JPH0830919B2 - Image recording device - Google Patents

Description

The present invention relates to an image recording apparatus for visualizing a latent image formed by an electrophotographic method as a toner image.

[Conventional technology]

Conventionally, as a developing method of a developing means used in this type of apparatus, a two-sentence developing method in which a polyester resin toner and iron powder are mixed, and a one-sentence developing method in which only a polyester resin toner is used for development. There is.

Of these, in the two-sentence development method, the toner in the developer decreases due to the developing operation or the toner increases due to toner replenishment,
The toner concentration in the developer fluctuates. If the toner density is low, the image density on the recording material (recording paper) will be low, causing
Further, the image disappears, and if the toner concentration is high, fog or the like occurs on the non-image portion. In order to overcome this point, conventionally, methods for controlling the toner concentration in the developer by the methods shown in (1) and (2) below have been proposed and implemented.

(1) A method in which a predetermined amount of toner is replenished when the number of rotations of the photoconductor accompanying image formation reaches a predetermined rotation.

(2) A method of directly detecting the toner concentration in the developer in the developing device and replenishing a predetermined amount of toner when the detection signal falls below a predetermined level.

[Problems to be solved by the invention]

However, in the above method (1), regardless of the type (blackening rate) of the recorded image, the toner density becomes excessive or deficient due to the fixed amount of replenishment, and the recorded image becomes too light or too dark, resulting in an image output. Not stable.

In the method (2), the toner concentration in the developer is directly detected, so that the replenishment control is easy, but it is difficult to detect with high accuracy, and the toner is not replenished until a certain level or less is reached. , Will be replenished only after reaching below that level. This causes the toner density in the developer to change drastically, and during continuous printing of the same image, the density of the first output image and the subsequent output image will differ, resulting in a light image and a dark image. Will be output. In addition, since human color vision is particularly sensitive, a multi-color (two-color or three-color or more single-color) or full-color printer having a plurality of developing devices must be used unless each toner density can be accurately kept constant. However, if the toner densities vary, not only it becomes difficult to reproduce faithful colors, but also in continuous printers, images with different coloring properties are output between recorded images. There was a problem.

The present invention has been made to solve the above problems, and controls the timing of developer replenishment so that the replenishment of developer is completed in parallel with the developing operation and before the completion of the developing operation for each developing operation. By doing so, an image recording apparatus capable of stably and continuously performing continuous image recording with a good image density by replenishing an appropriate amount of the developer while suppressing the change in the remaining amount of the developer in the developing unit as much as possible. The purpose is to provide.

[Means for solving problems]

An image recording apparatus according to the present invention develops an electrostatic image on the image carrier, an electrostatic image forming unit that forms an electrostatic image according to an image signal on the image carrier, and the electrostatic image on the image carrier. In an image recording apparatus having a developing means and a replenishing means for replenishing the developing means with a developer, a consumption amount calculating means for calculating a consumption amount of the developer during one development according to the image signal; In parallel with the developing operation of the developing means, and for each developing operation, the replenishing means replenishes the developing means with an amount of developer based on the calculated value of the consumption amount calculating means corresponding to the current developing operation, A control means for terminating the replenishment of the developer by the replenishing means before the developing operation is provided.

[Operation] In the present invention, the control means is in parallel with the developing operation of the developing means, and for each developing operation, the replenishing means causes the developing means to change the calculated value of the consumption amount calculating means corresponding to the current developing operation. While replenishing the amount of developer based on the above, the replenishment of the developer by the replenishing means is ended before the developing operation, while suppressing the change in the remaining amount of the developer in the developing means as much as possible.
An appropriate amount of developer is replenished.

〔Example〕

FIG. 1 is a block diagram showing the configuration of an image recording apparatus showing an embodiment of the present invention. Reference numeral 1 is a photoconductor, which has a photoconductive layer on its surface and rotates in the direction of the arrow. Reference numeral 2 is a charger, which uniformly charges the photoconductor 1. 3 is an exposure device, which is an LED array 3
and a light converging lens array 3b and the like. A developing device 4 includes a developing roller 4a and a stirring roller 4b.
It is composed of A replenishing device 5 is composed of a toner container (hopper) 5b for replenishing the developer (toner) and a replenishing roller 5a for replenishing the toner. 6 is a paper feed cassette,
Transfer paper P is stored. A transfer device 7 transfers the toner image formed on the photoconductor 1 to the transfer paper P by, for example, corona discharge. A cleaning device 8 includes a blade, a cleaning roller, and the like, and collects the residual toner on the photoconductor 1. A conveyance device 9 conveys the transfer paper P to the fixing device 10. Reference numeral 11 denotes a paper discharge tray on which the transfer paper P which has been heat-pressed and fixed by the quantification device 10 is placed. A reader unit 12 sends an image signal V _D (0,1) obtained by photoelectrically converting the reflected light of the document obtained by optical scanning to one terminal of an AND circuit 13. The scan signal S indicating the scan state of the reader unit 12 is input to the other side of the AND circuit 13. The scan signal S is a signal that becomes “0” when the reader unit 12 performs prescan, that is, when calculating the toner consumption amount, and becomes “1” at the time of image formation. A driver circuit 14 sends a drive signal for driving the LED array 3a of the exposure apparatus 3 according to the output of the AND circuit 13. Reference numeral 15 is a counter section, which is “1” (print dot) of the image signal V _D sent from the reader section 12.
To count. The counter unit 15 is composed of, for example, an UP counter. Reference numeral 16 denotes a toner consumption amount calculation circuit, which is composed of a pulse number output unit 16a and a latch 16b that holds the pulse number T _N output by the pulse number output unit 16a. The pulse number output unit 16a sends the pulse number T _N addressed according to the output (count value T) of the counter unit 15 to the latch 16b.
The latch 16b latches the pulse number T _N transmitted from the pulse number output unit 16a in synchronization with the prescan end signal P _E. Reference numeral 17 is a supply control unit corresponding to the control means of the present invention,
A pulse signal corresponding to the pulse number TN latched in the latch 16b is sent to the replenishment motor 18 in synchronization with the development start signal DS input according to the timing charts shown in FIGS. The replenishing roller 5a of the device 5 is driven to replenish the toner corresponding to the amount of developer consumed from the hopper 5b. At that time, as shown in the timing charts of FIGS. 2A to 2F, the replenishment controller 17 controls the hopper 5 corresponding to the hopper 5 in parallel with the developing operation of the developing device 4 and for each developing operation. The developing device 4 is replenished with an amount of developer based on the calculated value of the toner consumption amount calculation circuit 16, and the hopper 5
The replenishment of the developer by is finished before the developing operation,
An appropriate amount of developer is replenished while suppressing a change in the remaining amount of developer in the developing device 4 as much as possible. The supply controller 17 is composed of a pulse oscillator, a down counter, a motor driver and the like.

Next, the operation of FIG. 1 will be described with reference to FIGS.

FIGS. 2A to 2F are timing charts for explaining the operation of FIG.

The figure (a) shows the scan timing of the reader unit 12, the figure (b) shows the calculation timing of the pulse number T _N ,
FIG. 3C shows the developing timing of the developing device 4,
(D) shows the drive timing of the supply roller 5a, and (e)
Shows the pre-scan end signal P _E , and (f) shows the development start signal D _S.

First, the reader unit 12 prescans the document (shown in FIG. 2A) for toner replenishment control, which will be described later, and obtains an image signal V _D. At this time, since the scan signal S of "0" is input to the AND circuit 13, the driver circuit 14 does not operate and latent image formation is not executed.

The counter unit 15 counts the number of print dots of the image signal V _D , and sends the count value T to the toner consumption amount calculation circuit 16. Here, the pulse number output unit 16a latches the pulse number T _N stored with the sent count value T as an address 16
b latches in synchronization with the pre-scan end signal P _E (see FIG. 2 (e)). The pre-scan end signal P _E
The counter unit 15 is cleared by the signal OC output from the latch 16b in synchronism with. The number of latched pulses T _N is
Since it is calculated from the total number of dots, it corresponds to the amount of toner consumed for forming the image to be output from now on. As is well known, there is a proportional relationship between the dot number and the toner consumption amount, and it is easy to calculate the toner consumption amount from the dot number. Latch 16b
The pulse number T _N latched at is transmitted to the replenishment controller 17 at the next stage.

On the other hand, when the main scan (reading for image output) is performed (t = t ₂ ), the scan signal S having the content “1” is input to the AND circuit 13, and the driver circuit 14 at the next stage is read by the reader unit.
The exposure device 3 operates by the image signal V _D output from
The LED array 3a is selectively operated, and a dot-shaped electrostatic latent image is formed on the photoconductor 1 via the light converging lens array 3b. After a lapse of a predetermined Δt from t _2, the developing device 4 is driven in synchronization with the development start signal D _S sent at t ₃ , and the replenishment controller 17 is also synchronized with the development start signal D _S (section signal). , Replenish motor with pulse signal of pulse number T _N
The toner is sent to 18, and the replenishing roller 5a of the replenishing device 5 is driven to replenish the toner corresponding to the developer consumption amount from the hopper 5b. The image formation shown in FIGS. 2A to 2F shows a case where the same image is continuously formed on three sheets, and three images are formed according to the number of print dots read by one prescan. Toner supply for one sheet is performed in parallel with each image formation.

Needless to say, it is possible to suppress the fluctuation of the toner density due to the toner replenishment by gradually replenishing the toner during development, for example, while the stirring roller 4b is rotating.

Further, in the above embodiment, the monochrome printer has been described, but the present invention is not limited to this, and the present invention can be applied to a color printer. For example, the toner consumption of each color may be calculated from the image signals separated into a plurality of colors, and the toner may be replenished in synchronization with the development timing of each color. The case where the present invention is applied to a color printer will be described below.

FIG. 3 is a sectional view showing the outline of a full-color image recording system showing another embodiment of the present invention, which is roughly classified into an upper color image reading device 21 (hereinafter referred to as a color reader) and a lower color image recording device 22 (hereinafter referred to as a color image recording device 22). Color printer).

 First, the configuration of the color reader 21 will be described.

A document 23 is placed on a document table 24 at a predetermined position. Reference numeral 25 denotes a scanning unit, which optically reads the document 23. The scanning unit 25 includes a rod array lens 25a, a unity color separation line sensor 25b (hereinafter referred to as a color sensor), an exposure lamp 25c and the like. A flexible code 26 transfers the output of the color sensor 25b to the image processing unit 27.

The scanning unit 25 reads an image (main scan) when scanning in the direction of arrow A from the left position in this figure, and is positioned on the right side (shown by the dotted line) during standby, and has a print start command (operation unit not shown). Command) to scan in the direction of arrow B to reach the main scan start position (back scan). Images can be read in both main scan and back scan.

Next, the configuration of the color printer 22 will be described. The same parts as those in FIG. 1 are designated by the same reference numerals.

31 _Y , 31 _M , 31 _C and 31 _BK are developing devices, and toner hopper 32 _Y ,
32 _M, 32 _C, 32 _BK from supply roller _{33 Y, 33 M, 33 C} , 33 BK each yellow toner T _Y by the driving of the magenta toner T _M, cyan toner T _C, the black toner T _BK is replenished. A transfer unit 34 includes a gripper 34a for gripping the transfer paper P and a transfer drum.
34b and a transfer charger 34c. A peeling claw 35 separates the transfer paper P, which has been transferred, from the transfer drum 34b.

Next, the operation of FIG. 3 will be described with reference to FIGS. 4 and 5.

FIG. 4 is a schematic diagram for explaining the color sensor 25b shown in FIG. 3, and 41 is a photoelectric conversion element composed of, for example, a CCD or the like, on the upper surface of which one pixel (62.5 μm square) is divided into about 3 blue Filter B, Green Filter G, Red Filter R
The color separation filter of is attached. Note that manuscript 23
The scanning direction for reading is in the direction of the arrow.

FIG. 5 is a control block diagram of the full-color image recording system shown in FIG. 3, and the same parts as those in FIGS. 1 and 3 are designated by the same reference numerals.

51 is a first selector, which is a back scan start signal B
Color digital signals Y, M, C and BK sent from the image processing unit 27 are sent to the counter unit 15 in synchronization with _SS . 52 is the second
The selector selects the color digital signals Y, M, C, of the predetermined line in the synchronous memory 53 in synchronization with the main scan start signal R _SS .
Remember BK. Reference numeral 54 denotes a synchronous memory controller, which sends the color digital signal Y stored in the synchronous memory 53 to the driver circuit 14 in synchronization with the color printer 22. 55
Is a third selector which selects one of the replenishment motor drivers 56 _Y , 56 _M , 56 _C and 56 _BK in synchronization with the developing operation signal D _S. 57 _Y , 57 _M , 57 _C and 57 _BK are replenishment motors and replenishment control unit 1
The developer consumed according to the pulse signal of the pulse number T _N sent from 7 is replenished.

Next, the operation of FIG. 5 will be described with reference to FIGS. 6 (a) to 6 (g).

6 (a) to 6 (g) are timing charts for explaining the operation of FIG. 5, FIG. 6 (a) shows the scanning operation of the color reader 21, and FIG. 6 (b) shows the developing operation. 6C shows the replenishing operation, FIG. 7D shows the backscan start signal B _SS , and FIG. _8E shows the backscan end signal input to the latch 16b of the toner consumption amount calculation circuit 16. B _SE is shown, (f) shows the toner amount calculation timing, and (g) shows the development start signal D _S. The drawing shows only the replenishing operation when forming one color image.

When a print command is issued, the scanning unit 25 shown in FIG. 3 back scans in the direction of arrow B, the exposure lamp 25c is turned on, and the reading of the original 23 is started. Then, color separation signals AB, AG, and AR of analog signals are output from the color sensor 25b shown in FIG. 5, and the image processing unit 27 performs predetermined processing (for example, Log conversion, A / D conversion, masking processing,
Generation processing) and the output is a digital signal
Y, M, C, BK. The digital signals Y, M, C, BK are basic data of each toner finally printed by the color printer 22. The digital signals Y, M, C and BK of the image processing unit 27 are the first
It is sent to the selector 51 and the back scan start signal B
An image signal of one color is selected by _SS and transferred to the next stage. For example, if a toner image is formed in the order of yellow, magenta, cyan, and black color toners, the digital signal Y for yellow toner is selected in the first back scan, and the digital signals M, C, and BK
The digital signal is selected in this order.

When the digital signal Y is selected, as described above, the counter unit 15 starts counting the print dots, the toner consumption amount calculation circuit 16 calculates the toner amount, and the back scan end signal B _SE latches it in the latch 16b. It At this time,
The content of the counter unit 15 is cleared by the signal output from the latch 16b. Then, the signal T _Y which is converted to the supplied toner amount that is latched in the latch 16b is set to the replenishment control unit 17.

On the other hand, when the document reading scan (main scan) is started for image output, the image processing unit 27 similarly outputs digital signals Y, M, C, and BK. Then, the second selector 52
Selects the desired single digital signal.
In this case, since it is the first main scan, the digital signal Y for yellow toner is the main scan start signal R.
It is selected by _SS and stored in the synchronization memory 53 at the next stage. Digital signals for several lines are stored in the synchronous memory 53, and the synchronous memory controller 54 causes the color printer 22 to operate.
Is transferred to the next stage while synchronizing with the operation of
A latent image is formed thereon. Then, after a lapse of a predetermined time, the developing device 31 _Y for yellow toner starts to operate, the latent image is visualized by the yellow toner, and the development start signal D _S (shown in FIG. 6 (g)) Third selector
55 selects the replenishment motor driver 56 _Y for replenishing yellow toner, drives the replenishment motor 57 _Y with the toner amount T _Y calculated by the digital signal Y read during the back scan, and is consumed by this development. Toner is replenished.

Next, the scanning unit 25 of the color reader 21 starts back scanning and main scanning again, and the same scanning is performed for magenta, cyan, and black toner.

It should be noted that the data read during the back scan is finally density data, and is not used for high-definition image reproduction. Therefore, the scanning speed is increased and the image signal is sampled at a predetermined cycle. Then, if the toner amount is determined, high speed printing can be supported.

〔The invention's effect〕

As described above, according to the present invention, the control means is in parallel with the developing operation of the developing means, and for each developing operation, the replenishing means causes the developing means to consume the consumption amount calculating means corresponding to the current developing operation. The developer is replenished in an amount based on the calculated value and the replenishment of the developer by the replenishing means is ended before the developing operation, so that the change in the remaining amount of the developer in the developing means is suppressed as much as possible. There is an effect that the developer is replenished, and continuous image recording can be stably and continuously performed with a good image density.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an image recording apparatus showing an embodiment of the present invention, FIGS. 2 (a) to 2 (f) are timing charts for explaining the operation of FIG. 1, and FIG. FIG. 4 is a schematic cross-sectional view of a full-color image recording system showing another embodiment of the present invention, FIG. 4 is a schematic view illustrating the color sensor shown in FIG. 3, and FIG. 5 is a full-color image recording system shown in FIG. The control block diagram and FIGS. 6 (a) to 6 (g) are timing charts for explaining the operation of FIG. In the figure, 1 is a photoconductor, 2 is a charger, 3 is an exposure device, and 3a is LE.
D array, 3b light converging lens, 4 developing device, 4a developing roller, 4b developing roller, 4b stirring roller, 5 replenishing device, 5a replenishing roller, 5b hopper, 6 paper feed cassette, 7 transfer device,
8 is a cleaning device, 9 is a conveying device, 10 is a fixing device,
11 is a discharge tray, 12 is a reader unit, 13 is an AND circuit, 14 is a driver circuit, 15 is a counter unit, 16 is a toner consumption calculation circuit, 16a is a pulse number output unit, 16b is a latch, and 17 is a replenishment control unit. , 18 are replenishment motors.

Claims (1)

[Claims] 1. An image carrier, an electrostatic image forming means for forming an electrostatic image on the image carrier according to an image signal, and a developing means for developing the electrostatic image on the image carrier. In an image recording apparatus having a replenishing means for replenishing the developing means with a developer, a consumption amount calculating means for calculating a consumption amount of the developer during one development according to the image signal, and a developing means for the developing means. In parallel with the operation, and for each developing operation, the replenishing means replenishes the developing means with an amount of the developer based on the calculated value of the consumption amount calculating means corresponding to the current developing operation, and by the replenishing means. An image recording apparatus comprising: a control unit that terminates the supply of the developer before the developing operation.