JPS5835558A - Printer - Google Patents

Abstract

PURPOSE:To position easily and accurately a print density detecting head on a basis of the center position of a positioning mark, by forming a continuous positioning mark narrower than a mark for print density detection and reading the positioning mark by the print density detecting head. CONSTITUTION:An electrostatic latent image is formed by a laser light or electrostatic recording, and a toner image is transferred to a transfer paper 9 after development due to a developer. When the electrostatic latent image is formed, a latent image for print density control is formed also, and its toner image is transferred to form a print density control mark 17 on the transfer paper. In case that a print density detecting head 18 is positioned for assembling in a factory or maintenance and inspection, a continuous positioning mark narrower than the print density control mark is generated from a positioning mark generating circuit, and the density of its transferred toner image 21 in the breadthwise direction is read by the detecting head, and the detecting head is fixed to the peak value of a detection signal S2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printing device such as an electrophotographic printer typified by an electrostatic recording device or a laser printer, and the present invention relates to a printing device such as an electrophotographic printer typified by an electrostatic recording device or a laser printer, and the present invention relates to a printing device such as an electrophotographic printer typified by an electrostatic recording device or a laser printer. This will enable you to do the same.

FIG. 1 is a side view showing an outline of this type of printing apparatus.
, a transfer device 4, a cleaning device W15, and a charging device 6 are provided. While the latent image forming body 1 is rotating at a constant speed in the direction shown by the arrow, the latent image forming device 2 forms a latent image by irradiating a laser beam or the like. A latent image 7 is formed on the photosensitive material on the surface of the adult body 1 . When the surface on which the latent image 7 is formed reaches the position of the next developing device 3, toner is latent as a developer!
It is electrostatically attached to the surface, resulting in a visible image 8. This visible image 8 is electrostatically transferred to a recording medium 9 such as plain paper in the next transfer device 4, and when the transferred visible image 10 reaches the fixing section 11, it forms a visible image 10. The toner is heat-fused to the recording medium 9, and a hard copy 12 is completed. - Toner 13 remaining on the latent image forming body 1 without being transferred when the visible image 8 on the force-fed image forming body 1 is transferred to the recording medium 9 is
After being moved to the position of the cleaning device 5 and removed, the surface of the latent image forming body 1 is uniformly charged by the entire surface charging device 6, and then moved to the original position of the latent image forming device 2 to be next removed. Provided for latent image formation. Note that the recording medium 9 is fed by a paper feed tractor 14 at a constant speed in synchronization with the rotation of the latent image forming body 10.

FIG. 2 is a diagram showing a state in which information is printed on the recording medium 9, and as information 15, ABC, Japanese, etc. are printed. A feed hole 16h into which the pin 16 of the paper feed tractor 14 is inserted is formed on both the left and right sides of the recording medium 9, and a print density control mark 17 is printed outside the information printing area of the recording medium 1. There is. This print density control mark 17 is printed on the same line as the Japanese characters of the information pattern 15.

The print density control mark °17 is printed on the recording medium 9, for example, at one location per vertex, and the density of this print density control mark 17 is constantly monitored to detect when the amount of toner has decreased and the print density has become lighter. The detected signal is sent to the developer 11W13 as a toner replenishment signal to replenish toner. By the way, this I1 density control mark 17 is a control mark other than the original information pattern 15, so it has to be printed outside the information recording area as shown in the figure, and the recording area of the print density control mark 17 is It is not possible to ensure a particularly wide area, so the size of the print density control mark 17 itself is also limited.
For example, it has a small shape of about 3 x 1.7 cranes. Therefore, it is difficult to align the print density control mark 17 with the detection and gutter for detecting the density of the print density control mark 17, and the detection head must be replaced or inspected during assembly at the factory or for maintenance and inspection. When doing so, highly accurate positioning was not possible and it took a lot of time to adjust the position.

Figure 3 shows the detection head printing density control mark 17
Detection head 1 is a side sectional view of the part to be aligned to the center of
8 is attached to the device frame 20 or the like via an adjustment screw 19. When aligning, use the print density control.
Optically read the roll mark 17 and determine its center position C.
, and adjust the detection head 18 to the center position C using the adjusting screw 19.
Conventionally, in order to find the center position of this print density control mark 17 during assembly and maintenance inspection, etc., it is fixed with lock paint etc.
As shown in (a), the print density control mark 17 is directly scanned in the direction of arrow a1 by the detection head 18, and while looking at the read signal S+ of the detection head 18 as shown in (b),
The adjusting screw 19 is repeatedly operated based on the rising and falling parts of the read signal sI, and the detection head 18 is positioned at the center value of the read signal S+ by intuition.

However, since the print density control mark 17 has a certain width, the read signal s1 also has a waveform with a constant level, making it difficult to aim at the center position. Furthermore, if the print density control mark 17 is printed in black, it may cause the so-called edge effect, so it is usually formed with diagonal lines, mesh, halftone dots, etc. as shown in the figure. is also low, making aiming at the central position even more difficult.

The present invention solves this inconvenience when aligning the detection head to the center position of the print density control mark,
The purpose is to enable alignment to be performed easily, quickly, and accurately. To achieve this objective, the present invention
In an electrophotographic printing device that prints a print density control mark in addition to the information pattern and controls the density of the information pattern by reading the print density control mark, the detection head that reads the print density control mark is used as the print density control mark. This method includes an alignment mark generation circuit in addition to a print density control mark generation circuit, and from the alignment mark generation circuit, a strip-shaped 0 position that is narrower in width than the print density control mark and continuous is formed. The configuration is such that an alignment mark is generated and printed, the alignment mark is read by the detection head, the center position of the print density control mark is determined from the peak position of the read waveform, and the detection head is aligned. .

Next, an embodiment in which the present invention is applied to a laser printer will be described based on the drawings. FIG. 5 is a diagram illustrating the basic idea of the method of the present invention, in which a positioning beak 21 is printed in place of the print density control mark 17. This alignment mark 2
1 is narrower than the print density control mark 17;
Also, the position where the print density control mark 17 should be printed @
[Printed in a position + iui such that the center C of the alignment mark 17a and the center C of the alignment mark 21 match. The pattern should also be solid black, rather than diagonal lines, mesh, or halftone dots.

When such alignment mark 21 is read in the direction of arrow a1 with detection head 18, a read signal S2 having a peak as shown in (b) is obtained. If such a peak position exists, it is easy to align the detection head 18 to the peak position. Therefore, it is preferable that the alignment mark 21 be as narrow as possible in order to obtain a read signal with a peak. In addition, even if the distance between the recording medium 9 and the detection head 18 is not constant and is further away than the specified distance, in order to easily find the peak position, it is necessary to set a certain width so that a sufficient level can be obtained. The width dimension d is determined so as to meet these requirements. Also, unlike the print density control mark 17, the alignment mark 21 is printed continuously in the direction of the center line C until alignment is completed.

FIG. 6 is a block diagram showing the circuit configuration for generating such alignment marks 21. C17 is a print density control mark generation circuit, C21 is an alignment mark generation circuit, and C15 is an information pattern generation circuit. It is a circuit. 22 is the print density control mark generation circuit CI?
Alternatively, when printing the print information pattern 15 with a switching circuit that selects the alignment mark generation circuit C21, the switching circuit 22 selects the print density control mark generation circuit C.
17 is selected, and alignment mark generation path C21 is selected only during alignment operation. The OR circuit 23' uses the signal from the print density control mark generation circuit C17 or the signal from the alignment mark generation circuit C21 and the information from the information pattern generation circuit C15 to perform the next laser modulation! ! A print density control mark or alignment mark and an information pattern are simultaneously and continuously printed on the latent image forming body 1 via laser modulation 1) 24. When the latent image forming device 2 scans the latent image forming body 1 by generating modulated light in which the laser beam is modulated by the information signal from the OR circuit 23 in the laser modulator 24, a latent image 7 is formed. Then, information patterns 15, print density control marks 17, alignment marks 21, etc. as shown in FIG. 2 are printed.

That is, when printing normal information, the printing density control mark 17 and the information pattern 15 are printed by selecting the printing density control mark generation time 1aC17 in the switching circuit 22. When aligning the detection head 18 to the center of the print density control mark 17, if the alignment mark generation circuit C21 is selected by the switching circuit 22, the narrow aligned alignment mark 21 and the information pattern explained in FIG. 15 is printed. Then, the detection head 18 detects the aligned alignment marks 21 using the arrow a1.
direction to generate the detection signal S2, and adjust the adjustment screw 19.
Then, the detection head 18 is moved to the peak position of the detection signal S2. Since the alignment marks 21 are continuous, it is extremely easy to search for continuous alignment marks 21 compared to searching for the print density control mark 17, which is printed only once on a page, and scanning it with the detection head. , work efficiency is greatly improved.

Although the alignment mark 21 has been described as an example in which the detection head 18 detects the mark printed on the recording medium 9,
A detection radar may be disposed between the developing device 3 and the transfer device w4 to read the alignment mark 21 in a state before being transferred from the latent image forming body 1 to the recording medium 9 to perform alignment. .

It is preferable to read the alignment mark 21 on the latent image forming body 1 rather than reading the alignment mark 21 on the latent image forming body 1 because there is a possibility that the spacing between the alignment mark 21 and the detection head 18 may fluctuate due to fluctuations in the recording medium 9.

As described above, according to the present invention, in an electrophotographic printing apparatus that prints a print density control mark in addition to an information pattern, and controls the density of the information pattern by reading the print density control mark, the print density control mark In addition to the print density control mark generation circuit, an alignment mark generation circuit is also provided when aligning the detection head for reading the print density control mark with the print density control mark. Generate and print a wider and continuous band-shaped alignment mark, and read the alignment mark with a detection head from the peak position of the read waveform.
A configuration is adopted in which the center position of the print density control mark Φ is determined and the detection head is aligned. Therefore, by reading the alignment mark, a waveform signal with a peak can be obtained, and the detection head can be easily and accurately moved from the peak position of the signal to the center of the width direction of the print density control mark. It is possible to align the position, and the circuit configuration is simple and can be realized at low cost.

[Brief explanation of drawings]

Figure 1 is a side view showing an overview of the electrophotographic printing device, Figure 2
The figure shows the information pattern printed on the recording medium, Figure 3 is a side sectional view showing the adjustment mechanism of the detection head, and Figure 4 is a side sectional view showing the adjustment mechanism of the detection head.
5 is a diagram showing a conventional positioning method, FIG. 5 is a diagram showing a positioning method according to the present invention, and FIG. 6 is a block diagram showing a circuit configuration of a positioning section in a printing apparatus according to the present invention. In the figure, 1 is a latent image forming body, 3 is a developing device, 9 is a recording medium, 17 is a print density control mark, 18 is a detection head, and 21 is an alignment mark. Patent Applicant: Fujitsu Limited Agent, Patent Attorney: Minoru Aoyagi Figure 2 15 Figure 3

Claims (1)

[Claims] In a printing device that prints a print density control mark in addition to the information pattern, and controls the density of the information pattern by reading the print density control mark,
This method aligns a detection head for reading the print density control mark with the print density control mark, and includes an alignment mark generation circuit in addition to the print density control mark generation circuit, and from the alignment mark generation circuit, Generate and print a continuous band-shaped alignment mark that is narrower than the print density control mark, read the alignment mark with a detection head, and find the center position of the print density control mark from the peak position of the read waveform. , a printing device characterized in that the detection head is aligned.