JPH02111912A - Image recorder - Google Patents

Abstract

PURPOSE:To irradiate an image carrier with a light beam of the shape which is always constant or is assigned by independently providing a 1st spot width control means which controls the spot width of the light beam for exposing a photosensitive body with respect to the main scanning direction thereof or the spot width of the light beam with respect to the sub-scanning direction thereof respectively. CONSTITUTION:The 1st spot width control means is constituted of a CPU 52, a light quantity correcting circuit 1, a pulse correcting circuit 2, etc. The light quantity correcting circuit 1 outputs the control signals 1a to 1c based on the light quantity control signal to a laser driver 53. Laser driving currents Ia to Ic are, therefore, applied to a semiconductor laser 54 and the light output P of the laser 54 increases successively to Pa to Pc. The light quantity distribution on a photosensitive drum 58 which is the surface to be irradiated is so formed that the spot width L can be changed to la to lc relative to the light quantity if the light output P is controlled to Pa to Pc in such a manner. The adjustment of the light beam to the beam spot width at which always the prescribed ratio is attained is possible in this way and the exposing at the specified beam spot width is executable.

Description

Detailed Description of the Invention (Field of Industrial Application) This invention relates to an optical scanning type image recording system that records an image by performing optical scanning on a photoreceptor based on external digital image information. It is related to the device.

(Prior art) Conventionally, a light beam is modulated based on image information from an electronic computer, etc., and the modulated light beam is imaged and scanned on a recording medium using an optical element such as a light deflector or lens to create an image. Devices for recording information are widely known.

FIG. 9 is a schematic diagram showing an example of a laser beam printer, which is an example of a conventional image recording device, and 51 is an image input terminal that receives an image signal sent from an external device, such as a host computer, and receives a signal. The image signal is input to the CPU 52 via the line 51a. Reference numeral 53 denotes a laser driver, which generates a signal for on/off modulating a laser generator (semiconductor laser) 54 such as a semiconductor laser based on image No. 13. 55 is a scanner motor that rotates a rotating polygonal representation (polygon mirror) 56 at a constant speed. Reference numeral 57 denotes an imaging lens having fθ characteristics, which directs the laser beam directed toward the polygon mirror 56 onto the photosensitive drum 5.
Scan horizontally to 8. A beam detector 59 detects the deflected laser beam in front of the image writing position and sends an image writing start signal (BD signal) to the CPU 52. 6
0 is a recording paper, on which a toner image obtained by developing a N'J image formed by a laser beam on a photosensitive drum 5th using a known electrophotographic process is transferred and fixed.

In this type of image recording apparatus, the laser beam emitted from the laser generator 54 forms an image on the photosensitive drum 58 at about 1100 Ii.

[Problem to be solved by the invention]

However, the large shape of the laser beam is due to the laser generator 54. Polygon mirror 56. It varies depending on variations in the imaging lens 57, etc., errors in the arrangement position, etc. Furthermore, the amount of laser light varies depending on the driving current value of the laser driver 53, and thus the magnitude of the laser light on the photosensitive drum 58 varies.

The nature of this laser light and the variation in its shape are 21 papers 60
This will appear in the output image above as variations in image shape as shown in FIGS. 10(a) to 10(f).

10(a) to (f) are schematic diagrams for explaining the relationship between the size and shape of laser light and the output image form. In FIG. Line 22 and! A λ line 23 is formed.

In the same figure (b), 24 is a laser beam, and the laser beam 21
25 shows a horizontal line caused by the laser beam 24, and 26 shows a vertical line formed by the laser beam 24.

In the same figure (C), 27 is a laser beam, and the laser beam 21
2B indicates a horizontal line formed by the laser beam 27, and 29 indicates a vertical line formed by the laser beam 27.

In the figure (d), 21a indicates a laser beam which is an enlarged version of the laser beam 21, and a horizontal line 22a and a vertical line 23a are formed by irradiation with this laser beam 21a.

In FIG. 2(e), 24a indicates a laser beam that is an enlarged version of the laser beam 24, and a horizontal line 25a and a vertical line 26a are formed by irradiation with this laser beam 24a.

In the figure (f), 27a indicates a laser beam which is an enlarged version of the laser beam 27, and a horizontal line 28a and a vertical line 29a are formed by irradiation with this laser beam 27a.

As can be seen from these figures, when the size and shape of the laser beam change, the line widths of the horizontal and vertical lines of the output image vary. This change in line width has the problem of deteriorating the quality of characters, especially when outputting small kanji characters.

For this reason, conventionally the semiconductor laser 54. polygon mirror 5
6. The above problem has been solved by improving the accuracy of processing 1 assembly of the imaging lens 57 and the accuracy of their positional relationship.

However, there is a limit to adjusting the above-mentioned problem with mechanical accuracy alone, and pursuing this problem any further will result in a problem of significantly increasing product costs.

In addition, in recent years, the demand for the above-mentioned laser beam printers has been increasing as output devices for printing plate drafts and desktop publishing for Japanese word processors, etc., and the demand for high image quality such as uniform line width is becoming stronger. It has become to.

This invention was made to solve the above problems, and in a recording device that uses a light beam as an image drawing medium, the shape and size of the light beam can be adjusted individually in the main scanning direction and the sub-scanning direction. To obtain an image recording device that can always irradiate an image carrier with a light beam having a constant or specified arbitrary value size and shape even if the size and shape of the exposed beam vary by adjustment. With the goal.

[Means for Solving the Problems] An image recording apparatus according to the present invention includes a first image recording apparatus that independently controls the spot width in the main scanning direction of the light beam that exposes the photoreceptor or the spot width in the sub-scanning direction of the light beam. 1 is provided with spot width control means.

Further, width information input means for specifying and inputting the vertical line or horizontal line width of the output image on the photoreceptor, image reading means for reading the image width formed on the recording medium, and based on the image width read by the image reading means, A second spot width control means for controlling the driving of the first spot width control means may also be provided.

(Function) In the present invention, the first spot width control means independently controls the spot width in the main scanning direction of the light beam that exposes the photoreceptor or the spot width in the sub-scanning direction of the light beam, and The shape and size of the light beam used to expose the image are constant.

Further, when the width information input means specifies the vertical line or horizontal line width of the output image on the photoreceptor, the image reading means reads the image width formed on the recording medium, and the image reading means reads the width of the image formed on the recording medium and adjusts the width of the image based on the read image width. The second spot width control means is the first spot width control means.
The spot width of the light beam is adjusted so that the spot width of the light beam becomes a designated image width.

〔Example〕

FIG. 1 is a block diagram illustrating the configuration of an image recording apparatus showing an embodiment of the present invention, and the same parts as in FIG. 9 are given the same reference numerals.

In this figure, 1 is a light amount correction circuit, which controls the laser driver 53 based on the light amount control signal output from the CPU 52.
The laser driver 53 outputs the control signals 1a to 1c to the semiconductor laser 54, for example, the laser drive currents 1a to I.
Apply c.

2 is a pulse correction circuit that applies a modulation signal that determines the on time to the laser driver 53 based on a pulse width control signal output from the CPU 52;

Note that the CPU 52. Light amount correction circuit 1. 4. The first spot width control means of the present invention is controlled from the pulse correction circuit 2 and the like.
The first spot width control means is controlled by the photosensitive drum 58.
The spot width of the light beam (laser beam in this embodiment) that exposes the photosensitive drum 58 in the main scanning direction or the spot width of the light beam in the sub-scanning direction is independently controlled to control the spot width of the laser beam that exposes the photosensitive drum 58. Make it constant.

Next, referring to FIGS. 2 and 3, the spot width in the sub-scanning direction, that is, the line width control operation of the horizontal line, performed by the light amount correction circuit 1 shown in FIG. 1 will be described.

FIG. 2 is a characteristic diagram illustrating the light output characteristics of the light amount correction circuit 1 shown in FIG. The axis shows the drive current I.

FIG. 3 is a schematic diagram illustrating the relationship between light amount and beam spot width, where the vertical axis shows the light amount (light output) and the horizontal axis shows the spot width.

When the light amount control signal is transmitted from the CPU 52, the light amount correction circuit 1 outputs control numbers 18 1a to 1C as shown in FIG. 2 to the laser driver 53 based on the light amount control signal. As a result, a laser drive current I a −I c is applied to the semiconductor laser 54 . As a result, the light amount of the semiconductor laser 54 is changed to the optical output P, as shown in FIG.
increases to Pa''-Pc. In this way, the optical output P
When is controlled to Pa-Pc, the light amount distribution on the photosensitive drum 58, which is the irradiated surface, becomes as shown in FIG. 3, and the spot width can be varied as JZaxuc relative to the light amount.

Therefore, the line width of the horizontal line can be adjusted to a predetermined width by controlling the amount of laser light.
, 27a can be adjusted to a predetermined line width.

On the other hand, the line width for the line in the sub-scanning direction is adjusted to a predetermined line width by adjusting the on time of the modulation signal by the pulse correction circuit 2 shown in FIG. The pulse width adjustment operation for vertical lines will be described below.

FIG. 4 is a detailed block diagram illustrating the configuration of the pulse correction circuit 2 shown in FIG. 1, and the same components as in FIG. 1 are given the same reference numerals.

In this figure, 11 is a switch that switches terminals a to C according to a pulse width control signal output from the CPU 52. A pulse signal generator 12 generates a pulse signal 12a having a predetermined time width t1 in synchronization with the rising edge of the modulation signal 51b output from the CPU 52. Reference numeral 13 denotes an inverter circuit, which inputs an inverted pulse signal 13a obtained by inverting the pulse signal 12a to one side of the AND gate 14. The modulation signal 51b is directly input to the other side of the AND gate 14, the AND operation is performed, and a new modulation signal M1 is output to the laser driver 53. 15 is a pulse signal generator which generates a pulse 18 with a predetermined time width t2 in synchronization with the rise of the modulation signal 51b output from the CPU 52.
to occur.

16 is an OR gate circuit which takes an OR between the modulation signal 51b and the pulse signal 15a output from the pulse signal generator 15, and outputs a new modulation signal M2 to the laser driver 53.

FIGS. 5(a) and 5(b) are timing charts illustrating signals of each part in FIG. 4, and the same signals as those shown in FIG. 4 are given the same reference numerals.

Next, the pulse width control operation in the sub-scanning direction will be explained with reference to FIGS. 6(a) to 6(C).

FIGS. 6(a) to 6(C) are operation explanatory diagrams for explaining the pulse width control operation in the sub-scanning direction.

In these figures, 31 to 33 indicate laser beams, and the laser beam 31 has a substantially circular shape or a length-to-width ratio of 1.
．． 0 to 1.2, the laser beam 32 corresponds to the case where the shape has a horizontally long ratio of 0.7 to 1.0, and the laser beam 33 corresponds to the case where the ratio of the vertical and horizontal lengths of the shape is 0.7 to 1.0. The ratio is 1.2-1.
5, which corresponds to the vertically long case.

Reference numerals 31a to 33a indicate horizontal lines, which correspond to the state where the light amount has been corrected by the above-mentioned light amount correction circuit 1 so that the width of each horizontal line is the same.

31b to 33b indicate vertical lines, especially vertical line 31b
corresponds to a vertical line formed by the laser light emitted from the semiconductor laser 54 based on the modulation signal 51b when the switch 11 is connected to the terminal a when the shape of the laser light becomes the laser light 31.

The vertical line 32b is a vertical line formed by the laser beam irradiated from the semiconductor laser 54 based on the modulation signal M1 when the switch 11 is connected to the terminal when the shape of the laser beam becomes the laser beam 32. handle.

The vertical line 33b is a fir line formed by the laser beam irradiated from the semiconductor laser 54 based on the modulation signal M2 when the switch 11 is connected to the terminal C when the shape of the laser beam becomes the laser beam 33. handle.

For example, when the CPU 52 recognizes that the shape of the laser beam irradiated from the semiconductor laser 54 is the laser beam 31, the switch 11 is connected to the terminal a, and the modulated signal 51b is
Laser light is irradiated from the semiconductor laser 54 based on this.

As a result, a vertical line 31b is formed on the recording paper 60.

Further, when the CPU 52 recognizes that the shape of the laser beam irradiated from the semiconductor laser 54 is the laser beam 32, it connects the switch 11 to the terminal and outputs the modulated signal 51b.
The semiconductor laser 54 is activated based on the modulation signal Ml (see FIG. 5(a)), which is an AND signal of
irradiate laser light from As a result, the vertical line 32b
(having the same width as the vertical line 31b) is formed on the recording paper 60.

Furthermore, when the CPU 52 recognizes that the shape of the laser beam irradiated from the semiconductor laser 54 is the laser beam 33, the switch 11 is connected to the terminal C, and the pulse signal 15a output from the pulse signal generator 15 is and the modulation signal 51b (FIG. 5(b)).
(see), the semiconductor laser 54 irradiates laser light. As a result, the vertical line 33b (vertical line 31b
) is formed on the recording paper 60.

As a result, even if the shape of the beam spot irradiated from the semiconductor laser 54 is non-uniform in the main scanning direction and the sub-scanning direction, by adjusting the light amount and the ON time of the modulation signal, it is always possible to The photosensitive drum 58 can be irradiated with a beam having an aspect ratio of approximately 1:1 with respect to the horizontal and vertical directions (direction) and the sub-scanning direction.

In the above embodiment, a case has been described in which the aspect ratio of the beam shape is adjusted by signal processing, but the aspect ratio of the beam shape can also be adjusted by mechanical position adjustment of the optical system. This case will be described below with reference to FIGS. 7(a) to 7(e).

7(a) to (C) are a block diagram, a side view, and a plan view of an optical system in an image recording apparatus showing another embodiment of the present invention, and the same parts as in FIG. 1 are designated by the same reference numerals. It is attached. The configuration and operation will be explained below.

Laser light emitted radially from the semiconductor laser 54 becomes parallel light by the collimator lens 41, and is focused only in the sub-scanning direction by the cylindrical lens 42 onto the polygon mirror 5.
6 Tie at the top. After that, a spherical lens 43 which also has fθ characteristics. The toric lens 44 focuses the image on the surface of the photosensitive drum 58 in both the main scanning direction and the sub-scanning direction. In the sub-scanning direction, since an optical system is used that focuses on the -degree polygon mirror 56 and then focuses again on the surface of the photosensitive drum 58, the inclination of the polygon mirror 56 in the sub-scanning direction is corrected. The spherical lens 43 and toric lens 44 form a so-called correction optical system.

In particular, to control the spot width in the main scanning direction, that is, the line width of the vertical line, the position of the collimator lens 41 is changed in one direction by a piezoelectric element or the like (not shown). Changing the position of the collimator lens 41 is nothing but changing the size of the laser spot light, and thereby the spot width in the main scanning direction can be controlled to a predetermined value.

On the other hand, for controlling the spot width in the sub-scanning direction, that is, the line width of the horizontal line, the cylindrical lens 4
The position of 2 may be similarly changed in the direction of the optical glaze using a piezoelectric element or the like (not shown).

A change in the position of the cylindrical lens 42 is related only to the spot diameter in the sub-scanning direction, and does not affect the spot diameter in the main scanning direction.

In addition, in the above embodiment, the case where the length of the beam spot diameter in the main scanning direction and the sub-scanning direction is adjusted electrically and mechanically has been described. It is also possible to adjust the length of the beam spot diameter in the main scanning direction and the sub-scanning direction.

That is, the spot width in the sub-scanning direction (line width of horizontal lines) is controlled by position correction of the cylindrical lens 42 (mechanical correction), and the spot width in the main scanning direction (line width of vertical lines) is controlled by pulse width. It is also possible to perform correction (electrical correction).

Conversely, it is also possible to control the spot width in the sub-scanning direction by position correction (mechanical correction) of the collimator lens 41 and to control the spot width in the main scanning direction by pulse width correction (electrical correction). The effects can be expected.

Further, in the above embodiment, a laser beam printer that uses a semiconductor laser 54 as an exposure means to irradiate a laser beam has been described as an example, but the light beam is not limited to a laser beam, and an LED printer that uses an LED as an exposure means has been described. Even if there is a problem, the present invention can be applied.

Typically, in an LED printer, a recording head is installed in which LED elements are arranged in parallel in the horizontal direction for the number of pixels. Therefore, by controlling the exposure time of the image signal pulse width to each LED element using the pulse correction circuit 2 shown in FIG. 1, the line width of the horizontal line (direction perpendicular to the traveling direction of the recording paper 60) can be adjusted. becomes. Furthermore, by controlling the drive current value to each LED element, the magnitude of the sbot light can be varied even in the case of an LED printer, and the line width of the vertical line can be controlled.

Furthermore, the vertical and horizontal images formed on the recording paper 60 are read by an image reading means such as a COD, and one or several dots of vertical or horizontal lines are formed in the serviceman adjustment mode or when printing starts. A width information input means (not shown) is provided in the operation section (not shown) to cause the image reading means to read the dot widths of the vertical and horizontal images formed on the recording paper 60 corresponding to the designated number of dots, and further read the dot widths. By controlling the driving of the pulse correction circuit 2 and the light amount correction circuit 1 (second spot width control means) based on the determined line width, image quality adjustment can be performed with higher accuracy.

In addition, if the dot specification from the width information input means can be switched arbitrarily using a dip switch or the like that has several types of line width values to be controlled, the printer user's preferred line width can be automatically adjusted. It is also possible to do so.

Furthermore, if one dot or several dots of vertical or horizontal lines are printed on the photosensitive drum 58 in the non-image area, the line width can be automatically corrected at any timing, and it is also possible to automatically correct the line width at any time during printing.

FIG. 8 is a flowchart showing an example of a beam spot width adjustment control procedure according to the present invention. Furthermore, (1)
~(8) shows each step.

First, the CPU 52 determines whether the laser beam irradiation position is a non-image area (1) If No, the process proceeds to step (8), performs normal image recording processing, and ends the process.

On the other hand, if YES in step (1), it is determined whether the spot width correction in the main scanning direction is completed.
), if YES, proceed to step (5) onwards; if NO, read out the light intensity correction data from the internal memory of the CPU 52 (3), output the light intensity correction data to the light intensity correction port 1281 (4), then in the sub-scanning direction 5) If YES, proceed to step (8); if NO, read out the pulse width correction data from the internal memory of the CPU 52 6) Output it to the pulse correction circuit 2 7) , proceed to step (8).

〔Effect of the invention〕

As described above, the present invention includes a first spot width control means that independently controls the spot width in the main scanning direction of the light beam that exposes the photoreceptor or the spot width in the sub-scanning direction of the light beam. Therefore, even if the shape and size of the exposed light beam varies depending on the mounting accuracy of the exposure scanning system, the beam spot width can always be adjusted to a predetermined ratio with respect to the main scanning direction and the sub-scanning direction. Therefore, exposure can be performed with a constant beam spot width, and high-quality images can be realized at low cost without depending on the accuracy of each component constituting the exposure means.

Further, width information input means for specifying and inputting the vertical line or horizontal line width of the output image on the photoreceptor, image reading means for reading the image width formed on the recording medium, and based on the image width read by the image reading means, and a second spot width control means for controlling the driving of the first spot width control means, the light beam can have a spot width of an arbitrary ratio requested by the user in the main scanning direction and the sub-scanning direction. You can record images with . Therefore, an excellent effect is achieved in which images can be easily created with the original intended image.

[Brief explanation of drawings]

FIG. 1 is a block diagram illustrating the configuration of an image recording apparatus showing an embodiment of the present invention, FIG. 2 is a characteristic diagram illustrating the light output characteristics of the light amount correction circuit shown in FIG. 1, and FIG. 4 is a detailed block diagram illustrating the configuration of the pulse correction circuit shown in FIG. 1, and FIGS. is a timing chart explaining the signals of each part in Fig. 4, and Fig. 6 (
a) to (C) are operation explanatory diagrams explaining pulse width control operations in the sub-scanning direction, and FIGS. 7(a) to (c) are blocks of an optical system in an image recording apparatus showing another embodiment of the present invention. FIG. 8 is a flowchart showing an example of a beam light spot width adjustment control procedure according to the present invention;
FIG. 9 is a schematic diagram showing an example of a laser beam printer, which is an example of a conventional image recording device, and FIGS. 10(a) to (f)
FIG. 2 is a schematic diagram illustrating the relationship between the size and shape of laser light and the output image form. In the figure, 1 is a light amount correction circuit, 2 is a pulse correction circuit, 52 is a CPU, 53 is a laser driver, 54 is a semiconductor laser,
58 is a photosensitive drum. Figure 9th man 54 Cow 11 I tree racer 58 Gu9 drum M2 1 Figure 8 Figure 51゜Procedure correction (t (method)) 2. Name of the invention Image recording device 3. Person making the amendment Relationship to the case

Claims (2)

[Claims] (1) In an image recording apparatus that exposes a photoreceptor with a light beam signal modulated by a modulation signal corresponding to image information to form a latent image and visualize it on a recording medium being conveyed, the photoreceptor is An image recording apparatus comprising first spot width control means for independently controlling the spot width of an exposing light beam in the main scanning direction or the spot width of the light beam in the sub-scanning direction. (2) Width information input means for specifying and inputting the vertical line or horizontal line width of the output image on the photoreceptor, image reading means for reading the image width formed on the recording medium, and image width read by the image reading means. 2. The image recording apparatus according to claim 1, further comprising: second spot width control means for controlling driving of said first spot width control means based on said first spot width control means.