JPH0348596Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a recording apparatus that is used as a liquid crystal shutter and performs recording by irradiating a photoreceptor with a light image corresponding to an image to be recorded.

[Prior art]

Conventionally, this type of device uses a liquid crystal shutter in which a large number of microshutters are arranged in the main scanning direction of a photoreceptor, and each microshutter is controlled to open and close in accordance with a recording signal. It is configured to form an electrostatic latent image of an original on a photoreceptor by modulating light from a light source. As a means of visualizing this electrostatic latent image, a reversal development method is used in which toner is attached to the low potential portion of the electrostatic latent image (in this specification, the level of potential indicates a comparison of absolute values). A vessel is used.

However, in such a recording device, since the entire surface of the photoreceptor is charged and exposed to light by a light source, toner also adheres to non-image forming areas where there is no transfer paper before and after the image forming area. hand,
A problem arises in that toner is wasted. Therefore, as a means to solve this problem,
There is a method in which the light source of the liquid crystal shutter is turned off when it leaves the image forming area of the photoreceptor to maintain a high charging potential on the surface of the photoreceptor. A method has been proposed in which the charged potential on the surface of the photoreceptor is maintained at a high level by keeping the microshutter in the closed state.

However, when optical writing is performed on a photoreceptor using a liquid crystal shutter, light leaks even when the microshutter is closed, making it difficult to completely block light from the light source. That is, as shown in FIG. 5, when the photoreceptor is charged to the initial potential Vo, when the liquid crystal shutter is opened and closed using a control signal according to the recorded information to perform optical writing, when the liquid crystal shutter is opened, it is fully charged. Optical attenuation takes place V _L
The potential drops to . On the other hand, when the liquid crystal shutter is closed, light is attenuated to V _D due to leakage light. Therefore, as shown in FIG. 4, when reversing and developing an electrostatic latent image, by applying a developing bias voltage V _B that is equal to or slightly lower than V _D to the developing device,
A method is adopted in which toner is attached to the _VL portion to form a visible image.

[Problems with conventional technology]

However, in the former method described above, when the light source is turned off, no light hits the photoreceptor at all, so the surface potential of the photoreceptor is maintained at the initial potential Vo, which is lower than the developing bias voltage V _B. The potential becomes quite high. Therefore, when the developing device is of a two-component developing type, a so-called carrier pull phenomenon occurs in the region of the above-mentioned initial potential Vo. Further, in the case of the one-component development method, as is clear from the development characteristics shown in FIG. 4, toner adheres to the region of the initial potential Vo.

In addition, in the latter method, by keeping the liquid crystal shutter closed and keeping the light source on, the potential of the non-image forming area is set to V _D and it is possible to prevent the adhesion of toner and carrier. For example, when a halogen lamp that generates a large amount of heat is used, a problem arises in that the temperature inside the device increases, and the life of the halogen lamp itself is shortened due to continuous lighting.

[Purpose of invention]

In view of the above-mentioned conventional drawbacks, the present invention prevents toner or carrier from adhering to the non-image forming area of the photoconductor, and also prevents the temperature inside the device from rising even when a lamp with a large amount of heat, such as a halogen lamp, is used as a light source. An object of the present invention is to provide a recording device that makes it possible to reduce the shortening of lamp life.

[Summary of the idea]

In order to achieve the above object, the present invention includes a photoreceptor, a charging means for charging the photoreceptor, and a system that modulates and irradiates the photoreceptor with light from a light source by optically opening and closing a liquid crystal shutter. In the recording apparatus, the light source includes an optical recording means for forming an electrostatic latent image on a photoreceptor, and a developing means for developing the electrostatic latent image by attaching toner to a low potential portion of the electrostatic latent image. The area is illuminated with a low light intensity that is approximately equal to the leakage light intensity when the liquid crystal shutter is closed in the image forming area, and after a period of time has elapsed during which the light intensity is stabilized when the light source is turned on at a low light intensity, the liquid crystal shutter is turned on. It is characterized by being set in an open state.

[Example of idea]

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 is a schematic configuration diagram of the recording apparatus of the present invention, and FIG. 3 is a perspective view showing the configuration of a light source section used in the recording apparatus of the present invention. As shown in FIG. 2, a recording device using a liquid crystal shutter charges the surface of a photosensitive drum 1 with a charger 2, and performs optical writing using a print head 5 containing a liquid crystal shutter 3, an imaging lens array 4, etc. It will be done.

The liquid crystal shutter 3 is composed of a large number of microshutters arranged parallel to the main scanning direction (rotation axis direction) of the photosensitive drum, and each microshutter is selectively opened and closed according to print data. Then, by selectively transmitting light from a light source 6 disposed above the liquid crystal shutter 3 to each microshutter, an electrostatic latent image is formed on the photosensitive drum 1 in accordance with print data. This latent image is developed by a developing device 7, and a toner image is formed on the photosensitive drum 1.

The toner used in the developing device 7 is a toner having the same polarity as the charging polarity of the charger 2, and the developing sleeve 7a is supplied with a bias voltage having the same polarity as the above-mentioned polarity from a bias power source 7b. Therefore, the developing device 7 is a developing device of a so-called reversal development type in which toner is attached to the low potential portion of the electrostatic latent image.

The formed toner image is transferred by a transfer device 8 onto paper 9 that is sequentially fed at predetermined intervals from a paper feed section (not shown). Furthermore, the toner remaining on the photosensitive drum 1 is removed from the surface of the photosensitive drum 1 by the cleaner 10.

In the recording apparatus having the above configuration, the light source 6 is composed of a light transmission rod 12, a light source lamp 13, etc., as shown in FIG. Optical transmission rod 12
is a roughly cylindrical rod-shaped member made of a transparent material with a high refractive index such as quartz glass or methacrylic resin. Reflective material 12
A is painted. The light emitted by the light source lamp 13, which is a bean-shaped halogen lamp, enters the light transmission rod 12 from the entrance surface 12b, which is one end surface of the light transmission rod 12, and repeats internal reflection until the light is provided at the other end surface. The light propagates toward the reflecting mirror 12c. During its propagation, the light incident on the diffuse reflection material 12a is diffusely reflected, and a part of the diffusely reflected light is emitted from the peripheral surface of the light transmission rod 12 and illuminates the liquid crystal shutter 3.

The light source 6 having such a configuration has a relatively uniform light amount in its longitudinal direction, and a bulb-shaped halogen lamp that has a large light amount and is inexpensive can be used as the light source lamp 13.

In the recording apparatus of the present invention, the light source lamp 13 is controlled in three states. The first state is a lighting state for the image forming area of the photoreceptor during actual printing, and is hereinafter referred to as full lighting. The second state is a lighting state with a lower light intensity than full lighting, and is hereinafter referred to as half lighting. The amount of light during half-lighting is set such that the amount of light leaking from the microshutter in the closed state when fully lit is approximately equal to the amount of light transmitted through the microshutter in the open state during half-lighting. This half-lighting is a lighting state for the area corresponding to the space between the sheets of the photoreceptor during continuous printing, that is, the non-image forming area which is the area between the above-mentioned image forming areas.

The third state is a state in which the light source lamp 13 is turned off, and is a standby state in which no printing is performed.

The above-mentioned control of full lighting and half lighting is performed using light source lamp 1.
It may be controlled by the energizing voltage of 3 or by the energizing rate.

Next, the timing of controlling the light source lamp 13 described above will be explained.

FIG. 1 is a timing chart showing the lighting state of the light source lamp 13 and the opening/closing of the micro shutter. , (c) shows the drive of the micro-shutter, (d) shows the light transmittance of the micro-shutter, (e) shows the amount of light emitted from the micro-shutter, and (f) shows the surface potential of the photoreceptor. ing.

The period up to t ₁ is the period during which printing is actually performed in the image forming area corresponding to the first sheet of paper. Therefore, the light source lamp 13 is fully lit, and the micro shutter opens and closes according to the print data. The photoreceptor is driven, and an electrostatic latent image is formed on the surface of the photoreceptor according to print data. At _t1 , when printing is completed, the microshutter is turned off, that is, driven to close. At _t2 , a predetermined period after _t1 , the light source lamp 13 is switched from fully lit to half-lit as described above, but the amount of light emitted from the light source lamp 13 does not immediately decrease due to thermal inertia. (In the figure, the above-mentioned set light amount is expressed as K%.) At a predetermined timing _t3 after the light source lamp 13 is switched to a half-lit state and the emitted light amount of the light source lamp 13 does not decrease to K%. , switch all micro shutters from closed drive to open drive.

Through the above operations, the amount of light emitted from the microshutter is maintained at approximately K%, although there are slight fluctuations. Furthermore, since the microshutter is switched to open drive after a predetermined period of delay after the light source lamp 13 is switched, the amount of afterglow irradiated onto the photosensitive drum 1 due to thermal inertia immediately after the light source lamp 13 is switched is extremely small. The fluctuations mentioned above are very slight.
Therefore, the potential on the photosensitive drum 1 also maintains approximately V _D ,
The fluctuation in potential due to the above-mentioned fluctuation in the amount of emitted light is also slight, and carriers do not occur and toner does not adhere.

Furthermore, prior to _t5 , which is the timing to actually start printing in the image forming area corresponding to the second sheet of paper, at a predetermined timing _t4 , the light source lamp 13 is switched from half-lit to fully lit, and
Switch all micro shutters to open drive.
At this time, since the response speed of the microshutter is faster than the rise of the light emitted from the light source lamp 13, there is no particular need to delay switching to full lighting of the light source lamp 13.

Note that the above embodiments concerned the non-image forming area between the area corresponding to the first sheet and the area corresponding to the second sheet, but the non-image forming area following the area corresponding to the final sheet It is clear that the image forming area can also be controlled in the same way.

[Effects of the invention] According to the recording device of the invention, the light source is turned on at a low light intensity for the non-image forming area, and the liquid crystal shutter is set to the open state after a predetermined period of delay from the lighting. No carrier drag or toner adhesion occurs in non-image forming areas.

Furthermore, since the light source is energized at a low voltage or a low energization rate to the non-image forming area, it is possible to prevent the temperature of the device from rising and to extend the life of the light source.

[Brief explanation of drawings]

Fig. 1 is a timing chart showing the lighting state of the light source lamp and the opening/closing of the micro shutter used in the recording device of the present invention, Fig. 2 is a schematic configuration diagram of the recording device of the present invention, and Fig. 3 is a FIG. 4 is a perspective view of the light source used in the recording apparatus of the present invention, and FIG. 5 is a graph showing the relationship between the potential Vs of the photoreceptor and the image density D.
The figure is a graph showing the relationship between the amount of received light E and the potential Vs of the photoreceptor. 1... Photosensitive drum, 2... Charger, 3... Liquid crystal shutter, 4... Imaging lens array, 5... Print head, 6
...Light source, 7...Developing device, 7a...Developing sleeve, 7b
...bias power supply, 12...optical transmission rod, 13...light source lamp.

Claims (1)

[Scope of utility model registration request] a photoreceptor; a charging means for charging the photoreceptor;
an optical recording means for forming an electrostatic latent image by modulating and irradiating the photoreceptor with light from a light source by optical opening and closing of a liquid crystal shutter; and toner for adhering to a low potential portion of the electrostatic latent image. In the recording apparatus, the light source is turned on with a low light intensity that is almost equal to the light leakage amount when the liquid crystal shutter is closed in the image forming area in the non-image forming area of the photoreceptor. At the same time, the recording apparatus is characterized in that the liquid crystal shutter is set to an open state after a time period has elapsed during which the light amount is stabilized when the light source is turned on at a low light amount.