34results about How to "Realize printing" patented technology

A nozzle embedded type 3D printing device for a thermosetting wood-plastic composite material belongs to the technical field of 3D printing, and comprises a rack, and an extrusion movement mechanism, a powder laying mechanism, a powder bed mechanism, a printing platform movement mechanism and a binder feeding system which are arranged on the rack, and the extrusion movement mechanism is fed through the feeding system. The printing efficiency of existing printing equipment can be improved, the manufacturing and maintenance cost of the existing equipment is reduced, the accuracy and consistency of a printing structure are ensured, and printing of a high-precision complex structure is achieved; the provided equipment combines the advantages of extrusion type printing equipment and a powder bed structure, the requirement of single extrusion printing for the formability of extruded materials is met, controllable printing of large-flow, high-viscosity and large-layer-thickness printing shapes and precision is achieved, the equipment is suitable for various types of binder materials, the variety and size range of powder bed materials is large, and the equipment is suitable for large-flow, high-viscosity and large-layer-thickness printing. And the rapid part forming machining requirements of wide material application range, large forming size and high part strength are met.

The utility model relates to a rapid imaging camera, and belongs to the technical field of photography and camera shooting equipment. The 3D printer comprises a printer body, at least two printing heads and at least two paper storage bins, the printer body comprises a lens and an optical imaging module, the lens is used for collecting optical images and transmitting the optical images to the optical imaging module, and a first mounting cavity and a second mounting cavity are formed in the printer body; the printing head is detachably connected with the printing cavity, and the printing head is electrically connected with the optical imaging module, so that the printing head can receive an image signal transmitted by the optical imaging module and print an image; each paper storage bin can be arranged in the corresponding second mounting cavity; each paper storage bin is provided with a containing chamber for containing and limiting printing paper, and the sizes of the printing paper contained in the containing chambers of different paper storage bins are different; printing paper in the paper storage bin passes through the printing head and then is output out of the machine body; therefore, the rapid imaging camera can print different types of photos, and the application range of the camera is expanded.

The utility model relates to a rapid imaging camera, which belongs to the technical field of photographic equipment and comprises a camera body, more than one printing head and a separation blade connected in the camera body in a sliding manner. The machine body comprises a lens and an optical imaging module, and the lens is used for collecting optical images and transmitting the optical images to the optical imaging module; a printing cavity and a paper storage bin used for storing printing paper are arranged in the machine body. The printing head can be selectively installed in the printing cavity, the printing head is detachably connected with the printing cavity, and the printing head is in signal connection with the optical imaging module so that a corresponding image can be printed on printing paper. The blocking piece is movably connected into the paper storage bin and used for limiting the printing paper in the paper storage bin. The blocking piece can move in the axis direction of the paper storage bin, so that the blocking piece can abut against and be fixed to the end faces of the printing paper of different sizes, the printing paper of different sizes is fixed in the paper storage bin, and printing of photos of different sizes is achieved.

The invention relates to the technical field of 3D printing, and provides a leveling device of 3D printing equipment and the 3D printing device.The leveling device of the 3D printing equipment comprises a printing platform and a moving platform and further comprises four screw rods, a distance sensor, a temperature regulation and control mechanism, a blowing mechanism and a collecting box, the screw rods are in threaded connection with the moving platform, and the distance sensor is arranged on the moving platform; the distance sensor is arranged on the printing head and used for measuring the distance between the printing head and the printing platform, the temperature regulation and control mechanism is used for regulating and controlling the temperature of the printing platform, the temperature change of the printing platform during printing is reduced, and the purging mechanism purges the surface of the printing platform through airflow generated by the temperature regulation and control mechanism. The collecting box is arranged on the moving platform and located on the side, away from the blowing box, of the printing platform, and through the technical scheme, the problems that in the prior art, temperature and impurities affect leveling, and the printing accuracy is reduced are solved.

The invention discloses an epoxy modified room-temperature self-crosslinking water-based acrylate dispersion as well as a preparation method and application thereof, and belongs to the field of water-based acrylic resin. The dispersoid is obtained by extracting an organic solvent from an acrylate polymer, adjusting the pH value to 7.5-8.5, mixing with ionized water and binary hydrazide, dispersing and filtering. The acrylate polymer is obtained by carrying out solution polymerization on a mixed solution of a part of initiator, a hard monomer, a soft monomer, a first type of hydrophilic monomer, a second type of hydrophilic monomer, epoxy resin and a combined cross-linking monomer and a residual initiator dissolved in an organic solvent at 80-83 DEG C, wherein the mixed solution is prepared from the initiator, the hard monomer, the soft monomer, the first type of hydrophilic monomer, the second type of hydrophilic monomer, epoxy resin and the combined cross-linking monomer. The main solvent of the dispersion is water, the viscosity is low, and the content of the organic solvent is 1t; the water-based ink has the advantages of low content of VOCs (volatile organic compounds), multiple cross-linked network structure, high cross-linking degree (78-83%), excellent resolubility after being prepared into ink, good adhesive force on a plastic film, good water resistance, good storage stability and high glossiness.

The invention discloses 3D printing biological material ink based on a drug sustained-release polycitrate material and a preparation method and a printing method of the 3D printing biological material ink, and relates to the technical field of 3D printing biologication.The 3D printing biological material ink is prepared from a medical polycitrate polymer, nano-hydroxyapatite and an active drug ingredient; the addition amount of the hydroxyapatite is 5-65% of the total mass of the obtained biological material ink; the active pharmaceutical ingredients are gastrodin, notoginsenoside, recombinant wnt3a protein and LL-37 peptide; when the active medicines are gastrodin and notoginsenoside, the addition amount of the active medicines is 4-12% of the total mass of the obtained biological material ink; when the used active drugs are recombinant wnt3a protein and LL-37 peptide, the addition amount of the active drugs is 0.001-0.002% of the total mass of the obtained biological material ink; and the particle size of the nano hydroxyapatite is 60-80 nm. According to the method, 3D printing process parameters are selected, post-treatment is adopted to adjust a cross-linked network structure of a poly-citrate polymer, biological material scaffolds with different mechanical properties and degradation properties are obtained, and stable and long-acting release of carried drugs is ensured.

The utility model discloses 3D printing equipment which comprises a forming chamber used for providing a closed forming space for 3D printing operation. The printing platform is rotatably arranged in the forming chamber and used for bearing a formed 3D object; the first robot is arranged on the first side of the printing platform and comprises a first mechanical arm which moves on the upper side of the printing platform according to a first movement path; the first printing assembly is arranged on the first mechanical arm and is used for melting powder or granules and then depositing the melted powder or granules onto the printing platform according to a first printing path so as to form the 3D object layer by layer; the second robot is arranged on the second side of the printing platform, forms a first preset angle with the first robot, and comprises a second mechanical arm which moves on the upper side of the printing platform according to a second movement path; and the cutting assembly is arranged on the second mechanical arm and is used for carrying out material reduction treatment on the 3D object deposited on the printing platform according to a material reduction path.

A printing device is used for printing ink and comprises a guide rail, a driving assembly and a roller assembly. The guide rail is arranged along a first direction; one end of the driving assembly is connected with the guide rail and can move in the first direction. The roller assembly comprises an air bag, a gauze and a sleeve. The axial direction of the air bag is a second direction, and the second direction is perpendicular to the first direction; the gauze sleeves the air bag, the gauze and the air bag are arranged at intervals to form an ink bin, the ink bin is rotationally connected with the air bag, and the ink bin is used for containing ink; the sleeve sleeves the surface of the gauze, an opening is formed in the sleeve, and the other end of the driving assembly is relatively fixed with the air bag; when the driving assembly drives the roller assembly to move in the first direction, the sleeve and the gauze rotate with the second direction as a rotating shaft, the size of the air bag can be changed, and the air bag is used for squeezing the ink and enabling the ink to penetrate through the gauze and the opening so as to print the ink.

The invention relates to a method for assisting 3D printing based on a solid support bath and a product. The method comprises the following steps: preparing silicone elastomer ink; filling the silicone elastomer ink into a printing needle cylinder, and printing in a container containing a solid matrix with a certain particle size or repose angle according to a set printing requirement; after printing is completed, the whole container is heated for a certain time; and taking out the semi-cured printing piece, and continuously heating to obtain a completely-cured printing component. According to the method, the selection range of printing ink is expanded, printing can be conducted in solid particles or matrixes with different particle sizes or repose angles, and by adjusting printing parameters, a complex three-dimensional structure can be obtained through printing by adopting simple printing equipment only under the supporting effect of the solid particle matrixes; and a printing component can be obtained through simple post-treatment.

A limiting shell is arranged between a template mounting plate and side supporting plates of the light guide plate screen printing machine, the inner wall of the limiting shell is connected with the lower ends of the side supporting plates through a plurality of springs, and a plurality of inserting holes are formed in the two side supporting plates correspondingly; inserting pins correspondingly matched with the inserting holes are fixed to the top ends of the two side supports correspondingly, a second sliding rail is arranged below the formwork mounting plate, sliding strips are slidably connected to the two opposite inner walls of the second sliding rail correspondingly, and a placement bottom frame is fixedly connected between the two sliding strips. A barrier strip is arranged in the middle of the placement bottom frame and perpendicular to the length direction of the placement bottom frame, and a first mounting plate with a first sinking groove and a second mounting plate with a second sinking groove are arranged on the front side and the rear side of the barrier strip respectively. According to the invention, the dismounting space of the template is enlarged, the template is convenient to dismount and mount by personnel, and the dismounting and mounting time of the light guide plate and the template is greatly saved, so that the overall production efficiency is improved.

The invention discloses a continuous printing, oil supplying and stamping device and a continuous printing, oil supplying and stamping method.The continuous printing, oil supplying and stamping device comprises a printing mechanism, a guiding mechanism, a stamping mechanism and an oil supplying mechanism, the guiding mechanism is arranged above a paper inlet of the printing mechanism, and the stamping mechanism is arranged on one side of the printing mechanism; the printing mechanism is arranged on the side portion of the stamping mechanism, the oil supply mechanism is arranged on the side portion of the stamping mechanism, the printing mechanism is used for printing certificates, the guiding mechanism is used for guiding paper to enter the printing mechanism, the stamping mechanism is used for stamping the certificates printed by the printing mechanism, and the oil supply mechanism is used for providing ink for the stamping mechanism. The automatic stamping machine has the advantages that the automatic oil supply mechanism is arranged, and the active oil supply mechanism is used for automatically supplying ink to the stamping mechanism, so that the stamping mechanism can supplement ink in time after stamping a file, the continuity of stamping is guaranteed, and the working efficiency is effectively improved.

This invention discloses a method for printing documents under the ReWorks real-time operating system, relating to the field of document printing technology. The method includes: creating a file conversion task for the document to be printed, setting the initial execution priority of the file conversion task; attaching a scheduling event callback function, executing a dynamic priority scheduling strategy to update the execution priority of the file conversion task, and outputting the updated execution priority; calling the Qt support library to convert the document to be printed into a PostScript format file; sending the PostScript format file to the printer through a pre-configured first communication interface; and the printer receiving and parsing the file through a second communication interface and executing document printing. This invention solves the technical problem of difficulty in directly printing documents under the ReWorks real-time operating system in existing technologies, achieving the technical effect of document printing under the ReWorks real-time operating system.

The utility model discloses an achievement conversion information acquisition system, and relates to the technical field of information service. The storage device comprises the main body and the storage mechanism, the storage mechanism comprises the fixing plate, the storage mechanism is arranged, the sliding blocks are clamped in the sliding grooves in a sliding mode, and the storage bag is fixedly connected between every two sliding blocks, so that an operator can select different storage bags for classified storage according to different achievements; the information management efficiency and accuracy are improved, the sliding blocks can slide in the sliding grooves, the positions and the intervals of the storage bags can be flexibly adjusted according to actual needs, when more information needs to be stored, the intervals of the adjacent storage bags can be properly increased so as to contain more data, when the information is less, the intervals can be reduced, the applicability and the use experience are improved, and the practicability is high. Operators do not need to switch among multiple devices, the working efficiency is improved, and the printer on the inner side of the printing opening in the outer surface of the main body can print information in the system in a paper form.

The utility model relates to the technical field of strapping, in particular to strapping equipment with a needle type printing function, which comprises a casing, a tape reel and a printing component are mounted in the casing, a strapping tape is wound on the tape reel, and one end of the strapping tape is led out of the tape reel and penetrates through the printing component. Wherein the printing assembly comprises a guide plate, a needle type printing head, a colored tape box and a colored tape driving assembly, the guide plate is provided with an inner cavity penetrating through the guide plate so that the binding tape can penetrate through, the guide plate is provided with a first opening and a second opening which penetrate through the two side walls in the thickness direction of the guide plate and are oppositely arranged, and a guide wheel abutting against the binding tape is installed at the first opening. A colored tape is stored in the colored tape box, part of the colored tape is led out of the colored tape box and located at the second opening, the colored tape located outside the colored tape box is attached to the binding tape at the second opening, the colored tape located at the second opening is located between the needle type printing head and the binding tape, and the colored tape driving assembly can drive the colored tape and the binding tape to synchronously move at the second opening.

This invention relates to the field of FDM printing, and in particular to a modular, multifunctional FDM printhead for space additive manufacturing. It includes a coaxial extrusion component, a heat dissipation component, and a printhead switching component. One end of the printhead switching component is fixedly connected to the end of a motion mechanism, and the other end is fixedly connected to the heat dissipation component. The coaxial extrusion component is fixed to the heat dissipation component. The coaxial extrusion component includes a heating block, an outer nozzle, and an inner nozzle. An inner nozzle connecting pipe is located at the center of the upper end of the heating block, and the inner nozzle is fixed to the lower end of the inner nozzle connecting pipe. The outer nozzle is coaxially sleeved around the inner nozzle and fixedly connected to the lower end of the heating block. An inner throat communicating with the outer nozzle is located at an eccentric position on the upper end of the heating block. The outer nozzle has a large downward-pointing conical shape, and the inner nozzle has a slender needle-like structure. The lower ends of the outer and inner nozzles are flush. This invention enables recessed structure printing, modular switching, and prevents backflow of composite materials.

The utility model relates to the technical field of printing equipment, in particular to metal reel plate printing equipment convenient to replace. In order to solve the problems that a plurality of roller sets of common metal reel plate printing equipment need to be disassembled together with a transmission structure during disassembly, the disassembly and subsequent assembly difficulty is increased, the operation efficiency is reduced, and the subsequent printing operation is influenced, the following technical scheme is provided: the device comprises a rack, a motor, a motor base, an ink fountain, a hot air blower, a material storage roller, a preheating roller, an auxiliary roller, a printing roller and a material rolling roller are arranged in the machine frame, and positioning pieces are symmetrically installed on the wall bodies of the two sides of the material storage roller, the preheating roller, the auxiliary roller, the printing roller and the material rolling roller. According to the utility model, the storage roller, the preheating roller, the auxiliary roller, the printing roller and the winding roller are influenced by a driving and transmission structure in the disassembly and assembly process, the disassembly and assembly difficulty is reduced, and the operation is simple and easy.

The invention relates to printing equipment and method, and the printing equipment comprises a printing mold, a printing cloth structure and a curing structure; the printing mold is arranged between the printing cloth structure and the curing structure; and the curing structure corresponds to the printing mold. According to the printing equipment, through the curing structure installed on one side of the printing mold, curing is achieved while bottom color printing is conducted, stations do not need to be additionally added for bottom color printing and curing, existing equipment can be conveniently transformed, and the printing equipment is compatible with more kinds of printing modes.

The application provides a three-dimensional printer and a working method thereof. The three-dimensional printer comprises a machine box, a printing platform, a printing device and a driving device arranged in the machine box. The driving device can drive the printing platform and the printing device to move relatively. The printing device comprises a wire printing module and a particle printing module. The wire printing module and the particle printing module can independently execute a printing task. The wire printing module and the particle printing module can also execute a composite printing task. The particle printing module can realize the extrusion molding of super-soft and elastic particle consumables. The three-dimensional printer and the working method thereof can mold a composite structure part with a hard skeleton and a super-soft and elastic coating layer, and have multiple molding modes.

The present invention provides a printing device, a computer-readable medium, a printing system, and a printing method. The printing device comprises: a receiving unit that receives a second printing job including printing data in which storage destination information indicating a storage destination of a first printing job is encoded from a relay unit, the relay unit receiving the printing job from a user terminal, sending the printing job indicating a limited function that is further limited than the function that can be realized by the printing device as a relay destination to the printing device, and not sending the printing job indicating a function other than the limited function to the printing device; an acquiring unit that acquires the first printing job from the storage destination indicated by the storage destination information; and a printing unit that performs printing based on the first printing job.

The invention belongs to the technical field of droplet jet printing, and relates to a multi-component droplet jet printing system and method. The device comprises a micro-fluidic base shell, a liquid drop generation module, a liquid drop detection module and a liquid drop sorting module, liquid in a plurality of parallel liquid channels is subjected to micro-fluidic mixing treatment through a micro-fluidic mixer, uniform mixed flow is obtained, the uniform mixed flow is treated through a continuous jet type micro-liquid drop generation method, and the liquid drop separation efficiency is improved. The continuous monodisperse liquid drops can be obtained, the continuous monodisperse liquid drops are detected through the liquid drop detection module, the continuous monodisperse liquid drops are processed through the liquid drop sorting module according to the detection result, non-printing target liquid drops can be subjected to directional deflection, and liquid drop sorting is completed. Through micro-fluidic mixing treatment, the component concentration proportion of the monodisperse liquid drops can be regulated and controlled online in real time, sorting and printing are carried out according to needs, and the device is suitable for the fields of pattern printing, electronic circuit printing, functional material screening, gradient biochemical reaction, additive manufacturing, biological manufacturing and the like.

The application discloses an information processing system, method, device, electronic equipment and computer storage medium. In the system, when the connection state between the cloud server and the printing device is in an abnormal state, the cloud server can send a to-be-printed instruction to the terminal device through a first data channel, the terminal device sends the to-be-printed instruction to the printing device, the printing device judges whether printing has been performed for a target order by using a local idempotent cache after receiving the to-be-printed instruction, and then only prints in the case of not printing, and sends the printing completion result information to the terminal device after obtaining the printing completion result information, so that the terminal device sends the printing completion result information to the cloud server through the first data channel. The whole process facilitates normal printing of an order when the connection state between the cloud server and the printing device is in an abnormal state, avoids repeated printing of the order, and improves the order printing efficiency.

This invention belongs to the field of printing, specifically high-resolution image printing technology, and particularly to a technology for achieving high-precision printing output using a low-resolution printhead. This invention splits a high-resolution bitmap into multiple sub-images, printing them in stages. Utilizing the high-precision displacement characteristics of a linear raster motor, and based on the image precision, the printhead moves laterally a very short distance q after each printing cycle before proceeding to the next. After multiple printing cycles, all sub-images are printed, thus achieving high-precision printing. This invention eliminates the need for a high-precision printhead; high-precision image printing can be achieved using a low-precision printhead and the printing method described herein.

The invention provides a transmission mechanism of a printer and a thermal transfer printer, and belongs to the technical field of printing equipment. The transmission mechanism of the printer comprises a driving assembly and two one-way driving shaft assemblies. Each one-way driving shaft assembly comprises a thermal transfer ribbon shaft and a clutch assembly which is in transmission connection with the driving assembly and the thermal transfer ribbon shaft; the driving assembly drives the thermal transfer ribbon shafts to rotate in one direction through the clutch assembly, and the rotation directions of the two thermal transfer ribbon shafts are opposite. When the driving assembly rotates in one direction, one clutch assembly is connected with the corresponding thermal transfer ribbon shaft and drives the thermal transfer ribbon shaft to rotate, and the other clutch assembly is separated from the other thermal transfer ribbon shaft. The one-way driving characteristic ensures that a user can return the thermal transfer ribbon easily through the reversing driving assembly, position adjustment or unused thermal transfer ribbon rewinding is facilitated, waste of the thermal transfer ribbon is avoided, the utilization rate of the thermal transfer ribbon is improved, and flexibility and practicability are enhanced.

The utility model provides a multi-head screen printing mechanism and a screen printing machine with the multi-head screen printing mechanism. The multi-head screen printing assembly comprises a transmission part and a plurality of screen printing structures, and the transmission part is connected with the screen printing structures; and the moving assembly is arranged on the base assembly, and the multi-head screen printing assembly is installed on the moving assembly. According to the technical scheme, the problem that in the prior art, after one Logo is printed, another Logo is printed through rotating glass, and ink is exposed in air for a long time and becomes dry is effectively solved.

The present invention discloses an intelligent writing board system capable of automatically saving blackboard writing. The intelligent writing board capable of realizing blackboard writing display and pressure-resistance conversion is composed of a thick color-coated paint panel, a flexible pressure sensing array and a base support layer. The flexible pressure sensing array is based on piezoresistive resistors. The present invention gives full play to the teaching advantages of electronic courseware and traditional writing boards, and realizes automatic saving, transmission, printing, etc. of blackboard writing content. It saves students' time for taking notes in class, increases students' learning efficiency, and provides new ideas for the writing board teaching mode.

The invention provides a customized printing method and device, equipment and a storage medium. The method comprises the steps that the mapping relation between the actual size of a printing object corresponding to different shooting face images of all printing types and the actual size of a customized area is obtained; obtaining a customized image set of different shooting surfaces of each printing type according to the mapping relation; determining a target printing type according to the shape of the to-be-printed object; selecting a target customized image from the customized image set of the target printing type; and performing customized printing on a to-be-printed object based on the target customized image. The customized image set is obtained according to the mapping relation between the actual size of the printed object in different shooting surface images and the actual size of the customized area, the target printing type is determined according to the shape of the to-be-printed object, and then the target customized image is selected from the customized image set of the target printing type. Therefore, customized printing of the to-be-printed object can be completed, and customized printing requirements of commodities in different shapes can be met.

The invention discloses a method and a system for realizing data storage and automatic label printing. The method comprises the following steps of: obtaining a label template in a label template editor by utilizing each piece of dynamic element data; inputting or importing the dynamic element data and the parameter data corresponding to the dynamic element data in an input interface of the automatic printing system, and preprocessing the dynamic element data and the parameter data; based on a preset data transmission mechanism, the automatic printing system automatically transmits the preprocessed dynamic element data to the label template, and the label template is automatically filled according to the parameter data corresponding to the preprocessed dynamic element data; and automatically generating a printing task according to the filled label template, and sending the printing task to a printer for printing. According to the method, through friendly system input interface design and an efficient data processing mechanism, flexible customization of label templates and automatic filling and printing of data are achieved, the printing efficiency and user experience are improved, flexibility is enhanced, and the error rate is reduced.

This invention relates to the field of thermal sublimation printing technology, specifically to a thermal sublimation ribbon, a re-transfer film, and a transfer method suitable for printing PET ID cards. The ribbon has a base coating layer on one side of the substrate, and a dye layer on the base coating layer; it also includes an adhesion promoting layer; the adhesion promoting layer includes a release layer and an adhesive layer, with the release layer disposed on one side of the substrate and the adhesive layer disposed on the release layer. When this ribbon is used in conjunction with the re-transfer film, the pattern can be printed onto the re-transfer film first through the dye layer, and then the adhesion promoting layer can be printed onto the pattern layer. The release layer ensures complete transfer of the adhesion promoting layer, and the adhesive layer improves the adhesion of the pattern to the PET ID card, increasing the color density and durability of the ID card image.

The utility model belongs to 3D printing technical field discloses a kind of multicolor 3D printing nozzle and 3D printer, the 3D printing nozzle includes;Support, is equipped with extrusion assembly on support, and extrusion assembly includes at least two feed ports, at least two feeding channels, a discharge port and consumable mixing channel, each feed port is connected with one feeding channel, and consumable mixing channel is connected with discharge port;Drive assembly, drive assembly is set on support, and drive assembly includes drive part and feeding part, and drive part and feeding part form transmission cooperation, to carry out conveying to consumable in consumable mixing channel;And nozzle, nozzle is connected with the discharge port of extrusion assembly, and nozzle is used to carry out full-color printing or gradual printing after consumable in consumable mixing channel is fused with color mixing.The utility model effectively improves the printing speed of 3D printer, and realizes wasteless printing.

The invention provides a support-free 3D printing method which comprises the following steps that a three-dimensional model of a to-be-printed piece is divided into a plurality of printing units in the first direction, the first direction is parallel to the height direction of the three-dimensional model of the to-be-printed piece, and each printing unit is divided into a first area part and a second area part in the first direction; the printing units are sequentially printed from bottom to top in the first direction, when the printing units are printed, the first area part is firstly printed, and after the first area part is printed, the second area part is divided into at most two printing layers in the first direction; the lowermost printing layer in the at most two printing layers is subjected to scanning forming at first scanning power, first scanning speed and first scanning interval; wherein the energy density of the lowermost printing layer in each printing unit is set as E1, the energy density of the second area part in each printing unit is set as E2, and 0.25 * E1 < = E2.