JPH04189071A - Image forming device - Google Patents

Abstract

PURPOSE:To attain optimum smoothing correction and to attain stable print-out at all times by providing a relation revision means which revises the relation between a size and a position of a target print dot and a write pulse signal at any time to the device. CONSTITUTION:A CPU 11 receives a signal from sensors 15-17 via a port 18 to control a register section 19. A MACH section 5 selects any among 16 kinds of correction output patterns #1-#16 in which the size and the position of print dots differ from each other and gives the result to a post-stage register section 19. The register section 19 consists of 16 sets of 16-bit registers corresponding to the 16 kinds of the correction patterns. A data of any registration commanded by the MACH section 5 is transferred further to a post-stage shift register 20, in which the data is converted serially and a write pulse signal is sent. Since the write pulse signal is revised at any time, a picture with high quality is obtained, in which no ruggedness is remarkable.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to image forming apparatuses such as optical printers such as laser printers and digital copying machines, and particularly relates to image forming apparatuses such as optical printers such as laser printers and digital copying machines.
The present invention relates to an image forming apparatus using the WM) method.

[Conventional technology]

In an image forming apparatus using the PWM method, a circuit as shown in FIG. 4, for example, is provided in order to remove jaggedness caused by quantization of the image import portion.

In this circuit, a personal computer.

Print data sent from a host 1 such as a word processor is developed into a bitmap by the controller unit 2, and then sent to the FI
Data is transferred to the FO unit 3 in a hexadecimal format.

The FIFO section 3 is a FIFO-type line buffer memory having a capacity of 7 lines + 1 line being rewritten.

The LUT section 4 is a window latch, and for each dot of interest from the FIFO section 3, several dots around it are read out and latched.

The MACH section 5 performs template matching, that is, Lt
Pattern matching is performed between the data held by the JT unit 4 and data determined in advance by hardware.

The COMP section 6 generates correction data based on the output of the MACH section 5 in order to adjust the driving time of the writing section (driver) 7.

The writing section 7 controls the diode 8 on and off based on the output of the COMP section 6, so that a printed output can be obtained.

According to the circuit configured in this way, when printing a slightly oblique outline that is close to vertical as shown in FIG. By making the pixels white by about 275 dots,
As shown in Figure (b), the difference in level becomes smaller and the jagged edges become less noticeable.

In this conventional example, so-called PWM (Pulse Width Modular) is used to adjust the driving time of the laser diode 8 in order to print dots of a target size.
ation) method is used.

This is based on the relationship between the print dot size (dot diameter) and the laser diode driving time by the write pulse signal, as shown in FIG.

For example, in order to print dots of the usual size of 275 dots, the laser diode 8 is driven to emit light for a time of 7716 times of one dot.

[Problem to be solved by the invention]

However, the characteristics shown in FIG. 6 can change depending on the environment and changes over time.

Therefore, in the conventional configuration as shown in FIG.
If the characteristics shown by the solid line in the figure change to those shown by the broken line, even if the laser diode LD is driven for 7/16 of the time of 1 dot with the intention of obtaining 215 dots, 115 dots will be printed. There was a problem in that it became impossible to print with dots of the desired size.

This invention has been made in view of the above-mentioned points, and an object of the present invention is to make it possible to always stably print high-quality images with inconspicuous jagged edges, regardless of changes in the above-mentioned characteristics.

[Means to solve the problem]

In order to achieve the above object, this invention compares the surrounding patterns with a plurality of predetermined patterns for each bit of print data developed in a bitmap, and writes about the dot of interest based on the results. An image forming apparatus that performs pulse width modulation of a write pulse signal is provided with a relationship changing means for changing the relationship between the write pulse signal and the size and position of a target print dot at any time.

The relationship changing means includes a determining means for determining the relationship between the write pulse signal and the actual print dot size, and a write pulse for the target print dot size and position according to the determination result of the means. It may consist of means for changing the relationship with the signal.

Further, the determining means is means for exposing and developing a certain pattern outside the transfer area on the photoreceptor, and determining the relationship between the writing pulse signal and the size of the actual printed dot based on the density thereof;
Means for determining the relationship between the write pulse signal and the actual print dot size based on the temperature within the image forming apparatus, or determining the relationship between the write pulse signal and the actual print dot size based on the number of times the photoreceptor is used. You can use it as a means.

C Effect] In the image forming apparatus according to the present invention, the relationship between the size and position of the target print dot and the write pulse signal can be changed at any time, so smoothing correction can be made optimal for image forming apparatuses having a wide range of printing process characteristics. This makes it possible to consistently print high-quality images with no noticeable jagged edges, regardless of changes in the characteristics.

〔Example〕

Embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of a control section of an image forming apparatus according to an embodiment of the present invention, and parts corresponding to those in FIG. 4 are given the same reference numerals.

In this control section, CPU II is in charge of engine control of this image forming apparatus, operates according to a control program in ROM 12, uses RAM 13 and counter 14, and sends signals from sensors 15 to 17 via boat 18. input to control register section ]9,
Drives and controls sequence equipment, etc. (not shown).

The MACH unit 5 selects, for example, 16 types of correction output patterns #1 to #16 with different print dot sizes and positions as shown in FIG. 19.

The register unit 19 is composed of 16 16-bit registers corresponding to the 16 types of correction output patterns, and transfers the data in any one register instructed by the MACH unit 5 to the shift register 20 in the subsequent stage. It is transferred and serially converted to create a write pulse signal (laser operation signal).

Now, when printing dot #8 in FIG. 2, if the printing process characteristics are as shown by the solid line in FIG.
Set the data shown in figure (a).

On the other hand, if the printing process characteristics are as shown by the broken line in FIG. 6, the data in the register corresponding to the #8 dot in the register section 19 is rewritten to the data shown in FIG. 3 (b), and the write pulse signal is The immediate operation time of the laser diode 8 is lengthened.

By the way, the CPU II determines the current printing process characteristics, that is, the relationship between the write pulse signal and the actual print dot size, as follows.

(2) After exposing and developing a certain pattern outside the transfer area on the photoreceptor, its density is measured with a dedicated sensor and judgments are made based on the results.

(2) A temperature detector installed in the image forming apparatus detects the temperature inside the image forming apparatus, and a judgment is made based on the result.

■ The number of times the photoreceptor is used (usage frequency) is totaled by a counter, and a judgment is made based on the cumulative value.

In this way, in this embodiment, the relationship between the size and position of the target print dot and the write pulse signal can be changed at any time, so it is possible to produce high-quality images without noticeable jagged edges, regardless of changes in the printing process characteristics. can always print stably.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to perform optimal smoothing correction for image forming apparatuses having a wide range of printing process characteristics, and to always produce high-quality images with unnoticeable jagged edges that are stable regardless of changes in printing process characteristics. can be printed.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the configuration of a control section of an image forming apparatus according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing an example of a correction output pattern for explaining the operation of this embodiment. 3(a) and 3(b) are explanatory diagrams showing different examples of data to be set in the register section 19 of FIG. 1. FIG. FIG. 4 is a circuit diagram for explaining a conventional example. FIG. 5 is also an explanatory diagram. FIG. 6 is a diagram showing printing process characteristics. 1...Host 2...Controller part 3...FI
FO section 4...LUT section 5...M A CH section 7
...Writing section 8...Laser diode 11...C
PU 12...ROM 13...RAM1
4...Counter 19...Register section 20...Shift register Applicant Rico Co., Ltd. - Figure 2 Figure 3

Claims (1)

[Claims] 1. For each bit of print data expanded into a bitmap, patterns around it are compared with a plurality of predetermined patterns, and based on the results, a write pulse signal is generated for the dot of interest. An image forming apparatus that performs pulse width modulation, characterized in that the image forming apparatus is provided with a relationship changing means for changing the relationship between the size and position of a target print dot and a write pulse signal at any time. 2. The image forming apparatus according to claim 1, wherein the relationship changing means includes determining means for determining the relationship between the write pulse signal and the actual print dot size, and determining the target print dot according to the determination result of the means. an image forming apparatus comprising: means for changing the relationship between the size and position of the write pulse signal and the write pulse signal. 3. The determining means is a means for exposing and developing a certain pattern outside the transfer area on the photoreceptor, and determining the relationship between the writing pulse signal and the actual print dot size based on the density thereof. The image forming apparatus according to claim 2. 4. The image forming apparatus according to claim 2, wherein the determining means is a means for determining the relationship between the write pulse signal and the actual print dot size based on the temperature within the image forming apparatus. 5. The image forming apparatus according to claim 2, wherein the determining means is a means for determining the relationship between the write pulse signal and the actual print dot size based on the number of times the photoreceptor is used.