JPH0351167A - Page printer - Google Patents

Abstract

PURPOSE:To eliminate a missing image and to prevent waste of toner by setting the data developing region of a frame memory on the basis of the output of a sensor detecting the leading and rear ends of paper during feed and developing image data to the set region. CONSTITUTION:The size of preliminarily manually inserted paper in the lateral direction thereof is detected by LEDs 49a, 49b and a charge coupling element (CCD) 48 and the size thereof in the longitudinal direction is detected by a manual insert paper sensor 25 and a timer and pattern data is written in a frame memory 42 on the basis of the size data. By this method, it is prevented that a toner image larger than the paper is formed and the formation of a missing image on the paper can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a page printer equipped with so-called cassette paper feeding and manual paper feeding.

[Conventional technology]

Image data input from a host computer or the like is optically written onto a photoreceptor using a page printer, such as a print head, and an electrostatic latent image formed on the photoreceptor based on the optical writing is transferred to paper using a known electrophotographic process. This is a device that prints on

In the case of a page printer such as the one mentioned above, in the case of cassette feeding, the paper is supplied by the paper loaded in the paper feed cassette inside the page printer, and in the case of manual paper feeding, the operator manually feeds the paper. This is done by

In the case of cassette paper feeding, the size of the paper to be fed can be known in advance before printing starts by installing a specific protrusion on the attached paper cassette and detecting this information on the page printer itself. . Therefore, in the case of cassette paper feeding, a data writing area of a frame memory that stores data to be printed on paper is set in advance, and data is written in that area.

Furthermore, in the case of manual paper feeding, the size of the paper to be fed cannot be specified in advance, so the data writing area of the frame memory is set to the maximum writing area.

[Problems with conventional technology]

However, in the case of manual paper feeding, the data writing area of the page printer can also be specified from an external host device. This means that printing will not be possible. In other words, in this case, the print data is developed (written) in a wider print area than the paper manually fed into the frame memory, so a toner image is formed on the photoreceptor drum corresponding to the print area of the frame memory. Some parts may not be transferred to the manual feed paper. Therefore, the printed image on the paper becomes a missing image.

Further, the toner image that has not been transferred is removed by a cleaner. This also leads to waste of toner.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above-mentioned conventional drawbacks, it is an object of the present invention to provide a page printer that does not create defective images and does not waste toner.

[Key points of the invention]

In order to achieve the above object, the present invention converts print information input from a host device into image data for each page,
A page printer that prints out a sheet of paper based on the image data, a frame memory that expands and stores the image data, a transport mechanism for the paper, and a sensor that detects the leading and trailing edges of the paper that is being transported. It is characterized by comprising a setting means for setting a data development area of the frame memory based on the output of the sensor, and a development means for developing the image data in the area set by the setting means.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a schematic diagram of the page printer of this embodiment. In the figure, a page printer P has a photosensitive drum 1
, a charger 2 that uniformly charges the photosensitive surface of the photosensitive drum l;
, Printing Radar 3 that exposes the photosensitive surface according to the image data
, a developing device 4 that develops the electrostatic latent image formed on the photosensitive surface by this exposure with toner, a transfer device 5 that transfers the toner image developed by the developing device 4 onto paper, and removing the toner remaining on the photosensitive surface. It has a cleaner 6 that does the following. In addition to these components, the page printer P is also equipped with a paper feed cassette 7 for loading paper, and a paper feed roller 8 is attached to the paper feed cassette 7.
Remove each sheet of paper one by one.

The conveyance path for the paper carried out from the paper feed cassette 7 is formed by a turn guide 9, a temporary guide 10S 11.12, and is sequentially formed by a slip roll 13, a conveyance roll 14, and a paper discharge roll 15.
is arranged to convey the paper to the paper discharge tray 16. Also,
A fixing roll 17 is disposed on the conveyance path and fixes the toner image transferred onto the paper onto the paper. Also, an interface controller board 1 provided below the paper feed cassette 7
8 is provided with an interface controller circuit which will be described in detail later, and the printer controller board L9 is provided with a printer controller circuit which will also be described later.

On the other hand, a paper feed unit 20 is attached to the lower part of the page printer P as an option. This paper feeding unit 20 has a paper feeding force sensor 21 and a manual paper feeding table 22, and increases the types of paper that can be used in the page printer P and allows the operator to manually feed paper. A manual paper guide side plate 23 whose upper surface is slidable in the direction perpendicular to the plane of the paper in FIG. 2 is provided on the manual paper feed table 22, and guides the manual feeding of the paper 24 when the paper 24 is manually fed in the direction of the arrow. This manual paper guide side plate 23 is provided with an LED, which will be described later. Further, a manual paper sensor 25 is provided at the tip of the manual paper feed table 22 in the paper transport direction (same as the manual paper feeding direction), and detects when the paper 24 is located directly below the manual paper sensor 25. Furthermore, a manual paper feed roll 26 is disposed at the tip of the manual paper feed tray 22 to convey the manually fed paper 24.

Further, paper is loaded in the paper feed cassette 21 in the paper feed unit 20, and like the paper feed cassette 7 described above, the paper feed roller 21 is loaded with paper.
7, the paper is carried out from the paper feed cassette 21 one by one. The transport path for the paper 24 manually fed into the manual paper feed table 22 and the paper taken out from the paper cassette 21 is a paper guide 30 extending to a paper supply port 29 provided on the side of the main body of the page printer P. Guide plate 30
’ is formed. Conveyance rolls 32 and 33 are disposed on this guide plate 30', and a conveyance roll 31 is disposed on a paper conveyance path 31' from the manual paper feed roll 26 to the guide plate 30'.

FIG. 1 is a system block diagram illustrating a circuit system of a page printer P having the above-mentioned mechanical configuration.

This system is an interface controller (hereinafter referred to as 1/
F controller) circuit 34, a printer controller circuit 35, a guide plate position detection circuit 36, and the above-mentioned manual paper sensor 25. The I/F controller circuit 34 includes a CPtJ (central processing unit) 37 and a ROM 3.
8, a RAM 39, a reception buffer 40, an image data generator 41, and a frame memory 42;
Signals are input from the manual paper sensor 25 and various switches and sensors (not shown), and control signals are output from the printer controller 43 to the guide plate position detection circuit 36 and each load section (not shown).

In addition, a host computer 44 which is an external host device
The print data such as character codes and control data is sent to the I/F controller circuit 34 via the host interface 45.
This is a circuit that outputs to.

The CPU 37 controls each part according to a program stored in the ROM 3B. For example, character codes and control data output from the host computer 44 via the host interface 45 are temporarily stored in the reception buffer 40, and the above-mentioned character codes and control data stored in the reception buffer 40 are read and sent to a predetermined circuit. Output.

For example, the character code is output to the image data generator 41, and the control data is read to the CPU 37, where corresponding processing is performed. The CF$037 also outputs the pattern data output from the image data generation section 41 based on the character code to the frame memory 42, and stores one page of pattern data in a preset effective print area in the frame memory 42. write to.

The printer controller 43 also receives the pattern data input via the PR bay face 46 and the CPU 3.
This is a circuit that performs specific printing control based on control data output from the print head 3 based on the control data output from the print head 3 by signals supplied from the manual paper sensor 25, various switches, sensors, etc.
Controls the output of the above pattern data to. It also outputs control signals to various load units and the guide plate position detection circuit 36 that transport the paper carried out from the paper feed cassettes 7 and 21 and the paper 24 that is manually fed.

The guide plate position detection circuit 36 includes a CCD (charge coupled device) controller 47, a CC048, and LEDs 49a and 49b provided on the paper guide side plate 23 described above. The manual paper guide side plates 23 are provided on both sides in the paper width direction, and the LED 49a is provided on one manual paper guide side plate 23, and the LED 49b is provided on the other manual paper guide side plate 23. Further, the C0D 48 is provided in the manual paper feed tray 22 and arranged in a line in the direction perpendicular to the plane of the paper in FIG. Therefore, by sliding the manual paper guide side plate 23 in the direction perpendicular to the plane of the drawing, the CCD 48 detects the light emitted from the LEDs 49a and 49b, and sends this detection signal to the CCD controller 47. The CCD controller 47 outputs light reception detection data on the CCD 4 B to the printer controller 43 in accordance with a control signal from the printer controller 43 .

In the page printer P having the above configuration, the printing processing operation of the manually fed paper 24 will be described below.

First, the main power of the page printer P is turned on, and initial setting operations for the print head 3, fixing roll 17, etc. are performed.

Next, the paper 24 is set on the manual paper feed tray 22, and the manual paper guide side plate 23 is slid and set to match the width of the paper 24. At this time, the manual paper guide side plate 23
When the manual paper guide side plate 23 is slid, the LEDs 49a and 49b provided on the manual paper guide side plate 23 also move in the direction perpendicular to the plane of the paper in FIG. Then, the manual paper guide side plate 23
When paper size 4 is set, LED 49 a, 49
The light b is detected by the CCD 48 and sent to the COD controller 4.
7 to the printer controller 43.

The printer controller 43 determines at which position on the CCD 48 of one line the light is most strongly incident, and selects the two LEs.
The distance between D49a and D49b, that is, the distance between the manual paper guide side plates 23 is calculated. This interval data is output to the CPU 37 of the T/F controller circuit 34, and the data write area of the frame memory 42 is set based on the interval data.

FIG. 3 shows the maximum data write area 4 of the frame memory 42.
2a is a diagram illustrating the range of an effective print area 42b corresponding to the paper 24. FIG. For example, if a sheet of paper 210 mm wide x 297 mm long is inserted as the paper 24, the manual paper guide side plates 23 are set with an interval of 210 mm, so the interval data detected by the CCD 48 is, for example, 240 dp. When the pixel density is i, the interval is approximately 1985 pixels. Here margin 42b
If ' is 5-, then 5anX2 (#95) 1890 dots, which is obtained by subtracting the pixel bone, is set as the effective data writing width in the X direction from the address (0, O) of the frame memory 42.

Next, while the CPU 37 is executing the above process, when the paper 24 is inserted further into the manual paper feed table 22, the manual paper sensor 25 turns ON, and the motor (not shown) starts rotating to transport the manual paper. For example, the roll 26 has a conveying speed v
(60mm/5ec). Further, at the same time as the manual paper sensor 25 is turned on, a timer (not shown) starts, and then the paper 24 is transferred to the manual paper transport roll 26.
The trailing edge of the paper 24 is conveyed by the manual paper sensor 25.
Measure the time it takes to complete the passage. The time data measured by this timer is output to the CPU 37, and
7 sets a valid write area in the X direction from the address (0, 0) shown in FIG. 3 based on the time data measured by the timer. At this time, the CPU 37 calculates the moving area for writing in the X direction using the following arithmetic expression.

'y' = (L (sec) xv (mm/5ec) -
2m (am)) In the example, it is 5 m.) If the time measured by the timer is, for example, 4.95 seconds, then by substituting t = 4.95 seconds into the above equation, Y = (
4,95 (sec) x60 (mm/5ec) -2X
5 (r++m) )X9.45 (dot/mn+
) #2712 (dots) That is, a valid write area for 2712 dots is set in the frame memory 42.

During this time, the paper 24 is transported through transport paths 31' and 30' by transport rolls 31 → 32 → 33, passes through the paper supply port 29 of the page printer P, and the leading edge of the paper 24 is brought into contact with the resist plate 28 by the slip roll 13. transported to. At this time, the resist plate 28 is being raised in the direction of the arrow by a mechanism not shown, and the slip roll 13 has an extremely weak conveying force, so that the paper 24 is only further conveyed after the leading edge of the paper 24 contacts the resist plate 28. There is no feeding power.

While the paper 24 is being conveyed and on standby, the character code sent from the host computer 44 is converted into pattern data by the image data generating section 41 and written into the frame memory 42 as described above.

At this time, the effective write area for pattern data is the shaded area in FIG. 3 that has already been set by the above process. Therefore, 1890 dots of the above pattern data are written from the address (0, 0) in 1 word units for every l line in the X direction, and further, by repeating writing of the above pattern data for 2712 lines in the X direction, the write effective area is Pattern data is written to the entire area, and even if pattern data exceeding this area is output, it is buffered to the RAM 39 or the like and is not written to the frame memory 42.

In this way, limited pattern data corresponding to the paper size of the manually fed paper 24 is stored in the frame memory 4.
2, the CPU 37 outputs the pattern data from the frame memory 42 to the print head 3 at a predetermined timing, and outputs a control signal to the printer controller 43. The printer controller 43 outputs a drive signal in accordance with this control signal, lowers the registration plate 28, and refeeds the paper 24 on standby. Through the above processing, an electrostatic latent image is formed between the leading edge of the toner image on the photosensitive surface developed by the developing device 4 and the paper 24.
The leading edges of the sheets of paper 24 almost coincide with each other with the margins shifted, and the toner image is transferred to the paper 24.

At this time, the area where the toner image is created on the photosensitive surface is paper 2.
4, and the toner image of this holder is transferred onto the paper 24. The toner image transferred to the paper 24 is thermally fixed by the fixing roll 17, and then transferred to the paper ejection roll 1.
5, the paper is discharged onto the paper discharge tray 16. Furthermore, only so-called residual toner that has not been completely transferred by the transfer device 5 remains on the photosensitive surface, and the toner image that should be transferred to the paper does not remain on the photosensitive surface.

As described above, in this embodiment, the widthwise size of the paper 24 that is manually fed is detected in advance using the LEDs 49a, 49b, and the CCD 48, and the lengthwise size of the paper is detected using the manual paper sensor 25 and the timer. By writing pattern data to the frame memory 42 based on the above, it is possible to prevent a toner image larger than the paper 24 from being formed and to prevent a defective image from being created on the paper.

Although CCD4B is used in this embodiment to detect the position of the manual paper guide plate 23, a plurality of ordinary switches and sensors such as microswitches are arranged to detect the position of the manual paper guide side plate 23.
It is also possible to detect the interval between.

In addition, although manual paper feeding was described in the above embodiment,
In addition to manual paper feeding, for example, when using a so-called universal cassette in which paper of various sizes can be set, it is not necessary to provide a size detection mechanism in the cassette, and the same method can be used.

〔Effect of the invention〕

As described above in detail, according to the present invention, since data is always written in the frame memory in advance according to the paper size, defective images such as missing images are not created.

Further, since no unnecessary toner image is formed on the photosensitive surface, waste of toner can be prevented.

[Brief explanation of drawings]

FIG. 1 is a system block diagram of a page printer according to an embodiment, FIG. 2 is a schematic configuration diagram of a page printer according to an embodiment, and FIG. 3 is a diagram illustrating a data writing area to a frame memory. 1... Anger drum, 2... Charger, 3... Print head, 4... Developer, 5... Transfer device, 6... Cleaner, 7 .21...Paper feed cassette, 20...Paper feed unit, 22...Manual paper feed stand, 23...Manual paper guide side plate, 24...Paper, 25...Manual paper feed sensor, 26 . . . manual paper conveyance roll, 31 to 33 . . . transportation roll, 34 . . . I/F controller circuit, 35 . . . printer controller circuit, 36 . 42...Frame memory, 43...Printer controller, 47...CCD controller, 4th...CCD. 49a, 49b...LED.

Claims (1)

[Scope of Claims] A page printer that converts print information input from a host device into page-by-page image data, and prints out the image data on a sheet of paper based on the image data, comprising: a frame memory that expands and stores the image data;
a conveyance mechanism for the paper; a sensor for detecting a leading edge and a trailing edge of the paper during conveyance; and a setting means for setting a data expansion area of the frame memory based on the output of the sensor;
A page printer comprising: a developing means for developing the image data in an area set by the setting means.