is a cross-sectional view showing the transfer unit 110 of the present embodiment. The transfer unit 110 includes a transfer belt 110a to transfer the printing medium by moving the transfer belt 110a. As shown in FIG. 3, the printing medium enters the " B " direction by the transfer belt 110a and exits the " C " direction (hereinafter, also referred to as a "transport path of the printing medium"). That is, the transfer belt 110a moves in correspondence with the transfer path of the printing medium.

The image forming unit 120 forms an image on the printing medium by transferring the toner according to the printing data. As shown in FIG. 3, the image forming unit 120 includes four sub-image forming units 120a to 120d corresponding to each of C, M, Y, and K colors. Each of the four sub-image forming units 120a to 120d performs exposure, development, and transfer according to the printing data.

In addition, the image forming unit 120 forms a test image for adjusting the image forming characteristics under the control of the controller 140. Adjustment of image forming characteristics includes determination of developing conditions, color alignment, and the like.

4 is a diagram showing a test image of this embodiment. As shown in FIG. 4, the test image of the present embodiment may be formed as the first density mark 20a. "D" in FIG. 4 indicates a moving direction of the conveyance belt 110a. The first concentration mark 20a is formed at a predetermined position on the surface of the conveyance belt 110a. The first density mark 20a consists of four marks corresponding to each of the four sub-image forming parts 120a through 120d.

The concentration evaluator 130 evaluates the concentration of the test image formed on the conveyance belt 110a. As shown in FIGS. 3 and 4, the concentration evaluator 130 is provided on the movement path of the conveyance belt 110a to detect the light reflected by the first concentration mark 20a. It includes.

The first sensing unit 130a performs a sensing operation under the control of the controller 140. The first sensing unit 130a performs a sensing operation with a predetermined driving voltage.

The concentration evaluation unit 130 evaluates the concentration of the first concentration mark 20a according to the detection result obtained by the first detection unit 130a and transmits the evaluation result to the control unit 140.

The concentration evaluator 130 may further include a second detector 130b to improve the reliability of the detection result or the evaluation result. As illustrated in FIGS. 3 and 4, the second sensing unit 130b may be disposed in parallel with the first sensing unit 130a across the moving direction D of the transfer belt 110a. In this case, as shown in FIG. 4, the controller 140 controls the image forming unit 120 to form the second density mark 20b in correspondence with the second sensing unit 130b.

The controller 140 performs overall control of the image forming apparatus 100. The controller 140 controls the transfer unit 110 and the image forming unit 120 to form an image on the printing medium according to the printing data.

In addition, the controller 140 controls the transfer unit 110 and the image forming unit 120 to form a test image in order to adjust the image forming characteristics of the image forming unit 120. The control unit 140 moves the transfer belt 110a and moves the transfer belt 110a like the actual printing operation so that the first concentration mark 20a and / or the second concentration mark 20b are formed on the transfer belt 110a. The image forming unit 120 is controlled. The control unit 140 of the present embodiment determines the size W 'of the first concentration mark 20a and / or the second concentration mark 20b in the conveying direction D by the positional deviation of the conveying belt 110a. The image forming unit 120 is controlled to be. That is, the size of the density mark in the conveying direction is preferably made as small as possible in the image forming apparatus 100 in consideration of minimizing toner consumption. In other words, the size of the concentration mark in the conveying direction may be the minimum size through which the concentration evaluator 130 may evaluate the concentration. Specifically, the size W 'of the first concentration mark 20a and / or the second concentration mark 20b in the conveying direction D may be determined by the following [Formula 2].

[Equation 2]

W '(mm) = position deviation of the conveyance belt 110a in the feed direction D + sensed light size + margin

In Equation 2, the positional deviation of the conveyance belt 110a in the conveying direction D is a mechanical characteristic of the image forming apparatus 100, and the first detecting portion 130a and / or the second detecting portion ( 130b) is a positional deviation that may occur in the transport direction D, and the sensing light size is in the transport direction D of the sensing light generated by the first sensing unit 130a and / or the second sensing unit 130b. Is the cross-sectional width of and margin is the design margin. For example, the positional deviation of the conveyance belt 110a in the conveying direction D may be 3 mm, the margin may be set to 10% of the offset, and the sensing light size may be a negligible value for the offset.

On the other hand, the control unit 140, when the first sensing unit 130a and / or the second sensing unit 130b detects the first concentration mark 20a and / or the second concentration mark 20b, the transfer belt ( The transfer unit 110 is controlled to stop the movement of the 110a. In other words, the first detection unit 130a and / or the second detection unit 130b may have the first concentration mark 20a and / or the second concentration mark 20b while the movement of the conveyance belt 110a is stopped. Perform a detection operation on.

5 is a flowchart showing a control process of the image forming apparatus 100 of the present embodiment. Hereinafter, the first concentration mark 20a and the first sensing unit 130a will be representatively described, and the same applies to the second concentration mark 20b and the second sensing unit 130b unless otherwise described.

First, the control unit 140 controls the transfer unit 110 and the image forming unit 120 so that the first concentration mark 20a is formed on the transfer belt 110a while moving the transfer belt 110a normally (S101). .

Next, the controller 140 checks whether the first mark of the first concentration mark 20a reaches the first detection unit 130a (S102). If the result of the check in step S102 has not yet been reached, step S101 is continued.

If it is determined in step S102 that the first mark of the first concentration mark 20a reaches the first sensing unit 130a, the control unit 140 stops the movement of the transfer belt 110a. 110 is controlled (S103).

Next, the controller 140 controls the first sensing unit 130a to perform a sensing operation on the first mark of the first density mark 20a (S104). Next, the controller 140 checks whether the sensing operation is completed with respect to the density mark (S105).

As a result of the checking in step S105, if the sensing operation is not completed yet, the controller 140 changes the driving voltage of the first sensing unit 130a by a predetermined value (S106), and performs the sensing operation again (S104). .

If, as a result of checking in step S105, the control unit 140 detects the second detection unit 130b for the first mark of the second concentration mark 20b when the detection operation of the first detection unit 130a is completed. The operation is performed (S106 and S104).

On the other hand, when the detection operation of the first detection unit 130a and the second detection unit 130b for the density mark is completed as a result of the check in step S105, the control unit 140 completes the detection operation for all density marks. Check whether or not (S107).

If, as a result of the check in step S107, it is determined that the detection operation for all density marks is not completed, the control unit 140 resumes the movement of the transport belt 110a (S108), and the first detection unit 130a. It is checked whether the density mark of the next color of) reaches the first detection unit 130a (S102). In this way, steps S101 to S108 are repeatedly performed.

On the other hand, if it is determined in step S107 that the detection operation for all density marks is completed, the controller 140 based on the density evaluated by the density evaluator 130 according to the detection result, the image forming unit 120. Image forming characteristics are adjusted (S109). When the adjustment of the image forming characteristics is completed in step S109, all the operations are finished.

As such, since the first detecting unit 130a performs the sensing operation on the first concentration mark 20a while the movement of the conveying belt 110a is stopped, the moving direction D of the conveying belt 110a is performed. The size W 'of any one of the first concentration marks 20a may be such that the first sensing unit 130a can perform the sensing. Therefore, the amount of toner required for the first density mark 20a can be minimized.

As mentioned above, the present invention has been described in detail through preferred embodiments, but the present invention is not limited thereto and may be variously implemented within the scope of the claims.

1 is a view showing a test image formed by a conventional image forming apparatus.

2 is a block diagram showing the configuration of an image forming apparatus according to an embodiment of the present invention;

3 is a cross-sectional view showing a transfer unit according to an embodiment of the present invention,

4 is a view showing a test image formed by the image forming apparatus of one embodiment of the present invention,

5 is a flowchart illustrating a control process of an image forming apparatus according to an embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

100: image forming apparatus 110: transfer unit

120: image forming unit 130: density evaluation unit

140: control unit

Claims (16)

In the image forming apparatus, A conveying unit having a conveying belt for conveying a printing medium; An image forming unit which transfers toner to the printing medium to form a color image; A density evaluator provided on the movement path of the conveyance belt to evaluate the density of the image formed by the image forming unit; Controlling the image forming unit to form a test image whose size in the conveying direction is determined by the positional deviation of the conveying belt, adjusting the characteristics of the image forming unit based on the density of the transferred test image, and evaluating the density And a control unit which controls the transfer unit so that the moving speed of the transfer belt is equal to or less than a predetermined value when the density of the test image is evaluated by the unit. The method of claim 1, And the size in the conveying direction of the test image is determined by the following equation. [Equation 2] Size of test image in the feed direction = Position deviation of the feed belt in the feed direction + Sensing light size + margin The method of claim 1, And the controller controls the transfer unit to stop the movement of the transfer belt. The method of claim 1, And the test image is formed on the conveyance belt. The method of claim 1, The image forming unit includes a plurality of sub image forming units provided corresponding to a plurality of colors and arranged along a conveying direction of the printing medium. And the control unit controls the transfer unit such that concentrations of the plurality of test images corresponding to the plurality of sub image forming units are sequentially evaluated. The method of claim 1, And the density evaluator comprises at least one detector configured to sense light reflected from the test image. The method of claim 6, And the density evaluator evaluates the density of the test image while changing the level of the driving voltage of the detector. The method according to any one of claims 1 to 7, And adjusting the characteristics of the image forming unit includes at least one of determination of development conditions and color alignment. A conveying unit having a conveying belt for conveying a printing medium, and a plurality of image forming parts for transferring a toner to the printing medium to form a color image; In the control method of the image forming apparatus comprising a density evaluation unit provided on the movement path of the conveying belt to evaluate the density of the image formed by the image forming unit, Controlling the image forming unit to form a test image whose size in a conveying direction is determined by a positional deviation of the conveying belt; Controlling the transfer unit such that the moving speed of the transfer belt is equal to or less than a predetermined value when the concentration of the test image is evaluated by the concentration evaluation unit; And adjusting a characteristic of the image forming unit based on the density of the transferred test image. The method of claim 9, The control method of the image forming apparatus, characterized in that the size of the test image in the conveying direction is determined by the following equation. [Equation 2] Size of test image in the feed direction = Position deviation of the feed belt in the feed direction + Sensing light size + margin The method of claim 9, In the controlling of the transfer unit, the control method of the image forming apparatus, characterized in that for controlling the movement of the transfer belt is stopped. The method of claim 9, And said test image is transferred to said conveyance belt. The method of claim 9, The image forming unit includes a plurality of sub image forming units provided corresponding to a plurality of colors and arranged along a conveying direction of the printing medium. In the controlling of the transfer unit, the transfer unit is controlled such that concentrations of the plurality of test images corresponding to the plurality of sub-image forming units are sequentially evaluated. The method of claim 9, And the density evaluator comprises at least one detector configured to sense light reflected from the test image. The method of claim 14, And the density evaluator evaluates the density of the test image while changing the level of the driving voltage of the detector. The method according to any one of claims 9 to 15, Adjusting the characteristics of the image forming unit includes at least one of determining the development conditions and color alignment.

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