JPS6263959A - Image recorder - Google Patents

Abstract

PURPOSE:To prevent the white omission of an image and the solidification or melt-fixing of a toner in a developing device by counting the emission time of a laser beam while correcting it in accordance with the printing rate and integrating and storing the counted value and sending a prescribed signal if stored contents exceed a preliminarily set reference value. CONSTITUTION:A counter 8 counts the laser light emission time, and a modulator 5 reads out successively the printing rates of individual sections to output a signal which switches the value of one count of a counter 8, and the counted value of the counter 8 is integrated successively and stored in a memory 9. A comparator 10 compares always the stored value of the memory 9 and sends a signal to a controller 11 if the stored value exceeds a preliminarily set level, and the controller 11 sends a reset signal RST1 to memories 2 and 3 to reset their contents at every time when one recording paper is printed. When the toner is replenished or a cartridge is replaced, the controller 11 outputs a reset signal RST2 to the memory 9 to reset its contents. Thus, white omission due to lack of the toner and the solidification or melt-fixing of the toner due to excess replenishment are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image recording apparatus that scans a photoreceptor with a laser beam to form a latent image.

[Conventional technology]

Devices that apply electrophotographic methods include electrophotographic copying machines and laser beam printers. Among these, laser beam printers are particularly in the spotlight as they are capable of high-speed image processing as computer terminal printers amidst the recent trend toward office automation. This system replaces the optical system of a conventional electrophotographic copying machine with a modulated laser beam as a terminal signal to obtain high-quality images through the same process as that of a copying machine.

FIG. 8 shows a layout diagram of the main processes around the photosensitive drum of such a laser beam printer.

In this figure, 21 is a photosensitive drum serving as an image carrier, and photosensitive layers 22 . It is composed of a substrate 23. , 24 are primary chargers that charge the photosensitive drum 21 uniformly. Reference numeral 25 is scanned with a laser beam by a scanner (not shown).

26 is a developing device, which includes two dofter blades and a magnet roller 28. It is composed of a sleeve 29, and the inside thereof is filled with toner T serving as a developer. A pre-exposure lamp 30 exposes the entire surface of the photosensitive drum 21 before charging.

A recording paper guide 31 guides the fed recording paper. 32
A transfer charger transfers a toner image in which a latent image formed on the photoreceptor drum 21 is visualized onto recording paper by, for example, corona discharge. 33 is a cleaner, and a rubber blade 34
．． Magnet roller 35, screw 36. It is composed of a housing 37 and the like.

First, the photoreceptor drum 21, which has been uniformly charged by the charger 24, is irradiated with a laser beam 25 modulated in accordance with an image signal, and an electrostatic latent image is formed on the photoreceptor drum 21-]-
is formed. Subsequently, the photoreceptor drum 21 is transferred to a developing device 26.
The latent image is visualized through a developing process. Thereafter, a developed image is transferred by a transfer charger 32 onto a recording paper (not shown) -1- introduced by a transfer paper guide 31. The transferred toner image is fixed on the recording paper by a fixing device (not shown), and is discharged to a discharge tray (not shown).

An example of an image formed in this manner is shown in FIG.

In this figure, 38 is a recording paper, and 39 is a transferred developed image.

On the other hand, the untransferred developed toner remaining on the photoreceptor drum 21 is removed from the photoreceptor drum 21 by a rubber blade 34.
The toner is removed from the surface of the toner 1, adsorbed by the magnetic roller 35, and further stored in a toner collection box (not shown) forming a part of the casing 37 by a screw 36. Also,
The charge remaining on the photoreceptor drum 21 is removed by the pre-exposure lamp 3.
Static electricity is removed by 0 light. In this way, the portion of the photoreceptor drum 21 from which the charge has been removed is sent to the first step, the primary charging step, and is used repeatedly.

In the process of irradiating the laser beam 25, the recording paper 3
Photosensitive drum 21-L in a portion corresponding to the visible image 39 on 8
An image scanning method is adopted in which the laser is irradiated to the image 39, the background other than the visible image 39 is irradiated with the laser, and the background other than the visible image 39 is not irradiated with the laser. This is because this method does not cause scan marks on the background image and is superior in reproducibility of images.

FIG. 1θ is a diagram illustrating the behavior of the surface potential of the photosensitive drum 21 when forming a latent image.

In this figure, the vertical axis shows potential, and the horizontal axis shows each process step. Incidentally, the process steps are composed of a -next charging stage a, a laser exposure stage, a developing stage C2, a transfer stage d, a pre-exposure stage e, and a -next charging stage f. Further, an example is shown in which the photosensitive layer 22 of the photosensitive drum 21 is made of a phthalocyanate organic semiconductor. Further, the -order charging step f is performed with negative polarity.

'-The surface potential obtained by the primary electric appliance 24 is the dark potential V
d and the bright area potential Vh due to laser irradiation (Vd-
Vh), Tsuma! It is converted into a latent image potential of about 550V by J Cocoa-ys).

As the toner T, a magnetic component developer is used.

The toner T in the developing device 26 is caused by mutual friction, the sleeve 29
It is charged by the contact friction of the doctor blade 27 and the like. The charged toner T is placed on the sleeve 29 with a uniform thickness by the doctor blade 27. The sleeve 29 rotates, and the toner T is attracted to the latent image area to be developed by the electric field between the potential of the developing bias voltage applied to the photosensitive drum 21 and the sleeve 29 and the electrostatic latent image potential. . A portion of the latent image shown in FIG. 1O corresponding to the bright area potential Vh is developed.

For this purpose, the toner T must be charged to a polarity (in this case, negative) that develops a relatively high potential (bright area potential) Vh in the positive direction. In FIG. 11, toner T does not adhere to the negative potential portion of the dark potential Vd, and the bright potential Vd at the laser irradiated area near the ground potential.
h is a conceptual diagram showing how negatively charged toner T adheres.

Conventionally, in the apparatus described in -1- below, in order to prevent white spots on the image due to lack of developer, a sensor using a piezoelectric element or the like is placed inside the developer 26, and the toner is detected by changes in the output of the sensor. A method is adopted to detect a shortage of resources.

FIG. 12 is a diagram illustrating the structure of the developing device 26 shown in FIG. 8.

In this figure, 28 is a magnet roller, and four poles S I + Nl + S2 * N2 are arranged on the inner periphery. The pole S1 serves as a developing pole, the pole N1 serves as a cutting pole, the pole S2 serves as a transport pole, and the pole N2 serves as a toner collection pole. A high voltage power supply unit 40 applies a developing bias voltage to the sleeve 29. 41 is a piezoelectric element that changes its output voltage according to the change in the weight of the toner T, compares this output voltage with a reference voltage (not shown) set in advance by a comparator 42, and determines whether the amount of toner is insufficient based on the comparison value. In this case, the display lamp 43 is turned on to notify the user.

[Problem that the invention seeks to solve]

However, in such a configuration, if the toner is concentrated at the position of the piezoelectric element 41, the indicator lamp 43 will not light up even if there is a shortage of toner because the weight applied to the piezoelectric element 41 is considerable, and the image will not be displayed. - had the disadvantage of white spots occurring. Conversely, the piezoelectric element 41 inside the developing device 26
If the toner T is biased away from the piezoelectric element 4, even though the toner T is sufficiently grooved.
Since the weight applied to toner 1 is too small, the indicator lamp 43 indicating toner shortage lights up. Therefore, in order to replenish the toner T, an excessive replenishment state occurs, and the toner T solidifies in the developing device 26 and the image density decreases in that area, or the toner T is fused to the sleeve 29-1-. There were drawbacks such as unevenness in the image.

In addition, in an image recording apparatus that employs a so-called process cartridge method, that is, a method in which a cartridge in which a drum, developer, cleaner, etc. are integrally formed is disposable, the method for detecting the remaining amount of toner as described above is suitable. Since there was no such thing, there were problems such as the inability to accurately detect the state of toner consumption.

Furthermore, in the process cartridge system, as mentioned in section 2, the lifespan of the developing device, drum, cleaner, etc. must be comprehensively judged and the appropriate replacement period must be indicated. There was no proper measurement method to display the lifespan of the product.

On the other hand, as in Japanese Patent Application Laid-Open No. 58-224363, a method has been proposed in which the number of dots forming an image area is accumulated and when the accumulated value exceeds a predetermined level, toner is replenished. However, this method is based on the assumption that the amount of toner consumed per dot is always constant, but the amount of toner consumed by one dot in solid black is different from the amount of toner consumed by one dot with a margin around it. Due to the edge effect, a single dot with a margin around it receives a stronger developing force and consumes a large amount of toner, resulting in problems such as the inability to accurately measure toner consumption.

This invention was made in order to solve the problem mentioned in "-", and it accurately grasps the amount of toner consumption and displays the appropriate toner replenishment time, and eliminates white spots in images and toner in the developing device. An object of the present invention is to obtain an image recording device that can prevent the occurrence of coagulation or fusion of.

[Means for solving problems]

The image scanning type image recording device according to the present invention includes a first storage means that divides and stores an image signal into predetermined areas, and stores the printing rate of each area stored in the seven first storage stages. a count-p stage that counts the emission time of the laser beam corresponding to the image signal of each region stored in the first storage means while correcting it according to the printing rate; A third storage means accumulates and stores the count value of the means, and compares the contents of this third storage seven stages with a preset reference value, and sends a predetermined signal when the reference value is exceeded. A signal sending means is provided.

[Effect]

In this invention, an input image signal is divided into predetermined image areas and sequentially stored in the first storage means. At this time, the second storage means stores the printing rate of each area stored in the first storage means. Therefore, the counting means counts the laser emission time corresponding to the image signal of each region stored in the first storage means while correcting it according to the printing rate of each region stored in the second storage means, The data is stored in the third storage means while being integrated. The content stored in the third storage means is compared with a preset reference value, and if the reference value is exceeded, the signal sending means sends a predetermined signal, such as a toner replenishment signal or a cartridge replacement signal. It is something.

〔Example〕

FIG. 1 is a control block diagram of an image recording apparatus showing an embodiment of the present invention. Reference numeral 1 denotes an interface controller (hereinafter referred to as IF controller), which divides an input signal into each area and inputs it to a memory 2. , input the printing rate for each area into the memory 3. The memory 2 can store input signals according to preset sizes.

4 is a clock generator that synchronizes the speed of the image signal.

A modulator 5 modulates the count number of a counter, which will be described later, according to the printing rate of each section. A modulator 6 modulates the image signal into a laser input voltage. A laser 7 emits light in response to a signal modulated by the modulator 6. A counter 8 measures the light emission time of the laser 7 with respect to the image signal. 9
is a memory that integrates and stores the contents of the counter 8. 10
is a comparator that compares the value stored in the memory 9 with a preset value. Reference numeral 11 denotes a controller that controls the entire apparatus, and sends out a toner replenishment signal S serving as a toner replenishment or toner replenishment notice signal.

An image signal fV sent from a facsimile, computer, etc. is divided into predetermined image areas in the memory 2 by the IF controller 1 and sequentially stored, so that one page is stored as a whole. On the other hand, as shown in FIG. 2, the printing rate for each section is stored in the memory 3. Thereafter, the image signal fv is output from the memory 2 according to the clock signal oscillated by the clock generator 4.
is read out and converted into a laser input voltage by modulator 6. The laser 7 is switched off based on this modulated signal, and a latent image is formed on the photosensitive drum 21.

A counter 8 uses the signal from the modulator 6 to count the laser emission time. On the other hand, the modulator 5 sequentially reads out the printing rate for each section from the memory 3 and outputs a signal that changes the value of one count of the counter 8. The memory 9 sequentially integrates and stores the runt values of the counter 8. The comparator 10 constantly compares the values stored in the memory 9, and sends a signal to the controller 11 when the value exceeds a preset level. Upon receiving this signal, the controller 11 sends a reset signal R3Tl to the memories 2 and 3 every time one image is printed, and resets the contents. Then, when toner is replenished or the cartridge is replaced, the controller 11 outputs a reset signal RST2 to the memory 9, and its contents are reset.

Next, the operation of the counter 8 shown in FIG. 1 will be explained with reference to FIGS. 2 to 4.

FIG. 2 is a diagram showing the relationship between laser emission time and toner consumption. The vertical axis shows the toner consumption (g) per one force count operation of the counter 8, and the horizontal axis shows the printing rate (%) (laser 7 shows the irradiated area/total area). I, H show the toner consumption characteristic curves of each device. Note that the laser irradiation area is determined by the product of three factors: laser scanning width, laser scanning speed, and laser emission time.

As can be seen from the toner consumption characteristic curve (2) shown in FIG. 2, the amount of toner consumed per one count of the counter 8 varies depending on the printing rate (%).

This is mainly due to the edge effect; the smaller the printing rate, the more white areas intersect with the printed area.

Therefore, the white background area (dark area potential Vd) and the printed area (old capital potential Vd)
h), the edge effect becomes stronger and the amount of toner consumption increases.

Figures 3 and 4 are schematic diagrams explaining how the image area is divided. Figure 3 shows the case where the image area is divided into nXm, and Figure 4 is a partially enlarged view. , one section is composed of Ixj pixels.

For example, as shown in Figure 4, one section has i blocks horizontally and j blocks vertically.
In the case where pixels are formed from i pixels, if the memory read speed of the modulator 5 is set to l/i, the printing rate of the same section can be made to correspond to the i pixels. Furthermore, if the printing rates from the Jl (multiple of i)th section to the J1+n-1th section are sequentially read out from the memory 3 by repeating j times, the printing rate corresponds to the image signal fυ of each section. can be done. Therefore, counter 8
By correcting the count according to the printing rate, it is possible to make the toner consumption period proportional to the count number. As a correction method, as shown in FIG. 2, the toner consumption characteristic curves (1) and (2) of each device are determined in advance, and the number of counts per unit light emission is changed. For example, as shown in FIG. 2, if 10 counts are made per unit light emitting time at a printing rate of 20%, if the printing rate is 40%, the number is corrected (by the modulator 5) to 6 counts. As shown in FIG. 5, the toner consumption per count can be made constant regardless of the printing rate.

In this way, the laser emission time is counted according to the printing rate, and when the time exceeds the reference value preset in the comparator 10, a predetermined signal is sent to the controller 11. When this signal is received,
The controller 11 outputs a toner replenishment signal S.

FIG. 6 is a diagram explaining a method for determining the reference value set in the comparator 10 shown in FIG. 1, and the horizontal axis is the memory 9.
The stored value (count value) is shown, and the vertical axis is the toner consumption amount (count value).
g) is shown.

As can be seen from this figure, the time to output the toner replenishment signal S that foretells the toner replenishment time or cartridge replacement time is determined by the content of the memory 9, that is, the count value D.
It should be set when the value is reached.

The count value is the value obtained by subtracting the current toner consumption amount E from the initial toner amount C filled in the developing device 26, and represents the limit light emission time that does not cause white spots on the image. Note that when the toner replenishment signal S is sent out, the toner replenishment amount is E, (g). In addition, in the process cartridge method, when the contents of the memory 9 reach D,
The user may be prompted to prepare the cartridge for replacement, or send a notification signal indicating that the cartridge can be replaced to a display means (not shown) of the operation unit. Also,
Sends a toner replenishment signal S to a host computer etc.
The cartridge may be prepared or capable of being replaced. Next, the operation of the correction circuit 6 shown in FIG. 1 will be further explained with reference to FIG. 1'G7.

FIG. 7 is a characteristic diagram showing the relationship between developing bias potential and toner consumption, where the vertical axis shows the relative value of toner consumption;
The horizontal axis indicates the developing bias potential (V).

As can be seen from this figure, the developing bias potential is -400
The toner consumption when the developing bias potential is 1450V is the toner consumption when the developing bias potential is 1450V (
1 (g)), the bias potential is -400V
In the case of , the actual toner consumption is 0.8 times the toner consumption, and when the bias potential is 1500V,
The actual toner consumption is 1.2 times the toner consumption.

Therefore, when storing the toner consumption amount in the memory 9, the content is multiplied by a coefficient according to the bias potential and stored to obtain the toner consumption amount with high accuracy. It goes without saying that a more accurate toner consumption amount can be obtained by performing corrections that take into account temperature and humidity, drum potential Vd r vh , laser power, and the like.

Further, in the above embodiment, the comparator 10 constantly compares the preset D and the toner consumption amount X and y, and outputs the toner replenishment signal S for replenishing toner at point D shown in FIG. As described above, two comparators and two memories are provided, and one comparator constantly compares toner consumption with Dl shown in FIG. 6, and when the toner consumption reaches Dl, the controller 5 issues a retoner replenishment notice Needless to say, if the configuration is such that a signal can be sent to notify the user, time will be given for toner replenishment, so the device can be operated continuously and the utilization efficiency of the device can be increased.

Further, although the above embodiments have been explained using a laser beam printer as an example, even if it is an electrophotographic printer using an LCD, LED, OFT, etc., or an image forming apparatus using a stylus method or a magnetic stylus method, it is possible to use a laser beam printer as an example. Any material that forms a latent image and can be visualized with a developer can be used.

Further, in an apparatus having a toner hopper, the toner replenishment signal S can be used as a signal for replenishing toner from the hopper to the developing device.

Furthermore, if the cleaner 33 is configured to be able to detect the amount of toner collected, it is possible to notify the time to dispose of the collected toner.

〔Effect of the invention〕

As explained above, the present invention includes a first storage means that divides and stores an image signal into predetermined regions, and a second storage means that stores the printing rate of each region stored in the first storage means. means, a counting means for counting the emission time of the laser beam corresponding to the image signal of each area stored in the first storage means while correcting it according to the printing rate, and integrating and storing the count value of the counting means. a third storage means for
Since a signal sending means is provided which compares the contents of this third storage means with a preset reference value and sends out a predetermined signal when the reference value is exceeded, the printing rate can be adjusted for the entire image area. The amount of toner consumed can be calculated accurately, the user can be notified of the timing of toner replenishment, and the toner can be replenished just in time. Furthermore, it is possible to prevent white spots due to lack of toner and coagulation or fusion of toner due to excessive replenishment, which have been problems in the past. Further, the process cartridge type image recording apparatus has advantages such as being able to display an advance notice of the appropriate time to replace the cartridge.

[Brief explanation of the drawing]

FIG. 1 is a control block diagram of an image recording apparatus showing an embodiment of the present invention, FIG. 2 is a diagram showing the relationship between laser emission time and toner consumption amount, and FIGS. 3 and 4 are divisions of image areas. FIG. 5 is a diagram showing the relationship between toner consumption and printing rate. FIG. 6 is a diagram explaining how to determine the reference value set to the comparator shown in FIG. 1. FIG. 7 is a diagram explaining the condition. Characteristic diagram showing the relationship between developing bias potential and toner consumption,
Figure 8 is a layout diagram of the main processes around the photoreceptor drum of a laser beam printer, Figure 9 is a diagram showing the image output by the laser beam printer shown in Figure 8, and Figure 10 is the behavior of the surface potential of the photoreceptor drum. 11 is a conceptual diagram illustrating the toner charging operation, and FIG. 12 is a diagram illustrating the configuration of the developing device shown in FIG. 8. In the figure, 1 is an interface controller, 2.3.9
is a memory, 4 is a clock generator, 5°6 is a modulator, 7 is a laser, 8 is a counter, 10 is a comparator, and 11 is a controller. Fig. 1 Fig. 2 Fig. 4 Fig. 5 Ichigogakushin ('/.) Fig. 6 Fig. 7 “□ Lower iN 1.0 Electricity Crow 11 pairs: 11 Yi luck [ 1 1
1 Figure 8 2 M Figure 9 Figure 10 Figure 11 Mouth Figure 12

Claims (1)

[Claims] In an image-scan type image recording apparatus that scans a photosensitive drum with a laser beam modulated according to an image signal to form a latent image, a first storage means that divides the image signal into predetermined areas and stores the divided areas. and a second storage means for storing the printing rate of each area stored in the first storage means, and a laser beam emission time corresponding to the image signal of each area stored in the first storage means. a counting means for counting while correcting according to the printing rate; a third storage means for integrating and storing the count value of the counting means; and a reference value set in advance and the contents of the third storage means. 1. An image recording apparatus comprising: signal sending means for comparing the reference value and sending out a predetermined signal when the reference value is exceeded.