JPH0398382A - Printer - Google Patents

Abstract

PURPOSE:To attain accurate print without disturbing a printed picture even when a print density switching signal is inputted in any case by not switching the print density and informing it with respect to the print density switching signal inputted for a print density switching disable period. CONSTITUTION:A control means controlling the printing and the print density sets a print density switching disable period including the printing period onto, e.g. one recording paper sheet. When a print density switching signal to switch the print density is inputted to the control means during the print density switching disable period, the control means informs the disabled print density without switching the print density. Thus, the disturbance of a print picture due to a change in the print density during the printing onto the recording paper is prevented and an external device such as a computer connecting to the printer recognizes it that the print density is not switched.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printing device that forms images, and more particularly, to a printing device that can print at a plurality of printing densities.

[Conventional technology]

Laser printers scan a photoreceptor drum with laser light that is modulated based on print information to form a latent image, develop a toner to obtain a visible image, transfer this to recording paper, and then fix it. It is. In recent years, printing devices are required to have high resolution, and laser printers, which are capable of high-speed, high-density printing using laser light modulated at high speed, have become popular as output devices for computers and the like.

On the other hand, some output devices such as computers are capable of printing at a plurality of printing densities, even if they are capable of high-density printing, in order to be compatible with relatively low-density printing devices.

Additionally, laser printers and the like have been put into practical use that can enlarge or reduce images by printing at a plurality of printing densities without deteriorating the printing quality.

[Problem to be solved by the invention]

Conventionally, in a laser printer capable of printing at a plurality of printing densities, when a printing density switching signal is received from a host computer, the printing density is changed from the time when the printing density switching signal is input. Generally, when printing is performed based on the same image information, the higher the density of printing, the smaller the printed image becomes. Furthermore, it takes a certain amount of time to switch the printing density. Therefore, conventional laser printers have the disadvantage that if the print density is changed during a printing operation, characters and images will be distorted and normal printing cannot be performed.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above technical problem and provide a printing device that can perform normal printing without disturbing the printed image even if a printing density switching signal is input in any case.

[Means to solve the problem]

In order to achieve the above object, a printing device according to the present invention includes:
It includes a printing device that prints on recording paper at a plurality of printing densities, and a control device that controls the printing operation and printing density in the printing device based on the input of a printing density switching signal, and the control device controls the printing The present invention is characterized in that a density switching disabled period is set, and in response to a printing density switching signal input during the printing density switching disabled period, the printing density is not switched and a notification to that effect is notified.

[Effect]

In the printing apparatus according to the present invention, the control means for controlling the printing operation and the printing density sets a period during which the printing density cannot be switched, for example, including a printing operation period on one sheet of recording paper.

Furthermore, if a print density switching signal for switching the print density is input to the control means during this print density switchability period, the control means notifies the user of this without switching the print density. Therefore, disturbances in the printed image due to changes in print density during printing on recording paper are prevented, and external devices such as computers connected to this printing device recognize that the print density cannot be changed. can do.

〔Example〕

This embodiment will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the electrical structure of a laser printer 100 including a printer engine section 150, which is a printing device according to the present invention, and FIG. 2 briefly shows the structure related to the printing operation of the laser printer 100. FIG. The following description will be made with reference to these drawings. laser printer 1
00 includes, for example, a video controller section 200, and print data output from an external computer or the like is converted into an image signal by this video controller section 200.

Reference numeral 51 denotes a laser element such as a laser diode, which is driven ON/OFF based on an image signal VDO applied from the video controller section 200 to the laser driver 41 via the line 22. At this time, the video controller section 200 switches and outputs the output speed of the image signal VDO based on the set printing density.

On the other hand, various command signals including designation and change of print density are sent from the video controller unit 200 to the line 23.
, and a microprocessor (hereinafter abbreviated as rMPUJ) which is a control means via an interface circuit 33.
40 is input.

Further, internal status information in the printer engine section 150 and error messages to be described later are outputted to the video controller section 200 via the interface circuit 27 and line 28.

The laser beam from the laser element 51 passes through a collimator lens and a cylindrical lens (not shown), and is reflected by a rotating polygon mirror 52. The scanner driver 43 is
Based on the signal from the MPU 40, the scanner motor 53
As a result, the rotating polygon mirror 52 is rotated at a rotation speed corresponding to the set printing density. This rotating polygon mirror 5
The laser beam 20 reflected by the reflection mirror 54
is reflected and scans on the photosensitive drum 11.

In addition. The BD signal processing circuit 45 outputs a BD signal to the MPU 40 for specifying the image writing timing in the main scanning direction based on a detection signal from a laser light detector 55 placed at the scanning start position of the laser light 20. do.

At this time, the photosensitive drum 11 is driven by a drum motor 56 and a drum driver 46 at a constant rotational speed regardless of the set print density, and its surface is
It is uniformly charged by the corona discharge in step 3. Therefore, by scanning and exposing the photosensitive drum 11 with the laser beam 20, an electrostatic latent image is formed. This electrostatic latent image is developed into a toner image by the developing unit 14, and is transferred onto the recording paper l as described later. Note that 12 is a cleaner for cleaning the photosensitive drum 11.

Next, the configuration for conveying the recording paper 1 will be described. 2
is a cassette for storing recording paper 2, and a plurality of types of cassettes 2 are prepared depending on the size of the recording paper 1 to be stored. At the right end of the cassette 2 in FIG. 2, one or more protrusions 2a are formed at predetermined positions along the direction perpendicular to the plane of the drawing, depending on the size of the recording paper 1 to be stored. The protrusion 2a selectively presses a plurality of microswitches 18 provided in the laser printer 100 when the cassette 2 is attached to the laser printer main body. Thereby, the laser printer 100 recognizes the size of the recording paper 1. In other words, the protrusion 2a and the microphone port switch 18 constitute a detection means for detecting the size of the recording paper 1.

A paper feed cam 3 feeds the recording paper 1 stored in the cassette 2 one by one, and the paper feed cam 3 conveys the recording paper 1 to the positions of paper feed rollers 4a and 4b. A registration shutter 5 stops the recording paper 1 conveyed by rotation of the paper feed rollers 4a and 4b. At this time, the paper feed rollers 4a and 4b continue to rotate without slipping against the recording paper 1. When the registration solenoid 6 is driven to release the registration shutter 5 upward in FIG.
is sent to the photosensitive drum 11 by paper feed rollers 4a, 4b and transport rollers 7a, 7b.

A transfer charger 15 is driven by the high-voltage driver 25 based on a signal from the MPU 40, and transfers the toner image on the photosensitive drum 11 onto the recording paper 1 as described above.

Fixing rollers 8a and 8b heat fix the toner image on the recording paper 1.

A heater 24 raises the surface of the fixing roller 8a to a predetermined temperature. The recording paper 1 printed in this manner is discharged onto the stacker 10 by paper discharge rollers 9a and 9b.

Next, the characteristic operation of a certain laser printer 100 based on the above structure will be explained with reference to the flowcharts of FIGS. 3A and 3B.

When the laser printer 100 is powered on, the third
Step SIO in Figure A is executed to initialize the contents of the random access memory provided in the MPU 40, and execute initialization processing such as rotating the rotating polygon mirror 52. At this time, the size of the recording paper 1 is recognized from the microswitch 18.

Subsequently, in step S20, communication processing of printer control commands and the like are executed with the video controller section 200. That is, as will be described later, a command communication control routine is executed, and when a command is received, the command is decoded and sent back, or processing corresponding to the received command is performed. In the main routine of step S30, various known printer controls are executed.

Next, the print density changing operation in the command communication control routine shown in step S20 will be explained. First, in step 821, it is determined whether or not a printer control command has been sent from the video controller section 200.
If not received, return. When a printer control command is received, it is determined in step 822 whether it is a print density switching request command, and if a command other than a print density switching request command is received, step S
At step 23, the MPU 40 interprets the various commands received and performs processing according to the commands, such as driving various device groups such as the primary charger 13 and the laser element 51 via a device driver or the like.

For example, when a print command is input, the drum motor 56 is operated via the drum driver 46, and
The primary charger 13 is operated.

On the other hand, when the print density switching request command is received in step S22, it is determined in step S24 whether the transfer charger 15 is in the on state. If it is in the on state, the process moves to step S28, and error information is transmitted from the printer engine section 150 to the video controller section 200.

This error information is output, for example, as one of the status information in response to the print density switching request command. This allows the video controller section 200 to recognize that the printing density has not been switched in the printer engine section 150.

In addition, even if you wait for the video control mode to receive this error information and send the print density change request command again to change the print density from the next page onwards, or if you print multiple pages consecutively. Appropriate processing can be performed by temporarily stopping the printing operation from the next page onward. In addition, in a configuration in which the video controller section 200 is omitted and the processing performed by the video controller section 200 is executed by an external device, the above-mentioned appropriate processing is performed based on software installed in an external device such as a computer. It will be done.

On the other hand, if the transfer charger 15 is in the OFF state in step S24, the process advances to step S25 to receive a signal representing the print density from the video controller unit 200. Note that the print density setting value is held within the MPU 40, and when the print density is switched, its contents are updated to the received setting value.

After that, in step 826, after arithmetic processing to be described later is performed, a signal is output to the scanner driver 43, and the polygon mirror 52 is
is rotated at a rotation speed according to the set printing density.

This changes the printing density in the sub-scanning direction.

For example, the rotation speed of the rotating polygon mirror 52 at 240 dpi is RA%, and the frequency of the video clock is FA% 300 dp.
The rotational speed of the rotating polygon mirror 52 at the time of i is RB%, and the frequency of the video clock is F. Then, there are 1 2 relationships. When changing the print density from, for example, 240 dpi to 300 dpi by a print density switching request command, the MPU 40 performs the above calculation and calculates the rotation speed R. will be output to the scanner driver 43.

Further, the frequency FB of the video clock of the image signal representing the print density in the main scanning direction is determined by the video controller section 20.
0, the butterfly is determined to satisfy the above formula.

In addition, in step S27, in order to change the output timing of the BD signal as the rotational speed of the polygon mirror 52 is changed, data corresponding to the printing density is sent to the BD signal processing circuit 45.
given to.

FIG. 4 is a timing chart for explaining the timing of each operation in the printing operation. When the signal PRINT rises at time t1 as a print command, the MPU 40 that receives this sets the signal DRMD to high level to operate the scanner motor 53 and drum motor 56, and after a predetermined period W1 has elapsed, turns on the primary charger 13. .

When the rotation of the scanner motor 53 becomes stable, the signal SRDY becomes high level. When the printer engine section 150 completes preparation for printing, it issues a vSYNC request signal, and after a predetermined period W2 has elapsed since the video controller section 200 outputs the vertical synchronization signal VSYNC, it outputs the image signal VDO. In synchronization with this vertical synchronizing signal VSYNC, the registration shutter 5 is released, the transfer charger 15 is activated, and the like. The release period of the registration shutter 5, the ON period W4 of the transfer charger 15, etc. are set in accordance with the size of the recording paper 1 detected as described above.

As described above, in this embodiment, during the ON period W4 of the transfer charger 15, the MPU 40 outputs error information without switching the printing density in response to the printing density switching request command. In addition, the transfer charger 15
Since the ON/OFF control of the transfer charger 15 is performed by the MPU 40, the MPU 40 recognizes the ON/OFF state of the transfer charger 15. Therefore, the above operation can be achieved simply by changing the software without requiring the addition of a new configuration. Moreover, period W4 is recording paper I
Assuming the size of the largest recording paper 1, the invalid period is set to the minimum necessary length compared to the case where the invalid period of the print density switching request command is fixed. It is possible to avoid prolonging the process unnecessarily.

As described above, in this embodiment, a case has been described in which the period W4 in which the transfer charger 15 is in the on state is set as the period in which error information is output without performing a printing density switching operation in response to a printing density switching request command. However, in the present invention, if the period corresponds to the size of the recording paper 1, for example, the period when a video signal for one page is being input, or the period corresponding to the size of the recording paper 1, or the period when the primary charger 1
It may be the ON period of 3, or it may be a period corresponding to the length of the recording paper 1 in the conveyance direction after the registration shutter 5 is released and conveyance of the recording paper 1 is restarted. can be set.

Also, instead of the print density switching request command, only the printing density specification command is used, the newly specified printing density and the current printing density are compared, and only if they are different, the same processing as the above printing density switching request command is performed. You can do it like this.

Alternatively, a print density change permission flag may be provided, and error information may be output in response to a print density change request command input when the flag is not set.

Furthermore, although the case of a laser printer that performs main scanning using a rotating polygon mirror has been described, the present invention can be similarly implemented in a printing device that forms a latent image on a photoreceptor using an LED array or a liquid crystal shutter. can do.

〔Effect of the invention〕

As explained above, according to the present invention, in a printing device capable of printing at a plurality of printing densities, even if a printing density switching signal is input during printing operation, normal printing can be performed without disturbing the printed image. I can do 16 things.

[Brief explanation of drawings]

FIG. I is a block diagram showing the electrical structure of a laser printer 100 according to an embodiment of the present invention, and FIG.
3A and 3B are flowcharts for explaining the operation of the MPU 40 in the laser printer 100, and FIG. 4 is a sectional view showing the configuration of the laser printer 100.
2 is a timing chart showing the operation timing of 0. 1...Recording paper 2...Cassette 2a...Protrusion 11...Photosensitive drum 13...Primary charger 53...Scanner motor 100...Laser printer 150...Printer engine section 200・・・Video controller section

Claims (1)

[Scope of Claims] A printing device that prints on recording paper at a plurality of printing densities, and a control device that controls printing operations and printing densities in the printing device based on input of a printing density switching signal, The control means sets a print density switching disabled period, and in response to a printing density switching signal input during the printing density switching disabled period, the printing density is not switched and a notification to that effect is provided. Device.