JPS61200562A - Image forming device - Google Patents

Abstract

PURPOSE:To supply a developer properly all the time and to improve the quality of recording images by detecting the picture element dot density of an effective picture element part of an image forming device to be recorded and determining the supply amount of a developer. CONSTITUTION:A controller 65 sends out paper size data to a laser unit 51 firstly on the basis of information from the paper size detecting means 57-1 of a cassette. A CPU 65-2 reads data on a solid-black image out of a ROM 65-3 on the basis of respective paper sizes. Further, the number of black dots of the effective image part which is counted by a laser unit 51 is stored in a ROM 65-4 from a laser unit 51-3 through an I/O port 65-1. The CPU 65-2 executes a supply counter routine corresponding to cassette data size. Then, the supply amount of a developer is determined and a toner supply motor 66 is put in operation. Thus, invariably proper developer supplying operation becomes possible and recording picture quality is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a developer replenishing device in an image forming apparatus, particularly a copying machine or the like.

[Prior art]

Conventional image forming apparatus 1 For example, in an electrophotographic copying apparatus having a two-component developing system, various proposals have been made for replenishing developer (toner, etc.).
There are (1) a method of measuring the developer concentration in a developing device, and (2) a method of measuring the density of a toner image formed on a photoreceptor drum.

However, in the conventional proposed method as described above,
In the former case (1), the concentration of the phenolic agent in the phenotypic organ is:
It does not directly correspond to the shading of the recorded image, so if the artist's density is high, the shading will be affected due to the difference in toner consumption and toner replenishment amount, as well as the time difference between the stirring process from toner replenishment to development. Control characteristics are greatly affected.

There was a drawback that the difference between excessive concentration and underconcentration became large.

In addition, in the case of the latter method (2), since an optical detection method is usually used to measure the developer concentration on the surface of the photoreceptor drum, contamination due to toner scattering during use, etc. There was a drawback that control characteristics deteriorated. In addition, there was no appropriate method to deal with changes in the formed image area due to changes in paper size, etc., and furthermore, the black level or white level was not determined for areas other than the effective area of the image to be dot sampled. Since this was not done, there was a possibility that the toner would be deposited outside the above-mentioned effective area.

〔the purpose〕

The present invention has been made in view of the problems of the prior art regarding the replenishment of developer as described above.

It is an object of the present invention to provide an image forming apparatus that eliminates the above drawbacks and at the same time improves the quality of recorded images by detecting and replenishing an appropriate amount of developer.

〔Example〕

The present invention will be explained below based on examples.

FIG. 1 shows a main body configuration diagram of an example of an electrophotographic copying machine which is an embodiment of an image forming apparatus according to the present invention. 200 is a laser beam printer using an electrophotographic method using laser light; 100 is a reader unit;
Digital image signal VID from reader unit 100
Image recording is performed based on EO.

First, in the reader unit 100, 21 is a document;
Reference numeral 2 denotes a transparent original platen on which the original is placed; 23, an original platen cover; 24, an illumination lamp for exposing the original; and 25, a reflector for efficiently projecting the amount of light from the illumination lamp 24 onto the original. , 26 is a short-focus single-quadrant lens for introducing light from the original 21, and 27 is a multi-chip CCD sensor for converting optical image information formed by the lens 26 into an electrical signal. . 28 is a lighting lamp 24
1 Reflector 25. Lens 26 and multi-chip CCD
A sensor fixing base that can place and fix the sensor 27 and move back and forth horizontally in the left and right directions in FIG. 1; 29 is a shaft that holds the sensor fixing base 28; 30 is a fixing base that supports the shaft 29; 31 is a sensor A drive wire for causing the fixed base 28 to perform the reciprocating motion, 32 a sheep for transmitting the drive of this wire 31, 33 fixing the wire 31, and a drive wire 34 connected to a motor 35 which is a rotational drive source. A connected drive sheave. Also, 36 is a multi-chip C
A cable for leading the output from the CD sensor 27 to the processing unit 37.
7 controls the output of the multi-chip CCD sensor 27, the operation of the illumination lamp 24° motor 35, etc. Reference numeral 38 indicates a limit switch for advancing the curve operated by the sensor fixing base 28, and 39 indicates a home position sensor of the sensor fixing base 28. Reference numeral 40 denotes an operation panel through which the operator inputs copy commands and the like.

Next, the operation of the reader unit 10G will be explained. First, when a Sicobee command is input through the operation panel 40, a signal instructing the illumination lamp 24 to be turned on is sent from the control processing unit 37, and the illumination lamp 24 is turned on.

Next, the motor 25 is rotated in the normal direction, whereby the sensor fixing base 28 starts to move forward in the direction of arrow A in the figure. Due to this movement, the original 21 is read and scanned line by line of the optical image by the multi-chip CCI sensor 27, which is moved in the sub-scanning direction, and converted into an electrical signal. When the sensor fixing base 28 has reached the end point of the forward movement, it operates the forward limit switch 38, whereby the motor 35 is reversely rotated and the sensor fixing base 28 starts to move backward. When the end point of the backward motion is reached, the motor 35 is stopped by activating the home position sensor 39, and the sensor fixing base 28 is stopped at the home position.

On the other hand, as described above, the printer 200 is an electrophotographic laser printer that uses laser light, and forms an image based on the digital image signal VIDEO from the reader unit 100.

In the printer 200, 51 is the reader unit 10
52 is a scanner unit for scanning laser light, and 53 receives the laser light to perform horizontal synchronization for image recording, etc. 54 is a photosensitive drum; 55 is a charger for charging the photosensitive drum 54; 56 is a voltage supply to the charger 55; 5T is a copy paper stored in a cassette, 57-1 is a size detection means for the copy paper 57, 58 is a paper feed roller that rotates to feed the copy paper, and 59 is a high-pressure unit for feeding the copy paper. , the copy paper 5
A registration roller 60 for synchronizing the tips of 7 is
This is a visualization device for making visible @ (visualization) by attaching a developing agent (toner) to the above-mentioned house a. Further, 61 is a transfer charger for transferring the visible image onto the copy paper 57 fed at a predetermined timing by the registration roller 59, and 62 is a fixing device for fusing the toner on the transfer paper 57 with heat. 63 is the photosensitive drum 54 after the end of transfer T.
A cleaner 64 for removing unnecessary toner on the
This is a static elimination lamp for removing the potential on the surface of the photoreceptor drum 54. Further, 65 is a front roller of a toner replenishment amount detection circuit which will be described later in FIG. 3, 66 is a toner replenishment motor (see FIG. 3), 67 is a copy paper transport section, and 68 is a paper discharge tray.

Next, the operation of the printer 200 will be explained.

First, a uniform potential is applied to the photoreceptor drum 54 using the charger 55.
to charge the battery. The image signal VIDEO from the control processing unit 37 of the reader unit 100 is output as a modulation signal of laser light by the laser unit 51, and the laser unit 51 emits the laser light modulated according to this V I DEO signal. The laser beam is deflected and scanned by the scanner unit 52 in a direction substantially perpendicular to the rotation direction of the photosensitive drum 540 (arrow B). The electrostatic latent image thus formed on the photosensitive drum 54 is visualized by the developing device 60, while the resist roller 59
The toner on the photoreceptor drum 54 is transferred to the copy paper 57 synchronously conveyed by the transfer charger 610, and the toner image is then fixed to the copy paper by the fixing device 62. The paper is configured to be discharged onto a paper discharge tray 68 outside the machine via.

In particular, a specific table block circuit diagram of the reader unit 100 of this embodiment is shown in FIG.
FIG. 3 shows a block circuit of the laser unit 51 and the controller 65 of the toner replenishment amount detection circuit. Also,
FIG. 4 is a timing chart of each output signal in these circuits.

First, in FIG. 2, c, , c2 , c, , c4 represent each chip of the multi-chip CCD line sensor 27 (FIG. 1), and a portion 41 surrounded by a dotted line represents an analog switch section. 70a and 70b are analog switches for switching the output O8 of the chip IC1, and 70c and 70d are
Similarly, the analog switch for switching the output O82 of chip 2C2, 70θ, 70 amount is chip 73G.

, and γOcr, 70h are analog switches for switching the respective outputs O8 and O84 of the chip 4C. 71 is a sample and hold circuit for making the output signal O81 of the analog switch 41 constant; 72 is an amplifier for amplifying this signal; 73
teeth.

An analog/digital converter for converting an analog signal into a digital signal of predetermined bits.

74 compares the digital signal to a threshold.

A dither comparator 75 for forming a binary signal indicating white/black (assuming black recording in this embodiment)
a dither ROM that outputs digital data stored in advance in the comparator 74 as a threshold value according to an address;
76 is a dither kakunta that determines the output address of the dither LOM 75, and 77 and 78 are f' for storing bit data obtained by comparing the numerical value of the dither LOM 75 and the image data in the comparator 74. tAM,
A selector 79 supplies read and write addresses to the AM77.

80 is a selector that supplies an address for continuous output and writing to the RAM 1; 81 is a synchronous control circuit 85 in synchronization with a synchronization signal 8D for each line sent from the printer 200; and a 2BD signal. An inverter 82 reverses the signals that are alternately output for each section.

A printer oscillator for matching the signal output to the characteristics of the printer 200; 83 a read counter for counting the oscillation clock from one oscillator; 84 counting in response to a clock synchronized with the multiple read operations of the reader unit 100; A write counter 85 is a synchronous control circuit for controlling read/write of the RAMs 77 and 78.

Further, 86 is a multi-chip CCD sensor 27 (first
An oscillator 87 for the reader 100 outputs a clock pulse φ that determines the transfer of the readout output of the reader 1 in FIG.
An 8G synchronization circuit 88 synchronizes the 00 oscillator 86 with the BD signal from the printer 200 and generates a shift pulse SH to the multi-chip CCD sensor 27.

A generating circuit 89 generates the vertical transfer lock φV for operating the vertical transfer registers of the odd chips of the CCD sensor 27, that is, the line sensor chips 1.3G, . signal and
a counter 90 that performs a counting operation based on the SH pulse;
is the counter 89 according to the oscillator 86 for the reader 100.
During the SH signal period, the horizontal transfer locks φH3 to φH4 for operating all line sensor chips 01 to C4 and the switching signals (data select signals) DS to DS4 of the analog switch 41 are activated according to the count value of . This is a controller that does not allow it to occur.

Next, the operation shown in FIG. 2 will be explained. First, the oscillation signal φ from the oscillator 86 for the reader 100 and the 8G signal from the printer 200 are synchronized by the BD synchronization circuit 87, and the waveform-shaped 8G signal is sent to each chip C', ~C.
Input to the SH terminal of 4. For this purpose, each chip C1 to C
Charges are transferred in parallel from the four light receiving elements.

Here, the odd numbered chips, that is, the original 21
Line sensor chips 1 and 3CI that read (Fig. 1)
-Cs (FIG. 2), this charge is transferred in the vertical CCD register by the vertical transfer lock φ■. Here, when recording at the same magnification, the same pulse as the shift pulse SH for driving the shift gate is used to lock the vertical transfer φV.
is applied as .

For this reason, after being delayed by the vertical COD register for spatially different pixels, it is output in synchronization with the line output of the adjacent even-numbered chips C, ,C, and in synchronization with the same -BD signal. At this time.

All pixels in the horizontal CCD register 7'lC are transferred during 1/4 of the pulse SH interval by the horizontal transfer pulse φH controlled by the controller 90 (FIG. 2). Further, to the adjacent chip 2C1, after the end T of the horizontal transfer pulse φH3 described above, a horizontal transfer pulse φH is outputted.

In this way, the pixels of all chips C3 to C4 of the multi-chip CCD 27 are connected to the analog switch 41 (FIG. 2).
One line is sequentially transferred and output within the pulse SH interval.

If the analog switch 41 is used to connect the outputs of multiple line sensor chips CI to C4 in this way, a delay in switching time will occur. In order to have a dummy pixel other than the effective pixel, the analog switch 41 is configured to respond at this time. Further, Fi for one dummy pixel is removed by a method described later.

Now, with the configuration as described above, the analog switch 41
The output O5l is outputted as one pixel data at an analog level. The sample and hold circuit 71 (Fig. 2) performs sample and hold, and the amplifier 72 corrects the signal value so that it matches the standard value of the A/D converter 73, and then A/D converts the analog value. to make a digital signal of predetermined bits.

In order to convert this into dot data indicating white/black and output it to the printer 200, the address is read from the dither counter 76 at dither 1 (, 0M75) and output in order to perform dither processing. A clock signal CLK from which the transfer lock for one dummy pixel has been removed is input from the controller 90 to 76 for counting.

Therefore, the line sensor chip IC, and 2G.

Since the dither matrix does not become discontinuous at the seams between the two, defective images such as streaks do not appear in the reproduced image.

Dot data obtained by comparing the output value of the dither ROM 75 and the image signal as described above.

Store it in either line memory RAM 77 or 78. At this time, first, the line memory RAM 77 is selected when the write terminal WE of the synchronous control circuit 85 becomes low level.

At this time, the selector 79 selects the write address bus from the write counter 84, so that the output of the write counter 84 is input to the address line ADH of the LAM 77 (for line memory). At this time, the write counter 84, like the dither counter 76,
Since the clock CLK from which the transfer lock for one dummy pixel is removed from the controller 90 is counted, the bit data of the dummy pixel is not stored in the AM 77.

Furthermore, when the synchronization control circuit 85 sets the WE terminal to a high level, the write terminal WE of the RAM 77 becomes a high level, and the chip select terminal C8 becomes a low level.
The data of the previous line stored in AM77 is read out, and a continuous image signal VI with one dummy pixel removed is obtained.
It is output to the printer 200 as DEO. At the same time, the dot data currently output from the comparator 74 is stored in the line memory RAM 78. in this way,
The line memory RAMs 77 and 78 alternately perform memory writing and reading, and output one image signal VIDEO in synchronization with the printer 2001C.

Next, the toner replenishment method will be explained in detail with reference to FIG. As mentioned above, the printer 200 is the printer 1
00) The received video signal VIDEO is processed by the laser unit 51. 51-1 in the laser unit 51
5 is an AND circuit that calculates the logical sum of the video signal VjDEO and a signal from the #J consideration valid signal circuit 51-5, which will be described later.
1-2 is the signal of the AND circuit 51-1 and the laser 51-3
The laser drive unit 51-4 for blinking is
The light of laser 51-3.

Beamtect (B) to synchronize the rotation of the scanner
D) The circuit 51-5 is connected to the I10 port 65-1 of the controller 65 (also shown in FIG. 1) and sets only the image effective portion to a high level using the paper size information, vertical synchronization signal VSYNC, and beam detect signal 80. The image valid signal circuit 51-6 performs an AND operation that takes the logical sum of the VIDε0 signal, the image valid signal, and the image clock signal.
In this circuit, the V I DEO signal has a black level as a high level, and the image valid signal has a high level in a valid section. 51-7 is a counter circuit for counting the black part, 51-Ill, VSYNC4M number (D
A latch circuit for detecting the data value of the final T signal.

The output value of this circuit is connected to I10 port) 65-1.

Next, the operation of the laser unit) 51 and the controller 65 will be explained. First, the one-image valid part number circuit 51-5 generates image valid signals 5l-5c based on the VSYNC signal and the paper size information sent from the controller 65 by the code signal (the timing chart is shown in 41g11). This signal is the latch circuit 51-8
and is sent to the controller 65. On the other hand, as shown in the timing chart related to the horizontal synchronizing signal in FIG. 4(2), image valid signals 5l-5b are generated based on the BD double signal and paper size information. Also, this image valid signal 5
1-5b and the image valid signal 51-5c have an AND gate configuration, so that signals other than signals synchronized with the VSYNC signal do not go to high level. Further, a counter 51-7 counts an output signal obtained by taking the logical sum of the VIDEO signal, the CLK signal, and the image valid signals 5l-5b. That is, counting the black signal of one image effective part is K.

Next, VS of the timing chart shown in Fig. 4 ([)
The latch circuit 51-8 latches the black count value of the image signal at the falling edge of the image valid signal 51-5c generated by the YNC signal. Also, 65-2 is a CPU
After confirming that the level of the image valid signal 51-5c has changed from high to low at the I10 port 65-1, the data in the latch circuit 51-8 is read.

Next, the operation of the controller 65 will be explained. First, paper size data is sent to the laser unit 51 based on information from the paper size detection means (FIG. 1, 57-1) of the cassette. Here, the CPU 65-2 calls data for an all-black image from the M65-3 based on each paper size. And as a concrete figure,
In the case of A4 size with a resolution of 16 dots/m, it is 210
X297X16X16=F3A200H. In this case, if an error of 1/100,000 or less is ignored, only the data of F3A2 is valid and it is sufficient to have 16-bit data.

The effectiveness in this case may be determined by using 8-bit data (an error of about 1/200 can be ignored) using the method described later.

This data is stored for each cassette size. Furthermore, the value obtained by counting the number of black dots is output from the laser unit 51.
10 is stored in the AM65-4 through the boat 65-1.

Here, the %CPU 65-2 operates a replenishment counter routine for the cassette size data.

That is, the replenishment time is determined according to the cassette size.

Next, the toner replenishment motor 66 is operated in accordance with the unit time obtained by dividing the black data by the replenishment time and the total number of data.

In the above embodiments, the case of two-component development of white/black was explained, but the invention of Momo can be applied to the case of other colors than black.

〔effect〕

As described above, according to the present invention, since the image forming apparatus is configured to detect the pixel dot density of the effective image portion to be recorded and determine the amount of developer replenishment, appropriate developer replenishment is always ensured. This made it possible to improve the recorded image quality.

[Brief explanation of the drawing]

Fig. 1 is a main body configuration diagram of an electrophotographic copying machine according to an embodiment of the present invention, Fig. 2 is a block circuit diagram of its reader unit, and Fig. 3 is a controller for the laser unit and toner replenishment circuit of the printer. The block circuit diagram, Figure 4, is
It is a timing chart of each signal. 21・・・・・・・・・Manuscript 27・・・・・・Multi-chip CCD sensor (
light receiving element) 37...Funtrol processing unit 51...
......Laser unit 51-7...Counter 54...Photosensitive drum 57...Copy paper 57-1...Copy paper size Detection means 60...Developer 65...Toner (developer) replenishment amount detection circuit controller 66...Toner replenishment motor 76.・・・
...Dither counters C1 to C4... Line sensor chip Fig. 1 [Fig. 3 U1]

Claims (1)

[Claims] In an image forming apparatus equipped with a plurality of light receiving elements for converting optical image information into electrical signals and an image forming means for forming an image on a recording material according to the electrical signals, calculate the colored pixel ratio in an effective image portion. 1. An image forming apparatus comprising: a means for determining a developer replenishment amount based on the calculated value and recording material size information.