JPH01282575A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain a record with high quality without being influenced by character styles by controlling the formation condition of an electrostatic latent image formed on an image carrier and the image forming process of a developing condition, etc., in response to the variety of recorded characters. CONSTITUTION:The developing bias power source 13a of a bias voltage A and the developing bias power source 13b of a bias voltage B are prepared in a developing device and selected by switching a switch 12. When a definite character style like Ming style is preferable, the power source 13a of the developing bias A is selected and a DC component -400V is set. When reverse development is performed, a potential contrastive with the potential of a bright part is 300V and lines become thinner. When a character of thick lines like a Gothic type is preferable, a developing bias B13b is selected and impressed on a sleeve 2. A DC component -600V is set and the potential contrastive with the one of the bright part is 500V so that the thick lines are developed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention causes a laser or LED to emit light in accordance with information to be output to form an electrostatic latent image on an image carrier in accordance with the information, The present invention relates to an image forming apparatus that visualizes this electrostatic latent image using toner.

[Prior art] Laser beam printer (LBP), LED printer, L
A printer using an electrophotographic process, such as a CD printer, forms an electrostatic latent image on a photoreceptor according to output information, develops this electrostatic latent image with toner, and prints the developed toner image on recording paper. It is something to be transcribed.

These printers are capable of high-quality recording,
It has come to be widely used as an output device for document processing devices and image processing devices because it has many features such as being able to record at high speed, generating little noise during recording, and being able to record on plain paper.

To explain LBP, an electrostatic latent image corresponding to the recorded information is created on the photosensitive drum by scanning a photosensitive drum uniformly charged by a charger with a laser beam modulated according to recorded information. is formed. This kind of silence
By developing the EW image with toner and transferring this toner image onto recording paper, recording information can be recorded on the recording paper.

[Problem to be solved by the invention] However, the above-mentioned laser beam printer (LB
P) Or in electrophotographic printers, the image forming process conditions for recording are fixed, so
Depending on the recorded image, it may not be possible to obtain an image of desired quality. For example, in LBP, character information processed by a character processing device is sometimes recorded, but even if the characters are the same, the types of characters may be different. That is, it may be recorded in Gothic font or in Mincho font. In such cases, the image formation process is fixed, so even if Gothic characters can be recorded as thick, dark, and good images, if you try to record fine Mincho characters, the recorded characters will be distorted. It had the disadvantage that it became thick.

On the contrary, in order to reproduce Mincho typeface characters in detail,
Assuming that the various conditions for the image formation process had been set, it would no longer be possible to record Gothic characters with high quality.

[Means for Solving the Problems] The present invention provides conditions for forming an electrostatic latent image on an image carrier;
Alternatively, by controlling the image forming process such as development conditions for developing this electrostatic latent image according to the type of characters to be recorded, high-quality recording can be performed regardless of the type of characters. An image forming apparatus is provided.

[Embodiment] FIG. 1, FIG. 2, FIG. 7, and FIG. 8 show an embodiment of an LBP (laser beam printer) to which the present invention is applied.

In FIG. 7, 70 is the LBP printer main body, and an image based on a recording signal supplied from an external character processing device etc. through a signal line 71 is printed onto recording paper supplied from a recording paper cassette 72 to the main body 70. recorded. The recording paper on which recording has been completed is discharged onto the paper discharge tray 73.

Reference numeral 29 indicates a font cartridge in which Gothic characters are stored.

Therefore, when a character code is included in the recording signal, this character code is recorded on the recording paper as a character type in the font cartridge 74, that is, a Gothic character. Therefore, by preparing in advance a plurality of font cartridges of different character types and installing the font cartridges containing the necessary character types into the main body, it is possible to record the character type according to the operator's wishes.

1 and 2 show a recording section and a laser beam deflection section housed in the main body 70, and in FIG. 1, 1 is a photosensitive drum which is an image carrier; - Uniform charging is performed by the charger 5. Thereafter, an electrostatic latent image corresponding to the recorded information is formed on the photosensitive drum 1 by image exposure 6 using a laser beam modulated by the recording signal. This electrostatic latent image is visualized by adhering toner by an electric field applied between the photosensitive drum 1 and the developing sleeve 2 having the magnet 3. On the other hand, the recording paper 11 - 1 is guided onto the transfer charger 7 by the transfer guide 11 and the transfer roller 10 .

The toner image formed on the photosensitive drum 1 in this manner is transferred onto the recording paper 11-1 by applying corona transfer from the back surface of the recording paper 11-1 by the transfer charger 7. The toner image transferred onto the recording medium 11-1 is fixed onto the recording paper by a fixing device (not shown). Toner and paper dust remaining on the photosensitive drum 1 without being transferred are collected by a cleaner 8. Further, the charge remaining on the photoreceptor drum 1 is removed by exposure by the pre-exposure lamp 9, and the photoreceptor drum 1 repeats the steps after the -th charging again.

In such a configuration, the photosensitive drum 1 is charged by -order charging.
is cut off to a dark area potential of -700V, and the portion exposed by image exposure 6 is attenuated to a bright area potential of -100V.

FIG. 2 is a perspective view showing a deflection section of a laser beam that is irradiated onto a photosensitive drum. Laser light 22 emitted from a semiconductor laser 21 is reflected by a polyhedral mirror 24 rotated by a motor 23, and is reflected on the left side in the figure. Perform a repeated scanning motion from the beginning to the right. This reflected laser beam passes through an f.0 lens 25, which is used to keep the scanning speed of the laser spot irradiated onto the sensitive drum 1 constant. Other lenses are omitted in this figure. Finally, the laser beam 22 is reflected by a mirror 26 and irradiated onto the photosensitive drum 1 shown in FIG. In addition, in order to synchronize the writing start position on the photosensitive drum 1 with the recording signal, the beam is reflected by a mirror 27 placed at the end of the scanning laser beam 22 and received by a photodetector 28. , to generate a synchronization signal.

Therefore, by driving the laser 21 with a recording signal, image exposure 6 can be performed on the photosensitive drum 1.

A developing bias power supply 13 with a bias voltage A is provided in the developing unit.
A and a developing bias power supply 13b of bias voltage B are prepared, and either of the power supplies is selected by the switch 12. If finer details are preferable, such as in Mincho typeface characters, the development bias is switched with the switch 12 so that the development bias A13a is applied to the sleeve 2. The developing bias Al 3a was set to a DC component of -400 V, and when performing reversal development, the contrast potential with the bright area potential was 300 V, and the line became thinner.

On the other hand, if thicker lines are preferred, such as in a Gothic typeface, the developing bias is switched with the switch 12 so that the developing bias B13b is applied to the sleeve 2. The developing bias B13b is set to a DC component of -600V, and the contrast with the bright area potential is 500V.
It was developed thickly. The relationship between latent image potential and developing bias is
As shown in Figure 2 (b), in the case of Gothic typeface, the line width is GW, and in the case of Mincho typeface, the line width is MW,
It can be seen that the line width can be controlled.

For other character fonts, the development bias value may be set as appropriate depending on the character.

In addition, in any case, the AC component of the developing bias is V,
A square wave was used at =1600V and f=1800Hz.

The switch 12 is configured so that the discriminator 12 discriminates the identification section 31 provided in the font cartridge inserted into the main body, and the switch is automatically selected according to the result of this discrimination.

FIG. 8 shows the identification section 30 and the discriminator 12 in detail, and the cartridge 29 has four frames 30a-30b.
Decide in advance where to attach the printer body 20.
The top presses four microswitches 31a to 31b, which are provided on the side and constitute a discriminating section, to switch from OFF to ON. Therefore, by selecting the position and number of the frames according to the type of characters stored in the font cartridge, it is possible to discriminate between 16 types of font cartridges at most.

In the above embodiments, the DC component of the development bias, which is one of the development conditions, was changed to develop the optimal thickness for each font, but the peak voltage of the AC component was
0 or the frequency f may be changed, or by selecting development conditions by combining these, the thickness of the pattern during development may be optimized.

[Example 2] In the previous example, it was possible to obtain the optimum line width for the font by changing the development conditions, but it was also possible to obtain the optimum pattern according to the character type by changing the latent image forming conditions. Obtainable. In other words, depending on the character font you record,
- By switching the voltage applied to the charger, recording is performed with a line width that corresponds to the font. FIG. 10 shows such an embodiment, in which a power source 5b of voltage vb
The power source 5c with the voltage Vc is selected by a switch 5a, and the switch 5a is switched and selected by the output of the discriminator 12a. Components with the same numbers as in FIG. 1 operate in the same manner as explained in FIG. 1.

The voltages Vb and Vc have a dark potential of -700V and a light potential of -150V when a Mincho character font is determined, and a dark potential of -600V and a bright potential of -600V when a Gothic character font is determined. It is switched to obtain a potential of -100V.

In this case, the relationship between the latent image potential and the developing bias is
As shown in Figure (C), the Mincho font takes the characteristic curve M, and the Gothic font takes the characteristic curve G, and the line widths formed are Lm, t, and g, respectively, and the respective character fonts are It is possible to achieve line widths that suit your needs.

[Embodiment 3] Unlike the above embodiment, the bright area potential may be changed depending on the character font. For example, for a Mincho font, you can set the dark area potential to -700V and the light area potential to -150V, and for a Gothic font, you can change the dark area potential to -700V and the bright area potential to -1100V. good.

FIG. 3 shows an example in which the developing bias conditions are fixed and the intensity of the laser beam is selected depending on the type of character font in the laser beam printer shown in the first embodiment. The semiconductor laser 21 has a switch 1
The voltage V1 or the voltage 2 of the power supply 17 is selectively applied via the voltage source 6. On the other hand, the recording signal sent from the signal line 71 is transmitted to the semiconductor laser 21 by the driver 14.
A voltage power source is applied from a power source 13 according to the recording signal. Since the intensity of the laser beam depends on the drive voltage, by controlling the switch 16 using the discriminator 12, the intensity of the laser beam can be controlled according to the character font. For example, when the recording signal is in Mincho type, the switch 6 selects the voltage v1 of the power supply 17 and applies it to the laser semiconductor 21. Then, this voltage is applied V'on10ff with a signal from the driver 14 to blink the laser. Note that when the laser is emitted at a voltage vI, it emits 1.6μJ/cm' as shown in Figure 6.
The photoreceptor drum 1 is irradiated with a light amount of , and the bright area potential on the photoreceptor drum becomes -150.

On the other hand, when the recording signal is in Gothic type, the switch 16 selects the voltage 2 of the power supply 17 and applies it to the laser 21. At this time, the laser is emitted with a voltage of v2, and as shown in FIG.
The bright area potential is -100V.

FIG. 6 is a characteristic curve LP showing the relationship between the amount of laser light and the potential of the photosensitive drum, and shows that the potential of the photosensitive drum can be controlled by controlling the intensity of the amount of laser light, as mentioned above. It shows. At this time, the developing bias voltage is DC component -500V, AC component V, p=16
00V.

f-1800Hz was used.

The method of changing the latent image potential has the following two advantages. One is that the line width can be changed efficiently. FIG. 12(a) shows the Mincho font characteristic curve M and the Bossif font characteristic curve G, and the Gothic line width GW and Mincho line width M when the bright area potential vL is changed by 50V.
It shows the change in W. (b) is the developing voltage V. This is a characteristic curve showing a change in line width when C is changed, and shows that a Gothic line width GW and a Mincho line width MW can be obtained.

It can be seen from these two that the latent image potential has a greater influence on the line width than the development potential.

Another is that there is no need to worry about the occurrence of reverse fog.
In the case of reversal development, if the difference between the dark area potential and the development bias potential becomes too large, toner with a small amount of charge or toner charged with the opposite polarity will adhere to the dark area of the photoreceptor drum. , which appears as fog on the image and becomes a problem.

In Example 2 of the present invention, only the bright area potential is changed, so if the developing bias is fixed in advance to a value that does not cause reverse fog, it is possible to freely change the line thickness while preventing reverse fog. It is possible to change the thickness and print with a thickness that matches the font.

[Example 4] In a laser beam printer, characters are recorded as a collection of dots, but by changing the light emitting time per dot, the size of each dot can be changed to create a line thickness that matches the font. You can also adjust it accordingly. For example, as shown in FIG. 4, a recording signal is applied to the semiconductor laser 21 via the driver 14, and the voltage applied by the power source 17a is
By applying power in accordance with this recording signal, the semiconductor laser 21 can be driven in accordance with the recording signal. A clock, either clock A or clock B, is applied to this driver 14 via a switch 18. In the driver 14, if a recording signal is applied as shown in FIG. 5a and a clock A is applied as shown in FIG.
A laser is emitted from the Further, when a clock B as shown in d is applied, a laser beam is emitted from the semiconductor laser as shown in e. As is clear from comparing C and e in FIG. 5, the laser lighting time width is controlled according to the clock width. Therefore, by configuring the discriminator 12 to select clock A when it discriminates a Mincho font cartridge, and select clock B when it discriminates a Gothic font cartridge, the thickness of the line is adjusted according to the font. It is possible. In this case, the laser light amount in Figure 6 is 2.8μJ/cm
When the value is 2 or more, it can be used in a region where the bright area potential of the photoreceptor drum is saturated. Therefore, it has superior environmental stability and durability stability compared to the method described above in which the line width is changed using laser power.

In the above embodiments, members with the same number have the same function.

Further, instead of the font cartridge 29 used in the above embodiment, a font cartridge 29a as shown in FIG. 9 can be used. In this case, a resistor is attached to each font cartridge 29a so that when it is installed in one main body 70, it is connected to the pin 33 on the main body side. The laser 21 and the power supply to the laser 21 are connected in series to this pin 33, and the resistance value changes the current value flowing through the laser, thereby making it possible to change the beam intensity of the laser beam.

Further, a pin 33 provided on the main body may be connected to a developing bias power source to change the developing conditions.

Furthermore, the font cartridge 29 used in the first embodiment
Instead, a font cartridge 29b as shown in FIG. 11 may be used.

This font cartridge 29b is provided with four dip switches 34b in a part thereof, and the states of the switches are set to predetermined states according to the type of character font.
The state of this switch is transmitted to the main body 2 via a connector (not shown).
It may be set to 0.

Furthermore, the depth switch 34c may not be provided on the font cartridge 29c, but may be provided on a part of the main body 20 as shown in FIG. 11, and this switch may be set according to the character font depending on the font cartridge installed. This allows you to manually enter character font information into the main body.

Furthermore, recently there are methods for storing character fonts in mask ROMs, laser disks, etc., but in addition to character font data, control data for laser emission intensity and control data for factors that change line width, such as development bias voltage, etc. The control data may also be stored, the cartridge may be installed in the printer, and the printer may be controlled by reading out such control data.

In this way, the method of reading control data allows the font cartridge packages themselves to have the same shape, which has the advantage of making it possible to use common cartridges.

Furthermore, since the microswitch 31 on the main body is not required, the mechanism becomes simple and costs can be reduced.

Furthermore, by storing the control data together with the character data, a plurality of character fonts can be stored in - number of font cartridges.

In this case, as in Embodiment 4, it is necessary to have control data that determines the line thickness for each character font, and to read this control data and control the printer using signals from the printer itself or the printer's host side. Good.

In addition, in the above embodiment, only LBP was explained, but based on the same idea, the present invention is an LED using an electrophotographic process, in which the light emission of a large number of LEDs arranged in a row is adjusted based on recorded information. This can be applied to printers.

Furthermore, an LCD using an electrophotographic process that controls a large number of liquid crystal shutters arranged in a row based on recorded information.
This can be applied to printers.

[Effects of the Invention] As explained above, by changing the development conditions or electrostatic latent image forming conditions depending on the type of character font,
It is possible to realize the optimal line width thickness according to the type of each character font and form high-quality character images.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a recording section of an LBP according to a first embodiment of the present invention, FIG. 2 is a perspective view of a laser beam deflection section of an LBP according to a first embodiment, and FIG. 3 is a main A block diagram of an LBP according to a third embodiment to which the invention is applied; FIG. 4 is a block diagram of an LBP according to a fourth embodiment to which the invention is applied; FIG. 5 is a timing chart of an LBP according to a fourth embodiment; Fig. 6 is a characteristic diagram showing the relationship between the amount of laser light and the potential of the photoreceptor drum, Fig. 7 is a perspective view of the LBP according to the first embodiment, and Fig. 8 shows the font cartridge shown in Fig. 7 in detail. 9 is a perspective view showing another embodiment of the font cartridge, FIG. 10 is a vertical sectional view showing a second embodiment of the LBP to which the present invention is applied, and FIG. 11(a) is a font cartridge. FIG. 11(b) is a perspective view showing another embodiment of the printer main body. FIGS. 12(a), (b), and (c) are perspective views showing other embodiments of the cartridge. 2 is a characteristic diagram showing the relationship between bright area potential, dark area potential, and line width. In the figure, l is a photosensitive drum, 2 is a developing sleeve, and T
is toner, 5 is a primary charger, 6 is an image exposure device, 7 is a transfer charger, 8 is a cleaner, 9 is a pre-exposure lamp, 12 is a discriminator, 13a, 13b is a developing bias, 17 is a power source, 19a
, 19b is a clock generator, 20 is the printer main body, 21
is a semiconductor laser, 22 is a laser beam, 29.29a. 29b is a font cartridge, 30 is an identification section, 34b
, 34c1 is a dip switch. Patent applicant Canon Co., Ltd. rd ~ N) Figure 6 Figure 8 29c

Claims (2)

[Claims] (1) An electrostatic latent image forming means for forming an electrostatic latent image on an image carrier according to information to be output, and an electrostatic latent image formed on the image carrier by the electrostatic latent image forming means. In an image forming apparatus having a developing means for visualizing information to be output by attaching toner to the image forming apparatus, a notifying means for indicating the type of character forming an electrostatic latent image, and a type of character notified by the notifying means. an image forming apparatus comprising: a control means for controlling developing conditions by the developing means according to the development conditions of the developing means; (2) an electrostatic latent image forming means for forming an electrostatic latent image on an image carrier according to information to be output; and an electrostatic latent image formed on the image carrier by the electrostatic latent image forming means In an image forming apparatus having a developing means for visualizing information to be output by attaching toner to the image forming apparatus, a notifying means for indicating the type of character forming an electrostatic latent image, and a type of character notified by the notifying means. An image forming apparatus comprising: a control means for controlling electrostatic latent image forming conditions by the electrostatic latent image forming means in accordance with the above.