JPS6080860A - 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 The present invention relates to an image forming apparatus, and particularly to an image forming apparatus that variably controls image forming conditions according to changes in projection magnification of an image on a microfilm or the like.

Conventionally, in this type of apparatus, in order to obtain images with appropriate image density, etc., only the exposure amount of the lamp for document illumination or the developing bias of the developing device was variably controlled. Na(′.

As a result, the following problems arise.

For example, when only the exposure amount is variably controlled in reversal development, the potential of the latent image corresponding to the non-image area is set to be slightly higher than the applied development bias potential to prevent blurring. The light amount has been corrected so that it is correct. However, when low-density film is used as an original, there is insufficient potential contrast between the image area and the non-image area, resulting in extremely low density in the image area, and conversely, when the density of the image area is increased, the non-image area This may cause fogging. In addition, when high-density film is used as an original, the amount of light may be insufficient and an appropriate image cannot be obtained, or images may not be properly controlled. .

Furthermore, even when only the developing bias is variably controlled,
It eliminates fog by adjusting the potential of the non-image area and changing the developing bias by "n", and it is possible to obtain a suitable IE image for standard original film, but the density is only 5 mm (. For films, the potential contrast varies greatly depending on the film density, making it impossible to obtain a proper image.

In other words, as mentioned above, controlling only one of the exposure amount or the developing bias cannot control the density of various films.
Therefore, the range in which an appropriate image can be obtained is narrow, making it impractical for originals with a wide range of densities.

Therefore, in order to obtain a proper image, it is desirable to variably control both the exposure amount and the developing bias based on the original density.

However, even when both the developing bias and the exposure amount are automatically controlled, there is no problem if the lens magnification for image projection is one type, but when there are many types of lens magnification, , since the brightness of the projected image differs depending on the difference in each lens, if you set the exposure amount and development bias based on the original density using only one lens as a reference, it is necessary to change it to a lens with a different magnification. If this happens, the above settings will be deviated, making it impossible to obtain a proper image.

In addition, the above-mentioned devices that automatically control the exposure amount and developing bias to obtain a proper image generally do not allow the operator of the device to easily obtain a suitable image without making any mistakes. However, it is not possible to satisfy the operator under all conditions.

Therefore, depending on the type of document, it is preferable to be able to variably control the image density according to the individual preferences of each operator.

The present invention has been made to solve the above-mentioned problems, and in addition to means for controlling image forming conditions such as exposure amount or developing bias by varying T according to the density of the original, the present invention further includes:
By providing a means to variably control at least one of the image forming conditions, such as exposure amount or developing bias, according to the magnification of the projection lens, it is possible to adjust the original density from low to high density even when the lens magnification changes. An object of the present invention is to provide an image forming apparatus capable of obtaining an optimal image.

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

FIG. 1 is a schematic diagram showing a microfilm copying apparatus using a reversal development method, which performs exposure using an optical scanning method, as a part/embodiment of the present invention.

Here, as the immediately known structure, a lamp 3 driven by a voltage source 2 is provided so as to illuminate the microfilm through a light lens q, and , an integrated mirror system B consisting of a projection lens 5a, mirrors 7 and g whose reflective surfaces are at right angles to each other, and a slit means for exposure/3, so as to image the light transmitted through the microfilm λ on the photosensitive drum/3. to be placed. Furthermore, the photosensitive drum/
- wide charger 15. AC or -
Wide charger/DC secondary static eliminator with opposite polarity/B, Lamp for full exposure/7. A developing device /g to which a developing bias is applied by a bias generation source 27, a charger /q for transferring a toner image onto a transfer paper 20, and a cleaner 2shio for cleaning residual toner on the photosensitive drum. Place them in order.

Note that the magnification changing means 30 operates so that the projection lens 5a can be replaced with another projection lens 5b having a different magnification. Further, the mirror system B is movable from the home position A to the exposure start position B.

Here, one feature of the present invention is that the detection element 2/ detects the density of the microfilm by receiving part of the light transmitted through the microfilm and guided to the photosensitive drum/. Arranged on the road of slit means/3,
Connected to this is an amplifier 22 for amplifying the detection signal of the detection element 2/, and further connected is a CPU 23 for processing the amplified signal according to a predetermined function.

Further, the output signal of the CPU 23 is guided to the voltage source 2B and the bias generation source 27, and the exposure amount of the lamp 3 and the
The developing bias of the developing device/g can be variably controlled based on the density of the microfilm λ. Furthermore, the bias generation source 27 is provided with a volume 2g so that the developing bias can be manually adjusted 7j.

Next, the operation of the copying apparatus configured as described above will be explained below.

, the photosensitive drum / is uniformly charged by -order charging 2: ÷ 75, then in secondary charge removal 21; / B, the primary charge is removed while projecting the image light of the micro film, and then・
It is uniformly exposed with lamp /7. As a result, an electrostatic latent image corresponding to the projected image pattern is formed on the photosensitive drum. Next, this image is visualized as a toner image by a developing device 7g, and the toner image is transferred onto a transfer paper 20 by a transfer charger /9. After that, a fixing device (not shown)
The toner image is fixed on the transfer paper 2θ and is discharged from the apparatus.

In this case, the detection element 2/ reads the microfilm-〇 projected light image pattern when the mirror system B is reversed from the home position A to the exposure start position B, and detects the amount of light in the image area and non-image area. Detect. The detected light intensity contrast is then converted into an electrical signal and output. Next, this electric signal is amplified by amplifiers 2, 2, and the CPU,
23.

Here, calculations are performed according to a predetermined function, which will be described in detail later, and the voltage source 2A and the bias generation source 27 are controlled based on the results, and the exposure amount of the lamp 3 and the developing unit/g are controlled.
Set the developing bias for each. Furthermore, depending on the projection magnification, that is, depending on the difference between the projection lenses 5a and S2, or depending on the operator's preference, the volume, 2
By adjusting g, the developing bias can be set within a range that will be described in detail later.

Next, the functions used in the actor 1 of the CPU 23 mentioned above will be explained. This function is determined by a characteristic curve showing the relationship between the exposure amount and the developing bias in order to obtain an appropriate image for original films having different transmitted light amount contrasts in image areas and non-image areas. Therefore, we experimentally found the optimal values for the exposure amount and developing bias for three types of originals with different accuracy, that is, for each output voltage difference of the detection element that detects the image area and non-image area of the original. It is shown in Table 1 below. Based on Table 7, the vertical axis is the output voltage difference of the detection element corresponding to the density of the original film, and the horizontal axis is the developing bias and exposure amount. The resulting characteristic curve is shown in Figure 2. show.

According to the Ω diagram, the exposure amount and development bias are approximately:
It can be seen that it is a function of the voltage difference obtained at the detection element 2/. In other words, a proportional relationship is established between the developing bias and the output voltage difference of the detection element 2/, and a logarithmic relationship is established between the exposure amount and the output voltage difference of the detection element 2/. The relationship can generally be approximately expressed by the following equation.

V(B)-βx (V(Ll-V(Dl)10gE=
KX (V(L)-V(DJ) +α where E: exposure amount, V(B): development bias, V(L), V(O):
The output voltage of the image area and non-image area obtained from the detection element, β
: constant for determining the developing bias, K, α: constant for determining the exposure amount.

Therefore, by substituting the values in Table 1 into the above two equations, the values of each constant are calculated as follows.

β=2gθ, =/g/, α=-/3 By substituting these values into the above two equations, the exposure 1 (E) and the developing bias (V (B)) can be calculated as follows. It can be determined as a function of the output voltage difference (VCLL-(DI)) of the detection element.

V(B)-2g Ox (V(L)-V(D))1o
gE-/g/1VL)-v(D))-1'1 Therefore, C
In the PU, by performing calculations according to these functions based on the density information of the original film, it is possible to determine appropriate exposure amount and development bias setting values and obtain an appropriate image.

Next, the setting of the developing bias when the projection magnification is changed by changing the lens will be explained. FIG. 3 shows characteristic curves A, B, and C suitable for three types of lenses having different lens magnifications, which will be described in detail below.

, in FIG. 3, a, -a3. b, -b3. C
, ~C, C, each shows three types of lenses with different magnifications, and the numbers attached to the bottom right of each Alphabella) a, b, and c indicate the case of three types of original film with different densities. , the range where an appropriate image can be obtained when using these lenses and original film, respectively.
It was expressed as 3.b1-3.C1-3. As is clear here, even if the same type of original film with the same density is used, if the lens magnification is different, for example a,
,b, ,c, the range in which an appropriate image can be obtained varies greatly. Therefore, for example, using lens a, the characteristic curve A is changed to al, C2 as shown in FIG.
If the developing bias and exposure amount are set within the range of b1, b2, . c, and an appropriate image cannot be obtained. That is, depending on the combination of lens magnification and document, an appropriate image may not be obtained and the purpose of providing the characteristic curve may be lost.

Therefore, in this embodiment, the appropriate image range is set to C1 to C3 as shown in FIG. 3, depending on each lens. b1~3°C,~3
For example, set characteristic curve A for a, ~3, characteristic curve B for b1~3, and characteristic curve C for C1~3. .

Here, as a variable setting means for the characteristic curve, the characteristic curve A is set as shown in FIG. 2 (Actually, the CPU stores it as the function described above). By increasing or decreasing only the developing bias at the indicated volume of 2 g, characteristic curve B or C can be easily obtained by translating characteristic curve A in the vertical axis direction.

Furthermore, instead of increasing or decreasing the developing bias, the characteristic curve may be moved in parallel in the horizontal axis direction by increasing or decreasing the exposure amount. However, in practice, the developing bias has a wider variable range and can be controlled more favorably.

Each of the characteristic curves A, B, and C is expressed as a function in CPUK 1. as described above. It is also possible to control both the exposure amount and the current bias according to each lens.

Furthermore, a display device is provided to inform whether or not the characteristic curve is within the appropriate range for each lens. The practical case becomes l'=:5'.

Furthermore, in the above embodiments, a copying apparatus for microfilm has been described, but the present invention is not limited thereto. This has the problem that the range of projection magnification is wider than that of general copying machines, and therefore the image density is likely to be affected by this. It goes without saying that it can produce great effects even when used for equipment.

As explained below, the present invention provides a means for variably controlling the image forming conditions such as the developing bias or the exposure lamp in accordance with changes in lens magnification, thereby providing appropriate control according to each lens magnification and document density. An image can be obtained, and if the variable control means is manually operated, the image density can be adjusted according to the operator's preference.
It is highly practical and has excellent effects.

[Brief explanation of drawings]

FIG. 7 is a schematic diagram showing an embodiment of the present invention, FIG. 2 is a characteristic curve diagram showing the relationship between the developing bias and the exposure amount for obtaining an appropriate image with respect to the output voltage difference of the detection element, and FIG. The figure is a characteristic curve diagram showing the relationship between the developing bias and the exposure amount for an appropriate image of 443 images using three types of lenses with different magnifications. Lamp. Da... focus lamp, 5a, Shio b... throw) 16 lenses. Ro... Mirror type, 2g... Mirror. /3... slit means, 15 - wide charger. /Otsu...Secondary static eliminator, /7 ・Lamp. 7g ・Developer, /9 For transfer:;)'Heavy equipment. , 2/... Element under test, , 2.2 ・Amplifier (AMP
). 23 ・CPU, , 25 Cleaner. Suot... Voltage source, , 27 Bias source. 2g...Volume, 30 Variable cultivation means. 3/...Static eliminator.

Claims (1)

[Claims] The apparatus for forming an image with an optimized image density by detecting the original density is characterized by having means for variably controlling at least one of the image forming conditions in accordance with changes in projection magnification. Image forming device.