Claims
- 1. A process of forming images on a printing form comprising a first layer of ferroelectric material having a threshold frequency for triggering the photoelectric effect comprising the steps of:
- positioning said first layer between a first electrode covering an entire side surface of the first layer and a light-transparent image forming electrode arranged on at least a portion of an opposite side surface of the first layer;
- applying an electric field between the electrodes that is of a magnitude less than a coercive field strength of the non-irradiated first layer;
- irradiating a portion of the first layer from the opposite side surface through the light-transparent electrode with light radiation of a frequency above the threshold frequency for initiating the photoelectric effect in the first layer, which generates charge carriers from the first layer;
- polarizing the printing form in accordance with the image to be formed with the charge carriers generated by the photoelectric effect; and
- removing the light-transparent electrode from the opposite side surface of the first layer whereby the first layer is now ready for printing.
- 2. The process of claim 1, wherein said step of polarizing includes a second step of irradiating the first layer in accordance with the image to be formed.
- 3. The process of claim 1, wherein the step of irradiating also irradiates a charge generator layer positioned on a side of the first layer opposite a source of the radiation.
- 4. The process of claim 1, further comprising a further step of irradiating said first layer with electromagnetic radiation having a frequency below the threshold frequency of said first layer; and
- increasing the temperature of the first layer upon irradiation of the first layer with the electromagnetic radiation.
- 5. The process of claim 1, wherein said step of irradiating irradiates light imagewise through said second electrode and on said first layer at the same time said electric field is applied.
- 6. The process of claim 1, wherein the light-transparent image forming electrode is a dielectric platelet including charge carriers, said step of irradiating irradiates light imagewise through said dielectric platelet and on said first layer at the same time the electric field is applied.
- 7. The process of claim 6, further comprising the step of applying said charge carriers to said dielectric platelet prior to positioning on said first layer by corona discharge.
- 8. The process of claim 1, wherein the light-transparent image forming electrode is a dielectric platelet including charge carriers, and further comprising the step of arranging an additional ferroelectric layer between the first layer and the first electrode, a magnitude of a coercive field of the additional ferroelectric being greater than a coercive field of the first layer,
- applying the electric field between said dielectric platelet and said first electrode, and wherein said step of irradiating includes the steps of:
- irradiating said dielectric platelet, first layer and additional ferroelectric layer with light above a threshold frequency of said additional ferroelectric layer; and
- generating free charge carriers in said ferroelectric layer causing said additional ferroelectric layer to become conductive, the applied electric field having a magnitude less than the coercive field strength of the first layer when not irradiated and greater than the coercive field strength of the additional ferroelectric layer to polarize said first layer when the additional ferroelectric layer becomes conductive.
- 9. The process of claim 8, further comprising the step of applying said charge carriers to said dielectric platelet prior to positioning on said first layer by corona discharge.
- 10. The process of claim 1, wherein the light-transparent image forming electrode is at least one dielectric platelet including charge carriers, and applying the electric field between said first electrode and said at least one dielectric platelet to generate an electric field in said first layer of a magnitude below a coercive field of the first layer, wherein said step of irradiating irradiates the surface of the first layer causing said electric field to exceed the magnitude of said coercive field and polarize said first layer in accordance with said image to be printed.
- 11. The process of claim 10, further comprising the step of applying said charge carriers to said dielectric platelet prior to positioning on said first layer by corona discharge.
- 12. The process of claim 1, wherein the light-transparent image forming electrode is a dielectric platelet including charge carriers and further comprising the step of further irradiating said first layer at the surface from which said electrode was removed with a light having a frequency above the threshold of said first layer to depolarize the first layer in accordance with said image to be printed producing a negative image.
- 13. The process of claim 12, further comprising the step of applying said charge carriers to said dielectric platelet prior to positioning on said first layer by corona discharge.
Priority Claims (1)
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44 34 766 |
Sep 1994 |
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Parent Case Info
This is a continuation of application Ser. No. 08/533,767, filed Sep. 26, 1995, abandoned.
US Referenced Citations (5)
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Continuations (1)
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533767 |
Sep 1995 |
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