JPH03149574A - Image forming device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image forming apparatus having a two-component development system consisting of toner and carrier.

[Conventional technology]

In such an image forming apparatus, the method of controlling toner density is to optically expose a reference density original, make it visible in a developing section, detect the density with a reflective sensor, and control toner density based on the result. (Japanese Unexamined Patent Publication No. 128977), and a similar method is known in which a plurality of detection pattern sizes are provided and one of these patterns is selected according to specific conditions. (Japanese Unexamined Patent Publication No. 121073/1983).

Furthermore, there is also a known developer deterioration detection method that compares the density of a reference density original with the density on the photoreceptor and determines that the developer has deteriorated if the density on the photoreceptor becomes lower than a predetermined level.
JP-A-59-184374), and a method of detecting the density of a reference density original along with the copying operation and varying the developing bias in order to vary the image density of the copy based on the pattern density detection result (JP-A-59-184374). Law No. 33661) is also known.

[Problem to be solved by the invention]

In the above conventional technology, when an image forming apparatus is delivered to a user and started up, a developer is used as a starting agent, and this developer is supplied at a predetermined mixing ratio of toner and carrier (for example, carrier 98%, 2°). After setting the developer as a starting agent in the development unit, the carrier in the developer is charged and the toner concentration in the developer is normally controlled (the developer is stirred and the toner concentration is detected to determine the control level). , Detection of toner concentration at startup is important as data that determines the control level to obtain stable copied images thereafter.Even if the developer has the same toner concentration, the detection level differs depending on the image forming apparatus.Also, If the toner concentration detection data is different from the developer (starter) at startup and this data is used as toner concentration control data, this is due to the fact that as the developer gets older, its developer resistance increases. Therefore, there was a problem that the image density determined as the original design value could not be obtained.

An object of the present invention is to provide a stable system by warning that when the resistance of the developer exceeds a predetermined value, it is necessary to stop the matching detection mode with the starting agent and set a new developer. An object of the present invention is to provide an image forming apparatus capable of obtaining a copy image density.

[Means to solve the problem]

According to the present invention, the above object is achieved by setting a developer made of toner and carrier manufactured at a predetermined mixing ratio in a developing device as a starter, and performing charging, exposure, and development at a predetermined reference pattern density; The density level of the reference pattern density formed on the photoconductor is detected by a photoreflection type density sensor, and the detected output value vsp and the output value of the photoreflection type density detection sensor on the surface of the photoconductor on which no pattern is formed are detected. V, and determines a developing bias value for controlling the toner concentration in the developer from the comparison result. A measuring means for measuring the resistance value of the developer before or after the creation timing, and a means for canceling the matching detection mode with the start agent when the resistance value is equal to or higher than a predetermined level. achieved by

[Effect]

The image forming apparatus operates to measure the resistance value of the developer before or after the reference pattern creation timing, and when the measured resistance value is equal to or higher than a predetermined level, the matching detection mode with the start agent is canceled. It works like that.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus embodying the present invention, and FIG. 2 is a block diagram showing the circuit configuration of the image forming apparatus according to the present invention. In FIG. 1, 1 is a pressure plate, 2 is an original, 3 is a contact glass, 4 is an exposure lamp, 5 is a cleaning device, 6 is a first mirror, 7 is a second mirror, 8 is a third mirror, 9 is a lens, 10 is a fourth mirror, 11 is a fifth mirror, 12 is a sixth mirror, 13 is a static elimination lamp, 14
is a charger, 15 is a light reflection type pattern density detection sensor,
16 is a photoreceptor, 17 is a developing unit, 18 is a toner hopper, 19 is a toner supply roller, 20 is a paper feed roller, 21
2 is a registration roller, 22 is a transfer charger, 23 is a separation charge t, 24 is a conveyor belt, 25 is a fixing unit,
26 is a paper discharge tray, 27 is a paper feed force set, 28 is a document abutment scale, and 29 is a main drive motor.

In FIG. 2, 30 is a developer resistance value detection section of the developing unit 17, 31 is a sensor section, and 32 is a resistance (R)/voltage (
V) Conversion unit, 33 is a gate array, 34 is an operation unit, 35
is a developer initial setting switch, 36 is a power supply, 37 is a timing pulse generator, and 38 is a central processing unit (CPU).
, 39 is a drive circuit, 40 is a RAM, 41 is an LED display section for indicating replacement with a new developer, 42 is a load section, and 43 is a developing bias.

FIG. 3 is a flowchart showing the operation of the image forming apparatus according to the present invention. In FIG. 3, CP is the copying operation count of the machine, DATAP is the data vs.
ATAG is data V s s (7) / MoJ, TO
N is rOJ to turn off toner replenishment, "1" toner replenishment on, T is the standard for whether or not to replenish toner L/ < JL/
, M indicates a memory that determines the output of the developing bias.

The flowchart in FIG. 3 will be explained. Operation unit 36
The print start key is turned on (S1), and it is determined whether the developer initial setting switch 35 is on (S2).

This determines the pattern density development bias for correctly controlling toner replenishment in the subsequent normal copying mode. If the developer initial setting switch 35 is off, when the copy count CP of the machine reaches 10 sheets in S3, the cp is cleared (S-4) t, and then the determination routine for toner supply on/off is executed. to go into. Charger 1 in S5
4 and the exposure lamp 4 are turned on, and the developing bias 43 is turned on with the condition output stored in the memory M in the RAM 40 (the value of the memory M8 set in the developer initial setting). A reference pattern provided on the back surface of the document abutting portion scale 28 in FIG. 1 is exposed, projected onto the photoreceptor 16, and then visualized by the developing unit 1-17. The visualized pattern density is detected by the pattern density detection sensor 15 as a density (VS-
Detect. Thereafter, the density of the background portion of the photoconductor 16, that is, the density (Vs
G) and S6), these ratios are 4 V sr/
V sa is input to the memory TsDATA in the RAM 40 (S7).

FIG. 4 is a schematic diagram showing a photoreceptor and a pattern density detection sensor, and FIG. 5 is a schematic diagram showing a developing unit and a photoreceptor.
45 is a developing sleeve, and 45 is a developer resistance measurement (detection) section 30.
These are the electrodes that make up the.

Returning to FIG. 3 again, in S8, TS DATA
If the value is greater than the predetermined ratio T3, it is determined that the toner density is high, and the memory TO in the RAM 40 is stored in step 516.
"0" is input to N, and in the opposite case, it is determined that the toner density is low, and rlJ is input to TON in S9. TON=rl
J (S17), the timer is set to T, (se
e) Set the time, replenish the toner, and after T2 has elapsed (Sll
), ) Toner replenishment is turned off (S12) and the routine shifts to the normal copying subroutine (Sl-3). Since the copy subroutine is well known, a description thereof will be omitted. In S14, set the copy counter to “
+1'' and it is determined in the next step 315 whether or not copying is complete. In the case of continuing copying, the determination of CP≧10 is made again (S
4) is performed, but at this time, since CP=1 (because CP has been cleared once), the routine shifts to the normal copying routine. At this time, if TON=l (S17), toner replenishment is performed for Tl (seC). In this way, the judgment of "dark" or "light" obtained in the toner density detection mode is determined by copy 1.
It is maintained for 0 times, and the determination is made again every 10 times.

When the developer initial setting switch is turned on in S2, RAM4
Set the value of memory M in 0 to 260 (318)
This turns on the developing bias 43 and turns on the exposure lamp 4.
, the charger 14 and the main drive motor 29 are turned on (S
19) Next, the resistance value R, of the developer is measured in S20, and if the value is greater than lOISΩ-cm, S
At step 21, a new developer replacement display is displayed on the LED display section 41, and at step S22, the main drive motor 29, exposure lamp 4,
The developing bias 43 and charger 14 are turned off.

FIG. 6 is an explanatory diagram showing the output of the pattern density detection sensor;
FIG. 7 is an explanatory diagram illustrating the relationship between the vsp value and the developing bias value, and FIG. 8 is an explanatory diagram illustrating the relationship between the number of copies and resistance.

Again, in FIG. 3, the resistance value R0 is 10ss at 520.
If less than Ω-cm, the detected pattern density value vs.
For example, if V in S23 and P≧0.7, r220J is applied to M8 in S24, and 325 TeVsp is determined by p.
;: If there is 0.5 Te, r260J to Mm with S26
Then, in S27, if i V 3F ≧0.3, r300J is input into M in S28. If VSP is less than 0.3 in S27, a new developer replacement indication is displayed on the LED display section 41 in S29, and the main drive motor 29, exposure lamp 4, developing bias 43, and charger 14 are turned off in S330. .

The resistance value R0 of the developer gradually increases from the initial state of the developer, and the toner is crushed and adheres to the carrier constituting the developer, reducing electrostatic adhesion and peeling. In other words, when the developer approaches its characteristic lifespan, the resistance value of the developer becomes larger than the initial value (see Figure 8). In Figure 8, the developer resistance R0 is 10' at the initial value.
The value over time is 10ISΩ-cm or more in ''Ω-cm.-
The developer resistance value R0 between the electrodes 45 provided in the developing unit 17 is measured, and if it is greater than or equal to IQIS Ω-cm, the message ``Despite the developer initial setting, the aged developer is not used again.'' ” and displays a new developer replacement message.

Next, the development bias determined by the developer initial setting will be explained. When a new developer is shipped from the factory, the ratio of carrier to toner is, for example, 98=2, and if the developer is set in the image forming apparatus and the toner density is controlled at the above value when copying. However, in reality, it is rarely controlled at the above value due to the characteristics of the developing unit F or mechanical variations in the gap between the developing unit 17 and the photoreceptor 16. Therefore, in order to perform stable toner concentration control, Perform developer initial settings.

The output value V5F that detects the pattern density using new developer is 0.5 to 0.7 (V) 17) When the density is 2
It is configured to be controlled by %. Therefore, if this negative vsp value is lower than 0.5 (V), a large amount of toner adheres to the photoreceptor 16. In other words, (
3) has a large developing ability and a VjP value of 0.7.
If it is higher than (V), less toner is attached. That is, the developing ability shown in (1) of FIG. 6 is small.

Note that (2) in FIG. 6 shows an intermediate developing ability, and as shown in (1) in FIG. 6, when the amount of toner adhering to the pattern is small, the vP value becomes high.

If the toner is controlled during normal copying when the developing capacity is high, even if the toner is thin, the VSP value will be high (thus, the toner density will decrease and the resulting image will become thinner. Conversely, when the developing capacity is low, the vsp value is difficult to lower even if the toner is dark, so the toner density increases and the resulting image becomes too dark.To prevent this, the vsr value is set in the default mode. to be detected.

As shown in Figure 6, ■3. When the value is low, that is, when the developing ability is high, the difference ΔV between the developing bias 43 and the surface potential on the photoreceptor 16 is made small, and the amount of toner adhering to the photoreceptor 16 is reduced. Furthermore, when the vsP value is high, the machine variation is corrected by increasing the ΔV and increasing the amount of toner adhering to the photoreceptor 16. [Effect of the Invention] As explained above, according to the present invention, the variation in the machine is corrected. For example, measure the resistance value of the developer before or after the reference pattern creation timing,
If the level exceeds a predetermined level, the matching detection mode with the developer used as a starting agent is canceled and canceled, so in order to stably control the toner concentration, it is possible to use a new developer or It is possible to provide an image forming apparatus capable of stabilizing an image by determining whether the developer is

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram illustrating the configuration of an image forming apparatus implementing the present invention, FIG. 2 is a block diagram showing the circuit configuration of the image forming apparatus according to the present invention, and FIG. 3 is a schematic diagram illustrating the circuit configuration of the image forming apparatus according to the present invention. Flowchart explaining the operation, FIG. 4 is a schematic diagram showing the photoconductor and pattern density detection sensor, FIG. 5 is a schematic diagram showing the developing unit and photoconductor, and FIG. 6 is an explanatory diagram showing the output of the pattern density detection sensor. , FIG. 7 is an explanatory diagram illustrating the relationship between the VSP value and the developing bias value, and FIG. 8 is an explanatory diagram illustrating the relationship between the number of copies and resistance. 4... Exposure lamp, 14... Charger, 16... Photoreceptor, 17... Development unit, 30-... Developer resistance detection section, 35... Developer initial setting switch, 43...・
-Developing bias, 45-...electrode. J'1i'1 etc.} ) 1 I 11 [but] Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] A developer made of toner and carrier manufactured at a predetermined mixing ratio is set in a developing device as a starter, and charged, exposed, and developed at a predetermined standard pattern density.
The density level of the reference pattern density formed on the photoreceptor is detected by a light reflection type density sensor, and this detected output value V_S_P is compared with the density level of the light reflection type density detection sensor on the surface of the photoreceptor on which no pattern is formed. In the image forming apparatus, the image forming apparatus detects and controls the matching property with the starting agent, which compares the output value V_S_G and determines a developing bias value for controlling the toner concentration in the developer from the comparison result. A measuring means for measuring the resistance value of the developer before or after the pattern creation timing, and a means for canceling the matching detection mode with the starting agent when the resistance value is equal to or higher than a predetermined level. An image forming apparatus characterized by: