JPS6234176A - Printing device - Google Patents

Abstract

PURPOSE:To eliminate a clutch mechanism and to align a transfer position to a printing position on a form by setting a distance between a position where the tip of the form is detected and a transfer position larger than a distance between a position where an latent image is started and the transfer position. CONSTITUTION:The positions are set so as to establish the following distance relationship: a distance between A and B is less than a distance between B and D, where A, B and D denote a position where a printing head 13 starts forming an electrostatic latent image, a position where the tip of the sheet 16 coincides with the tip of the latent image and a position where the tip of the sheet 6 is detected by a light emitting diode 35 and a transistor 36 during conveyance, respectively. In the time corresponding to the difference of these distances, a timer, etc., set the timing when the printing head 3 starts printing, and the head is positioned at a desired printing place on the form 16. Thus the clutch mechanism temporarily stopping the form 16 is made unnecessary, and simultaneously printing can be executed at a precise position.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a printing device that records information obtained by a computer or the like on paper as images such as characters.

[Prior art and problems]

To explain a conventional printing device, as shown in FIG. 6, paper l for printing is fed from a recursor center 3 by a paper feed roller 2, and when the leading edge of the paper 1 is touched, it activates a microswitch 4 located below. After that, the rollers stop with their tips abutting the standby position C of the pair of upper and lower standby rolls 5 that are stopped. Next, in response to an activation signal from the microswitch 4, the print head 6 starts optical printing on the photoreceptor drum 8, which has been charged in advance by the charger 7, to form an electrostatic latent image. The electrostatic latent image is developed by a developing device 9 into a visible image. The paper 1 once stopped on the standby roll 5 is fed again at a predetermined timing. Therefore, here, the formation start position of the electrostatic latent image on the photoreceptor drum 8 is A, the position where the leading edge of the paper 1 and the leading edge of the electrostatic latent image on the photoreceptor drum 8 match is B, and the upper and lower standby rolls 5 are The standby position of is C, and the length along the circumference of photoreceptor drum 8 between AB is β. , BC is the length between them.

A. -7! At the same time as printing starts, a timer set to a time corresponding to the length of The leading edge of the image on the body drum 8 was aligned at position B, and the visible image was transferred onto the paper 1 by the transfer device 10.

In this case, a clutch mechanism such as a spring clutch or an electromagnetic clutch is required for the switching operation to rotate or stop the standby roll 5, and there is a problem that the structure is complicated and expensive, and the operation of the clutch mechanism There are variations in the time, and this variation causes the timing to deviate, resulting in misprints on pre-printed paper, etc. This is a disadvantage, and the machine load fluctuates each time the standby roll 5 is switched between rotating and stopping. As a result, there is a drawback that the photosensitive drum 8 causes wow and flutter, resulting in printing blur.

[Purpose of the invention]

In view of the above-mentioned conventional drawbacks, the present invention provides a printing device that has a simple structure that eliminates the 9-clutch and 7-chi mechanisms, accurately matches printing positions, eliminates the source of wow and flutter, and enables blur-free printing. The purpose is to provide.

[Key points of the invention]

In order to achieve the above object, the present invention includes an image carrier, a print head that forms an electrostatic latent image on the image carrier, a visualization means that visualizes the electrostatic latent image, and a printer. In a printing device comprising at least a transfer means for transferring a developed image obtained by an imaging means onto a sheet of paper, a position A at which formation of an electrostatic latent image by the print head on the image carrier starts and a position A on the sheet of paper. A position B where :41 and the leading edge of the electrostatic latent image on the image carrier match.

The relationship between the position where the leading edge is detected during general transport of the paper toward the position B and before the developed image is transferred is such that the distance between AB ≦ the distance between I and D. It is characterized by

[Embodiments of the invention]

An embodiment in which the present invention is applied to a liquid crystal printer will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to the present invention. An electrostatic latent image is formed on the photoreceptor drum 2 as an image carrier charged by the charger 11 by the print head 13 . The electrostatic latent image is formed by a developing device 14 as a visualization means.
The image is visualized to form a toner image, which is transferred to a sheet of paper 16 by a transfer device 15 at a predetermined timing described later, and the toner image transferred and formed on the sheet of paper 16 is fixed by a fixing device 17.

Untransferred toner remaining on the photosensitive drum 12 is cleaned by a cleaner 18, and the surface potential of the photosensitive drum 12 is made uniform by an eraser 19 in preparation for the next image formation.

As shown in FIG. 2, the print head 13 has a light source 20 made of a fluorescent lamp inside, and the light source 20 has an opening 21 inside, and the outer peripheral surface of the portion facing the opening 21 is is covered by a reflecting plate 22. Further, the light source 20 is divided into four parts including shields #Fj and 23 on the upper side and a transparent dustproof glass 24 provided horizontally opposite the opening 21 on the lower side.

Further, a liquid crystal shutter 26 is arranged with a micro shutter 25 located at a lower position corresponding to the opening 21,
A control circuit 27 for controlling the opening and closing of the microphone 1-shaft 25 of the liquid crystal shutter 26 is provided near the shielding plate 23, and the control circuit 27 and the microshank 25 are electrically connected by a heat seal 28. The micro-shutters 25 are arranged on the liquid crystal shutter 26 in a line in the main scanning direction perpendicular to the rotational direction (sub-scanning direction) of the photosensitive drum 12 mentioned above. Furthermore, print head 1
3 is covered with an upper housing 29 and a lower housing 30, and a lens 31 is attached to an opening provided in the lower housing 30 at a position corresponding to the micro shutter 25. Therefore, the light from the light source 20 is.

The opening 21 of the light source 20. Dustproof glass 24 and lens 3
1 to the photoreceptor drum 12.

It is configured to perform optical writing on the photosensitive surface of the photosensitive drum 12.

In addition, the liquid crystal shank 2 built into the print head 13
6, a liquid crystal substance is sealed between two stacked glass substrates 26a and 26b as shown in FIG. 3, and a common electrode provided on the upper glass substrate 26b and the lower glass substrate 26a A micro shack 25 is formed at the intersection with a large number of signal electrodes provided in the . The opening and closing of the micro-shutter 25 is performed by a publicly known two-frequency drive, and the photosensitive drum 1 is opened and closed based on the input printing information.
An electrostatic latent image is formed on 2. Micro Shack 2 above
The size of one piece of 5 is approximately 84 μm, which is 300 dots/
It has a resolution of inches.

On the other hand, the paper 16 is fed from the cassette 33 by the paper feeder 32 based on the print command. The fed paper 16 is transported by a pair of transport 1 calls 34, and the path of the paper 16 is at a predetermined position τD from the transport roll 34 until the leading edge of the paper 16 reaches the surface of the photosensitive drum 12. A light emitting diode (LED) 35 and a phototransistor (PTr) 36 are provided vertically facing each other. Here, a position A where formation of an electrostatic latent image by the print head 13 on the photoreceptor drum 12 starts, a position B where the leading edge of the paper 16 reaches and matches the leading edge of the electrostatic latent image on the photoreceptor drum 12, The photosensitive drum 1 whose relationship with the above-mentioned positions is from position A to position B
Distance along the path of the paper from position B to position BD (hereinafter expressed as dirt) (hereinafter expressed as ~L□) with respect to distance A [3 (hereinafter expressed as wrinkles) along the outer periphery of paper 2 The position is determined at a point at which LT does not become short, that is, L time ≧ 0. Since LT ≠ 0 in general, a timer with variable settings and time is provided, and the timer causes the print head 13 to print the electrostatic image. The timing to start forming is adjusted for each machine of the image forming apparatus. For example, in FIG. STY).When the paper 16 reaches the position where the light emitting diode 35 and the phototransistor 36 face each other during one paper feed, the leading end is detected by the paper switch of the phototransistor 36 and the paper switch is activated. (Sr1
), the timer starts at the same time as 5T3), and when the timer setting time elapses, the tie is up (STa
), At the same time, printing is started by the print head 13 (5T5), and the formation of an electrostatic latent image on the photoreceptor drum 12 is started. At this time, the setting time of the timer is set to about 10 fins in terms of the traveling distance of the paper, and the above is about 10 fins.
becomes. After the timer times up, the leading edge of the paper 16 reaches point E in FIG. 1, and positions A, B, D, and point E are determined so that the distance from point E to position B becomes Lo. In this way, the leading edge of the paper 16 is brought into alignment with the leading edge of the toner image without ever stopping once, and transfer can be performed without any deviation.

The timer is provided to finely adjust the LT when the LT differs from printing device to printing device due to variations in the parts that make up the printing device.When using parts with a high degree of IN, LT', 0, the average exposure of the phototransistor 36 may be activated to immediately start printing without using the timer, as shown by the broken line in FIG.

FIG. 5 is a schematic pronk diagram according to an embodiment of the present invention.

A print signal 37 sent from the post computer is input to an interface section 38 and sent to a print control section 39. The print control unit 39 is a control unit (hereinafter referred to as a mechanical control unit) that controls operations of the image forming apparatus such as driving the liquid crystal shutter 26, charging the photosensitive drum 12, and feeding paper.
40 and a timer 41 having a time setting corresponding to the ratio MitL. The timer 41 is an analog timer, and the set time can be adjusted using the volume 42.

In this embodiment, the case of a liquid crystal printer has been described, but the present invention is not limited by the type of printer, and can also be applied to a laser printer, a LEED printer, and a multi-stylus printer using a dielectric drum.

〔Effect of the invention〕

According to the present invention, the leading edge of the paper for printing and the leading edge of the electrostatic latent image on the image bearing member coincide with the starting position of forming the electrostatic latent image by the printing head on the image bearing member. Il! to position B on the paper before the image obtained by visualizing the electrostatic latent image is transferred. Since the relationship between the position at which the leading edge of the paper is detected during printing and the distance between AB and BD is the distance between AB and BD, the print head is By timing the start of printing, you can accurately align the position of the print on the paper, eliminating misalignment of the print, making it possible to print accurately on paper on which tables, etc. have been printed in advance, and eliminating the need to temporarily stop the paper. This eliminates the need for a clutch mechanism, eliminates printing blur caused by wow and flutter, and simplifies the structure.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to a second embodiment of the present invention. FIG. 2 is a schematic diagram of the print head. FIG. 3 is a perspective view of the liquid crystal shutter. FIG. 4 is a flowchart showing the operation of the print head according to the embodiment of the present invention from the input of a print command to the start of printing. FIG. 5 is a schematic block diagram of the same as above. FIG. 6 is a schematic configuration diagram showing a conventional example. 11... Charger. 12... Photoreceptor 1. 13... To print, 1° 14... Present (Image). 15... Transfer device. 16... Customer. 17... Fixed; A device. 18... Cleaner. One. ... Eraser. 20 ... Light source. 21 ... Opening. 22 ... Reflection plate. 23 ... Shielding plate. 24 ... Cold protection glass. 25 ... Microphone 1 height. 2G ... - Liquid crystal shutter, evening. 27... Control circuit. 28... Heat seal. 29... Upper part of the housing. 3α... Lower part of the housing. 31... Lens. 32... - Paper feed roller. 33...Cassette. 34...Transportation roll. 35...Light emitting diode. 36...Phototransistor. Patent applicant Casio Computer Co., Ltd. Same as above
Casio Electronics Co., Ltd. Figure 3 Button 7 Directive Figure 5 Figure 6

Claims (1)

[Scope of Claims] An image carrier, a print head that forms an electrostatic latent image on the image carrier, a visualization device that visualizes the electrostatic latent image, and an image obtained by the visualization device. A printing device comprising at least a transfer means for transferring a developed image onto a sheet of paper, the formation start position A of an electrostatic latent image by the print head on the image bearing member, and a position A between the leading edge of the sheet and the image bearing member. The relationship between a position B where the leading edge of the upper electrostatic latent image matches and a position D where the leading edge is detected while the paper is being transported toward the position B before the developed image is transferred. However, the distance between AB≦B
A printing device characterized in that the distance between D.