JPH0782257B2 - Image forming device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and in particular, it is possible to select a density level of a recorded image from a plurality of types, for example, an electronic copying machine, a laser beam printer, The present invention relates to an image forming apparatus such as an LED printer.

(Prior Art) In a conventional image forming apparatus, for example, an electronic copying machine, means for setting an obtained image density is provided. The operator sets the desired density level by that means.

(Problems to be Solved by the Invention) In a conventional image forming apparatus, it is not easy to optimally set the image density, and in order to obtain an image of optimum density, images obtained in various modes and density levels are required. Have to compare. Therefore, many copies are required, which not only takes time and labor for the operation but also wastes the recording paper and the developer.

Therefore, an object of the present invention is to provide an image forming apparatus capable of setting a desired density level more easily.

(Means for Solving Problems) The present invention irradiates a rotatable photoconductor and exposure light capable of expressing at least two kinds of light and shade on the photoconductor in a direction orthogonal to the recording paper conveyance direction. Exposure means for forming an electrostatic latent image, developing means for developing the electrostatic latent image on the photoconductor into a toner image, and transfer means for transferring the toner image on the photoconductor onto the recording paper. And a designating unit for designating a test mode, and a direction of a density level image in which at least two kinds of light and shade are expressed on one sheet of the recording paper in the test mode in a direction orthogonal to the conveying direction of the recording paper. The image forming apparatus is characterized in that

(Operation) When the test mode is set, an image having a density level that expresses at least two types of shading is formed on one sheet of recording paper in a direction orthogonal to the conveying direction of the recording paper.

(Effect of the Invention) According to the present invention, by forming images of different density levels on one sheet of recording paper in a direction orthogonal to the transport direction of the recording paper, electrostatic charges in the direction orthogonal to the transport direction of the recording paper are formed. Since a latent image is formed on the photoconductor and the electrostatic latent image reaches the development area as the photoconductor moves, it is possible to test the latent image and the image having different density levels to be developed under substantially the same conditions.

In addition, if the density level is changed in both the recording paper transport direction and the direction orthogonal to the transport direction, the density level is changed only in the recording paper transport direction. Since they can be arranged in a pattern, images can be formed at more image levels. Therefore, it is possible to reduce the "trial printing" and minimize the waste of the recording paper.

The above-mentioned objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments with reference to the drawings.

(Embodiment) FIG. 2 is a structural schematic view showing the internal structure of an electronic copying machine as an embodiment of the present invention. The electronic copying machine 10 includes a main body 12, and a document table 14 is provided on the upper surface of the main body 12. In the embodiment, the ADF (Automatic Docum
ent Feeder) is provided.

Below the document table 14 inside the main body 12, an exposure light source 16 is provided so as to be movable in the arrow direction. A reflecting mirror, such as a concave mirror, that moves integrally with the light source 16 in relation to the light source 16.
18 and a movable mirror 20 are provided. The light from the exposure light source 16 is reflected by the reflected light 18 and is applied to a document (not shown) placed on the document table 14, and the reflected light from the document, that is, the document image is incident on the movable mirror 20. The original image incident on the movable mirror 20 is received by the movable mirrors 22 and 24 which are movable in the arrow direction by a distance shorter than the exposure light source 16. The original image from the movable mirror 24 is focused by the zoom lens 26, and is projected and imaged on the photoconductor 30 by the fixed mirror 28.

With respect to the photoconductor 30, a charging corotron for uniformly charging the photoconductor 30 prior to exposure with a document image.
32 are provided. The photoconductor drum 30 is rotatably provided in the direction of the arrow, and a developing device 34 for developing an electrostatic latent image formed by the exposure into a toner image is provided downstream of the exposure position of the photoconductor 30 by the fixed mirror 28. Is provided.

A transfer corotron 40 for transferring the above-mentioned toner image to the recording paper 36 fed from the paper feed cassette 36 is provided further downstream of the developing device 34. This transcription corotron
The recording paper 38 to which the toner image has been transferred by 40 is fixed and discharged as is well known in the subsequent steps.

A size sensor 42 for detecting the size of the recording paper 38 accommodated in the paper feed cassette 36 is provided in association with the paper feed cassette 36. As the size sensor 42, any one such as a photo sensor, a magnetic sensor or a micro switch can be used.

FIG. 3 is a block diagram showing an example of the control system of the embodiment shown in FIG. The control system includes a CPU44, and this CPU44
A ROM 46 for preliminarily storing a control program and necessary information, which will be described later, and a RAM 48 having a timer area, a counter area, or another storage area are connected to this. C
An I / O port 50 is further connected to the PU 44. This I / O
A key matrix 52 is connected to the port 50, and a test key 54, which is provided on the operation panel and is used to set a test mode, is connected to the key matrix 52. The size sensor 42 provided at the position shown in FIG.
Connected to port 50. A motor driver 56 and an AVR unit 58 are further connected to the I / O port 50. The motor driver 56 supplies a drive voltage to the main motor 60 for rotating the photoconductor 30 and the mirror motor 62 for driving the exposure light source 16, that is, the movable mirror 20. An encoder 66 is connected to the mirror motor 64.
The pulse signal from 66 is input to the I / O port 50. The exposure light source 16, the charging corotron 32, and the developing device 34 are connected to the AVR unit 58. Therefore, from this AVR unit 58, a voltage that determines the amount of exposure light is applied to the exposure light source 16 and the charging corotron 32 is applied. A high voltage for controlling the charging voltage is applied, and a developing bias is applied to the developing device 34.

FIG. 1 is an illustrative view showing a basic example of a recording sheet on which an image is formed according to this embodiment. In this example, as shown in FIG. 1, the density level of an image recorded on one sheet of recording paper 38 is switched to a plurality of levels (7 levels in this example) for copying.

Here, the image forming operation as shown in FIG. 1 will be described with reference to FIG. Prior to the first step S1, the operator operates the test key 54 (FIG. 3) to obtain a test image as shown in FIG. Then, in the first step S1, the CPU 44 detects the length in the conveyance direction of the recording paper at that time based on the size data from the size sensor 42, and reaches the density switching points A1 to A7 shown in FIG. The distance data of is calculated. As shown in FIG. 1, when recording seven density levels on one sheet of recording paper, in step S1, the CPU 44 obtains distance data obtained by dividing the length of the recording paper 38 in the transport direction into seven equal parts. Ask.

Then, in the next step S3, the CPU 44 stores the distance data obtained by the calculation in a predetermined area of the RAM 48 and sets it in a counter (not shown) formed in the RAM 48. The distance data thus obtained is used as the moving distance data of the movable mirror 20 (FIG. 2).

In the next step S5, the CPU 44 gives a command to the AVR unit 58 and sets the voltage of the exposure light source 16 so that the darkest density level is obtained. That is, this step S5
Then, the exposure light amount of the exposure light source 16 is set so as to obtain the darkest image.

In the next step S7, the CPU 44 gives a command to the motor driver 56. In response, the mirror motor 64 is energized,
The exposure light source 16, that is, the movable mirror 20 starts to move in a predetermined direction. Then, based on the pulse from encoder 66, CP
When U44 detects that it has reached the image position in step S9, CPU44 in the next step S11.
Decrements the counter in RAM 48 with each pulse from encoder 66. Then, in step S13, it is determined whether or not the counter has become "0".

When it is detected in step S13 that the counter has reached “0”, that is, when it is detected in step S3 that the movable mirror 20 has moved by the distance data for one density level set in the counter, CPU44 is
In the next step S15, it is determined whether the control for all the density levels has been completed.

If not completed yet, the CPU 44 sets the distance data previously stored in the RAM 48 in step S3 to the counter in the next step S17 and sets the next density level in step S19. To A
Give a command to the VR unit 58. Therefore, the exposure light amount by the exposure light source 16 is set so that the density level is one step lower than the first level in the second level until the counter reaches "0" in step S13.

In this way, steps S11 to S19 are repeated, and if "YES" is determined in step S15, that is, if the lightest density level is set in the seventh section,
Go to the next process.

In this way, the exposure light source for each of the sections A1 to A7 shown in FIG.
Since the exposure light amount by 16 is changed, the developing device 34 (second
Figure) density of toner image developed by recording sheet
The image density recorded on 38 is divided into seven levels as shown in FIG. Therefore, the operator can set the required density level simply by looking at one test sheet as shown in FIG.

FIG. 5 and FIG. 6 are illustrative views showing examples of images formed on the recording paper, respectively. In the example of FIG.
Whereas the area of the recording paper 38 is divided only in the carrying direction in the example of FIG. 1 described above, the recording paper 38 is divided not only in the carrying direction but also in the direction orthogonal to the carrying direction, and more. The image is formed at different density levels of. Like the image shown in FIG. 6, the image shown in FIG. 5 can be formed by, for example, an LED printer or a laser beam printer in which the exposure light amount can be changed in the direction orthogonal to the recording paper conveyance direction. You can

In the example shown in FIG. 6, an electronic copying apparatus having a printing function prints a symbol indicating a mode on each section (area) of the recording paper 38 divided into four. That is, "N4"
Indicates that the density level is the fourth level, that is, the intermediate level, "AE" indicates the density level in the automatic exposure mode, and "P" indicates the density level in the photo original mode. “C” indicates the density level in the contrast enhancement mode. In this way, by printing the symbols in the respective areas or sections, it is very convenient because the operator can determine at a glance which mode should be set.

It is needless to say that the symbols shown in FIG. 6 are merely examples, and other arbitrary symbols corresponding to respective concentration levels can be added.

FIG. 7 is a structural schematic view showing the internal structure of a laser beam printer as another embodiment of the invention. The laser beam printer 100 includes a main body 112, and a document table 114 is formed above the main body 112. An exposure light source 116, a reflecting mirror 118, and a movable mirror 120 are integrally provided below the document table 114 so as to be movable in the arrow direction. Then, the original image entered by the movable mirror 120 passes through the movable mirrors 122 and 124 to form a lens.
The light enters the light receiving element 180 through 126. This light receiving element 12
At 8, the incident original image is photoelectrically converted and an electric signal corresponding to the original is output. The electric signal from the light receiving element 180 is given to the image processing unit 182. The image processing unit 182 resolves the image into about 256 pixels (dots) per 1 mm ^{2 of} the image, divides the density level for each pixel into, for example, 12 levels, and stores it in a memory (not shown) together with the density level. To be done.
The laser scanner 184 outputs a laser beam for each pixel according to the data stored in the memory of the image processing unit 182. The laser beam from the laser scanner 184 is reflected by the fixed mirror 128 and is incident on the photoconductor 130.

In relation to the photoconductor 130, a charging corotron 132, a developing device 134 and a transfer corotron 140 are provided as in the case of the embodiment shown in FIG. Therefore, transfer corotron 140
On the recording paper 138 sent from the paper feed cassette 136,
The toner image is transferred.

The operation unit 186 shown in FIG. 8 is provided with a test key 154, a display 188 and a partial designation key 190. The display unit 188 displays, for example, a message "test point is not available" for asking the operator which part of the document is to be printed with the density changed. Looking at the display on the display 188, the operator
Set which part of each part shown in the figure should be used for test printing. For example, if the corresponding key "6" of the partial designation key 190 is operated to set the part A6, the part A6 shown in FIG. 9 is used for the test mode.

When the test key 154 is operated, the image processing unit 182
Then, the density level of the image data of the shaded portion A6 in FIG. 9 is corrected and stored again in a predetermined area of the memory. In FIG. 10, the data corresponding to the portion A6 of the stored manuscript data (for example, address 051000000).
Is read out and stored in the memory areas of the other portions A1 to A5 and A7 to A12 with the density level correction of +6 to -5 added. At this time, since the density level has 12 levels from "0 to 0B", "0" is stored when it is "0" or less and "0B" is stored when it is "0B" or more.

After that, the data is sequentially taken out from the memory area corresponding to the recording paper 138, and the laser scanner 18 according to the data
Change the output of the laser beam from 4. Then, as shown in FIG. 11, images having different density levels are recorded on the 12 portions on the recording paper 138. It goes without saying that the image recorded at this time is the same part A6 (FIG. 9) in each part.

In the method shown in FIG. 10, since the memory capacity of the image processing unit 182 becomes very large, when the test mode is set and the partial designation key 190 is operated, the corresponding portion (in the example shown in the figure, the partial Only the data of A6) should be stored in that memory. Then, the memory area will only have the capacity to store the data of that part.

In any of the above-mentioned embodiments, in order to change the density level of the recorded image, the exposure means, the exposure light source 16 in the embodiment of FIG. 2 and the laser scanner in the embodiment of FIG.
The amount of exposure light by 184 was changed.

Further, in the above-described embodiment, the setting of the density level in the case of mono color has been described. However, the present invention can also be applied to the setting of the color tone in the case of color recording. Similarly, when setting the color tone, the recording paper may be divided into a plurality of areas and each area may be recorded with a different color tone.

[Brief description of drawings]

FIG. 1 is an illustrative view showing a basic example of a recording sheet on which an image is formed according to an embodiment of the present invention. FIG. 2 is a structural schematic view showing the internal structure of an electronic copying machine as an embodiment of the present invention. FIG. 3 is a block diagram showing an example of the control system of the embodiment shown in FIG. FIG. 4 is a flow chart for explaining the operation for obtaining the recorded image as shown in FIG. FIG. 5 and FIG. 6 are each an illustrative view showing this embodiment of the recorded image. FIG. 7 is a structural schematic view showing the internal structure of a laser beam printer as another embodiment of the invention. FIG. 8 is an illustrative view showing the operating portion of the embodiment in FIG. FIG. 9 is an illustrative view showing a “portion” used in the test mode. FIG. 10 is an illustrative view showing a mode of correcting the density level in the image processing section of the embodiment in FIG. FIG. 11 is an illustrative view showing one example of a recorded image obtained by this embodiment. In the figure, 16,116 are exposure light sources, 20,120 are movable mirrors, 30,1
30 is a photoconductor, 32 and 132 are charging corotrons, 34 and 134 are developing devices, 42 is a size sensor, 44 is a CPU, 58 is an AVR unit, 64
Is a mirror motor, 66 is an encoder, 182 is an image processing unit, 1
Reference numeral 84 represents a laser scanner.

Continuation of the front page (56) References JP-A-56-80071 (JP, A) JP-A-60-243649 (JP, A) JP-A 61-59370 (JP, A) JP-A 61-14663 (JP , A) JP 61-59371 (JP, A) JP 55-41535 (JP, A) JP 59-195254 (JP, A) JP 60-19359 (JP, A) JP 55-18397 (JP, B2)

Claims (1)

[Claims] 1. A rotatable photoconductor, and exposure means for irradiating the photoconductor with exposure light capable of expressing at least two kinds of light and shade in a direction orthogonal to a recording paper conveyance direction to form an electrostatic latent image. A developing means for developing the electrostatic latent image on the photoconductor into a toner image, a transfer means for transferring the toner image on the photoconductor onto the recording paper, and a test mode for designating a test mode. An image including a designating unit, wherein an image of a density level that expresses at least two types of light and shade is formed on one sheet of the recording paper in the test mode in a direction orthogonal to a conveying direction of the recording paper. Forming equipment.