JPS61182059A - Picture formation device - Google Patents

Abstract

PURPOSE:To adjust picture density easily by forming a picture formation condition control means for setting the changing width of a picture formation condition to a small value near reference picture density and setting the changing width to a large value except the neighborhood of the reference picture density. CONSTITUTION:The picture formation condition control means 10 consists of an operation part 11, a DC controller 12 and a lamp regulator 13. When a digital density adjusting key 14 on an operation part 11 is set up to a required density value and a copying start button is depressed, a lamp regulator driving signal outputted from the DC controller 12 is turned to '0' and the output of a lamp regulator switch circuit 20 is turned to '1', so that 24V power source is supplied to a phase control circuit 22, an arc circuit 23 is driven, a halogen lamp 1 is turned on to stop the copying. The light of the halogen lamp 1 is increased/decreased by controlling an original lamp feeding voltage through a differential amplifier circuit 19, a phase control circuit 22 and an arc circuit 23 in accordance with the value of an original lamp dimming signal sent from the DC controller 12.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image forming apparatus that adjusts image density discontinuously.

(Prior Art) Conventionally, this type of image forming apparatus, such as an electrophotographic copying machine, has been designed to adapt to the changes in image forming conditions or when a special original such as a color original is received to obtain an appropriate image. In addition, a so-called desotal image density setting device is used, which adjusts one or more of the density determining factors of the image to be formed, such as exposure amount, charge amount, or developing bias, discontinuously to several levels by operating a push button or the like. We are prepared. However, in such an image forming apparatus, the condition of reproducing the image density of a copy above a certain level and not overlapping the background must be satisfied by discontinuously adjusting the image forming conditions, so density adjustment is required. The pitans were set in sufficient detail, and there were as many as 17 pieces. In other words, the density change range for density adjustment is #! based on Shibetanno II-F5. The density value at which the degree becomes maximum 24 is Fl, and the density value at which it becomes maximum light is F.
9, the range of change in image forming conditions during that period is kept constant;
F1→F1.5→F2...F4.5→F5→F5.5
...There were 17 levels from F9.5 to F10.

(Problem to be Solved by the Invention) However, in the case of such conventional technology, when a proper image cannot be obtained with the standard density value, the user can change
F6→F6.5→...F9 or F5→F4.5→F4
→...The problem is that the button has to be operated one step at a time in the direction of making the image lighter or darker, such as Fl, until the appropriate image is obtained, making the image density adjustment operation very complicated. was there.

The present invention has been made to solve the problems of the prior art, and its purpose is to maintain the standard image even under special conditions such as fluctuations in image forming conditions and color originals. It is an object of the present invention to provide an image forming apparatus that allows easy adjustment of the image T1kIf, focusing on the fact that an appropriate image can be obtained with density values around the density value.

(Means for Solving the Problems) Therefore, in order to achieve the above object, the present invention sets the image forming conditions discontinuously by an image forming condition control means, and adjusts the image density in stages. The image forming apparatus is provided with an image forming condition control means that sets a small variation width of the image forming condition near the standard image density, and sets a large variation range of the image forming condition other than the vicinity of the standard image density. It is configured as follows.

(Example) An example of an image forming apparatus according to the present invention will be described below based on the drawings.

FIG. 3 schematically shows an electrophotographic copying apparatus to which the present invention is applied, and the configuration thereof will be explained below.
2 is a halogen lamp as an example of a document lamp for illuminating the document 1, and 3 is an imaging optical system.

Reference numeral 4 denotes a photosensitive drum, which is supported rotatably in the direction of the arrow in FIG. 8 are arranged. Additionally, a light source for pre-exposure, a light source for non-image area exposure, a fixing device, etc. are arranged around the photosensitive drum 4, but these are omitted for the sake of explanation. In the figure, 9 is a transfer material.

Reference numeral 10 designates an image forming condition control means for controlling image forming conditions by controlling the light intensity of a document illumination lamp.
1, DC controller 12, and lamp regulator 1
3. It has a 3-pointed shape.

The above operation ":jS 11 includes a plurality of digital density adjustment keys 14, and image forming conditions are set by operating the digital density adjustment keys 14.

The % key 14 is connected to the microcomputer 15 of the DC controller 12.
Original lamp dimming signal (LINT) corresponding to key 14
) is output to the rande regulator 13 via the D/A converter 16, and is also output to the operational amplifier 1 during copy operation.
A lamp regulator operation signal (■, RD) is outputted via 8.

The original 1 lamp dimming signal (LINT) is input to the differential amplifier circuit 19 of the lamp regulator 13, and the lamp regulator operating signal (LRD) is input to the lamp regulator switch circuit 20. The differential amplifier circuit 19 amplifies the voltage difference between the constant voltage signal output from the power supply voltage fluctuation detection circuit 21 and the document lamp dimming signal (LINT), and controls the phase control circuit 22 and the triac according to the voltage difference. The original lamp supply voltage supplied to the original lamp 2 is adjusted by controlling the ignition circuit 23 using the above. The lamp regulator switch circuit 20 receives a rande regulator activation signal (L
RD) turns on/off the supply of 24V power to the phase control circuit 22. 24 is the temperature fuse, 25 is 11
00VAC source is shown respectively.

The density value set by the digital density adjustment key 14 is based on the standard meter F5, and the density value at which the sense of smell becomes the strongest is FO1, and the density value at which the sense of smell becomes the lightest is FIO.
O-+F1...F4→F5→...F9→FIO 1
There is one stage. The light intensity ratio of FIO and F5 is F
When you set the density to IO, FI will make the newspaper jump.
O/F5 is set at 1.7. In addition, the light intensity ratio of FO and F5 is set so that when the density is set in FO, the reproducibility of an original with reflection@H0,2 is equal to or higher than that of an original with a reflection density of 0.3 at F5. It is set to 0.79 in F5.

When a halogen lamp 2 with a rating of 80V and 200W is used as a document illumination lamp, the supply voltage of the halogen lamp 2 is 65V at standard i degree F5, and the above FO/F
In order to satisfy the light intensity ratio of 5/FIO, FO is 6v lower than F5, and FIO has a 11v supply voltage higher.

In the present invention, the original lamp supply voltage is set as shown in FIG. 2 for the density values FO to FIO. That is, standard M! The original lamp supply voltage is set to have a small variation range near the dark value F5, and a large variation range in other areas. The original lamp dimming signal (L
As shown in the figure, the voltage of F6. F7 or F4. F3 and concentration: A
When the PrrJ key 14 is operated, the range of change in image density is small, but Fl is reached near the density value FO or F'lO.

F2 or F9. When F8 and the density adjustment key 14 are operated, the range of change in image density is large.

In the above configuration, the image forming apparatus of the present invention copies a document as follows. First, when the digital density adjustment key 14 of the operation unit 11 is set to a desired density value and the copy start button is operated, the DC controller 12
Landreilator activation signal (LRD) output from
becomes O, and the output of the lamp reilulator switch circuit 20 becomes 11", so that the 24V power supply is connected to the phase control circuit 2.
2, the ignition circuit 23 is activated, the halogen lamp 2 is turned on, and copying is performed. halogen lamp 2
The amount of light can be increased or decreased using the set desotal density adjustment key 14.
The original lamp supply voltage is controlled by the differential amplifier circuit 19, the phase control circuit 22, and the ignition circuit 23 according to the value of the original lamp dimming signal (LINT) sent from the DC controller 12 in response to the This is done by This original lamp supply voltage is controlled as shown in FIG. 2 by an original lamp dimming signal (LINT) corresponding to the setting of the digital density adjustment key 14.

If you cannot obtain an appropriate image with no capri and good contrast using the standard density value F5, change the density value to F4. You will need to operate F3, F6, F7 and the digital density adjustment key 14, but even in the case of fluctuations in image forming conditions or special conditions such as colored originals, the density around the standard @dark value F5 is usually used. An appropriate image can be obtained by changing the value. If a proper image is still not obtained, change the darkness value to F2. Fl, FO or F
8°F9. It will be operated with FIO.

FIG. 4 shows another embodiment of the image forming condition control means in the image forming apparatus according to the present invention. In this embodiment, the image density is adjusted by changing the DC component of the developing bias. It is supposed to be done. The image forming condition control means 10 includes an operation section 11, a DC controller 12, and a high voltage transformer 27. The DC controller 27 has a D corresponding to the desotal concentration adjustment key 14.
In addition to outputting the C bias control signal (DCBC), the AC bias timing 9 pulses (ACB
TP) is output. Since the AC bias timing pulse (ACBTP) of the high voltage transformer 27 is -o'o and the AC bias switch circuit 28 is turned off, the AC bias timing pulse (ACBTP) is turned off.
The output of the 00H industrial oscillation circuit 29 is amplified by a current amplifier circuit 30, and further boosted (1300Vpp) by an AC lance 31.
) and then supplied to the developing cylinder 32 of the developing device 6. The high voltage transformer 27 also supplies a DC bias control signal (DCBC) to the AC lance 31 as a DC bias via a DC-DC inverter transformer 34 to which a DC bias differential amplifier circuit 33 and an oscillation circuit 35 are connected. , the image density is adjusted by controlling the voltage supplied to the developing cylinder 32. The DC bias control signal (D
CBC), the DC supply voltage supplied to the developing cylinder 32 is controlled as shown in FIG. Even in this embodiment, the DC supply voltage is set to have a small variation range near the W single density value F5, and a large variation range in other areas.

The rest of the structure and operation are the same as those of the embodiment shown in FIG. 3, so their explanation will be omitted.

In the illustrated embodiment, the image forming conditions are adjusted by controlling the original lamp supply voltage or the developing bias voltage, but it is of course possible to control the electric potential of the photosensitive drum.

(Effects of the Invention) The present invention has the above-described configuration and operation, and the range of change in the image forming conditions is set small near the standard image density, and set large in other areas, so that the image forming conditions can be selected. The number of density adjustment keys can be significantly reduced, and image density adjustment operations can be performed easily. Furthermore, even in the case of variations in image forming conditions or for colored originals, it is possible to make do with adjusting the image forming conditions to near the standard image density, so it is not impossible to obtain an appropriate image.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the image forming condition control means of the image forming apparatus according to the present invention, and FIG. 2 shows the relationship between the lamp dimming signal and the document lamp supply voltage in the image forming condition control means. 3 is a schematic diagram showing an electrophotographic copying apparatus to which the present invention is applied, FIG. 4 is a graph showing another embodiment of the image forming condition control means, and FIG. 7 is a graph showing the relationship between a DC bias control signal and a developing sleeve supply DC voltage. Explanation of symbols 10... Image forming condition control means Patent applicant Canon Co., Ltd. Figure 2 Ichino firing device Figure 3!

Claims (1)

[Claims] In an image forming apparatus in which image forming conditions are set discontinuously by an image forming condition control means and image density is adjusted stepwise, the range of change in image forming conditions near the standard image density is 1. An image forming apparatus comprising an image forming condition control means that sets a small image forming condition, and sets a large variation range of image forming conditions except near a standard image density.