JPH02108085A - Toner concentration controller for recorder - Google Patents

Abstract

PURPOSE:To reduce the variance of recording density and low-density recording just after replenishing toner by supplying a large quantity of toner when cumulative stored value of a cumulating means is large and a small quantity of toner when the value is small corresponding to the cumulative stored value thereof. CONSTITUTION:The cumulating means 210 compares the recording density detected by a pattern density sensor 18P with a set value and cumulating and storing deviation between both of them when the recording density is lower than the set value. Therefore, the cumulative value is large when remaining quantity of toner is small just before replenishing the toner and the cumulative value is small when the remaining quantity of toner is large. Corresponding to the cumulative stored value, a large quantity of toner is supplied when the value is large and a small quantity of toner is supplied when the value is small by a toner supply control means 210. Thus, the variance of the recording density and the low-density recording just after replenishing the toner are reduced.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a recording device that develops an electrostatic latent image formed on a latent image medium with toner, and particularly relates to a recording device that develops an electrostatic latent image formed on a latent image medium with toner, and in particular, the present invention relates to a recording device that develops an electrostatic latent image formed on a latent image medium with toner. The present invention relates to a toner density control device that detects the density of a toner development pattern of an electrostatic latent image and controls toner replenishment based on the detected density.

[Conventional technology]

In a recording device that visualizes an electrostatic latent image on a charge carrying medium by developing an electrostatic latent image, the electrostatic potential on the charge carrying medium, the developing toner concentration, and the developing bias potential.

etc. affect the density of the developed images 1 to 4. The charge-carrying medium is a photoreceptor, which is uniformly charged in advance, and the charged surface is exposed to image-specific light to form an electrostatic latent image, which is developed with toner and the toner image is transferred to recording paper. In a so-called electrophotographic recording apparatus, the exposure intensity also affects the recording density.

Therefore, in the past, the toner concentration was kept extremely constant.
The charging potential, exposure intensity, development bias potential, etc. before exposure are
The recording density is adjusted in response to the recording density designation or adjustment input from the operator or the host computer.

In order to keep the toner density constant, conventionally, a pattern density sensor detects the density of a visible pattern obtained by developing an electrostatic latent image formed in a predetermined pattern on a charge carrying medium with toner from a developing device. , a toner density sensor that detects the toner density of the developing device, a toner supply unit that supplies toner to the developing device, and a toner density standard that is set in accordance with the detected density of the pattern density sensor so that the detected density of the toner density sensor falls within the range. A toner concentration control device for electrostatic latent image development has been provided which includes a supply control means for supplying and energizing a toner supply means when the toner concentration is lower than a reference toner concentration (for example, Japanese Patent Laid-Open No. 57-136667 Public bulletin).

[Problem to be solved by the invention]

In this type of toner concentration control device, the toner concentration of the developer or the concentration of the developed pattern image decreases below a certain set value;
When the toner concentration or the developed pattern image density does not become high even after the toner supply is energized to the developing device, a toner near end message is displayed to prompt replenishment of toner in the toner tank (for example, replacement of the toner cartridge). If the recording operation is stopped during continuous recording of the specified number of sheets, it will cause inconvenience to the operator who is trying to obtain records, and it may also cause toner shortage (
Even when the toner near end is reached, it is possible to obtain a usable record although the recording density gradually decreases. If the continuous repeat recording ends after recording a predetermined number of sheets (for example, 50 sheets), the toner end message will be displayed and the recording device will stop. and continues to stop until the toner cartridge is replaced.

Therefore, the amount of toner consumed by the developing device from when the toner near-end is reached until the toner cartridge is replaced (the toner tank is refilled with new toner) is undefined, and a considerable amount of toner remains in the developing section of the developing device. There are cases where the remaining capacity is extremely low.

However, conventionally, when the toner cartridge is replaced, toner is supplied from the toner tank to the developing section of the developing device at a fixed speed, so the toner concentration of the developer in the developing section of the developing device immediately after the toner cartridge is replaced is the same as when the toner cartridge is replaced. There are various variations depending on the amount of toner remaining in the developing section immediately before. When the toner concentration of the developer or the concentration of the developed pattern image rises above a certain set value,
After the toner supply from the toner tank is stopped, the toner concentration in the developing section becomes a substantially constant value. Therefore, in the recording operation from replacing the toner cartridge (toner replenishment) until the toner concentration in the developing section reaches a substantially constant value, the recording density will vary.

For example, if the toner cartridge is replaced after recording a large number of records with relatively high toner consumption after the toner near-end, the toner density in the developing section will reach the set value after the toner cartridge is replaced. It takes a relatively long time, and the recordings obtained by the recording operations performed during that time are of low density, and there are density fluctuations in which the density gradually increases.

An object of the present invention is to reduce variations in recording density immediately after toner replenishment (toner cartridge replacement) as described above, or low density recording.

[Means to solve the problem]

The above-mentioned conventional problem is that the amount of toner remaining in the developing section immediately before toner replenishment (toner cartridge replacement) can vary significantly, but the toner supply speed from the toner tank to the developing section immediately after toner replenishment is constant. This is the cause.

Therefore, in the toner density control device of the present invention, the recording density of the developed pattern image detected by the pattern density sensor is compared with a set value, and when the recorded density is lower than the set value, an accumulating means for accumulating and storing the deviation between the two; and a toner supply control means for supplying toner by the toner supply means in accordance with the density detected by the pattern density sensor, and supplying a large amount of toner when it is large and a small amount of toner when it is small in accordance with the accumulated value stored in the accumulating means. , is provided.

[Effect]

According to this, the accumulating means compares the recording density of the developed pattern image detected by the pattern density sensor with the set value, and when the recorded density is lower than the set value, accumulates and stores the deviation between the two. Therefore, when the amount of toner remaining in the developing section immediately before toner replenishment is small, the accumulated value of the accumulating means is large, and when the amount of toner remaining in the developing section is large, the accumulated value of the accumulating section is small.

Accordingly, the toner supply control means supplies a large amount of toner when it is large and a small amount of toner when it is small in accordance with the cumulative storage value of the accumulating means. When the amount of toner remaining in the developing section is small, the toner supply control means supplies a large amount of toner, and when the amount of toner remaining in the developing section immediately before toner replenishment is large, the toner supply control means supplies a small amount of toner. .

Therefore, when the remaining amount of toner in the developing section immediately before toner replenishment is small, the toner supply control means will supply a large amount of toner when 1 to toner replenishment is performed, so that the toner concentration in the developing section will quickly increase. There is a low density recording period immediately after toner replenishment, and the recording density gradually increases (
fluctuations) will be shorter. That is, variations in recording density and low-density recording immediately after toner replenishment as described above are reduced.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

〔Example〕

FIG. 1 shows the main structural parts of an electrophotographic recording apparatus equipped with an embodiment of the present invention.

In the recording apparatus shown in FIG. 1, a photoreceptor 7 is a drum-shaped photoreceptor made of aluminum coated with OPC, and rotates in the direction of the arrow. 8 is a main charger for charging the photoreceptor 7, which is a scorotron charger with a grid electrode for uniformly charging the photoreceptor 7 to a negative potential. 1 is
Although not shown, a semiconductor laser generates a laser beam inside.

A scanning mechanism such as a polygon mirror that scans a laser beam in the axial direction of the photoreceptor 7 (direction perpendicular to the paper surface).

Sort 1 piece of image data (1 bit/1 dot) -7
= Image memory to store, pattern memory etc. that stores pattern data for recording density detection, image memory device that controls writing/reading thereof, and turning on (irradiation)/off (non-irradiation) of the laser beam in accordance with the image data. This is a laser exposure apparatus that includes an exposure controller and the like to control. 1
1 is a developing device that visualizes the electrostatic latent image formed on the photoconductor 7, which is charged by the main charger 8 and exposed by the laser exposure device 1. It is a negative/positive two-component magnetic brush development system that adheres toner. 16 is a replenishment roller for feeding the toner from the toner hopper 16 to the developing section, and 17 is a replenishment roller for feeding the toner from the toner hopper 16 to the developing section. When energized (turned on), it is connected to a power transmission system (not shown) driven by a main motor (not shown) and rotates at a predetermined constant speed. A plurality of grooves are formed on the side peripheral surface of the replenishment roller 17 substantially parallel to the rotation axis. When the replenishment roller 17 rotates, the toner that has fallen into the grooves in the toner hopper 16 falls into the developing section, and is transferred to the agitator 13. The toner is mixed with a carrier, stirred, and supplied to a developing brush, that is, a developing roller 12. As the developing roller 12 rotates, the developer adhering to it comes into contact with the surface of the photoreceptor 7, and part of the toner adheres to the unexposed area of the photoreceptor 7, and the rest falls to the agitator 13 together with the carrier. Part of the toner density sensor 15
Pass through the F conduit. The toner concentration sensor 15F has an electric coil (sensor coil) along a conduit,
The toner concentration of the developer is detected by detecting the magnetic permeability of the developer passing through the coil.

24 is an image density sensor (referred to as a P sensor) that detects the density of a toner image formed on the surface of a photoconductor, and is a reflective photosensor having an LED in a light emitting part and a phototransistor in a light receiving part. .

In this embodiment, the image density of an image density detection pattern of approximately 15 x 15 mm formed immediately before the starting edge of image recording for one sheet is detected. 25 is a transfer/separation charger that transfers the toner image on the photoconductor 7 onto the transfer paper (recording paper) fed from the paper feed section and then separates the transfer paper from the photoconductor 7; 28 is a cleaning device; 10 is a cleaning device; It is a static elimination lamp.

In addition, a heat roller (a roller with a built-in fixing heater) 26,
A conveyance section that sends the transfer paper to the heat roller 26, a discharge section that discharges the transfer paper that has left the heat roller 26, and a roll paper RP1.
．． There is a paper feed section, etc. that feeds recording paper of a designated recording size from RP2 and RP3, cuts it with cutters 21 to 23, and conveys it to a transfer section.

FIG. 2 shows an outline of the electric circuit configuration of the recording apparatus shown in FIG. 1. The main control board 200 includes a microprocessor 210. Read-only memory 23o.

Parallel 10 Poe 1-240. SilJ full I10 pot 250. A/D: M/verter 260 and timer 27
0 is provided. This main control board 200 includes an operation board 310. Main charger power supply/controller 1 to roller 8
PC, grid voltage power supply/controller 1-○-ra 8GPC,
Controller board 330 of the laser exposure apparatus. Heater control board 34o, high voltage power supply unit 350. Sorter 70
(Not yet arrived) 2-sided processing device 80. Paper feed unit 360.
An AC driver 370, a DC driver 380, and a signal processing circuit 390A are installed.

Main charger power supply/controller 8PC controls on/off of main charger 8 and charge voltage.

The grid voltage power supply/controller 5GPC controls the on/off and grid voltage of the grid electrode 8G of the main charger 8.

The heater control board 340 controls the on/off and temperature of the fixing heaters HTI and HT2 provided in the heat roller 26.

The high voltage power supply unit 1-350 controls on/off and energizing voltage of the bias electrode 5a of the developing device 11 and the transfer/separation charger 25.

Various AC loads 400 are connected to the driver 370, and 1 (various DC loads 410 and 1) are connected to the driver 370.
is connected.

Various sensors 420 are connected to the signal processing circuit 390A. The various sensors 420 include an electrometer 420P that detects the surface potential of the photoreceptor.

Typical AC loads 400 include a main motor that drives the paper feed and conveyance system, a photoconductor upper motor that drives the photoconductor 7,
These include fan motors, developing motors, etc. DC load 41
Typical 0. total counter, etc.

Typical of the various sensors 420 are a timing pulse generator that generates pulses synchronized with the rotation of the main motor;
These include a timing pulse generator that generates pulses synchronized with the rotation of the photoreceptor motor, 2 paper size (width of rolled paper) sensors, paper sensor (paper presence/absence), 9 surface electrometer 420p, and so on.

The P sensor 18P is connected to a signal processing circuit 390P, and the signal processing circuit 390P converts an analog signal indicating the detected density (pattern developed toner image density on the photoreceptor 7) into an A/
D converter 260.

The toner concentration sensor 15F is connected to a signal processing circuit 390F, and the signal processing circuit 390F provides the A/D converter 260 with an analog signal indicating the detected density (toner concentration in the developing unit 11).

A groove is formed on the surface of the toner supply roller 17, and when the roller 17 rotates, the toner in the groove enters the developing section. An electromagnetic clutch 17MD is connected to the roller 17, and when the electromagnetic clutch 17MD is energized (turned on), the roller 17 is connected to the power transmission system of the paper feeding/conveying system driven by the main motor, and is driven at a constant speed. Rotate. Electromagnetic clutch 17MD is connected to solenoid driver 390S, and solenoid driver 390S is connected to main control board 200.

The concentration deviation amount indication switch 30 is U (concentration up), N
3 marked with (density standard) and D (density down)
It is a rotary switch 30 having a contact point, and is installed inside the top plate of the recording device, separately from the operation board 310. A signal processing circuit 390E is connected to the switch 30, and the signal processing circuit 390E provides the main control board 200 with a signal indicating which contact point the slider of the switch 30 is in contact with.

FIG. 3a shows an overview of the control operation of the microprocessor 210 of the main control board 200.

The microprocessor 210 is powered on (step l: hereinafter, the word step will be omitted in parentheses).
Then, initialization (2) is executed to set the input/output port to the standby signal level and clear internal registers, counters, timers, etc. At this time, register n, which counts the number of sheets recorded since the power was turned on, is also cleared.

Next, the microprocessor 210 checks the signal level of the connector connection signal and the status signal line of each unit in the machine, determines whether or not externally connected equipment such as the sorter 709 and double-sided processing device 80 is connected, and takes appropriate action accordingly. The controller selects a control mode, determines whether each unit in the machine is normal or abnormal, and when an abnormality occurs, displays an abnormality display and stands by (3).

If it is normal, the microprocessor 210 instructs the heater control board 340 to warm up the heater (4).
. Microprocessor 210 then controls fuser heater control 2.
In step (5), it is checked whether the fixing temperature is within a predetermined range, and if it is within the predetermined range, constant temperature control is performed on the heater control board 3.
40. If the temperature is not within the predetermined range, wait until the temperature is within the predetermined range, and when the temperature is within the predetermined range and constant temperature control is instructed, Ready is displayed on the operation board 310 (6.
7).

The microprocessor 210 then operates on the operating board 310.
The printer waits for the print start key of the printer to be operated, or for a print start instruction to arrive when the host computer or image scanner is connected (8, 9), and while waiting, the controller Recording conditions, recording size, and
When the number of sheets, etc. is input, or when the host computer etc. instructs recording conditions, recording size, number of sheets, etc.
Read it to adjust or change print process parameters.

When the print start key on the operation board 310 is operated, or when a print start instruction is received from the host computer, etc., the rns setting (TNS) is executed to set the number of sheets ns (recorded sheet number unit) to perform the development pattern density. execution cycle).

FIG. 3f shows the contents of the rns setting J (TNS). In this case, if the specified recording size is AIT format, set 2 to register ns, and set the specified recording size to the specified recording size. If the specified recording size is A2T size, set 3 to register ns. If the specified recording size is A2M size, set 4 to register ns. If the specified recording size is A3T size, set 4 to register ns. If the specified recording size is A3M size. and set 5 to register ns. If the specified recording size is A4T, set 5 to register ns. If the specified recording size is A4M, set 7 to register ns. If the specified recording size is any other size, set 5 to register ns. 1
Write 0.

Referring again to Figure 3a. When rns setting J (TNS) is executed, it next checks whether the content n of register n is greater than or equal to ns (the content of register ns) (10), and if it is greater than or equal to ns, clears register n. (Contents 0
), execute "Determine toner density standard Ds & supply speed Ss" (TDCI), which will be described in detail later, and then execute "Toner density control" (TDC2) to start the recording operation and print one sheet. Recording is performed (10), and when one recording cycle is completed, the end process is started (13), and the contents of the recording number count register n (a register that stores the number of times one recording cycle has been executed since the power is turned on) are incremented by one. To update the numerical value 14), change the contents of the continuous recording number count register N (the number of continuous recordings since recording start was instructed) to 1.
Update it to a larger value (15), and the contents of register N will be the number of consecutive recordings Ns specified before the recording start instruction.
Check whether it has been reached (16). If it has not been reached, proceed to step 10 and below and perform another recording cycle (
12).

When the contents of the register N reach the number of copies Ns, the electromagnetic clutch 17MD is turned off (toner supply stopped), and it is checked whether the termination process is completed (18), and when it is completed, the main motor is stopped. (19). If a start instruction is issued again before the end processing is completed, the process proceeds to step 10 and subsequent steps.

By the above operation, after turning on the power, ns images (see Figure 3F) are printed.
After performing the recording operation (the contents of register n is ns), register n is cleared (11) and "toner density reference value D
s&Determination of supply speed Ss (TDCI) is executed, and then again after recording ns sheets. That is, every time the recording operation is performed ns times, "Determination of toner density reference value Ds & supply speed Ss (TDCI)" is performed.
is executed. [Toner density control J (TDC2) is executed every 1 recording operation.

In FIG. 3b, "toner concentration reference value Ds & supply speed Ss
The contents of Decision J (TDCI) are shown below.

When proceeding to this subroutine TDC], the microprocessor 210 displays a message "Adjusting recording density" on the operation board 310, notifies the host computer etc. that it is busy (not ready) (21), and starts exposing the pattern 31. The photoreceptor is charged for recording (22 to 25), and the electrometer 42
The detected potential of 0p is compared with a reference value for P sensor concentration detection, and the charging grid voltage of the main charger 8 is adjusted so that the detected potential becomes the reference value (26). Details of this content will be described later. After completing this adjustment, the developing motor is driven and the developing bias is turned on (27). As a result, the developing device 11 enters the developing energized state. Next, an image density detection pattern is projected (exposed) onto the photoreceptor 7 (28), and the density of the developed toner image on the photoreceptor of the pattern is measured by the P sensor 1.
Detected at 8P (29.30). In this detection,
The P sensor 18P detection voltage Vsg (high level when the reflectance is high) at the white dew tip outside the pattern is read 16 times in chronological order (29), and the P of the toner image in the black area inside the pattern is read 16 times (29).
The sensor 18P detection voltage Vsp (high level when reflectance is high: lower level than Vsg) is read 16 times (30). Next, the average value Vsga of Vsg and the average value Vs of Vsp
pa is calculated, and the ratio of the two, V spa/V sga, is calculated (31).

Next, V spa/V sga is 0.11 or more and 0.4
Check whether it is within the following range (32), and if it is within the range, it is the standard recording density, so set the toner density reference value Do (toner density reference standard value) to obtain the standard recording density. Write to reference register Ds (33)
, If Vspa/Vsga is outside the range of 0.11 or more and 0.4 or less, the correction amount (
+ or -) f (Vspa/Vsga) to standard value Do
(If the correction amount is -, it is substantially subtracted) and is written in the toner density reference register Ds (34). Then, "Determination of supply speed Ss J (35)", which will be described in detail later, is executed.

Next, the microprocessor 210 cancels all the states set for P sensor concentration detection, sets an end cycle (36), and returns to the main routine (FIG. 3a) (proceeds to subroutine TDC2).

FIG. 3c shows the contents of "Charging grid voltage adjustment J (26)." Proceeding to this step, the microprocessor 210 determines that the surface charged by the main charger 8 is connected to the surface electrometer 422.
Wait until P reaches P (261), and then read the detection potential Ps of the surface electrometer 420P (262). Then, refer to whether the contact position that the slider of the switch 3o is in contact with is U, N, or D (263
, 264), and compares the corresponding potential value with the detected potential Ps (265-267).

When the switch 30 is in the N position, the surface potential is 380
Since the value is specified as 420 or less, if it is out of that range, the grid voltage is changed in a direction in which the detected potential Ps falls within that range (268). When the switch 30 is in the U position, the surface potential is specified to be between 430 and 470, so if it is outside that range, the detected potential Ps
Change the grid voltage in the direction that falls within that range (26
8). When the switch 30 is in the D position, the surface potential is specified to be between 330 and 370, so if it is outside that range, the grid voltage is changed so that the detected potential Ps falls within that range (268). .

When the grid voltage is changed, the grid voltage is changed and the main charger 8 waits for the charged surface to reach the surface electrometer 420P (261), and when it reaches the surface electrometer 420P, the detection potential Ps of the surface electrometer 4202 is read (262). ).

As described above, when the detected potential Ps reaches the potential determined by the designation of the switch 30, the process proceeds to the above-mentioned [developing motor on, developing bias on J (27).

In this embodiment, the grid voltage of the main charger 8 is adjusted to set the surface potential of the photoreceptor 7 before exposure to a value determined by the specification of the switch 30, and this surface potential surface is used as the image density detection pattern. The image is exposed to light and developed by the developing device 11 to obtain a visible pattern, and the density of this visible pattern is detected by the P sensor 18P.

FIG. 3d shows the contents of "Determination of supply speed Ss J (35). In this, the density detection voltage Vsp (approximately 0 to 4 V, detected at low density voltage is high), but Vsp<1.00V.

1.00V≦Vsp<1.25V.

1.25V≦Vsp<1.50V.

1.50V≦Vsp<1.75V.

1.75V≦Vsp<2. OOV.

2.00V≦Vsp, check which range it is in (351 to 355
), Vsp<1. In OOV, set 1 to register Ss, 1.
00V ≦Vsp<1.25V T: sets 2 to register Ss, 1.25V≦Vsp<1.50V sets register S
Set 3 to S, set 4 to register Ss when 1.50V≦Vsp<1.75V, and set 4 to register Ss when 1.75V≦Vsp<2. In OOV, register 5slC5 and 2. If OOV≦Vsp, 6 is written to register Ss (356 to 361).

In this embodiment, the setting value for toner near-end determination is 2.0■, and when Vsp is 2.0■ or more (the density of the developed pattern image is below the image density corresponding to Vsp = 2.OV), ), [Toner replenishment process J (TS
E) is executed, and when toner is replenished and Vsp becomes less than 2.0■ after executing this "toner replenishment process" (TSE), "post-replenishment process J (TSS) is executed. These subroutines (TSE) are executed. SE.

The contents of TSS) will be described later with reference to FIGS. 3g and 3h.

FIG. 3e shows the contents of "toner density control J (TDC2)." Proceeding to this, the microprocessor 210
Detection voltage of F sensor 15F (toner concentration in developing device 11)
is digitally converted and read (41), and it is checked whether the read toner density is greater than or equal to the value Ds of the toner density reference register Ds (42). Then, the next process is performed.

Note that this "toner density control J (TDC2)" is 1
Particular attention should be paid to the fact that this is executed every recording operation (recording one sheet of 12 days).

(1) The read toner density is the toner density reference register D
When s is equal to or greater than the value Ds, the toner concentration is sufficient, so there is no need to supply toner, and the electromagnetic clutch 17MD is turned off (the replenishment roller F is stopped) and the register F tof is cleared (44). That is, if the detected toner concentration is equal to or higher than the reference value Ds, toner is not replenished.

(2-1) This "
When the toner concentration control J (TDC2) is entered, the electromagnetic clutch 17MD is off, so first the timer Ss
Start (41-42-45-46-47). The timer Ss performs a time-limited operation for Ss seconds and times out after Ss seconds have elapsed. This Ss is the content of the aforementioned register Ss (see Figure 3d). Then, the electromagnetic clutch 17MD is turned on (the replenishment roller 17 is rotationally driven) (48). As a result, toner supply from the hopper 16 to the developing section is started. The process then returns to the main routine (proceeding to subroutine 12 in Figure 3a).

(2-2) With the settings in (2-1) above, proceed to "Toner density control J (TDC2)", and if the detected toner density is equal to or higher than the reference value Ds, the process in (1) above will be performed, but the same as before. <If less than Ds, check whether timer Ss has timed out (41-42-115=49
), if the time has not exceeded, the process returns to the main routine, but if the time has exceeded, the electromagnetic clutch 17MD is turned off (supply roller 17 stopped = 1 hener supply stopped) and the process returns to the main routine (5
0), and starts a timer Tof (51). Note that the timer Tof times out after a time limit of Tof seconds, and Tof=10-Ss seconds, where Ss is the content of the register Ss (FIG. 3d). and register F
1 to tof (10 second cycle, electromagnetic clutch 17MD
(indicating that the on/off control is in the off period) is written (52) and the process returns to the main routine.

Note that the toner concentration detected by the sensor 15F is the reference value Ds.
During the period below, the electromagnetic clutch 17MD is turned on for Ss seconds, turned off for the next 10-Ss seconds, and is alternately turned on and turned on with a cycle of 10 seconds. The on-duty of this is S s/10 x 100%, and as shown in FIG. 3d, the toner image density of the image density detection pattern detected by the P sensor 18P is low (detection voltage V
Since the higher sp is set, Ss is set to a larger value, so the on-duty, that is, the constant (1
The duty of the "rotation" (supply) period of the alternating cycle (0 seconds) is high, that is, the toner replenishment speed is high (the amount of toner replenishment per unit time is large).

(2-3) With the settings in (2-2) above, proceed to "Toner concentration control J (TDC2)", and if the detected toner density is equal to or higher than the reference value Ds, the process in (1) above will be performed, but the same as before. If <Ds, the electromagnetic clutch 17MD is turned off, so check whether the timer Tof has timed out (41-4245-46-53
). If the time has not elapsed, the program returns to the main routine, but if the time has elapsed, the register Ftof is cleared and its contents are set to 054).
Start the timer Ss (47), and start the electromagnetic clutch 17.
Turn on the MD (rotate the replenishment roller 17) (48)
.

By repeatedly executing "toner concentration control J (22)" explained above, the toner concentration (toner concentration of developer) detected by the toner concentration sensor 15F is changed to "determination of toner concentration reference value Ds & supply speed Ss" ( While the toner concentration is lower than the toner concentration reference value Ds set by the TDCI), the toner replenishing roller 17 is driven to rotate intermittently with a period of 10 seconds and an on (rotation) duty of S s/10 x 100%. S
s is the value set in "Determination J of supply speed Ss (35), and the value becomes larger as the toner image density of the image density detection pattern detected by the P sensor 18P is lower (the detection voltage Vsp is higher). Therefore, the toner supply rate (toner supply amount per unit time) is high (large).

Next, with reference to FIG. 3g, the contents of the subroutine "toner replenishment process J (TSE)" shown in FIG. 3d will be explained.
(below the Ov compatible setting value) for the first time, the third
After step 61 in figure g, Vsp-2,0 (deviation of the density of the developed pattern image detected this time from the set value) is calculated and written to the accumulation register TDA (62). Then, write 1 to register M for counting the number of sheets recorded after reaching the toner near end (63), and write 1 (the density of the developed pattern image is below the set value) to register Ftne. (64), next step (
Proceed to subroutine 36) of FIG. 3b.

Also in the density detection of the next developed pattern image, Vsp≧2.
When it is 0v, F jne is 1, so V
sp≧2. Ov, and the toner near end is displayed (65). It should be noted that when detecting the density of the next developed pattern image, V3P<2. If it is OV, the process proceeds from step 351 to "post-replenishment processing JTSS, where F tne is cleared, so when Vsp ≥ 2. Ov, since F t and ne are 0, Vsp ≧2
．． In Ov, the process proceeds to steps 61-62-63-64.

Therefore, Vsp≧2. Toner near end is displayed when Ov.

When the toner near end is displayed (65), Vsp-2,
0 is calculated, it is added to the contents of the accumulation register TDA, and the sum (accumulation value) obtained by the addition is updated and written to the accumulation register TDA (66). and set the contents of register M to 1
Increment (67).

Next, the content TDA of the accumulation register TDA is checked (68 to 71), and if TDA is 4.0 or more, the content Ss of the register Ss (at this point, 6 is written in step 356). is updated to 10, and if TDA is less than 4.0 and 3.0 or more, SS is updated to 9 and TDA is 3.0.
If it is less than 2.0, Ss is updated to 8 and TDA is 2.
．． If it is less than 0 and 1.0 or more, update Ss to 7 and TDA
is less than 1.0, Ss remains 6 (72 to 7
5).

Next, it is checked whether the contents N of the register N in which the number of sheets to be recorded since the recording start instruction is written is 0 (continuous recording of the specified number of sheets has been completed) (76). When N=O (continuous recording of the specified number of sheets has not been completed), check whether the contents M of register M (the number of sheets recorded after detecting the toner near end) is 50 or more (
77). Then, if N=O or M is 50 or more, the toner end is displayed (7g-79), the electromagnetic clutch 17MD is turned off, and the toner replenishing roller 17 is turned off.
81), the recording apparatus is stopped, and a toner cartridge (not shown, but a cartridge attached to the toner hopper 16 to replenish the hopper 16 with toner) is replaced (81). The case cover for inserting and removing the toner cartridge is equipped with an open/close detection switch, and when the microprocessor 210 detects that this switch has been opened and then closed, it determines that the cartridge has been replaced. Then, the register M is cleared (83), and the toner near end display and toner end display are cleared (84).

At this point, even if the toner cartridge is replaced,
The toner density in the developing section of the developing device 11 is Vsp≧2. O
Vsp≧2.
Ov may last for a while. In this case, F tne
has not been cleared and its content is 1, so when it advances to the toner replenishment process J (TSE), steps 61-65-66-67-68 to 75 are executed.Register TDA has not been cleared. Therefore, even though the toner cartridge is replaced, the accumulation is performed (66), and the accumulated deviation value at this time t after VSP≧2.0■ before the toner cartridge replacement is stored in the register TD.
A is held in V4, and Ss corresponds to its content TDA.
1P<2. It is set to a larger value than when OV, 10
Second period, during SS seconds, electromagnetic clutch 17MD is on, 1
During 08s, the electromagnetic clutch 17MD is turned off and the clutch on/off duty control (Fig. 3e) is executed, so when the TDA is large (the amount of toner consumed from the time the toner near end is reached until the cartridge is replaced is large) Toner is supplied to the developing section by the replenishment roller 17 at high speed when the TDA is small (when the amount of toner consumed from the time when the toner reaches the near-end until the cartridge is replaced) is low.

Such toner supply increases the density of the developed pattern image, and V5P<2. When OV is reached, "post-replenishment process J (TSS: Fig. 3d) is executed.

The contents of this "post-replenishment process J (TSS)" will be explained with reference to FIG. 3h.
10 clears the register TDA (85), clears the register M (86), clears the register Ftne (87), and clears the toner near end display and toner end display (88). It also erases data indicating that the cartridge was replaced. That is, when the toner near end is detected, the data for toner replenishment processing set in the register is erased, and the toner shortage display is erased.

When the detected density voltage Vsρ of the developed pattern image becomes 2.0■ or more (pattern density is below the set value) by the toner replenishment process J (TSE) explained above, toner near end is displayed and the amount of density shortage (deviation ) is started, and if the accumulated value is large, the replenishment speed of the replenishment roller 17 (the duty of "rotation" in repetition of rotation and stop for 1 period of 10 seconds) is set high. When toner remains in the toner hopper 16, the toner is supplied to the developing section of the developing device 11 at high speed. However, if the remaining amount is small or disappears, the density of the developed pattern image will not increase even if the replenishment speed of the replenishment roller 17 increases, and the cumulative value TDA of the register TDA will gradually increase. The recording density continues to decrease.

When recording of the specified number of sheets is completed in this state, or before that, Vsp≧2. The number of records since becoming Ov is 50.
When this happens, the recording device is stopped and toner end is displayed. When the operator replaces the cartridges 1 to 1, the device stops (81) and the toner concentration control J (TD
The process proceeds to step C) (that is, the device stoppage is released), where a toner replenishment operation is started at a speed (duty) corresponding to the accumulated value of TDA, and then "recording operation J (12) is performed. Development pattern image When the concentration of exceeds the set value (
That is, Vsp<2. OVl:), TDA is cleared and toner replenishment operation is performed at the speed (duty) set in steps 351 to 361 shown in FIG. 3d.

During these toner replenishment operations, when the toner concentration of the developer in the developing section of the developing device 11 (the toner concentration detected by the sensor 15F) becomes equal to or higher than the reference value Ds, toner replenishment is stopped (
4l-42-43-44 in Figure 3e).

Thereafter, when the toner concentration becomes less than the reference value Ds, the third d
S set in "Determination of supply speed Ss (35)" shown in the figure
Toner replenishment (45 to 52 in FIG. 3e) is performed by the roller 17 at a speed (duty) based on s.

In the embodiment described above, the surface potential before pattern exposure for forming a visible pattern is specified by the instruction switch 30, and the grid voltage of the main charger 8 is adjusted to reach the surface potential. However, the main charger voltage may be adjusted. Alternatively, the exposure light amount may be adjusted by specifying the exposure light amount with the instruction switch 30, or the developing bias may be adjusted by specifying the developing bias with the switch 30. In any case, since the recording density range can be adjusted and set using the switch 3o, in this embodiment, the recording density can be changed without changing the hardware and process conditions of the recording element or unit. This allows the operator or service person to obtain a recording with a density higher or lower than the standard density range using the instruction means, and the versatility of the recording device is increased.

In the embodiment described above, as described above, the P sensor 18
1 to 1 image density of the image density detection pattern detected with P (
Although the reference density Ds is set based on the correlation between the density (Vsp) and the density (Vsg) of the white (no toner image) area, the reference density Ds may be set to a fixed value in the device, or may be set using a switch 30 or the like. A fixed value may be selected and set using . Furthermore, the detection of the toner concentration in the developer is omitted, and the replenishment roller 17 is not driven to rotate, for example, when Vsp is less than 1 V (on duty = 0%) based only on the toner image concentration detected by the P sensor 18P. , 1v or more, the above-described duty drive may be performed automatically. Further, although the toner supply speed is controlled by the rotation/stop duty of the roller 17, other means for variable control of the toner supply amount per unit time or per rotation of the replenishment roller may also be used. good. In any case, toner is supplied at high speed during recording operations that consume a large amount of toner, and toner is supplied at a low speed during recording operations that consume little toner, so that the delay in toner supply is short and the toner consumption speed is reduced. The appropriate amount of toner is supplied in a timely manner, which prevents problems such as insufficient recording density or excess toner.
Record density fluctuations are reduced.

In addition, in the above embodiment, when the recording size is large, the number (
ns) is set to a large number (ns) when the recording size is small, and a developed pattern image is formed every time the number of recording sheets (n) reaches the set number (ns).

The pattern density sensor 18P detects the recorded density of the developed pattern image, and the microprocessor 210
Corresponding to the density detected by the pattern density sensor 18P, if the detected density is low, the toner supply roller 17 supplies toner.

Therefore, when large-size recording (for example, ACT size) is performed, the density of the development pattern is detected every small number of sheets (2), and toner is quickly replenished in response to the high-speed toner consumption of the developing device 11, resulting in stable Record density is provided. During small size recording (for example, A4Y), development pattern density detection is performed for every number of sheets (7), so toner consumption for development pattern density detection is reduced.

〔Effect of the invention〕

As described above, according to the toner density control device of the present invention, the accumulating means compares the recorded density of the developed pattern image detected by the pattern density sensor with the set value, and when the recorded density is lower than the set value, the difference between the two Accumulate and memorize. therefore,
When the amount of toner remaining in the developing section immediately before toner replenishment is small, the accumulated value of the accumulating means is large, and when the amount of remaining toner in the developing section is large, the accumulated value of the accumulating section is small.

Accordingly, the toner supply control means supplies a large amount of toner when the accumulated value of the accumulating means is large, and a small amount of toner when it is small.

When toner replenishment is performed, the toner supply control means supplies a large amount of toner when the amount of toner remaining in the developing section immediately before toner replenishment is small, and the toner supply control means supplies a large amount of toner when the amount of toner remaining in the developing section immediately before toner replenishment is large. will supply a small amount of toner.

Therefore, when the remaining amount of toner in the developing section is small just before toner replenishment, the toner supply control means supplies a large amount of toner when toner is replenished, so that the toner concentration in the developing section increases quickly. Therefore, the low density recording period immediately after toner replenishment and the period in which the recording density gradually increases (varies) are shortened. That is, variations in recording density and low-density recording immediately after toner replenishment as described above are reduced.

[Brief explanation of drawings]

FIG. 1 is a side view showing the main mechanism of a recording apparatus equipped with an embodiment of the present invention. FIG. 2 is a block diagram showing a general configuration of an electric circuit incorporated in the recording apparatus shown in FIG. 1. Figure 3a, Figure 3b, Figure 3c, Figure 3d, Figure 3e,
3f, 3g, and 3h are flowcharts showing the control operation of the microprocessor 210 shown in FIG. 2. FIG. 1: Laser exposure device 5a: Developing bias electrode 7: Photoconductor 8: Main charger 8G negative electrode 10: Erase lamp 11: Developing device (developing device) (1 to 11: Developing pattern forming means) 12: Developing roller
13: Agitator 15F = Toner concentration sensor
16: Toner hopper 17: Replenishment roller (toner supply means) 17MD: Electromagnetic clutch 18P: P sensor (pattern density sensor) RP1 to RP
, : Recording paper 24 Ni registration roller 25
: Transfer/separation charger 26: Heat roller 28:
Cleaning unit 30: Instruction switch 420
p: surface electrometer

Claims (1)

[Scope of Claims] Development pattern forming means for forming a development pattern image for recording density detection; pattern density sensor for detecting the recording density of the development pattern image; toner supply means for supplying toner to a developing device; said pattern density an accumulating unit that compares the recorded density of the developed pattern image detected by the sensor with a set value and, when the recorded density is lower than the set value, cumulatively stores the deviation between the two; a toner supply control means for supplying toner by the toner supplying means, and supplying a large amount of toner when the value is large and a small amount of toner when it is small, in accordance with the accumulated value stored in the accumulating means; Control device.