JPH06183070A - Image forming device - Google Patents

Abstract

(57) [Abstract] [Purpose] In an image forming apparatus that executes a printing operation using bit image data and compressed image data, the printing operation is continuously executed even when the printing speed is switched. A data input means 52 for receiving bit image data and compressed image data is provided, and compression / decompression means 49-5 for decompressing the compressed image data into bit image data.
1 is provided, and partial storage means 48 for accumulating the bit image data output by these means up to a plurality of lines of a part of one screen is provided, and the bit image data is sequentially read from the partial storage means 48 to execute image printing. The image printing means 47 is provided, and speed control means 49 to 51 are provided for switching the operating speed of the image printing means 47 between low speed and high speed depending on whether or not the compressed image data is restored.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus which temporarily stores received image data and then executes a printing operation.

[0002]

2. Description of the Related Art A conventional example of an image forming apparatus will be described with reference to FIGS. First, in the color printer 1 which is the image forming apparatus, mechanically, as illustrated in FIG.
A drum cleaner 3, which is a toner cleaner, a drum charger 4, an exposure device, a laser scanner 5, a developing device 6, and a drum static eliminator 7 are provided on the outer peripheral surface of a photosensitive drum 2 which is a latent image carrier rotatably supported. The printing station 8 is formed by sequentially arranging the same and so on. Therefore, in the color printer 1, the surface of the paper transport belt 9 which is an endless belt-shaped image transfer belt in which the photosensitive drums 2 of the _four printing stations 8 ₁ to 8 _{4 having} the above-described structure are stretchably stretched Yellow, magenta, cyan, and black toners (not shown) are individually arranged on the developing units 6 of the printing stations 8 ₁ to 8 ₄ in the order of the moving direction of the surface of the sheet conveying belt 9 above. It is located in.

Here, in the color printer 1, the sheet feeding device 10 is arranged in proximity to a transport start position at one end of the paper transport belt 9 in the stretching direction, and the surface of the paper transport belt 9 at this transport start position is arranged. Freely rotatable paper holding roller 11
And the transfer charger 12 are sequentially arranged. Further, a fixing device 13 which also serves as a paper discharge mechanism is disposed opposite to a conveyance end position at one end in the stretching direction of the paper conveyance belt 9 on the side opposite to the paper feeding device 10 and the substantially horizontal tension. A belt static eliminator 14 and a belt cleaner 15 are arranged opposite to each other at a position facing the lower surface of the paper transport belt 9.

The sheet conveying belt 9 has a structure in which a conductive layer (both not shown) is formed under the insulating layer located on the surface, and two guide rollers 16 that come into contact with the conductive layer are provided. Ground line (not shown) on one side of 17
Are connected. Further, a belt supporting roller 18 is arranged at a position facing the photosensitive drums 2 of the printing stations 8 ₁ to 8 ₄ via the paper transport belt 9.

Further, in this color printer 1, the drum static eliminator 7 provided integrally with the lower part of the developing device 6 of each of the printing stations 8 ₁ to 8 ₄ is connected to a ground line via a resistor, for example, a metal plate. It is formed by. The detailed structure of the drum static eliminator 7 is disclosed in JP-A-3-182790 proposed by the present applicant.

[0006] Then, the color printer 1, as the circuit manner illustrated in FIG. 7, the printing station 8 ₁
8 _4, the sheet conveying belt 9, the sheet feeding apparatus 10, printer 19 is an image printing means by said fixing unit 13, etc.
And the page memory 2 is formed in the laser scanner 5 of the printing stations 8 ₁ to 8 ₄ of the printer body 19.
0 _{1 to} 20 ₄ are individually connected. Furthermore, a CPU (Central CPU) connected to these page memories 20 _{1 to} 20 ₄
RAM (Random Access Mem)
an ory) 22, a ROM (Read Only Memory) 23, an I / F (Inter / Face) 24 which is a data input means, etc. are connected.

Here, in the color printer 1, the MH
(Modified Huffman) code and other compressed image data is restored to bit image data by a decoder as a compression / decompression means, and JIS (Japan Industrial Standard) code and other character code data is converted into bit image data by C / G (Character Generator) ) And the CPU 21
And the RAM 22 and the ROM 23.

Therefore, here, the printer controller 2
By connecting the I / F 27 of the host computer 26 having the built-in 5 to the I / F 24 of the color printer 1, the color printer 1 executes image printing according to various data received from the printer controller 25 of the host computer 26. Has become.

In such a configuration, the color printer 1 has bit image data in which pixels are expanded on one screen, character code data obtained by compressing such bit image data for each character area by code conversion, and the like. Compressed image data obtained by compressing such bit image data line by line by code conversion or the like is selectively received from the host computer 26 to execute image printing.

Therefore, in the color printer 1, when the I / F 24 receives the character code data from the host computer 26, the CPU 21 restores the character code data into bit image data for each character and restores the page memory for each color. When the I / F 24 receives the compressed image data from the host computer 26, the compressed image data is stored in the CPUs 20 _{1 to} 20 _4.
When the I / F 24 receives the bit image data from the host computer 26 by restoring the bit image data for each line into the page memories 20 _{1 to} 20 ₄ for each color by the line 21, the bit image data is directly output. The page memories 20 _{1 to} 20 ₄ for each color are stored.

When the bit image data of one screen is stored in the page memories 20 _{1 to} 20 ₄ of each color in this way, the bit image data is sequentially read and the laser scanner 5 of each of the printing stations 8 ₁ to 8 ₄ is read. And the like, the printer body 19 prints a color image or a monochrome image on the printing paper 28.

Therefore, when the color printer 1 prints a color image as described above, the outer peripheral surface of the rotating photosensitive drum 2 is charged by the corona discharge of the drum charger 4 in each of the printing stations 8 ₁ to 8 _4. Then, the static electricity is selectively removed by the exposure of the laser scanner 5 to form an electrostatic latent image, and the electrostatic latent image on the outer peripheral surface of the photosensitive drum 2 is converted into a monochromatic image by the toner of each color supplied from the developing device 6. After development, the drum static eliminator 7 eliminates static electricity.

On the other hand, in the color printer 1, the printing paper 28 is fed from the paper feeding device 10 onto the paper carrying belt 9 in synchronism with the operations of the printing stations 8 ₁ to 8 ₄ described above, and the printing paper 28 is fed. The transfer charger 12 applies an electric charge while the paper holding roller 11 presses and holds the paper 28 on the paper carrying belt 9. Then, the printing paper 28 is charged together with the paper carrying belt 9, so that the transfer voltage is also applied to the printing paper 28 electrostatically attracted to the paper carrying belt 9.

Therefore, in the color printer 1, yellow, magenta, and cyan single-color images are printed from the photosensitive drums 2 of the printing stations 8 ₁ to 8 _{4 on} the surface of the printing paper 28 conveyed by the rolling paper conveying belt 9. Overprinting is sequentially performed and a black monochromatic image is printed, and the printing paper 28 is peeled from the paper transport belt 9 to fix the fixing device 13.
The color image is printed by heating and pressurizing with, and then discharging it outside the device.

In the color printer 1, the paper transport belt 9 after the printing paper 28 is peeled off as described above is continuously rolled for a predetermined time, and the surface thereof is subjected to corona discharge of the belt static eliminator 14. After the charge is removed, dust such as toner and paper dust attached to the surface is removed by rubbing the belt cleaner 15. Similarly, the photosensitive drum 2 of each of the printing stations 8 ₁ to 8 ₄ after transferring the monochromatic image on the printing paper 28 is continuously driven to rotate for a predetermined time, and the residual toner on the surface thereof is rubbed by the drum cleaner 3. By removing the color printer 1, the color printer 1 waits for the next printing operation.

In this color printer 1, most of the image data is actually converted into character code data in order to improve the overall printing speed by shortening the time required to receive the data from the host computer 26. The compressed image data is received and restored to bit image data. At this time, since it takes time to restore this data, for example, the same image is printed on a plurality of printing papers 2.
It is not desirable to repeat data restoration, such as when printing continuously on page 8. Therefore, the color printer 1 as described above, sequentially storing the bit image data sequentially restored from the character code data and the compressed image data in the page memory 20 ₁ to 20 _4, the page memory 20 ₁
Image printing is executed when one screen of bit image data is accumulated within 20 ₄ .

[0017]

In the color printer 1 described above, when the bit image data stored in the page memories 20 _{1 to} 20 ₄ becomes one screen, the printer main body 19
By executing the image printing in, the printing speed of the same image is improved.

[0018] However, in such a color printer 1, when the printer 19 the bit image data of the page memory 20 ₁ to 20 ₄ is read is executing an image print, the page memory 20 ₁ to 20 ₄ Since the bit image data of the next one screen cannot be stored,
Printing operation and for storing in the page memory 20 ₁ to 20 ₄ to restore the printer body 19 bit image data of the page memory 20 ₁ to 20 ₄ reads the image of the character code data and the compressed image data into bit image data It is necessary to alternately perform the operation to perform. For this reason, in the color printer 1 as described above, the printer main body 19 intermittently performs the printing operation, and it is difficult to determine whether the printing operation is in the middle or the end, and it is easy to give the user distrust.

Further, since the page memories 20 _{1 to} 20 ₄ for storing the bit image data of one screen as described above inevitably have a large capacity, this hinders reduction in size and weight of the color printer 1 and improvement in productivity. It is not desirable to do. More specifically, the color printer 1 as described above
However, a color image in which one pixel is expressed in 4 bits is 300
When printing on the A4 size printing paper 28 with a resolution of (dpi), the capacity of each of the page memories 20 _{1 to} 20 ₄ is about 4 megabytes, so that the total capacity is 16 megabytes. However, such a large capacity page memory 20
Mounting _{1 to} 20 ₄ significantly impedes the reduction in size and weight of the color printer 1 and the improvement in productivity.

The present invention provides an image forming apparatus which continuously executes a printing operation even when the printing speed is switched.

Further, the present invention is to obtain an image forming apparatus which executes a printing operation with high efficiency.

[0022]

The invention according to claim 1 is
At least data input means for selectively receiving bit image data and compressed image data is provided, and compression / decompression means for decompressing the compressed image data sequentially output by the data input means to bit image data is provided. Partial storage means for sequentially accumulating bit image data sequentially output by one of the input means up to a plurality of lines of a part of one screen is provided, and the bit image data of a plurality of lines sequentially accumulated by the partial storage means are sequentially read out to form an image. Image printing means for executing printing is provided, and speed control means is provided for switching the operating speed of the image printing means between low speed and high speed depending on the presence or absence of the restoring operation of the compression restoring means.

According to a second aspect of the present invention, at least a data input means for receiving the compressed image data is provided, and a compression / decompression means for decompressing the compressed image data sequentially output by the data input means into bit image data is provided. A partial storage means for sequentially accumulating bit image data sequentially output by the restoring means up to a plurality of lines of a part of one screen is provided.
Time for detecting the time required for data reception by the data input means and data decompression by the compression / decompression means by providing image printing means for sequentially reading the bit image data of a plurality of lines sequentially accumulated by the partial storage means and executing image printing. The detection means is provided, and the speed control means for variably setting the operation speed of the image printing means is provided corresponding to the longer required time detected by the time detection means.

[0024]

According to the first aspect of the invention, the speed control means can set the printing speed to high speed for bit image data or character code data and to low speed for compressed image data. Even if the printing speed is switched in this way, the printing operation is performed. It is possible to obtain an image forming apparatus that continuously executes the above.

According to the second aspect of the present invention, since the printing speed of the image printing means can be set to the best by the speed control means, it is possible to obtain the image forming apparatus which executes the printing operation with high efficiency.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the invention described in claim 1 will be described with reference to FIGS. First, as shown in FIG. 2, the color printer 29, which is the image forming apparatus of the present embodiment, mechanically supports toner on the outer peripheral surface of the photosensitive drum 30, which is a latent image carrier rotatably supported. A drum cleaner 31, which is a cleaner, a drum charger 32, an edge-emitting EL (Electro Luminescence) head 33, which is an exposure device, and a developing device 3.
4. The printing station 36 is formed by sequentially disposing the drum static eliminator 35 and the like. Therefore, in the color printer 29, the photosensitive drum 30 of the four printing stations 36 ₁ to 36 ₄ of the structure described above, the sheet conveying belt 37 is an image transfer belt endless belt which is rollably stretched The printing stations 3 are arranged so as to face each other and are arranged in the order of the moving direction of the surface of the paper transport belt 37.
They are arranged toner of yellow, magenta, cyan and black (not shown) individually to 6 _1-36 wherein the developing unit 34 of _4.

Here, in the color printer 29, the paper feeding device 38 is disposed in proximity to the conveyance start position at one end of the paper conveyance belt 37 in the stretching direction, and on the surface of the paper conveyance belt 37 at this conveyance start position. Further, a rotatable paper holding roller 39 and a transfer charger 40 are sequentially arranged. Also,
The paper transport belt 37 on the side opposite to the paper feeding device 38 and the like.
A fixing device 41 that also serves as a paper discharge mechanism is disposed opposite to one end of the sheet conveying belt 37 in the stretching direction, and a belt static eliminator is disposed at a position facing the lower surface of the sheet conveying belt 37 stretched substantially horizontally. 42 and the belt cleaner 43 are arranged to face each other.

The paper transport belt 37 has a structure in which a conductive layer (both not shown) is formed under the insulating layer located on the surface, and two guide rollers 44, which contact the conductive layer, An earth line (not shown) is connected to one of the 45 and the like. Further, the paper transport belt 37
It is arranged belt support roller 46 at a position facing the photosensitive drum 30 of the printing station 36 ₁ to 36 ₄ via.

Further, in the color printer 29, the drum discharger 35 provided integrally with the lower portion of the developing device 34 of each printing station 36 ₁ to 36 _4, for example, a metal plate connected to the ground line via a resistor It is formed by.

The color printer 29 has a circuit as shown in FIG.
6 _{1-36 4,} the sheet conveying belt 37, the sheet feeding apparatus 38, a printer 47 is an image print unit formed by the fixing unit 41, etc., of the printing station 36 ₁ to 36 ₄ of the printer body 47 Part memories 48 _{1 to} 48 _{4 as} partial storage means are provided in the edge emitting EL head 33.
Are connected individually. In addition, the CPU 50 connected to these part memories 48 _{1 to} 48 ₄ has a RAM 50,
A ROM 51, an I / F 52 as a data input means, etc. are connected.

Here, in this color printer 29, M
A decoder which is a compression / decompression means for decompressing compressed image data such as H code into bit image data, a C / G for converting character code data such as JIS code into bit image data, and an operating speed of the printer main body 47 are described above. The CPU 49 and the RAM 50 are provided with speed control means for switching between low speed and high speed depending on the presence / absence of a decoder restoring operation.
And the ROM 51.

Therefore, here, the printer controller 5
By connecting the I / F 55 of the host computer 54 having the built-in 3 to the I / F 52 of the color printer 29, the color printer 29 executes image printing according to various data received from the printer controller 53 of the host computer 54. Has become.

In such a configuration, the color printer 29 has bit image data in which pixels are expanded on one screen, and character code data obtained by compressing such bit image data for each character area by code conversion or the like.
1 for each line by bit conversion of bit image data
The compressed image data compressed to about / 20 is selectively received from the host computer 54, and the printer main body 47 executes image printing.

[0034] Therefore, when printing a color image printer 47 of the color printer 29, in the printing station 36 ₁ to 36 _4, the photosensitive drum is rotated 30
The outer peripheral surface of the photosensitive drum 30 is charged by corona discharge of the drum charger 32, and then static electricity is selectively formed by exposing the edge emitting EL head 33 to form an electrostatic latent image. The latent image is developed into a monochromatic image by the toner of each color supplied from the developing device 34, and then the drum static eliminator 35 eliminates the charge.

On the other hand, in the color printer 29, and feeds the printing paper 56 onto the paper conveying belt 37 from the sheet feeding apparatus 38 in synchronism with the operation of the printing stations 36 ₁ to 36 ₄ as described above, the printing paper 56 is a paper holding roller 39
Then, the transfer charger 40 applies an electric charge while being pressed and held on the paper transport belt 37. Then, since the printing paper 56 is charged together with the paper transport belt 37, a transfer voltage is also applied to the printing paper 56 electrostatically attracted to the paper transport belt 37.

Therefore, in the color printer 29, the printing paper 5 carried by the rolling paper carrying belt 37 is used.
Print the monochrome images of black with superimposed sequentially printing a single color image of yellow, magenta and cyan from the photosensitive drum 30 of each printing station 36 ₁ to 36 ₄ to 6 surface, the printing paper 56 from the sheet conveying belt 37 The color image is printed by peeling it off, heating and pressing it with the fixing device 41, and then discharging it to the outside of the device.

In the color printer 29, the paper transport belt 37 after the printing paper 56 is peeled off as described above is continuously rolled for a predetermined time, and its surface is subjected to corona discharge of the belt static eliminator 42. After the charge is removed, dust such as toner and paper dust attached to the surface is removed by rubbing the belt cleaner 43. Similarly, printing paper 56
Each printing station 36 ₁ after the transfer of the monochrome images to
36 ₄ of the photosensitive drum 30 is also continuously rotating drive for a predetermined time, it is removed by scraping the residual toner on the surface thereof in a drum cleaner 31, the color printer 29 is adapted to wait for the next printing operation ing.

Here, in the color printer 29, when the print data used for image printing in the printer main body 47 is received from the host computer 54 as described above, the operating speed of the printer main body 47 is set according to the type of the print data. It is designed to be switched. Therefore, the processing operation when the color printer 29 drives the printer body 47 according to the print data received from the host computer 54 will be described below with reference to the flowchart of FIG.

First, in the color printer 29, the CPU 49 reads the control code of the print data received by the I / F 52 from the host computer 54, and the print data is converted into bit image data, character code data, and compressed image data. It is sequentially checked to determine which is the case. Therefore, the print data received by the I / F 52 is sent to the CP.
If U49 determines that it is bit image data, RO
The printing speed for bit image data set in advance in M51 or the like is set in the printer body 47, and in this state, the bit image data is directly sent to the part memory 48 for each color.
And stores it in the _{1-48 4.} Then, since the part memories 48 _{1 to} 48 _{4 for} each color sequentially store bit image data up to a plurality of lines of a part of one screen, the bit image data are sequentially read out and the printer main body 47 displays a color image or a monochrome image. Printing will be performed on the printing paper 56.

Similarly, when the CPU 49 determines that the print data is character code data, the print speed for this character code data is set in the printer body 47, and then the bit image data converted from the character code data by the CPU 49 or the like. Part memory 4 for each color
8 _{1 to} 48 ₄ sequentially accumulate a part of a plurality of lines of one screen, and image printing is executed at high speed with bit image data sequentially read from these part memories 48 _{1 to} 48 ₄ .

When the CPU 49 determines that the print data is compressed image data, the print speed for the compressed image data is set in the printer body 47, and then the CPU 49
Bit image data, which is obtained by expanding compressed image data by, for example, are sequentially stored in part memories 48 _{1 to} 48 ₄ of each color up to a plurality of lines of a part of one screen.
Image printing is executed at a low speed with bit image data sequentially read from 8 _{1 to} 48 ₄ .

That is, in the color printer 29, the printer main body 19 sequentially executes image printing in the state where the part memories 48 _{1 to} 48 ₄ sequentially store a part of bit image data of one screen as described above. However, the printing stations 36 _{1 to} 36 _{4 of the} printer body 19
The drive speeds of the paper feed device 38, the paper transport belt 37, and the fixing device 41 are set to the dedicated print speeds preset in the print data as described above. Therefore, the printer main body 19 causes the part memories 48 ₁ to 4 4 to synchronize with the speed at which the part memories 48 _{1 to} 48 ₄ accumulate bit image data.
Since performing a read Te printing operation the bit image data from the 8 _4, without transmission of the bit image data stagnates useless, it is possible to perform a printing operation with extremely high efficiency.

Moreover, in the color printer 29, as described above, while the bit image data in the part memories 48 _{1 to} 48 ₄ is read out and the printer main body 47 is executing the image printing, the part memories 48 _{1 to} 48 48. _{Since 4} stores the subsequent bit image data sequentially, it is not necessary to alternately perform such bit image data accumulation operation and read operation. That is, this color printer 29
The printer main body 47 sequentially reads the bit image data in the part memories 48 _{1 to} 48 ₄ and continuously performs the printing operation. Therefore, for example, the user can easily determine whether the printing operation is in the middle or the end. Can be determined.

That is, the color printer 29
Since the print operation is continuously executed even if the print speed is switched to high or low, the print operation does not become stagnant even if it takes time to transfer or convert print data. It is possible to easily discriminate between the end and the end.

Further, in the color printer 29, since the bit image data stored in the part memories 48 _{1 to} 48 ₄ is a part of one screen as described above, a small capacity RAM is used as the part memories 48 _{1 to} 48 _4. By utilizing the color printer 29, the size and weight of the color printer 29 can be reduced and the productivity can be improved.

Although the color printer 29 of this embodiment has exemplified the use of bit image data, character code data and compressed image data as its print data, the present invention is not limited to the above embodiment. Alternatively, a printer device (not shown) or the like that uses bit image data and compressed image data without corresponding to the character code data can be implemented.

In the color printer 29 of this embodiment, the compressed image data received by the I / F 52 from the host computer 54 is expanded into bit image data by the CPU 49 or the like and stored in the part memories 48 _{1 to} 48 _4. I exemplify continuous execution in real time,
The present invention is not limited to the above embodiment. That is,
As illustrated in FIG. 4, by providing the compressed data memory 57 _{1-57 4} for temporarily storing the compressed image data, CP
A color printer 58 or the like, which is an image forming apparatus adapted to release the U49 from transmission control of print data, can also be implemented.

Next, an embodiment of the invention described in claim 2 will be described below with reference to the flowchart of FIG. In addition,
Since the image forming apparatus of this embodiment is structurally the same as the color printer 29 described above as the embodiment of the invention described in claim 1, the names and reference numerals are made common and detailed description thereof is omitted here. .

First, in the color printer 29, the MH
A decoder, which is a compression / decompression means for decompressing compressed image data such as a code into bit image data, a time detection means for detecting the time required for the data decompression of this decoder and the data reception of the I / F 52, and this time detection means The CPU 49, the RAM 50, and the ROM 51 form a speed control unit that variably sets the operating speed of the printer main body 47 in accordance with the detected longer required time.

With such a configuration, in the color printer 29, when the received print data is bit image data or character code data, the printer body 47 performs the printing operation in the same manner as the color printer 29 according to claim 1. If the print data executed and received is compressed image data, the CPU 49 restores the data of the decoder and executes I / O.
The time required to receive the data in F52 is detected, and the operating speed of the printer main body 47 is variably set according to the longer time required.

Therefore, the processing operation upon receiving such compressed image data will be described below with reference to the drawings. First,
The CPU 49 of the color printer 29 requests the host computer 54 for data transmission from the I / F 52 and receives the compressed image data. Therefore, the CPU 49 detects the time required for the I / F 52 to receive one line of this compressed image data and the time required for the decoder to develop one line of the compressed image data into bit image data, and stores it in the RAM 50 or the like. . Then, the CPU 49, which compares the required time in the RAM 50, extracts the longer required time and variably sets the operation speed of the printer body 47 in accordance with the required time.

By doing so, in the color printer 29, for compressed image data which requires time for both transmission and decompression, the printer body 47 of the printer body 47 corresponds to the time required for transmission and decompression. Since the operating speed is set, the printing speed can be set to the best and the printing operation can be executed with high efficiency.

In the color printer 29 of this embodiment, bit image data, character code data and compressed image data are used as the print data, but the present invention is not limited to the above embodiment. Alternatively, a printer device (not shown) or the like that uses only compressed image data without corresponding to the character code data and the bit image data can be implemented.

[0054]

According to the first aspect of the present invention, the partial storage means for sequentially accumulating bit image data sequentially output by one of the compression / decompression means and the data input means up to a plurality of lines of a part of one screen is provided. An image printing means for sequentially reading out bit line image data of a plurality of lines sequentially stored in the partial storage means and executing image printing is provided, and the operating speed of the image printing means is set to low speed and high speed depending on the presence or absence of the restoring operation of the compression restoring means. By providing the speed control means for changing over, the speed control means can increase the printing speed for bit image data or character code data and decrease the speed for compressed image data. It is possible to obtain an image forming apparatus that continuously executes the above.

According to a second aspect of the present invention, partial storage means for sequentially storing bit image data sequentially output by the compression / decompression means up to a plurality of lines of a part of one screen is provided, and the plurality of lines sequentially stored by the partial storage means. Image printing means for sequentially reading the bit image data of 1 to execute image printing, and time detection means for detecting a time required for data reception by the data input means and data decompression by the compression / decompression means,
By providing the speed control means for variably setting the operation speed of the image printing means in accordance with the longer required time detected by the time detection means, the speed control means optimizes the printing speed of the image printing means. Can be set to
This has effects such as being able to obtain an image forming apparatus that executes a printing operation with high efficiency.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit-like structure of a color printer which is an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a vertical sectional side view showing a mechanical structure of a color printer.

FIG. 3 is a flowchart showing a processing operation of image printing.

FIG. 4 is a block diagram showing a modified example of the circuit structure of the color printer.

FIG. 5 is a flowchart showing an image printing processing operation of the image forming apparatus according to the second embodiment of the invention.

FIG. 6 is a vertical sectional side view showing a mechanical structure of a color printer which is an image forming apparatus of a conventional example.

FIG. 7 is a block diagram showing a circuit-like structure.

[Explanation of symbols]

29, 58 image forming apparatus 47 image printing means 48 partial storage means 49 to 51 compression / decompression means, speed control means, time detection means 52 data input means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location B41J 2/505 29/38 Z 9113-2C 9211-2C B41J 3/10 101 Z

Claims (2)

[Claims] 1. A data inputting means for selectively receiving at least bit image data and compressed image data, a compression restoring means for restoring compressed image data sequentially output by this data inputting means to bit image data, and this compression restoring. Means and the data input means sequentially output bit image data sequentially output up to a plurality of lines of a part of one screen, and a partial storage means sequentially stores a plurality of lines of bit image data sequentially stored. An image forming apparatus comprising: an image printing unit that reads out and executes image printing; and a speed control unit that switches the operating speed of the image printing unit between a low speed and a high speed depending on the presence or absence of the restoring operation of the compression restoring unit. . 2. A data input means for receiving at least the compressed image data, a compression / decompression means for decompressing the compressed image data sequentially output by the data input means into bit image data, and a bit image sequentially output by the compression / decompression means. Partial storage means for sequentially storing data up to a plurality of lines of a part of one screen, image printing means for sequentially reading out bit image data of a plurality of lines sequentially stored by the partial storage means, and executing image printing, and the data input. Time detection means for detecting the time required for the data reception of the means and the data recovery of the compression / decompression means, and the operating speed of the image printing means can be freely changed corresponding to the longer time required by the time detection means. An image forming apparatus comprising: a speed control unit set to.